JPH09187044A - Dial detector - Google Patents

Abstract

(57) [Abstract] [Problem] Received signal 26 transmitted from telephone line 21
Accurately detect dial pulse signals from. SOLUTION: In a preprocessing unit 5, a first formant of a received signal is attenuated by a high pass filter, an absolute value of the first formant is obtained, the absolute value is shifted to a direct current side, a thinning process is performed, and a low speed sample signal 27 is output. . The voice removing unit 15 obtains the signal 71 after voice removal. The leading digit dial detector 6 removes the mute pulse and abnormal waveform to obtain the leading digit dial 28. The succeeding digit dial detecting section 7 having the voice signal removing function detects the end of the dial pulse signal, and the succeeding digit dial 29 without the influence of the mute pulse.
Get. Therefore, the PB signal 30 is transmitted. Even if the first digit dial is not known, even if the voice signal is superposed, the dial can be accurately detected without being affected by the interfering signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a harmonic component of a pulse type dial signal transmitted through a public telephone line,
The present invention relates to a dial detection device that converts dial information. More specifically, after the telephone line is connected to the destination,
An object of the present invention is to provide a novel dial detecting device capable of surely detecting dial information in a device of a callee when transmitting some information to the callee by operating a dial key of a telephone.

[0002]

2. Description of the Related Art A center device connected to a public telephone line is provided with a voice guidance device and a dial signal receiving device, and when a telephone call arrives from the public telephone line side, voice guidance is provided to prompt input of a member number and a product number. There is a mail order service in which members enter numerical data with dial keys to confirm the product and receive an order. There is also a service similar to this in which a ticket is reserved or financial information is distributed. Further, remote control such as controlling and reproducing the contents stored in the answering machine from a telephone at a remote place, or dial-in for selecting an extension telephone of PBX is widely used.

Numerical data input for performing these controls generally uses dial keys provided in a telephone. This is because inexpensive and general-purpose input can be performed by using a key attached to the telephone as an input means without using a dedicated input means.

P as means for transmitting dial key information
There are B (push button) signal system and pulse system.
The PB signaling method is more convenient for realizing services and the like that use dial key information. This is because information can be reliably transmitted using the frequency band allowed for the telephone line without being affected by the direct current limitation in the relay circuit of the public line. Since the original purpose of dialing is to inform the local subscriber exchange of the destination number, any method is the same as far as this original purpose is concerned. Have joined.

A service using dial key information is difficult to obtain an economic effect without a wide range of members. It is expected that a wide range of members will participate if dial key information can be entered from a pulse-type subscriber line telephone, but the direct current in the circuit of the relay system is cut and the frequency band 300
Since there is a direct current limitation of passing a telephone signal of up to 3.4 kHz, it is not easy to detect a dial pulse that turns on / off direct current, and the range of use of dial key information has to be limited.

The reason why it is not easy to detect the dial pulse waveform having no DC component after passing through the relay system is as follows.

First, the dial pulse waveform has a speed of 1
There is no feature to distinguish from a voice signal and line noise except that the make rate is 30% at 0 pps or 20 pps.

Second, since the dial pulse waveform representing the dial "1" or dial "2" is a single-shot waveform or a waveform close to it, it cannot be detected by a tuning filter or the like characterized by periodicity.

Thirdly, the reception level of the dial pulse waveform transmitted through the telephone line fluctuates greatly from -10 dBm to -40 dBm, but gain control is performed when the received signal is unclear whether it is a voice waveform or a dial pulse waveform. Stable detection is not possible because it cannot be applied.

Fourth, since the rotary dial type telephone performs dial mute (to prevent the dialer's handset from making annoying loud dial tone), the mute start time and end time, that is, Dial ・ Before and after the pulse waveform,
Since a pulse waveform very similar to the pulse waveform is generated, it is easy to make an erroneous detection.

Fifth, the voice signal contains a signal similar to the dial pulse waveform, although it is rare, and may be erroneously recognized as the dial pulse waveform representing the dial "1".

Sixth, since the dial pulse waveform has various waveform shapes depending on the combination of the telephone set, the local subscriber exchange, and the relay system, it is impossible to predetermine the waveform shapes and distinguish the waveforms.

There is a method of learning the waveform as a relatively effective detection method of the dial pulse waveform for solving such various problems. This is a method in which the dial pulse waveform is detected in some way during the initial period of dial reception, the characteristics of the waveform at that time are stored, and thereafter the characteristics are used for recognition. According to this method, many characteristics relating to the waveform, including the waveform amplitude, can be used for recognition, so that the recognition rate can be improved not only for recognition of the dial pulse waveform having periodicity but also for recognition of the dial "1".

However, this method requires a large amount of memory to store the characteristics of the dial pulse waveform, and the more stored content, the more stored information and the information representing the characteristics of the subsequent dial pulse waveform. There is a problem that the amount of processing required for the comparative recognition increases, and the recognition in real time becomes difficult. Further, if the detection of the dial pulse waveform is unsuccessful in the initial period, there is a risk that the subsequent recognition cannot be performed at all.

In Japanese Patent Laid-Open No. 2-231856, in order to reduce this risk, dials "0" and "2" which are long in duration and easy to detect are sampled pulse signal trains as initial learning dial pulse waveforms. Was used as. Since the receiving side knows the numerical value in advance, the waveform information such as the period, the receiving level or the presence of the mute pulse is collected using the time template or the amplitude template.

However, limiting the first dial to a known value on the receiving side imposes a limit on the degree of freedom of the numbering plan for various services and so on. Therefore, improvement is desired. Also, in this type of device, information was passed to the center device on the assumption that the recognition rate was as close as possible to 100%, but the actual telephone line exhibited extremely many transfer characteristics and exceeded the prediction range. May receive shaped dial pulse waveforms. Therefore, when the recognition limit is exceeded, it is required to notify the center device.

Further, in a usage mode in which the center device prompts the user on the public telephone line side to dial by voice guidance, the voice guidance signal is wraparound dial / pulse waveform in the 2-wire / 4-wire conversion unit in the dial detection device. Because of the superposition, the dial pulse could not be detected during voice guidance. Therefore, the center device tells the user to dial after the confirmation sound in advance in the voice guidance, and outputs the confirmation sound at the end of the voice guidance to detect the dial pulse during the silent period. However, since the content of the voice guidance is known in advance to the person who uses it many times, he / she has to wait until he actually hears the confirmation sound before dialing.

[0018]

When the problems to be solved by the present invention are listed, the first is to reliably detect the first dial pulse waveform after the start of communication, and the second is to reliably detect the first dial pulse waveform after the start of communication. The first is to detect even if the numerical value of the dial is unknown, the third is to reduce the memory and processing amount by reducing the dial pulse waveform information to be stored, and the fourth is the first digit. Is to reliably recognize the isolated dial pulse waveform in the subsequent digits following
The fifth is to eliminate the dial pulse waveform even if it is accompanied by the dial / mute waveform and perform accurate recognition, and the sixth is to make the recognition uncertain depending on the state of the telephone line.・ To detect the pulse waveform and notify the center device that is the recipient of the dial signal,
The seventh is to take a defensive measure so as not to erroneously recognize the PB signal or the voice signal, and the eighth is to perform dial detection independent of the reception level. The ninth is to perform dial detection even during voice guidance.

[0019]

SUMMARY OF THE INVENTION A device according to the present invention is a high-pass filter for shaping a waveform of a voice and attenuating a component corresponding to a first formant and a high-pass filter output for rectifying a signal band on a DC side. A pre-processing unit including an absolute value calculation unit to shift to and a thinning processing unit to reduce the number of samples, and a difference calculation that does not depend on the reception level to check the periodicity and detect that it is a dial pulse waveform,
The PB signal and the like are eliminated by calculating the amount of change around the average value, and the dial value is recognized by determining the period and the leading and trailing ends of the waveform, and if the waveform is abnormal, that fact is reported, and The dial digit pulse detector removes the voice superimposed on the dial / pulse waveform, finds and stores the waveform and waveform characteristics, and removes the voice superimposed on the dial pulse waveform, and dials the dial digit stored in the dial digit detector.・ The dial of the subsequent digit is detected based on the pulse waveform and waveform information, and the dial digit detected by detecting the pulse pulse waveform and removing the mute waveform from the detected dial pulse waveform The PB signal transmission unit for converting numerical values or abnormal waveform information into a PB signal and transmitting the PB signal to a system such as a voice guidance device in the subsequent stage. Minute is configured.

The functions which characterize the device according to the invention are listed below.

First, the frequency component corresponding to the first formant, which is the main energy component of voice, is attenuated by the high-pass filter, and the periodicity of the dial pulse waveform is selectively detected by the difference calculation. The dial pulse waveform can be detected without erroneously detecting voice or line noise.

Secondly, since the waveform selection by the difference calculation is possible if the dial pulse waveform is repeated a certain number or more, the dial pulse waveform can be detected even if the dial digit value of the leading digit is not known.

Third, since the frequency component of the dial pulse waveform is shifted from the telephone band to the band near DC by rectifying it in the pre-processing unit, and the sampling frequency is lowered by the thinning process, the dial pulse waveform is stored. Can be realized with a small amount of memory and can be processed in real time.

Fourth, since the succeeding digit is detected by using the leading digit dial pulse waveform and the waveform information, the dial pulse waveform of the succeeding digit is not required to have periodicity, and the isolated dial pulse waveform Can be detected.

Fifthly, since the exclusion judgment of the mute waveform is made in the recognition of the leading digit dial or the recognition of the subsequent digit dial, the dial value can be accurately recognized.

Sixth, since the abnormal waveform is determined after the detection of the leading digit dial pulse waveform, it is possible to prevent the inaccurate recognition result from being output.

Seventh, the leading digit dial detector determines the amount of change in the value compared with the average value of the waveform and dials the succeeding digit dial.
In the detection of the pulse waveform, the detection is made based on the waveform information stored in the leading digit dial detecting section.
It is possible to prevent erroneous detection of the B signal or the voice signal.

Eighth, by normalizing the difference calculation, it becomes possible to detect the dial pulse waveform independent of the reception level.

Ninth, since the two-line / four-line conversion section in the dial detecting device is adapted to remove the wraparound voice by the voice guidance, the dial / pulse waveform can be detected even during the voice guidance.

