JP2000209620A - Voice band impulse noise measuring device - Google Patents

Abstract

(57) [Summary] [Problem] To accurately measure the number of occurrences of voice band impulse noise occurring in a communication line formed between telephones 5 and 4 according to the purpose of use. SOLUTION: A voice band impulse noise measuring device 1 for measuring a voice band impulse noise generated in a telephone line in a state where a telephone line is formed between telephones 5, 4.
In, the voice band impulse noise generated in the speech line was input and passed through a plurality of band-pass filters 12a to 12c each having a pass frequency band set to a different frequency band in the voice band frequency region, and each band pass filter. A plurality of normalizing means 15a to 15i for normalizing the signal waveform of each voice band impulse noise;
A plurality of counters 16a to 16i for counting the number of occurrences of the voice band impulse noise normalized by each normalizing means are provided, and a communication line is established based on the number of occurrences of each frequency band counted by the plurality of counters. evaluate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring voice band impulse noise generated in a telephone line in a state where a telephone line is formed between the telephone line and a telephone terminal of a communication destination via a public telephone network. The present invention relates to a voice band impulse noise measuring device.

[0002]

2. Description of the Related Art When a public telephone network in which a number of exchanges are incorporated is newly constructed, or when a new exchange is incorporated in the public telephone network, it is confirmed that the public telephone network operates normally. After the operation, various tests will be conducted for maintenance.

[0003] Among these various tests, a DT (dial tone) signal and a BT signal transmitted from the exchange to the telephone set are included.
Tests have been conducted to measure voice band sound signals such as (busy tone busy tone) signal and RBT (ring back tone ringing tone) signal. It is important for the quality of telephones and public telephone networks that these dial tones, ring back tones, and busy tones be heard at an appropriate timing and volume for the user.

[0004] However, the user can enjoy a comfortable conversation with the other party in a state in which a telephone line is formed between the user's own telephone and the other party's telephone, and comfortably perform data communication by FAX or modem. To do so, it is necessary to improve the quality of the telephone line itself. When a long-distance call is made, the length of the communication line is long, so noise generated by various electronic devices including switches and repeaters existing on the path of the communication line and noise caused by crosstalk from adjacent channels are included. There is.

[0005]

Among these noises, a measurement method has been established for noise that constantly occurs, including crosstalk, and measures have been taken. However, measurement methods and countermeasures for sporadic impulse noise have not been sufficiently established. In particular, voice band impulse noise in the voice band frequency region gives a user considerable discomfort depending on its volume and frequency, and has a great effect on data communication by FAX or modem.

Hitherto, it has been practiced to electrically measure impulse noise generated in a communication line to determine the frequency of occurrence. However, in this measurement, evaluation was performed without subdividing the frequency limit in consideration of the general characteristics of impulse noise. Therefore, the obtained measurement result may be considerably different from the user's feeling.

[0007] Although impulse noise may vary depending on the generation source, all impulse noises are measured as the same impulse noise. Therefore, when impulse noise exceeding an allowable limit is generated, the type of the noise is determined. There was concern that it was difficult to identify.

[0008] The present invention has been made in view of such circumstances, and uses a plurality of band-pass filters having different passing frequency bands to reduce a voice band impulse noise generated in a communication line to a physical quantity matching a user's sense. It is an object of the present invention to provide a voice band impulse noise measuring device which can measure as a noise and can roughly analyze the type of noise from the measured value.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a telephone connected to a public telephone network in which an exchange is incorporated, and the telephone is connected to the telephone via the public telephone network. In a voice band impulse noise measuring device for measuring a voice band impulse noise generated in a telephone line in a state where a telephone line is formed between the telephone terminal and the telephone terminal, the telephone line is connected to a signal path of a telephone to a public telephone network, and is connected to the telephone line. The generated voice band impulse noise is input, a plurality of band pass filters each having a pass frequency band set to a different frequency band in the voice band frequency domain, and a signal of each voice band impulse noise passing through each band pass filter. A plurality of normalizing means for normalizing the waveform, and generation of voice band impulse noise normalized by each of the normalizing means. And a plurality of counters for counting the number of times, and so as to evaluate the communication line based on the number of occurrences of each frequency band, which is counted by the plurality of counters.