Tenth, since the voice removing unit removes the voice superimposed on the dial pulse waveform, the dial pulse waveform can be detected with high reliability.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit configuration of an embodiment of the present invention. Reference numeral 21 is a telephone line for transmitting a dial signal or a voice signal, and 1 is a telephone line interface for closing a DC loop of the telephone line and for performing a two-wire to four-wire conversion for separating a transmission signal 23 and a reception signal 22, 2 is an AD conversion circuit for sampling an analog signal at 8 kHz and converting it to a digital signal, and 3 is 8 kHz
Reference numeral 4 is a DA conversion circuit that converts a sampling signal into an analog signal, and 4 reduces the wraparound of the transmission signal 23, that is, echo, to the reception signal 22 caused by the imbalance of the 2-wire 4-wire conversion unit in the telephone line interface 1. In order to do so, the echo canceller cancels the echo component contained in the received signal 24 with the echo replica created from the transmitted signal 25 by digital processing and outputs it as the received signal 26.

Reference numeral 5 denotes a dial pulse waveform pre-processing unit for performing high-pass filter processing, thinning processing for reducing the number of calculations and information to be stored, and 27 for 20p.
Sample signal for ps dial pulse waveform detection and 10
2 of sample signal for pps dial pulse waveform detection
It is a slow sampled signal consisting of two signals.

Reference numeral 15 is a voice removing unit, which removes the voice signal superimposed on the low speed sample signal 27 when the leading digit dial is detected and a predetermined period (2) of the low speed sample signal 27 in the past.
(5 samples) The short term variation information 37 of the amplitude with respect to the average value and the first digit variation information 38 of the entire first digit dial are stored, and the voice signal superimposed on the low speed sample signal 27 is detected when the subsequent digit dial is detected. Remove it.

Reference numeral 6 is a leading digit dial detecting section for detecting the first dial pulse waveform immediately after the start of communication, recognizing the number of dial pulses, extracting waveform characteristics, and storing the waveform. Reference numeral 35 is a switch control signal. , The application destination of the signal 71 after voice removal is switched from the leading digit dial detecting unit 6 to the succeeding digit dial detecting unit 7.

Reference numeral 7 is a succeeding digit dial detecting portion for detecting the dial pulse of the second digit and thereafter using the leading digit dial waveform information 36 obtained by the leading digit dial detecting portion 6, and 28 is a leading digit dial detecting portion. 6 is the first digit dial numerical information recognized by 6, 29 is the subsequent digit dial numerical information recognized by the subsequent digit dial detecting unit 7, 8 is the first digit dial numerical information and the subsequent digit dial numerical information 28,
PB for converting 29 into dial signal 30 by PB signal
It is a signal transmission unit.

Numeral 9 stops the received signal when the PB signal is transmitted
A switch (SW) that outputs a B signal, and 10 is a DA converter that converts a reception signal or a PB signal from an 8 kHz sampling signal into an analog reception signal 31.
Reference numeral 11 is an AD converter for sampling the analog transmission signal 32 at 8 kHz and converting it into a digital signal, and 33 is a system signal line equivalent to a telephone line connecting with a system that provides a service using a dial signal.

Reference numeral 12 is a system line interface for performing 4-wire / 2-wire conversion of the transmission signal 32 and the reception signal 31, supplying DC to the system, and detecting DC loop closure.
Is the DC loop closure information in the system line interface 12. The DC loop closure information 34 is also included in the signal processing section 5, the voice removing section 15, the leading digit dial detecting section 6, and the succeeding digit dial detecting section 7 when the DC loop is closed.
After the PB signal sending unit 8 is initialized, the dial pulse waveform is detected, and is also used as control information for stopping the dial pulse detection when the DC loop is opened.

In FIG. 1, the echo canceller 4, the preprocessing unit 5 and the PB signal transmitting unit 8 are provided in the telephone band (300-300).
Since it is a signal processing of 3.4 kHz), it is necessary to process the signal at a sampling rate of 8 kHz, but the voice removing unit 15, the leading digit dial detecting unit 6, and the succeeding digit dial detecting unit 7 are slowed down by the preprocessing unit 5. Since the low-speed sample signal 27 is processed, it is inefficient to process it with a program mixed with the 8 kHz sample signal. Therefore, in the embodiment of the present invention, the functions of the preprocessing unit 5, the voice removing unit 15, the leading digit dial detecting unit 6, the succeeding digit dial detecting unit 7, and the PB signal sending unit 8 are not shown according to the program. 8k DSP (Digital Signal Processor)
It is divided into two types, one for Hz samples and the other for low speed samples.

In the 8 kHz sample DSP, one sample 125 μs is time-divided to perform echo canceller signal processing,
Preprocess dial pulse waveform and generate PB signal. The low-speed sample DSP divides the processing sequence into three steps, that is, a voice elimination processing, a leading digit dial detecting step, and a succeeding digit dial detecting step. Low-speed sample signals are input / output between two DSPs through serial transfer, and the dial recognition result is the leading and trailing digits dial numerical information 2
Transmission of 8 and 29 is performed by 8-bit parallel transfer. Although the embodiment of the present invention has been described with respect to the case where it is realized by using two DSPs in this way, it is not necessary to separate it into two if a DSP capable of high-speed arithmetic processing is used.

In the embodiment of the present invention, the RAM is repeatedly used so that the processing can be realized by a DSP having a 512-word data RAM. FIG.
In the above, the leading and subsequent digits dial numerical information 28, 29 after recognition of the dial numerical value is converted into a PB signal and transmitted to the system through the system signal line 33. Two
9 may be transmitted to the system using an interface such as RS232C.

FIG. 2 shows a detailed circuit configuration of the preprocessing section 5. Reference numeral 26 is a received signal that is sampled at 8 kHz and the echo is removed. Reference numeral 41 is a high-pass filter (HPF) for the purpose of attenuating a first formant having a large electric power in a voice signal which becomes an interference signal in performing dial / pulse detection, and further, a low-frequency cutoff of a telephone line. It also serves the purpose of removing ringing caused by group delay distortion near the frequency (about 300 Hz).

FIG. 3 shows a waveform diagram for explaining the operation of the high-pass filter 41 and the absolute value calculator 42. This figure shows a dial pulse waveform generated before and after the make-up period of the dial pulse due to band limitation. The waveform of the received signal 26 is shown in (a1) and the waveform shown in (a1) is shown in (a2). When the absolute value is directly obtained from the signal shown in (b1) of FIG.
The waveform obtained after passing through 1 is shown in (b1) as (b1)
The case where the absolute value is calculated by the absolute value calculation unit 42 from the waveform shown in FIG. There is ringing in the figure (a
1) In the case of (a2), it is equivalent to passing through a transmission system with a slow response, and it is difficult to form a boundary between the pulses, but in the cases of (b1) and (b2) in which the ringing is suppressed, the pulse is suppressed. The boundary between them becomes clear.

The cutoff frequency of the high-pass filter 41 is preferably about 600 Hz for the purpose of attenuating the first formant of the voice signal and the components near the low cutoff frequency (300 Hz) of the telephone line 21. The phase characteristic of the high pass filter 41 must be linear in order to prevent group delay distortion from being generated in the cutoff region of the pass filter 41. A filter with a linear phase characteristic has a finite impulse response (F
It is easily realized by symmetrically selecting the tap coefficients of the (IR) filter. The absolute value calculation unit 42 shifts the signal band to a low band including direct current in order to shift the occupied band of the received signal to the low band side, which enables the thinning-out process described below.

Reference numerals 43a and 43b are low-pass filters (LPF) required before thinning, and 43a is 20
pps for dial pulse waveform, and 43b for 10pps dial pulse waveform. Low pass filter 43
The cutoff frequencies of a and b will be described. The signal after absolute value calculation has the same cycle as the basic speed of dial pulse (20 pps or 10 pps), but 20 pps and 10 p
In the ps dial pulse waveform, the make period and the break period may be different, or a pulse waveform may occur in the middle part of the break period or the make period due to a waveform clip or the like due to the subscriber circuit on the sender side of the telephone line. Therefore, the frequency band needs to be about five times the basic period.

Therefore, the low pass filter 4 has a frequency of about 100 Hz for a 20 pps dial pulse waveform and a frequency of about 50 Hz for a 10 pps dial pulse waveform.
The cutoff frequencies are 3a and 3b. In the embodiment of the present invention, 20
Low pass filter 43 for pps and 10 pps
The cutoff frequencies of a and b are selected to be 125 Hz and 62.5 Hz. Since the low-pass filters 43a and 43b must have a linear phase characteristic like the high-pass filter 41, they are constructed by symmetrical FIR filters.

Reference numerals 44a and 44b denote thinning-out processing units for performing thinning-out processing to reduce the sampling speed.
0pps for dial pulse waveform, 44b for 10pps
For dial pulse waveform. The sample rate after thinning will be described. The sampling theorem teaches that the sampling frequency after decimation should be at least twice the cutoff frequency of the low-pass filters 43a and 43b, but in the embodiment of the present invention, the difference between pulse waveforms is calculated. It is necessary to detect the basic speed (cycle) of the dial pulse, and time resolution becomes a problem. It is equal to the sample period, and the sample frequency is increased to improve the resolution.

In the embodiment of the present invention, the sample frequency after thinning is selected to be four times the cutoff frequency of the low-pass filters 43a and 43b in order to make the sample frequency as low as possible and ensure the resolution. That is, in the thinning processing unit 44a, 500
To obtain the Hz sample signal, one sample is extracted every 16 samples from the 8 kHz sample signal and the low speed sample signal 27a is output. Further, the thinning processing unit 44b is 25
In order to obtain a 0 Hz sample signal, one sample is extracted every 32 samples from the 8 kHz sample signal and the low speed sample signal 27b is output.

The slow sample signals 27a and 27b are
Since they are obtained from the 20 pps and 10 pps dial pulse waveforms, respectively, either one or both of them is applied to the voice removing unit 15 as the low speed sample signal 27. In the following, the low-speed sample signal 27a or 27b is simply referred to as the low-speed sample signal 27 when it is not necessary to distinguish it.

As described above, according to the present invention, the sampling frequency is reduced to 1/16 of 8 kHz for 20 pps and 1/32 for 10 pps by the absolute value calculation and the thinning-out process. We are trying to reduce it.

FIG. 4 shows the internal structure of the voice removing unit 15. A part of the low-speed sample signal 27 is passed through a high-pass filter (HPF) 61 to obtain a signal 76 from which the audio signal component has been removed, and a DC component regenerator 62 reproduces the DC component to reproduce the DC component. Get 77. The other part of the low-speed sample signal 27 is passed through a delay unit 63 to obtain a delayed signal 78 in order to compensate for the delay time of the high-pass filter (HPF) 61. The error waveform remover 64 removes the error waveform by removing the error waveform by referring to the delayed signal 78 generated in the signal 77 after the DC component reproduction during the DC component reproduction. The signal 79 from which the error waveform is removed has a negative amplitude removed by a slicer, and is output as a signal 71 after audio removal as needed (details will be described later).

The switch 66 is turned on when the leading digit dial is detected by the switch control signal 35, and is turned off when the trailing digit dial is detected, and the low-speed sample signal 27 when the leading digit dial is detected is applied to the change calculation unit 67, and the average is calculated. The change amount of the short-term change amount information 37 indicating the change amount around the value is calculated, and the change amount storage unit 68 compresses the change amount of the short-term change amount information 37 and stores the change amount information of the entire leading digit dial. Then, it is output as the leading digit change information 38.

When the switch 66 is on, the change amount calculation unit 6
At 7, the input samples are sequentially stored in a FIFO (first-in first-out) type RAM (not shown) in order to calculate the amplitude change. The RAM is available for 20 pps and 10 pps, and each is configured so that it can store a waveform of about one basic period, that is, 25 samples.

In the leading digit detection period in which the switch 66 is turned on, the variation calculation unit 66 changes the amplitude of the low-speed sample signal 27a or 27b with respect to the average value of a predetermined past period (25 samples). Ask for minutes. One of the objects of the present invention is not to be impressed by signals such as PB dial signals, facsimile procedure signals, voices and music. Since the amplitude changes of these signals that have been band-limited and sampled at low speed by the preprocessing unit 5 are small, while those of the dial pulse waveform are large, it is possible to distinguish these signal waveforms from the dial pulse waveform based on the amplitude changes. it can.

The input signal at sample time n is X
₁ (n), the average value is A ₁ (n), and the change width around the average value is V
_The amplitude variation Z (n) is calculated by the following equation (1), where ₁ (n) and J are the number of samples in one fundamental period (25 samples in this example). The value of the change Z (n) is short-term change information 3
7 is output.

Z (n) = V ₁ (n) / A ₁ (n) (1) A ₁ (n) = (1 / T) ΣX ₁ (n−i) (2) V ₁ (n) = ( 1 / T) Σ | X ₁ (n−i) −A ₁ (n) | (3) where Σ in equations (2) and (3) represents the cumulative sum of i = 0 to J−1. .

The change storage unit 68 stores the change Z (n) obtained by the equation (1) for a period corresponding to the entire leading digit dial / pulse waveform. The need for such memory is described below. For example, when a boy produces a vowel sound such as "A-", the change in amplitude may be very similar to the dial pulse waveform over a period of several 10 ms. Therefore, in a time period of about one basic period such as when the change Z (n) is obtained, it may be impossible to distinguish between the voice and the dial pulse waveform. In order to avoid this, the value of the variation Z (n) is stored for a period corresponding to the entire leading digit dial pulse waveform, and distinction can be made by distinguishing by using the variation due to long-term observation.

Since the data RAM of the DSP (digital signal processor) is limited in the embodiment of the present invention, the variation Z (n) is stored while the RAM is reduced by using the following method. The value of the variation Z (n) calculated by the equation (1) is set to K blocks, and one block is associated with one variation information. Note that K needs to be K ≦ J / 2, and K = 12 in the embodiment of the present invention.

Further, the variation information is also limited to three values in order to reduce RAM, and one block is continuously expressed by the following equation (4).
Is stored if the above condition is satisfied, 1 is satisfied if the formula (5) is satisfied, and 0 otherwise. Z (n)> μ (4) Z (n)> ν (5)

The threshold value μ is set to 0.5 and ν is set to 0.35. The FIFO format RAM in the change amount storage unit 68 corresponds to about 15 basic cycles so that the start digit change amount information 38 including before and after the start digit dial can be stored.
It has a storage capacity of two blocks.

High pass filter 61, DC regenerator 6
2. The error waveform eliminator (64) and the slicer 65 remove the guidance voice signal and the like circling in the 2-line to 4-line converter included in the telephone line interface 1 which becomes an interfering signal when performing the dial pulse detection. Voice pulse guidance from the system is required to detect dial / pulse during voice guidance, for example, when the voice guidance is sent from the system through the system signal line 33 to prompt the telephone user to dial. Since the envelope change of the voice signal in the low-speed sample signal is gentler than the change in the dial pulse signal, the voice signal is removed by using this feature to pass the low-speed sample signal 27 through the high-pass filter 61.

FIG. 5 shows the waveform of each part of the voice removing unit 15. FIG. 11A shows a low-speed sample signal 27 which is an input signal, and shows a dial pulse waveform on which a wraparound voice signal is superimposed. High pass filter (HP
F) 61 removes a low frequency component which is an audio signal component and outputs a signal 76 shown in FIG.

The cutoff frequency of the high-pass filter (HPF) 61 is 10 H in the case of 20 pps for the purpose of passing the dial pulse waveform and attenuating the voice power waveform.
In the case of z and 10 pps, it is good to select about 5 Hz,
Further, since it must have a linear phase characteristic like the high pass filter (HPF) 41, it is composed of a symmetric FIR filter (finite impulse response filter). Here, when passing through the high-pass filter (HPF) 61, the average power of the signal is also removed from the signal 76 of FIG. The problem is that it becomes difficult.

To correct this, the DC component regenerator 62 performs DC component regeneration on the signal 76. The direct current component reproduction is performed by detecting a change amount from the negative amplitude side of the signal 76 in (b) and adding it to the signal 76. That is, only the negative amplitude portion of the signal 76 is selected, and a time constant that follows it relatively quickly in the negative direction (downward direction) and gently follows in the positive direction (upward direction). An amplitude change amount is detected by passing it through a DC component estimation filter (not shown). The output of the DC regenerator 62 becomes a signal 77 shown in FIG.

Further problems arise in this waveform. That is, since the time constant in the positive direction cannot be optimally set for an arbitrary dial pulse waveform in the DC component estimation filter, an error waveform 69 is generated at the end portion of the waveform in FIG. . This error waveform 69
Is a part of the pulse waveform that composes the dial pulse waveform and interferes with recognition, so it must be prevented. Therefore, a signal 78 that has passed through a delay unit 63 that delays the input signal 27 by a delay of a high pass filter (HPF) 61 and a signal 77 that includes an error waveform 69 are used, and an error waveform remover 64 outputs an error waveform 6
9 is removed.

The error waveform remover 64 compares the signal 78 and the signal 77 and selects the one having the smaller amplitude for each sample, whereby the error waveform 69 as shown in FIG. 5D is removed. The signal 79 is obtained. Since the sample value of negative amplitude in the signal 79 is an unnecessary portion as the dial pulse waveform, it is cut out by the slicer 65 to obtain the signal 71 after voice removal shown in FIG. 5 (e).

FIG. 6 shows a circuit configuration of the leading digit dial detecting section 6. The switch 51 is a switch for switching the application destination of the signal 71 after the voice signal is removed to the leading digit dial start detection unit 52 or the leading digit dial end detection unit 53, and a switch control signal 73 for switching the leading digit dial start detection unit 52 and It is obtained from the leading digit dial end detection unit 53.

The leading digit dial start detector 52 calculates the difference of the signal 71 after voice removal by a predetermined procedure (details will be described later), detects the beginning of the leading digit dial using the short-term change information 37, and The pulse shape information 72 for detecting the end of the digit dial is applied to the leading digit dial end detection unit 53. The leading digit dial end detection unit 53 detects the leading digit dial end and eliminates unnecessary waveforms using the pulse shape information 72, and the leading digit change information 38
Is used to obtain the leading digit dial waveform storage information 74 for storing as the leading digit dial waveform, the leading digit numerical value information 28, and the switch control signal 35 indicating the end of the leading digit. The leading digit dial waveform characteristic storage unit 54 obtains the leading digit dial waveform information 36 from the leading digit dial waveform storage information 74 (details will be described later).

7, FIG. 8, FIG. 9 and FIG. 10 show the flow of signal processing until the presence of a dial pulse waveform is detected in the leading digit dial detecting section 6. When the leading digit dial / pulse detection operation is started, the voice-removed signal 71 for 20 pps or 10 pps is input at a cycle of 2 ms or 4 ms (S1, FIG. 7) and sequentially stored in a FIFO (first in, first out) type RAM. . (S2).
At this time, the switch 51 is connected to the leading digit dial start detection unit 52. RAM for 20pps and 1
There is one for 0 pps, and each is configured to be able to store a waveform of about 8 basic cycles, that is, 200 samples.

In step S3, the magnitude of the signal, that is, the variation V around the average value A (n) shown in the equation (8) described later,
It is determined whether (n) is a predetermined value, for example, -40 dBm or more. This is because when the signal is extremely small, there is a high possibility that it is a dial pulse waveform of another line due to crosstalk, and the denominator V (n) of the equation (7) described below approaches 0, causing abnormal computation. . If the signal is small, it has the next signal input (S3N).

In step S4 (FIG. 8), it is determined whether the change amount Z (n) (change amount represented by the short-term change information 37) measured and calculated by the change amount calculation unit 67 is equal to or more than a predetermined change amount. judge. Here, the purpose is to detect the leading end of the leading digit dial pulse, and for one short sample change, that is, the change Z (n) at sample time n, even one sample is expressed by the following equation (6). If the determination condition is satisfied, the process proceeds to the next step (S4Y), and if not satisfied, the process waits for the next signal input (S4N). Α in the equation (6) is selected to be about 0.35. Z (n) ≧ α (6)

Next, difference calculation is performed (S5). By normalizing the difference calculation, the presence of the dial pulse waveform can be detected regardless of the level of the received signal 26. In the embodiment of the present invention, 5 cycles are prepared for each of 20 pps and 10 pps, and the difference calculation is performed. The reason for setting five is because the dial speed varies within a range of ± 10%. For example, when the speed is 20 pps, a period of 25 samples (50 ms) is applied to detect the basic velocity (cycle), and the short cycle side is set. 24 sample periods (48 ms) and 23 sample periods (46 ms) are applied, and 26 sample periods (52 ms) and 27 sample periods (54 ms) are applied to the long period side.