[0010] In the voice band impulse noise measuring apparatus configured as described above, the impulse noise generated in the speech line is transmitted to a plurality of band-pass filters each having a pass frequency band set to a different frequency band in the voice band frequency region. Are classified for each frequency band. Then, the number of occurrences of each audio band impulse noise is counted by a counter provided for each frequency band.

As described above, only the voice band impulse noise whose frequency is present in the voice band frequency region is extracted from the impulse noise generated in the communication line and the frequency of occurrence is counted. Value can be obtained.

Further, since the generated voice band impulse noise is classified into a plurality of frequency bands and the frequency of occurrence in each frequency band is measured, it is possible to efficiently identify the source of the noise. There is.

Still another invention has a telephone connected to a public telephone network in which an exchange is incorporated, and forms a telephone line with the telephone terminal of the other party via the public telephone network for the telephone. In the voice band impulse noise measuring device for measuring the voice band impulse noise generated in the telephone line in the state of being connected, the voice band impulse noise generated in the telephone line is connected to the signal path of the telephone to the public telephone network, and is passed therethrough. A plurality of bandpass filters whose frequency bands are set to mutually different frequency bands in the voice band frequency domain and a plurality of level comparisons for classifying each voice band impulse noise passing through each bandpass filter into a plurality of signal levels. Circuit and the signal waveform of each voice band impulse noise classified by each level comparing circuit. Number normalizing means, and a plurality of counters for counting the number of occurrences of the voice band impulse noise normalized by each of the normalizing means, for each frequency band and each signal level counted by the plurality of counters. The communication line is evaluated based on the number of occurrences of each call.

[0014] In the voice band impulse noise measuring apparatus thus constructed, the generated voice band impulse noise is classified into a plurality of frequency bands and divided into a plurality of frequency bands, similarly to the voice band impulse noise measuring apparatus of the invention described above. The frequency of occurrence is determined for each signal level, and the frequency of occurrence is determined for each signal level. Therefore, the quality of the telephone line can be evaluated with higher accuracy.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a schematic configuration of a voice band impulse noise measuring device according to an embodiment.

This voice band impulse noise measuring device 1
Are connected to a public telephone network 2 in which a plurality of exchanges are installed instead of ordinary subscriber telephones. One test terminal 4 is connected to the public telephone network 2 in addition to a plurality of general telephone terminals 3.

The test terminal 4 has its own telephone number, like the general telephone terminal 3, and performs a receiving operation in response to a calling operation from an exchange incorporated in the public telephone network 2, and performs a call receiving operation. Form a telephone line with the telephone. However, this trial terminal 4 is not provided with a handset, and even if a telephone line is formed, voice cannot be input from the trial terminal 4.

The voice band impulse noise measuring device 1 comprises:
Telephone circuit 5 having almost the same function as ordinary telephone terminal 3
A sequence control unit 6 for operating the telephone circuit 5 in accordance with a predetermined procedure, a signal receiving unit 7, a signal discriminating circuit 8, a signal processing circuit 9, a data collecting unit 10, and a collected file 11. ing.

The signal receiving section 7 receives various audio band sound signals transmitted from the public telephone network 2 to the telephone circuit 5, and the signal judgment circuit 8 and the signal processing circuit 9 convert the audio band sound signals under the optimum conditions. Amplify by a predetermined factor so that it can be processed. The signal discriminating circuit 8 includes a DT signal, an RBT signal, and a DT signal included in the audio band sound signal from the public line network 2 received by the signal receiving unit 7.
A signal and a BT signal are detected, and the reception state of each of these signals is transmitted to the sequence control unit 6 and the data collection unit 10.

FIG. 3 is a block diagram showing a detailed configuration of the signal processing circuit 9.

Various signals including voice band impulse noise input from the public line network 2 to the telephone circuit 5 incorporated in the voice band impulse noise measuring device 1 are received by the signal receiving section 7 and sent to the signal processing circuit 9. Is entered.

Note that the period during which the processing result of the signal processing circuit 9 is adopted is limited to the time during which a telephone line is formed between the telephone circuit 5 and the test terminal 4. The description of the DT signal, RBT signal, and BT signal received during the period or after the call line is cut off is omitted. Then, description will be made by taking as an example a case where voice band impulse noise generated in the communication line is input in a state where the communication line is formed.