Cycles that do not match these (for example, 49 m
In principle, the difference calculation result in the case of a dial pulse having an intermediate period of s, 51 ms, etc. does not become zero. Since the deterioration of the difference calculation result in the case of dial pulse input with an intermediate cycle depends on the sampling frequency after thinning, this relationship will be described in more detail. When the sampling frequency after thinning is set to be twice the cutoff frequency of the low pass filters (LPF) 43a and 43b, the time resolution in the difference calculation is 4 ms, similarly, when it is 4 times, it is 2 ms, and when it is 8 times, it is 1 m.
s. When doubled, the middle of the time resolution (for example, 4
The difference calculation result (r (n) obtained by the formula (7)) is 0.6 when dial pulse is input with a cycle of 8 ms, 52 ms, etc.
s, 51 ms, etc., the difference result is 0.3, and when it is 8 times, the middle of the time resolution (for example, 49.5 ms, 50.5 ms).
Etc.) will be 0.15.

If the sampling frequency after thinning is increased and the time resolution is made fine as described above, a good result can be obtained in the difference calculation, but at the same time, the calculation amount in the processing also increases. On the other hand, when voice is actually input and difference calculation is performed,
A difference calculation result of about 0.4 may be obtained regardless of the sampling frequency after thinning. In this example, the sampling frequency is set to four times the cutoff frequency of the low-pass filters (LPF) 43a and 43b from the viewpoint of avoiding erroneous detection due to voice and reducing the amount of calculation or storage.

In the difference calculation, the difference at the sample time n indicating the temporal sample position is r (n), the number of detected samples of one fundamental period is T, and the signal 71 after speech removal is X (n).
, The average value is A (n), and the change around the average value is V (n)
As in equations (7) to (9). A well-known correlation function may be used to detect the periodicity. However, in the case of a waveform that contains a large amount of direct current component, the correlation value becomes high and masks the waveform change that is truly desired to be observed. .

In view of this point, the embodiment of the present invention measures the degree of coincidence by subtracting the waveforms from each other. r (n) = {(1 / T) Σ | X (ni) −X (nTi) |} / V (n) (7) V (n) = (1 / T) Σ | X (nTi) -A (n) | (8) A (n) = (1 / T) ΣX (nTi) (9) where Σ in equations (7) to (9) is the cumulative sum from i = 0 to T-1. It represents. In the embodiment of the present invention, the detection cycle T is 5 for 20 pps and 5 for 10 pps detection.
Since individual pieces are prepared, the calculations of formulas (7) to (9) are performed 10 times each time a low speed sample is input.

In the difference judgment, the difference calculation result r of equation (7)
The difference is determined using (n). That is, it is determined whether the smallest of the ten difference calculation results r (n) satisfies the condition of the following expression (10) (S6Y) or not (S6N). In formula (10), β is selected to be about 0.3. r (n) ≤ β (10) When the elapsed period until Expression (10) is satisfied is observed using an actual dial pulse waveform, it is within 4 periods. Therefore, in the case of the embodiment of the present invention, the leading digit dial pulse waveform can be detected if the dial numerical value is "5" or more. Next, the cycle indicating the minimum r (n) selected in step S6 is temporarily stored as the cycle T _a (S
7).

In the pulse shape measurement (S8), the pulse shape of the dial pulse waveform is measured. Low speed sample signal 2
In FIG. 7, since the dial pulse waveform changes sharply as compared with the voice waveform, it can be used as a waveform feature. In measuring the pulse shape, firstly, a sample point b having the maximum amplitude between the sample time n and the past time n-2T _a is searched for.

Second, from the first sample point b to the past by a predetermined number of samples (for example, b to b when the cycle is 20 pps).
-13) is searched for the minimum or minimum sample point a, and thirdly, from the first sample point b to the future by a predetermined number of samples (for example, b to b when the cycle is 20 pps).
After searching for the sample point c that becomes the minimum or minimum between (up to +13), the left wave height ratio H ₁ = X (a) / X (b), the right wave height ratio H ₂ = X (c) / X (b). , Left waveform width W ₁ = b−a and right waveform width W ₂ = c−b are stored as pulse shapes.

However, if the pulse shape measured at this stage is used as a condition for identifying the waveform thereafter, the condition becomes too strict, so the wave height ratio is stored as a value multiplied by the relaxation coefficient. At this time, the switch control signal 73 switches the connection destination of the switch 51 to the leading digit dial end detection unit 53. The operation of steps S1 to S7 is performed by the leading digit dial start detection unit 5
2 takes place.

Next, the signal processing until the dial pulse waveform is cut out and recognized in the leading digit dial end detecting portion 53 of the leading digit dial detecting portion 6 will be described. Since the provisional period of the dial pulse waveform is known in step S7, the signal 71 after voice removal of either 20 pps or 10 pps is input (S9, FIG. 9). The one sample input in step S9 is the step S
FI storing the sample of the fixed provisional period obtained in 7.
The data is continuously stored in the FO format RAM (S10).

At this point, the RAM is 20 pps or 1
In order to exclusively use 0 pps, the embodiment of the present invention changes the configuration so as to be able to store a waveform for 16 basic cycles, that is, 400 samples. This change can be easily made by changing the setting method of the pointer that manages the RAM.
The limited RAM resources in P can be effectively utilized.

It should be noted that the storage capacity of the dial pulse waveform does not need to be 16 basic cycles, and 11 basic cycles are enough even if the cycle variation is taken into consideration. However, the dial pulse waveform is dialed by a rotary dial telephone.
Since the mute pulse waveform that occurs when the mute operation is turned on or off or the pulsed voice waveform that is present immediately before the dial pulse waveform is included, a storage capacity with a margin until the dial pulse waveform is recognized. Will be required.

In the end determination (S11), the end point of the dial pulse waveform is detected. The end time is the time when a pulse waveform satisfying the pulse shape no longer appears. The pulse shape is determined by comparing the value with the value obtained in step S4 centering on a predetermined sample number, for example, 13 sample past sample time n-13.

If the following equations (11) and (12) are satisfied on the left and right centering on the sampling time point n-13, it is determined that there is a pulse waveform but not the end (S11N). X (n-13-W ₁ ) / X (n-13) ≧ H ₁ (11) X (n-13 + W ₂ ) / X (n-13) ≧ H ₂ (12) performed for the signal, if a predetermined time (e.g. 1.5T _a) continuously not O and there pulse, it is determined that there is no pulse waveform at that time, and stops the input of a low-speed sample signals, predated 1.5T _a past The time point is set as the end of the dial pulse waveform (S11Y).

In the tip detecting operation (S12), the dial
The tip of the pulse waveform is detected. When detecting the tip, R
Returning 400 samples before the beginning of the waveform stored in the AM, that is, the end in the embodiment of the present invention, the pulse shape is measured as in step S8. That is, the search for the maximum value is started from the position 400 to 13 samples returned from the end, and if the maximum value is found, the minimum or minimum value is searched for the left and right 13 samples, and the left and right wave height ratio and the left and right waveform width are measured and stored in step S8 Then, the sample point satisfying the condition is set as the leading pulse waveform temporarily.

From the tentative head pulse waveform to the end side of 1.
It measured between the pulse shape of 5T _a, the true head pulse waveform if pulse. This reduces the probability that a voice waveform approaching the dial pulse waveform will be mistaken for the leading pulse waveform. The tip of the dial pulse waveform is the minimum or minimum sample point on the left side of the leading pulse waveform.

In the waveform classification operation (S13), dial
Accurate period detection of pulse waveform and waveform division. Cycle detection is performed with square waveforms and dials stored in RAM.
The product sum s (t, p) with the pulse waveform is calculated by the following equation (13), and the period of the square waveform when the value becomes maximum is set.

S (t, p) = (1 / K) Σ {ΣX (jt + i + p) + ΣX (jt + i + p)} (13) Here, the first Σ is j = 0 to K−1. The second Σ is i = 0 to L−1, and the third Σ is i = t−L to t
It represents the cumulative sum up to -1.

In the equation (13), t is a cycle and 23 ≦ t ≦ 27 in the embodiment of the present invention, and p is a phase value in which the leading end of the dial pulse waveform obtained in step S12 is 0 and 0 ≦ p <. t and K are integer values obtained by dividing the number of samples from the leading end to the end by the period t and discarding the remainder, and L is the number of samples in the section where the square waveform is set to 1, and in the embodiment of the present invention 8, X
Is a dial pulse waveform stored in RAM.

Equation (13) is calculated for all combinations by changing t and p in order, and t and p when the values are maximum are the optimum period T and phase P.
Regarding the cycle, the content T _a stored in step S7 is changed to T
To fix. Regarding the phase, the phase P is added to the tip sample point obtained in step S12 to make the tip again. The division of the waveform is equivalent to dividing the waveform into 0s at the tip and a period T.

FIG. 11 shows the state of the waveform division processing in step S13 when the value of the equation (13) is maximum. In the figure, (a) is a dial pulse waveform stored in RAM, (b) is a square wave having a period of the dial pulse waveform stored in RAM,
In (c), the waveform is divided at the cycle T with the new tip sample point being 0.

In the unnecessary waveform removing operation (S14, FIG. 10), when the unnecessary waveform which is the mute pulse waveform or the pulse voice waveform is near the dial pulse waveform, it is excluded to recognize the dial numerical value. The range to be excluded is two cycles. That is, even if there is a mute pulse or the like, it is at most one cycle, and it is sufficient to consider two cycles. The exclusion determination of FIG. 11A is independently performed for the leading end and the trailing end.

In the method described below, if the first or second cycle is the dial pulse waveform, it is certain that the dial pulse waveform is at the position corresponding to the change time point of the break period. It is utilized that the power almost equal to that in the fourth cycle or the fourth cycle is observed.

In the judgment of exclusion on the leading end side, first, the powers P _f3 and P _f4 in the front 1/3 section are measured for the third period T ₃ and the fourth period T ₄ from the leading end, and the smaller value is set to the front side. The reference power P _f is used, and the power P _b3 and P _b4 in the rear 1/3 section are measured and the smaller value is used as the rear reference power P _b . Second, the powers P _f1 and P _f2 in the front 1/3 section are measured for the first cycle T ₁ and the second cycle T ₂ , and the powers P _b1 and P _b2 in the rear 1/3 section are measured.

Thirdly, for the first cycle T ₁ , P _f1 > γ
If P _f and P _b1 > γP _b , it is regarded as a dial pulse waveform, and the others are excluded. Select γ around 0.4. Fourthly, when the first cycle T ₁ is excluded, the same exclusion determination as that of the first cycle T ₁ is performed for the second cycle T ₂ (see FIG. 12).

Next, in the exclusion judgment of the terminal part, the first and second cycles from the terminal end are excluded as in the case of the head part, and the front and rear electric powers of the third and fourth cycles from the terminal end are respectively measured and small. One is set as the reference power, and the first cycle and the second cycle from the end are compared to determine whether to exclude.

FIG. 12 shows a divided waveform (FIG. 11C) in the case where the mute pulse is excluded at the tip in the operation of step S14 already described, and the mute pulse to be excluded has one cycle. In eye T ₁ . The front side and rear side reference powers P _f and P _b are measured from the waveforms of the third cycle T ₃ and the fourth cycle T ₄ .

Compared with the power P _f1 and P _b1 of the first cycle T ₁ , the front side P _f1 satisfies the condition of P _f1 > γP _f , but the rear side P _b1 is P _b1 = 0, so P _b1 Since the condition of> γP _b is not satisfied, the mute pulse having the waveform of T _{1 in} the first cycle is excluded (S14). As for the dial numerical value, since the unnecessary waveform which is not counted as the dial pulse waveform in step S14 is excluded from the period number (pulse number) before the unnecessary waveform is excluded in step S13, the period number is 1
Is the value obtained by subtracting.

Next, in step S15, by using the leading digit change information 38 corresponding to the leading digit dial pulse waveform portion, whether the waveform of 400 samples stored in the RAM at this time is the leading digit dial pulse. , Or a signal such as a voice or PB signal that should be insensitive. The leading digit change information 38 corresponds to the leading digit dial pulse since the leading end and end addresses, the period T, and the unnecessary waveform portion to be excluded are known from the end point to 15 basic sample periods before. Only the information on the change in the period (in the embodiment of the present invention, about 20 blocks in the case of dial "0") is extracted and used for the determination of the change in the leading digit.

The information of the change of the extracted portion is such that “2” is continuous for P blocks or more or “0” for Q blocks or more.
If is not continuous, it is judged as a dial pulse,
The process proceeds to the next step (S15Y), and if it is other than that, it is determined that the signal should be insensitive, and the connection destination of the switch 51 is switched to the leading digit dial start detector 52 to start the leading digit dial detection in step S1. And returns to the next low-speed sampling signal (S15N). The value of P and Q is 4
It is a block (96 ms at 20 pps and 192 ms at 10 pps).

In the next step S16, it is determined whether or not the waveform is abnormal. In other words, when voice is mixed in during dialing, or when the dial pulse waveform fluctuates in time due to telephone line conditions, the waveform stored in RAM is used as the reference waveform to detect subsequent digits. Cannot be used. Also, the recognized dial digit of the first digit itself is not reliable.

Therefore, abnormal waveform detection is performed as follows with respect to the dial pulse waveforms that have not been excluded.
First, the power P _{f in} the front 1/3 section of the first cycle and the rear 1/3
The power P _b of the section is used as the reference power. Next, the power P _fx of the front side 1/3 section and the power P of the rear side 1/3 section after the second cycle
_bx is measured and compared with the reference power P _f (see FIG. 12). That is, four comparisons, P _fx <δ · P _f P _fx > ε · P _f P _bx <δ · P _b P _bx > ε · P _b are performed, and if any one is satisfied, it is regarded as an abnormal waveform. For the coefficients, for example, δ = 0.2 and ε = 5 are selected.

When it is determined as an abnormal waveform (S16
In Y), there is information other than the dial numerical value as the first digit dial numerical value information 28, for example, a dial signal B which is not normally used (the dial signal includes numerical values 0 to 9 and several signals including B). ) Is output from the leading digit dial end detector 53 of the leading digit dial detector 6 to the PB signal transmitter 8 as an abnormal waveform notification (S17).

Therefore, the connection destination of the switch 51 is switched to the leading digit dial start detection section 52, and the process returns to step S1 of leading digit dial detection start to wait for the next low speed sample signal (S1). If it is determined that the dial pulse waveform is normal (S16N), the first digit dial numerical information 28
Is output from the leading digit dial detecting unit 6 to the PB signal sending unit 8, and a switch control signal 35 indicating the end of the leading digit is output from the leading digit dial detecting unit 6 to the voice removing unit 15 (S18). The operations of steps S9 to S18 are performed by the leading digit dial end detection unit 53.

In the next step S19, the number of samples per cycle is k, the number of cycles excluded on the leading end side is m, and step S13
A new tip sample point p + m, where n is the tip sample point p obtained in step S and the dial numerical value recognized in step S14.
Store the samples from k to the new end sample point p + mk + nk as a dial pulse waveform. Further, a sample for one cycle from the end sample point is stored as a trailing waveform (see FIG. 13). The tail waveform is an isolated waveform (dial 1) in the recognition of the trailing dial pulse waveform.
It is used to increase the recognition accuracy of.

Since the dial pulse waveform and the tail waveform stored in step S19 are used as the reference waveform in the subsequent digit recognition, they are frequently read from the RAM.
Therefore, the storage position is rewritten so that the leading edge sample is stored at a predetermined RAM address, so that addressing can be easily performed. The storage capacity required in step S19 is 1
Since it corresponds to one cycle, in the embodiment of the present invention, 11 × 2
7 samples are enough, and about 100 samples out of the 400 samples used for waveform storage in step S10 are left over at this stage. This is used to store the pulse shape or subsequent digit samples in the subsequent operation to effectively use the DSP internal resources.

In step S20, the average amplitude required for comparing the reference waveform stored in step S19 and the subsequent digit waveform is calculated and stored. The average amplitude is obtained in each section obtained by dividing one cycle of the reference waveform into three. For the following description, a waveform divided in units of one cycle T is called a unit waveform,
A waveform obtained by dividing a unit waveform into three is called a divided waveform. The calculation formula of the amplitude average of the front side divided waveform is expressed by the following formula (1
4), similarly, the central divided waveform is shown in equation (15), and the rear side divided waveform is shown in equation (16).

P _f (k) = (1 / L) Σ | X ((k−1) T + i) −V (k) | (14) where Σ is from i = 0 to L−1. It represents the cumulative sum. P _c (k) = (1/8) Σ | X ((k-1) T + i) −V (k) | (15) where Σ represents the cumulative sum from i = L to L + 7. There is. P _b (k) = (1 / M) Σ | X ((k-1) T + i) −V (k) | (16) where Σ is the cumulative sum from i = L + 8 to T−1. It represents.

In the equations (14) to (16), k is a serial number of the unit waveform in which the first unit waveform is 1, and the upper limit is a value obtained by adding 1 to the dial numerical value, L = (T-8) / 2. (Truncated below the decimal point), M = T−L−8, T is the period, X is the reference waveform, and V (k) is the average value of one period shown in the following equation (17). The reason why the average section length at the center is 8 is that it corresponds to about 1/3 cycle in the embodiment of the present invention. V (k) = (1 / T) ΣX ((k-1) T + i) (17) Here, Σ represents the cumulative sum from i = 0 to T-1.

FIG. 13 is a waveform diagram showing the pulse shape measuring operation of the leading digit dial waveform characteristic storage unit 54 of the leading digit dial detecting unit 6. In step S21 the reference waveform (cycle T ₁ through T ₆₎ is measured and stored three portions of pulse shape among.

First, the left waveform width W ₃ , the left wave height ratio H ₃ , the right waveform width W ₄ , and the right wave height centering on the peak (time point b ₁ ) of the front divided waveform of the head unit waveform existing in the cycle T _1. Find the ratio H ₄ . Here the left wave height ratio H ₃ time a ₁ amplitude X of (a ₁₎ of the point b ₁ is amplitude X (b _1), i.e., since a value obtained by dividing the amplitude of the peak, H ₃ = X (a ₁ ) / X (b ₁ ). The right wave height ratio H ₄ also becomes H ₄ = X (c ₁ ) / X (b ₁ ) using the amplitude X (c ₁ ) at the time point c ₁ .

Secondly, the left waveform width W ₅ and the left wave height ratio H ₅ are centered on the largest peak value (time point b ₆ ) among the front side divided waveforms in each period from the period T _{2 to} the end of the period T _6. , Right waveform width W ₆ and right wave height ratio H ₆ are obtained.

Thirdly, the left peak width W ₇ and the left peak height ratio H are centered on the largest peak value (time point b ₃ ) in the rear side divided waveform in each cycle from the cycle T _{2 to} the end of the cycle T _{6. 7,} right waveform width W _8, obtain the right height ratio H _8.

Where H_Five~ H₈Is time point a₆, B₆, C
₆, A_Three, B_Three, C_ThreeEach amplitude X (a ₆), X (b₆), X (c
₆), X (a_Three), X (b_Three), X (c_Three) With H_Five= X (a₆) / X (b₆) H₆= X (c₆) / X (b₆) H₇= X (a_Three) / X (b_Three) H₈= X (c_Three) / X (b_Three).

The reason for having three measurement portions is that the leading pulse waveform (T _{1 in} FIG. 13) is a transient response and therefore has a different pulse shape, and the front divided waveform and the rear divided waveform have different response characteristics. Therefore, each representative, that is, the maximum portion of the front divided waveform (T _{6 in} FIG. 13) and the maximum portion of the rear divided waveform (T _{3 in} FIG. 13) are required. The representative is set to the maximum peak portion because it is easy to select. As described in the processing of step S8, the wave height ratio H is too strict if the numerical value as it is is used as the determination condition, so it is corrected to a value multiplied by the relaxation coefficient.

In step S22, it is determined whether or not the trailing waveform for one cycle (FIG. 13) following the end of the reference waveform should be compared when recognizing the subsequent digit. When unnecessary waveforms are excluded on the terminal end side of the waveform in step S14 and immediately before the terminal end of the reference waveform, one cycle power of the unit waveform (cycle T in FIG. 13).
_{If the} tail waveform power (Fig. 13) is more than a predetermined value (for example, -6 dB or more) compared to the power of ₆ ), the tail waveform is regarded as a mute pulse and the tail waveform comparison can be performed in the subsequent digit recognition. It is output as a part of the digit dial waveform information 36. The operations of steps S19 to S22 are performed in the leading digit dial waveform characteristic storage unit 54.

During the signal processing of steps S12 to S22, there is a silent signal period corresponding to the digit between the first dial and the second dial, and the digit gap is 20 pps dial.
There is an interdigit time of 450 ms or more in the case of a pulse waveform and 600 ms or more in the case of a 10 pp dial pulse waveform.
Therefore, in the processing of steps S12 to S22, the input of the low-speed sample signal 27 may be stopped and the processing may be completed within 400 ms.