The voice band impulse noise received by the signal receiving unit 7 and input to the signal processing circuit 9 is sent to three band-pass filters (hereinafter abbreviated as BPFs) 12a, 12b and 12c having different pass frequency bands. Is entered. Each of the BPFs 12a, 12b, 12c has a frequency characteristic shown in FIG. That is. Each BPF12
a, 12b, and 12c indicate that the pass center frequency f _C is 2
The pass bandwidth BW, which is set to 400 Hz, 1800 Hz, and 600 Hz and is 20 dB lower than the signal peak level at the pass center frequency f _C , is set to ± 200 Hz, that is, the combined pass bandwidth is set to 400 Hz.

Each BPF 12a. The voice band impulse noise that has passed through 12b and 12c
b and 13c, for example, after full-wave rectification, three comparators (comparators) 14a in which the signal levels of the center values are set to H (high) level, M (intermediate) level, and L (low) level, respectively , 14d, 14g, 14b, 14
e, 14h, 14c, 14f, and 14i.

Each of the comparators 14a to 14i outputs a normalized H level signal of, for example, 1 volt when the signal level of the voice band impulse noise input to itself is within the level range set for itself. That is, each BPF 12
a, 12b, and 12c, each voice band impulse noise divided for each frequency band is output to each comparator (comparator) 1
4a to 14i, the signal is further divided for each signal level. The normalized H-level voice band impulse noise output from each of the comparators (comparators) 14a to 14i is input to each of the latch circuits 15a to 15i as a normalizing means.

Each of the latch circuits 15a to 15c as normalizing means
15i stores and holds the input H level signal, and when the output command signal is input to the control terminal, outputs the stored and held H level signal to each of the next counters 16a to 16i.
Clear stored contents. Each of the latch circuits 15a to 15
The cycle T = 20 m from the clock circuit 17 is applied to the control terminal of i.
The s clock signal is input as an output command signal. Therefore, even if a plurality of H level signals are input in one cycle T (= 20 ms), each latch circuit 15a to 15i outputs one H in one cycle T (= 20 ms).
Outputs only the level signal. If no H level signal is input during the period T, the H
No level signal is output.

The H level signals output from the latch circuits 15a to 15i are input to the counters 16a to 16i, respectively. Each of the counters 16a to 16i receives the input H
The number of level signals, that is, the number of voice band impulse noises is counted. Then, when a reset signal is input from the data collection unit 10 to the reset terminal, the count value of the voice band impulse noise is reset to “0”.

The signal waveform of each part in the signal processing circuit 9 thus configured will be described with reference to a time chart shown in FIG.

From the signal receiving section 7, a plurality of types of voice band impulse noises b ₁ ,
When the received signal a including b ₂ and b ₃ is output, each BPF
Output signals c ₁ , c ₂ , c _{3 of} 12a, 12b, 12c
Contains only speech band impulse noises b ₁ , b ₂ , and b ₃ each having a corresponding frequency component.

These output signals c ₁ , c ₂ , c ₃ are full-wave rectified by the rectifier circuits 13a, 13b, 13c.
Output signals d ₁ , d of the rectifier circuits 13a, 13b, 13c
₂ and d ₃ include voice band impulse noises b ₁₁ , b ₂₂ , and b ₃₃ in a full-wave rectified state. Each output signal d ₁ ,
The signal levels of d ₂ and d ₃ are temporarily set to H (high)
In the case of the level range, each comparator 1 corresponding to the H level
Each of the normalized output signals e ₁ , e ₄ , e ₇ including a plurality of H level signals within the duration of the corresponding voice band impulse noises b ₁₁ , b ₂₂ , b ₃₃ from 4a, 14d, 14g.
Is output.

Each of the normalized output signals e ₁ , e ₄ and e ₇ including the plurality of H level signals is supplied to the latch circuit 15a, 1
Input to 5d and 15g. Each output signal e ₁ , e ₄ , e
_As shown in the waveform of FIG. ₇ , one voice band impulse noise b ₁ , b ₂ , b ₃ is represented by a plurality of adjacent H level signals. However, in general, the duration of one voice band impulse noise b ₁ , b ₂ , b ₃ is 20 ms
Because of the following, the plurality of adjacent H-level signals are combined into one H-level signal by the latch circuits 15a, 15d, and 15g. Therefore, the latch circuits 15a,
Each of the output signals f ₁ , f ₄ and f ₇ of 15d and 15g has one H level signal g ₁ and g synchronized with the generation timing of the original voice band impulse noise b ₁ , b ₂ and b ₃ respectively.
_4, g ₇ are included.