Next, with reference to FIG. 14 and FIG. 15, a description will be given of the process of detecting the first cycle of the subsequent digit recognition in the operation of the subsequent digit dial detecting section 7. In step S41 (FIG. 14), 20 pp measured by the leading digit dial detector 6
One sample of the signal 71 after voice removal of s or 10 pps period is input. It is stored in the FIFO format RAM (S42).

The storage capacity of the RAM for storing the signal after speech removal is 53 samples, which is the maximum period of 27 samples plus 13 samples for measuring the left and right pulse shapes. In step S43, the reference waveform X and the input waveform Y are compared. The comparison is performed independently for the three parts of the front divided waveform, the center divided waveform, and the rear divided waveform. The difference calculation for this is shown in the following equations (18) to (20).

E _f (k) = (1 / L) Σ [| Y (n-12-T + i) −X ((k-1) T + i) |] / P _f (k) (18) Here, Σ represents the cumulative sum from i = 0 to L-1. E _c (k) = (1/8) Σ [| Y (n-12-T + i) -X ((k-1) T + i) |] / P _c (k) (19) where Σ Represents the cumulative sum from i = L to L + 7. E _b (k) = (1 / M) Σ [| Y (n-12-T + i) -X ((k-1) T + i) |] / P _b (k) (20) where Σ Represents the cumulative sum from i = L + 8 to T-1.

In equations (18) to (20), n represents the current sampling time (sample position), L, M, T and X are the same as those in step S20, and Y is steps S41 and S42. Is the waveform that was input and memorized by
P _f (k), P _c (k) and P _b (k) are the average amplitudes of the divided waveforms stored in step S20. k has the same serial number as k in step S20, but the upper limit value is a value obtained by subtracting 1 from the upper limit value.

12 in the Y pointer expression in the expressions (18) to (20) is for convenience of pulse shape measurement.
This is to know the sample value on the right side from the peak value of the rear side divided waveform. After completion of the comparison operation, the smallest value in E _f (k) is selected, and it is set to the minimum value E _f and k at that time is k _f ,
Also minimum E _c for E _c (k), the k minimum E _b and at that time the E _b (k) and k _b.

The one-cycle difference value r (n) is expressed by the equation (2) under the condition of the front side divided waveform difference value obtained by the following equation (21) and the rear side divided waveform difference value obtained by the equation (22).
Obtain as shown in 3).

S _f = {Σ│Y−X _f │} / ΣX _f (21) where Y = Y (n-12 + T + i) X _f = X ((k _f -1) T + i ), And Σ represents the cumulative sum from i = 0 to L−1.

S _b = {Σ | Y−X _b │} / ΣX _b (22) where Y = Y (n-12 + T + i) X _b = X ((k _b -1) T + i ), And Σ represents the cumulative sum from i = L + 8 to T−1.

N in equations (21) and (22),
L, T, X and Y are the same as those in formulas (18) to (20).

The one-cycle difference value r (n) is s _f <λ and
Condition 1 for s _b <λ and s _f ≧ λ or s _b ≧
In condition 2 of λ, in condition 1, r (n) = (E _f + E _c + E _b ) / 3 In condition 2, r (n) = η (23), and η is a difference performed in step S44 described later. The threshold value λ is set to about 0.6 using a value that does not satisfy the determination, for example, η = 1.0.

The reason for performing such a difference calculation will be described. Normally, the dial pulse waveform and the subsequent dial pulse waveform are very similar to each other. Therefore, if the comparison is made in units of one cycle, the subsequent dial pulse waveform can be detected and the voice waveform and the like can be eliminated. However, in rare cases, the tip waveform is different from that of the leading dial pulse waveform, or when the number of waveforms of the leading dial pulse waveform is smaller than the number of subsequent waveforms, for example, when the leading digit is "5" and the trailing digit is "0". Pulse waveforms that do not exist in the reference waveform created from the first digit may be included in the pulse waveforms in the succeeding digits, and the conditions are too strict for comparison on a cycle-by-cycle basis. I can't do it and overlook it.

A simple method for solving this is to loosen the criterion of the difference calculation result, but the defense against the voice waveform and the like becomes loose. Therefore, in the embodiment of the present invention, one period T is divided into three so that comparison can be performed in divided waveform units (see FIG. 12), and a synthetic one-period waveform formed by a combination of divided waveforms is to be compared. . Thus, by preserving the characteristics of the reference pulse waveform and creating a large number of reference waveforms, it is possible to avoid overlooking the pulse waveform of the subsequent digit.

Further, the reason for determining the value of the one-cycle difference value r (n) used for the difference judgment by dividing cases by using s _f and s _b in the equations (21) and (22) will be described. Simply 1
When the cycle difference value r (n) is obtained by the average value of the three of E _f , E _c , and E _b , the reference waveform is input in the front side divided waveform and the center divided waveform as in the mute pulse shown in FIG. If the waveforms match very well, the 1-cycle difference value r
The value of (n) becomes a level recognized as a dial pulse.

Particularly, in the reference waveform having a large difference between the average amplitudes of the front side divided waveform and the rear side divided waveform created from the first digit, the difference value E _b (k) from the rear side divided waveform of the mute pulse becomes small. The tendency becomes stronger. In order to solve this, the individual difference values s _f and s _b standardized by the equations (21) and (22) are calculated for the front side divided waveform and the rear side divided waveform, and one cycle difference of the equation (23) is calculated. Formula (2
By dividing cases as in condition 1 and condition 2 of 3),
If one of s _f and s _b agrees very well (shows a small value) but the other does not agree, the one-cycle difference value r
You can make (n) bad (large value).

In step S44, a difference judgment is made. That is, the difference value r (n) obtained in step S44 is equal to the predetermined number ζ.
If the following, it is determined that they match, and proceed to a new step (S
44Y), otherwise enter the next sample (S
44N). At this time, the predetermined number ζ is selected to be about 0.5.
In step S45, when the voice waveform and the like pass the difference determination, the pulse shape is measured and determined to eliminate the voice waveform and the like.

Since the RAM (not shown) has a waveform storage capacity for two cycles, 13 samples are stored on the left side of the front side divided waveform and 13 samples are stored on the right side of the rear side divided waveform. Therefore, the pulse shape should be measured. (See FIG. 12). Find the peak value of the front divided waveform (the position is P ₁ (corresponding to b ₁ in FIG. 13)) and the peak value of the rear divided waveform (the position is P ₂ (corresponding to b ₃ in FIG. 13)), and center it Then, the pulse shape is compared with the pulse shape stored in step S21.

That is, if the following expressions (24) to (27) are satisfied, it is determined that the waveform is a dial pulse waveform. Y (P ₁ -W ₃ ) / Y (P ₁ ) ≧ H ₃ (24) Y (P ₁ -W ₄ ) / Y (P ₁ ) ≧ H ₄ (25) Y (P ₂ -W ₇ ) / Y (P ₂ ) ≧ H ₇ (26) Y (P ₂ -W ₈ ) / Y (P ₂ ) ≧ H ₈ (27) When these equations satisfy the front and rear pulse shapes, dial pulse waveform To consider.

In step S46, the counter is initialized. The counter becomes 0 at the division position of the unit waveform and becomes 1.
The number of samples up to 2T (rounded up to integer, the same applies below) is counted. However, the detection of the leading edge of the succeeding digit is special, and since the waveform for one cycle that already satisfies the difference condition is stored in the RAM, the value of the cycle counter is 1.0T when it is regarded as a dial pulse waveform. And This is a temporary decision, and if the result of the difference calculation subsequently performed becomes a better value (smaller value), it is re-corrected at that time.

In step S47, one sample is input as in step 41, and then stored in the FIFO RAM (S48, FIG. 15). In step S49, the counter is incremented. In step S50, the same difference calculation as in step S43 is performed. 1 in step S51
The difference value r (n-1) in the previous sample is compared with the difference value r (n) in the current sample, and if r (n-1)> r (n), then it is stored as the minimum difference value R _v. , The value of the counter at that time is stored as the minimum difference position R _p .

In step S52, the counter value is 1.2.
If it is T, the process proceeds to step S53 (S52
Y), and if it is less than that, the next input (S4) is performed to check the difference value.
It returns to 7) (S52N). The reason for setting the upper limit of the range for performing the difference calculation to 1.2T is that the leading digit dial is detected (S13).
This is because, since the period of the subsequent digit dial has a jitter with respect to the period T obtained in step 1, it is necessary to detect the dial value in a wide range of about 20%.

In step S53, the counter is initialized using the minimum difference position R _p . That is, 1.2T-R _p is used as the counter value. As a result, the boundary position of the unit waveform becomes 0 as the counter value. In step S54, the pulse shape of the unit waveform ending at the minimum difference position R _p is measured to determine the pulse shape value P _s . The measurement is step S45.
Perform in the same manner as described above. Next, when both the front side divided waveform and the rear side divided waveform are pulses, P _s = 2, and when one is not a pulse, P _s = 1 and when neither is a pulse, P _s = 0. In step S54, since the pulse shape has already been confirmed in step S45, P _s = 2 is always satisfied.

FIG. 16 shows steps S51 to S54.
It is shown that the likelihood (likelihood) is determined from the minimum difference value R _v , the minimum difference position R _p, and the pulse shape value P _{s obtained in} . In step S55, this likelihood information is measured. Likelihood information is used to detect the end of the dial pulse waveform and is measured every time a unit waveform is divided. The likelihood information in step S55 is 2 because it is immediately after the detection of the first unit waveform.

FIG. 17 shows a normal dial pulse in which the mute pulse rising at the time point a has a cycle from the time points b to d.
A waveform is shown in the case of being detected as a pseudo unit waveform from time points a to c because the pulse waveform is approached. In such a case, steps S47 to S55 (see FIG. 1) are shown.
4, it cannot be eliminated under the leading edge detection condition of the succeeding digit described in FIG. 15), so the determination is made in the processing of the second cycle.

18 and 19 show the flow of the operation of the processing of this second cycle. Steps S61 to S
At 63, the same processing as steps S47 to S49 is performed. In step S64, control is performed so that only sample values are stored until the counter exceeds the lower limit of the time range for waveform comparison (S64N) so as not to unnecessarily capture information. The lower limit is 0.5T, and when it exceeds this (S64Y), the process proceeds to step S65. Step S
In steps 65 and S66, the same processing as in steps S50 and S51 is performed, and the minimum difference value R _v and the minimum difference position R _p
Ask for.

In step S67, comparison with the tail waveform is performed. The comparison calculation is performed using equations (18) to (20), and k used in step S20 is set as a value indicating the tail waveform, that is, a value obtained by adding 1 to the dial numerical value recognized at the leading digit. After that, the three calculation results are averaged, and if the average value is, for example, 0.3 or less, the comparison result R _t of the tail waveform is set to 1,
If not satisfied, R _t = 0. However, when R _t = 1 it is not reset to 0. The comparison result of the tail waveform is used at the time of detecting the end as interpolation information of a waveform having a small amount of information such as dial "1".

In step S68, as in step S52, when the counter value is 1.2T or less, the previous processing is repeated (S68N), and the counter value is 1.2.
If it is T (S68Y), the process proceeds to step S69.

In step S69 (FIG. 19), exclusion determination of mute pulse or the like is performed. That is, when the mute pulse in FIG. 17 is set as the leading end, the determination is made by utilizing the shift of the minimum difference position in the second cycle. mute·
When the pulse is erroneously recognized as the tip waveform, the time point a becomes the tip sample point as shown in FIG. In the second cycle, the time point c is counted as 0, but from that time point c between the sampling points at which the counter reaches 1.2T, a regular dial
There is a pulse waveform.

Therefore, the minimum difference position R _p is the position that delimits the normal dial pulse waveform, that is, the time point d, which is smaller than the value measured from the time point b when the normal tip sample is obtained. The degree of decrease is the time points b and c of pulse waveform
Are almost equal to each other, and are 0.2T to 0.3T. Therefore, in the embodiment of the present invention, the minimum difference position R _p is 0.
If it is 8 or less, it is determined that the detection is erroneous due to the mute pulse. If it is determined to be erroneous detection and it is determined that the waveform should be excluded (S69N), the process proceeds to step S70. If not, a regular waveform is detected (S69Y),
Proceed to step S71.

At step S70, the counter value is set to 1.2.
Initialize T-R _p, and 1 dial number. Step S71 the value of the counter in initialized to 1.2 T-R _p, and 2 dial numbers. In step S72, the pulse shape value P _s is obtained as in step S54. In step S73, likelihood information is measured according to FIG. Likelihood information is measured and stored for each unit waveform.
If the pulse is excluded, the likelihood information obtained in step S55 is discarded and the likelihood information obtained in step S73 becomes the first stored value.

FIG. 20 and FIG. 21 show the flow of operations in the subsequent digit dial detecting section 7 after the third cycle of the end detection and dial numerical value recognition. The first half of the processing in the third and subsequent cycles is almost the same as the processing in the second cycle (FIGS. 18 and 19), and step S81 includes steps S61 and S82.
Is step S62, step S83 is step S63,
Step S84 carries out the same processing as step S64, step S85 carries out step S65, step S86 carries out step S66, step S87 carries out step S67, step S88 carries out step S68, step S89 carries out step S72, and step S90 carries out step S73.

At step 91, the counter is initialized and
Set its value to 1.2T-R _p . Since the minimum difference value R _v is not performed clear unit waveforms segment when it becomes 0.5 or more divided by 1.0 T, the counter sets the 0.2T. In step S92, the dial numerical value is incremented. In step S93, the end is determined. The end determination is made based on the arrangement of the likelihood information, and if the sum of the latest three pieces of likelihood information shown in FIG. 16 is 1 or less, the end is determined (S93Y).

When the mute pulse is not added to the tail of the dial pulse waveform, the likelihood information is arranged in the sequence "00".
When it reaches 0 ", it is the end (sum is 0),
If there is a pulse, "100", "010",
It becomes one of "001" (the sum is 1). The reason for determining the end by the arrangement of the three pieces of likelihood information appears when noise appears in the middle of the dial pulse waveform.
This is to allow sequences such as 01 ”,“ 101 ”, and“ 110. ”Such a determination cannot be made with the sequence of two likelihood information. If it is not determined to be the end, step S8.
The operation from 1 is repeated (S93N).

If it is determined to be the end (S93Y), the process proceeds to step S94. In step S94, the dial numerical value is determined. The dial number is the dial number stored in the previous step minus three. In step S95, dial waveform recognition is performed. That is, step S22
In FIG. 10, when it is determined that the tail waveforms can be compared and the tail waveform comparison result R _t is 1, it is considered as a dial pulse waveform, and when R _t = 0, the dial pulse is Discard the dialed value without considering it as a waveform.

In step S22, if the tail waveform comparison is not enabled, it is regarded as a dial pulse waveform. By performing such recognition processing, the probability of erroneously recognizing a voice signal as a dial "1" is reduced. If it is determined in step S96 as a dial pulse waveform,
The dial numerical value is output from the subsequent digit dial detecting section 7 to the PB signal transmitting section 8 as the subsequent digit dial numerical value information 29.
After that, initialization operation such as clearing of the RAM for storing the input waveform to detect the subsequent dial pulse waveform is performed, and then the process returns to step S41 (FIG. 14).

[0152]

According to the present invention, the following effects occur.

First, since the leading digit dial is detected by the difference calculation using a plurality of cycles, the dial pulse waveform can be detected even if the dial numerical value is not known on the detecting side, and it depends on the receiving level. Not possible to detect.

Secondly, in the first digit detection, the pulse shape at the time of detecting the dial pulse waveform is measured to detect the end of the dial pulse waveform, so that the end detection excluding the voice waveform can be performed.

Thirdly, in the detection of the leading digit, the unit waveform is accurately distinguished by the product-sum operation with the rectangular waveform, and the comparison judgment with the divided waveform power of the portion which is surely the dial pulse waveform is made. Since this is done, it is possible to exclude the interfering signals such as the mute pulse at the leading end and the trailing end and accurately recognize the dial value.

Fourthly, since the make rate of the dial pulse is 30% in the detection of the succeeding digit, one period of the reference waveform is divided into three, and the difference between the combined waveform and the input waveform is calculated. It is possible to make a determination without loosening the determination reference of the difference calculation result, and further, the front side divided waveform difference value s _f and the rear side divided waveform difference value s _b are divided into cases, and the front side and the rear side are equal to each other. Since the coincidence or non-coincidence of the waveforms is determined based on the one-cycle difference value r (n) at that time, it is possible to reduce the case where the voice waveform or the mute pulse waveform is mistakenly recognized as the dial pulse waveform.

Fifth, since the end is detected by using the likelihood information in the subsequent digit detection, the dial numerical value can be accurately recognized without erroneously recognizing the end in the middle of the dial pulse waveform.

Sixth, in detecting the subsequent digit, the minimum difference position in the second cycle is checked, and if it is smaller than a predetermined value, the tip position is corrected. Therefore, a pseudo dial pulse waveform including a mute pulse is obtained. Can be excluded.

Seventh, since the correction is made by the minimum difference position of the initial value of the counter which divides the dial waveform in the subsequent digit detection, the dial pulse waveform including the jitter can be detected.

Eighth, since it is determined whether or not it is the dial waveform by comparing with the effective tail waveform in the subsequent digit detection, it is less likely that the voice signal is erroneously recognized as an isolated dial pulse waveform. .

Ninth, the sampling rate is decreased by the absolute value calculation and the thinning-out processing, and before the dial pulse waveform is detected, the low-speed sampling signal for 20 pps and 10 pp
An independent means for storing the low-speed sample signal for s is prepared,
After the dial pulse waveform is detected, the configuration is changed so that it becomes an integral storage means, so that it can be realized using an inexpensive DSP with a small storage capacity.

Tenthly, since the abnormal waveform judgment is performed after the division of the leading digit dial waveform and the special dial value is notified to the receiving side system, the system side requests the caller to make a call again. Will be possible.

Eleventh, since the received signal is passed through a high-pass filter having a cutoff frequency sufficiently higher than the low cutoff frequency of the telephone line and having a linear phase characteristic, the ringing and the first formant of voice are attenuated. The dial pulse waveform can be detected reliably.

Twelfthly, the average value for a certain past period is calculated,
By storing the variation information around the average value for the period corresponding to the entire first digit dial pulse, it is possible to make judgments for a long period of time, and to be surely not impressed by signals such as PB dial signals, facsimile procedure signals, voice, and music. You can

Thirteenth, since the wraparound voice is removed by the 2-line / 4-line converter, the dial pulse can be correctly detected even during the voice guidance.

Fourteenth, since the pulse-like error waveform generated in the DC component reproducing process performed during voice removal is compared with the low-speed sample signal before voice removal and removed, misidentification of the dial number can be reduced. Therefore, the effect of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a detailed configuration of a preprocessing unit which is a component of FIG.

FIG. 3 is a waveform diagram illustrating the operation of a high-pass filter and an absolute value calculation unit, which are components of FIG.

FIG. 4 is a circuit configuration diagram of a voice removing unit which is a component of FIG.

5 is a waveform diagram of each part of the voice removing unit of FIG.

6 is a circuit configuration diagram of a leading digit dial detection unit which is a component of FIG.

FIG. 7 is a flowchart illustrating an operation flow of a leading digit dial detection unit in FIGS. 1 and 6.

FIG. 8 is a flowchart illustrating an operation flow of the leading digit dial detection unit in FIGS. 1 and 6 together with FIG. 7;

9 is a flowchart illustrating an operation flow of the leading digit dial detection unit in FIGS. 1 and 6 together with FIGS. 7 and 8;

10 is a flowchart illustrating an operation flow of the leading digit dial detection unit in FIGS. 1 and 6 together with FIGS. 7, 8 and 9.

FIG. 11 is a waveform diagram for explaining a waveform division operation of the leading digit dial detection unit.

[Fig. 12] Mute on the tip side of the leading digit dial detector
It is a waveform diagram explaining the operation of excluding the pulse.

FIG. 13 is a waveform diagram for explaining a pulse shape measuring operation of the leading digit dial detection unit.

14 is a flowchart showing a flow of a dial waveform detecting operation in a succeeding digit dial detecting unit which is a component of FIG.

15 is a flowchart showing a flow of a dial waveform detecting operation in the subsequent digit dial detecting unit which is a component of FIG. 1 together with FIG.

FIG. 16 is a likelihood diagram for explaining a method of determining likelihood information.

FIG. 17 is a waveform diagram illustrating a mute / pulse exclusion operation of a succeeding digit dial detection unit.

FIG. 18 is a flowchart showing a flow of a mute / pulse exclusion operation in a succeeding digit dial detection unit.

19 is a flowchart showing the flow of a mute / pulse exclusion operation in the succeeding digit dial detection unit together with FIG.