Each output of the latch circuits 15a, 15d, 15g
Force signal f₁, F_Four, F₇Are the corresponding counters 16a,
Input to 16d and 16g. Each counter 16a, 16
d and 16g are output signal f₁, F_Four, F₇include
H level signal g₁, G_Four, G ₇The number of occurrences of
Has a frequency range specified by the BPFs 12a to 12c,
And a section divided by each of the comparators 14a, 14d and 14g.
Voice band impulse noise with constant signal level range
b₁, B_Two, B_ThreeIs counted.

The sequence control section 6 and the data collection section 10 of FIG. 1 carry out the measurement process of the speech band impulse noise according to the flowchart shown in FIG.

First, the sequence controller 6 sends an off-hook command to the telephone circuit 5 to bring the telephone circuit 5 into an off-hook state (S1). Next, when the signal discriminating circuit 8 detects the DT signal transmitted from the public line network 2 (S2), the sequence control unit 6 sends a dial command designating the test terminal 4 to the telephone circuit 5. Then, a dial signal designating the test terminal 4 is transmitted from the telephone circuit 5 (S3).

Then, when an RBT signal for calling the test terminal 4 is received from the exchange of the public line network 2 (S4), the test terminal 4 performs an off-hook operation and detects a conduction sound transmitted by the test terminal 4 (S4). S5) It is determined that a telephone line has been established (formed) between the telephone circuit 5 and the test terminal 4 (S6).

When the communication line is established, after a lapse of 3 to 5 seconds, the data collection unit 10 simultaneously sends a reset signal to each of the counters 16a to 16i of the signal processing circuit 9, and resets the counters 16a to 16i. The count value is reset to “0”. Then, to start the counting of the counter 16a~16i voice band impulse noise b ₁ again, b _2, b ₃ from "0" (S8).

When a predetermined measurement period Ta, such as 30 minutes or 1 hour, ends (S9), the data collection unit 10
Reads the number of occurrences of voice band impulse noise of each measurement condition counted by each of the counters 16a to 16i of the signal processing circuit 9 (S10). Then, the data collection unit 10
The collected number of generated voice band impulse noises is totaled for each frequency band and for each signal level, and data is edited so that a technician can understand at a glance the quality of the communication line (S11). Then, the data editing result is written to the collection file 11 (S12).

As described above, since a series of measurement processing for the voice band impulse noise generated in the telephone line has been completed, the sequence control unit 6 sends an on-hook command to the telephone circuit 5, and The established communication line is forcibly cut off (S13).

In the voice band impulse noise measuring apparatus 1 configured as described above, the impulse noise generated in the communication line formed between the telephone circuit 5 and the test terminal 4 via the public telephone network 2 is passed. Different frequency bands (center frequency: 2400H) in a voice band frequency range of 300 Hz to 3400 Hz, for example.
(z, 1800 Hz, 600 Hz) are divided for each frequency band by a plurality of band-pass filters 12a, 12b, 12c. Further, the signal level of each voice band impulse noise divided into each frequency band is compared with each comparator 14.
a to 14i, H (high) level, M (medium) level,
It is divided into L (low) levels.

As described above, the number of occurrences of each frequency band and each signal level in the voice band impulse noise generated in the communication line is measured by each of the counters 16a to 16i.

Accordingly, only the voice band impulse noise whose frequency is present in the voice band frequency region is extracted from the impulse noise generated on the speech line as a result, and the frequency of occurrence is counted. Measured values can be obtained.

Further, since the frequency range and signal level of the voice band impulse noise which occur frequently are specified, the selection range of the type of the voice band impulse noise is narrowed, and it is possible to estimate the cause of the voice band impulse noise. is there.

The present invention is not limited to the above embodiment. In the embodiment, the received voice band impulse noise is divided into three frequency domains. However, the number of frequency domain divisions is not limited to three, and can be divided into an arbitrary number. In addition, each BPF 12a-12
It is also possible to set the pass frequency range to be set to c to a specific frequency and extract only the voice band impulse noise having the specific frequency.

For example, when the frequency range and signal level range of voice band impulse noise generated by a specific electronic device incorporated in the public telephone network 2 are known, the frequency range and signal level of the known voice band impulse noise are known. By setting the range to the BPFs 12a to 12c and the comparators 14a to 14i, it is possible to immediately determine that a specific electronic device is abnormal when the corresponding voice band impulse noise is detected.