FIG. 20 is a flowchart showing a flow of a dial numerical value recognition operation in a succeeding digit dial detection unit.

21 is a flowchart showing the flow of dial numerical value recognition operation in the succeeding digit dial detection unit together with FIG. 20.

[Explanation of symbols]

 1 Telephone line interface 2 AD converter 3 DA converter 4 Echo canceller 5 Pre-processing unit 6 Leading digit dial detecting unit 7 Subsequent digit dial detecting unit 8 PB signal sending unit 9 Switch 10 DA converter 11 AD converter 12 System line Interface 15 Voice remover 21 Telephone line 22, 24, 26, 31 Received signal 23, 25, 32 Transmitted signal 27, 27a, 27b Low speed sample signal 28 Lead digit numerical value information 29 Subsequent digit numerical value information 30 Dial signal 33 System signal Line 34 DC loop closure information 35 Switch control signal 36 First digit dial waveform information 37 Short-term change information 38 First digit change information 41 High-pass filter (HPF) 42 Absolute value calculator 43a, 43b Low-pass filter ( LPF) 44a, 44b thinning processing unit 1 Switch 52 First digit dial start detection unit 53 First digit dial end detection unit 54 First digit dial waveform characteristic storage unit 55 Switch 61 High-pass filter (HPF) 62 DC component regenerator 63 Delay device 64 Error waveform remover 65 Slicer 66 Switch 67 Change calculation unit 68 Change storage unit 69 Error waveform 71 Signal after voice removal 72 Pulse shape information 73 Switch control signal 74 First digit dial waveform storage information 76 Signal with voice signal component removed 77 Signal after DC component reproduction 78 Delayed signal 79 Signal with error waveform removed

Claims (17)

[Claims] 1. A reception signal (26) including a dial signal.
The preprocessing means (5) for shifting the occupied frequency band to the low frequency side including the direct current component by obtaining the absolute value of and performing low speed sampling and outputting the low speed sampling signal (27); As a signal (71) after removing the audio signal included in 27) and removing the audio, a short-term change information of the amplitude of the low-speed sample signal (27) in a predetermined period is used as short-term change information (37). The short-term change information (37) is stored only for a period corresponding to the entire period of the leading digit dial, and the stored contents are stored in the leading digit variation information (3).
8) voice removing means (15) for obtaining, and the short-term variation information by performing difference calculation on a plurality of different periods for the components of the dial signal included in the signal (71) after the voice removal. (37) detects the start of the leading digit dial, detects the end of the leading digit dial from the leading digit change information (38) and represents the leading digit dial waveform characteristic (36), and First digit dial numerical information (28) showing the numerical value of the first digit dial,
Switch control signal (35) indicating the end of the first digit dial
The first digit dial detection means (6) for obtaining the signal, the first digit dial waveform information (36) and the signal (71) after voice removal are received, and the signal (7) after voice removal is received.
1) and the leading digit dial waveform information (36) are compared in waveform to perform a difference operation to detect the waveform of the component of the subsequent dial signal and to output the subsequent digit dial numerical information (29). A dial detecting device including a detecting means (7). 2. The leading digit dial detecting means (6) detects the end of the waveform when the leading digit dial detecting means (6) does not detect a waveform within a predetermined period from the time when the beginning digit dialing start is detected by the short period change information (37). Recognize as (S
11Y) The dial detection device according to claim 1. 3. The leading digit dial detecting means (6) performs a product-sum operation of the waveform represented by the leading digit change information (38) and a square wave representing the period of this waveform to optimize the period and phase. A value is obtained and divided into unit waveforms (S13), and the power (P _f , P _b ) of the front side divided waveform of the front side portion and the rear side divided waveform of the rear side portion in this division is judged to exclude the mute pulse. The dial detecting device according to claim 1, wherein the determination (S14) is performed. 4. The leading digit dial detecting means (6) includes a switch control signal (3) indicating the end of the leading digit dial.
Until the time point 5) is obtained, the waveforms of the components of a plurality of dial signals having different dial speeds are detected so that each waveform information can be separately stored and stored, and the switch control signal (3
After the time point 5) is obtained, the waveform information detected from the components of a plurality of dial signals having different dial speeds are not individually divided but integrated and integrated into the leading digit dial waveform information (3
The dial detection device according to claim 1, wherein the dial detection device is stored to obtain (6) (S19). 5. When the succeeding digit dial detecting means (7) compares the waveforms and performs difference calculation, the leading digit dial waveform information (36) indicates the front side of the cycle of the waveform represented by the waveform information (36).
The front side divided waveform difference value (s _f ) and the rear side divided waveform difference value (s) of the waveform (Y) divided into three in the center and the rear side and the reference waveform (X)
_{When b} ) is less than or equal to the predetermined value (λ) of the waveform difference value, and the one-cycle difference value (r (n)) is less than or equal to the predetermined value (ζ) of the one-cycle difference value, the waveform matching is detected. (S43-S46) The dial detection device according to claim 1. 6. When the succeeding digit dial detecting means (7) compares the waveforms and performs difference calculation, the leading digit dial waveform information (36) indicates the front side of the cycle of the waveform represented by the waveform information (36).
The counter value that counts the number of sections for dividing the waveform is made wider than the jitter of the period of the dial pulse signal, by comparing the waveforms with the waveform divided into three parts in the center and the rear side as a unit. Initialization is performed using the value of the minimum difference position (R _p ), which is the position where the difference value obtained by the difference calculation by comparing the waveforms measured in the selected range is the minimum value (S 50 to S 53). ) The dial detecting device according to claim 1. 7. The following digit dial detection means (7) is a position where the difference value obtained by the waveform comparison and the difference calculation shows a minimum value when the waveform comparison and the difference calculation are performed. When the second minimum differential position is detected within a predetermined period after the minimum differential position is first detected, the pulse of the first minimum differential position is recognized as a mute pulse and excluded, and the second minimum differential position is detected. The dial detection device according to claim 1, wherein the minimum difference position is recognized as a new tip sample position (S65, S66). 8. When the succeeding digit dial detecting means (7) compares the waveforms and performs difference calculation, the leading digit dial waveform information (36) indicates the front side of the cycle of the waveform represented by the waveform information (36).
The waveform comparison is performed with the waveform divided into three parts in the center and the rear side as a unit, and the minimum difference value (R _v ) showing the minimum difference value obtained by the difference calculation and the temporal position of this minimum difference value. The likelihood information indicating the existence of a pulse waveform is measured based on the minimum difference position (R _p ) indicating the pulse shape value and the pulse shape value (P _s ) indicating the waveform of the component of the detected subsequent dial signal. Then, when the measured value shows a predetermined value, it is determined that the pulse waveform is terminated (S55, S7).
3, S90) The dial detection device according to claim 1. 9. The succeeding digit dial detecting means (7) compares the waveform of the leading digit dial waveform information (36) and the signal (71) after the voice removal to perform a difference operation to calculate a difference of the succeeding dial signal. When detecting the waveform of the component, it is determined whether or not it is a dial pulse waveform by comparing the waveform with the tail waveform of the leading digit dial waveform information (36) (S67). Dial detection device. 10. The preprocessing means (5) outputs the received signal (26) from a low cutoff frequency of a telephone line (21) in order to obtain an absolute value of the received signal (26) including the dial signal. 2. The dial detection device according to claim 1, further comprising a high-pass filter (41) having a substantially linear phase characteristic that cuts off at a sufficiently high frequency. 11. The pre-processing means (5) includes a decimation processing unit (44) for decimation sampling the output of the absolute value computing unit (42) to obtain the low speed sample signal (27). The dial detection device according to claim 1. 12. The leading digit dial detecting means (6)
Stores the amount of change (Z (n)) in the received signal with respect to the average value of the received signal (26) in a predetermined period in the past for the period corresponding to the leading digit dial signal, and within the period, the predetermined period or more is exceeded. 2. The dial detecting device according to claim 1, wherein if there is a change of a predetermined value or more, it is regarded as a dial waveform, and if not, it is regarded as a dial signal (S15). 13. The leading digit dial detecting means (6)
However, when the waveform of the component of the dial signal cannot be detected in the signal (71) after the voice removal and an abnormal waveform is detected, a dial numerical value is provided to notify that no dial signal was detected. Other notification information is output (S
16, S17) The dial detection device according to claim 1. 14. The leading digit dial detecting means (6)
However, when the waveform of the component of the subsequent dial signal is detected by comparing the waveform of the leading digit dial waveform information (36) with the voice-removed signal (71), the leading digit dial waveform information (36) The dial detection device according to claim 1, wherein it is determined whether or not it is a dial pulse waveform by comparing the waveform with the waveform of the tail of the dial detection waveform (S22). 15. A signal (76) in which the voice removing means (15) removes a component based on a voice signal included in the low-speed sample signal (27) to remove a low frequency component.
And a DC component regenerator (6) for obtaining a signal (77) in which the DC component of the signal (76) from which the low frequency component has been removed is reproduced to obtain a DC component.
2) and a delay device (6) for delaying the low-speed sample signal (27) to obtain a delayed signal (78) in order to compensate for a time delay in the high-pass filter (61).
3) and the error waveform (69) which may be included in the signal (77) reproduced from the direct current component is removed with reference to the delayed signal (78) to obtain a signal (79) from which the error waveform is removed. Error waveform remover (64) and a slicer (65) for slicing the signal (79) from which the error waveform has been removed to obtain a signal (71) after speech removal having an amplitude of one polarity. The dial detection device according to claim 1. 16. A change calculation section (67) for obtaining the short-term change information (37) a plurality of times by the voice removing means (15) in a period corresponding to the entire period of the leading digit dial. The dial detecting device according to claim 1, further comprising: a change storage unit (68) for storing the plurality of short-term information (37) and obtaining the stored content as the leading digit change information (38). . 17. The leading digit dial detecting means (6)
However, the leading digit dial start detection unit (72) for obtaining pulse shape information (72) representing the pulse shape of the dial waveform of the leading digit from the signal (71) after the voice removal and the short-term change information (37). 52) and the pulse shape information (72), it is detected from the leading digit change information (38) and the voice-removed signal (71) that the leading digit dialing is finished, A leading digit dial end detection unit (53) for obtaining digit dial numerical information (28), the switch control signal (35), and leading digit dial waveform storage information (74) to be stored as a leading digit dial waveform. The dial detection according to claim 1, further comprising: a leading digit dial waveform characteristic storage unit (54) for storing the leading digit dial waveform storage information (74) to obtain the leading digit dial waveform information (36). Location.