Further, in the embodiment, the specially designed test terminal 4 having no handset is used. However, when a normal telephone terminal 3 is used, when the handset is picked up and the handset is picked up, voice or sound is output from the handset. A soundproof cover may be attached to the handset so that ambient noise does not enter the telephone line.

Further, in the embodiment, as shown in FIG. 3, the signal processing circuit 9 is constituted by a plurality of analog hardware circuits including a BPF, a rectifier circuit, a comparator, a latch circuit, a counter, and the like. It is also possible to configure each circuit component with a digital circuit. In this case, the received signal a is naturally subjected to A / D conversion, and then the above-described various digital signal processing is performed.

[0048]

As described above, in the voice band impulse noise measuring apparatus of the present invention, voice band impulse noise is divided into a plurality of frequency bands by using a plurality of band-pass filters having different pass frequency bands. Further, the voice band impulse noise divided into a plurality of frequency bands is divided into a plurality of signal levels, and the number of occurrences of the voice band impulse noise for each frequency band and each signal level is measured.

Therefore, the voice band impulse noise generated in the communication line can be measured as a physical quantity matching the user's sense, and the source can be easily determined from the measured value.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a voice band impulse noise measuring device according to an embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram of a band-pass filter incorporated in the voice band impulse noise measuring device.

FIG. 3 is a detailed block diagram of a signal processing circuit incorporated in the voice band impulse noise measuring device.

FIG. 4 is a time chart showing a signal processing operation of a signal processing circuit incorporated in the voice band impulse noise measuring device.

FIG. 5 is a flowchart showing the operation of the voice band impulse noise measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Voice band impulse noise measuring device 2 ... Public telephone network 3 ... Telephone terminal 4 ... Test terminal 5 ... Telephone circuit 6 ... Sequence control unit 7 ... Signal receiving unit 8 ... Emerging judgment circuit 9 ... Signal processing circuit 10 ... Data collection unit 11: Collection file 12a to 12c BPF 13a to 13c Rectifier circuit 14a to 14i Comparator 15a to 15i Latch circuit 16a to 16i Counter 17: Clock circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuo Furuya 5-10-27 Minamiazabu, Minato-ku, Tokyo Inside Anritsu Corporation (72) Inventor Yu Ueno 3-9-1-2 Nishishinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. (72) Inventor Hiroshi Yamashita 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. F-term (reference) 5K019 AC07 BA51 BB38 CC09 CD05 DA04 DC05 5K042 AA03 BA05 CA04 CA23 DA13 DA22 EA02 FA06 FA08 GA01

Claims (2)

[Claims] 1. A telephone (5) connected to a public telephone network (2) in which an exchange is built, and a telephone (4) connected to a telephone terminal (4) of a called party via the public telephone network. A voice band impulse noise measuring device (1) for measuring voice band impulse noise generated in a communication line in a state where a communication line is formed between the telephone lines, wherein the telephone line is connected to a signal path for the public telephone network, and A plurality of band-pass filters (12a to 12c) each having a pass frequency band set to a different frequency band in the voice band frequency domain, and Multiple normalization means (1.
5a to 15i), and a plurality of counters (16a to 16i) for counting the number of occurrences of the voice band impulse noise normalized by each of the normalizing means, for each frequency band counted by the plurality of counters. A voice band impulse noise measuring device, wherein the speech line is evaluated based on the number of occurrences of the voice call. 2. A telephone set (5) connected to a public telephone network (2) in which an exchange is incorporated, and a telephone set (4) for communicating with the telephone terminal (4) via the public telephone network. A voice band impulse noise measuring device (1) for measuring voice band impulse noise generated in a communication line in a state where a communication line is formed between the telephone lines, wherein the telephone line is connected to a signal path for the public telephone network, and A plurality of band-pass filters (12a to 12c) each having a pass frequency band set to a different frequency band in the voice band frequency domain, and A plurality of level comparison circuits (14a to 14i) for classifying voice band impulse noise into a plurality of signal levels, and each voice band impulse classified by each level comparison circuit. A plurality of normalization means for normalizing the size of the signal waveform (15a
15i), and a plurality of counters (16a to 16i) for counting the number of occurrences of the voice band impulse noise normalized by each of the normalizing means, and for each frequency band counted by the plurality of counters. A voice band impulse noise measuring device, wherein the speech line is evaluated based on the number of occurrences for each signal level.