JPH0758654A - Receiver - Google Patents

Abstract

PURPOSE:To automatically control the additional circuit means of a receiver in an optimum setting state by discriminating a reception mode from reception signals. CONSTITUTION:The reception signal is converted to a first intermediate frequency signal and bisected, one of them is converted to a first demodulation signal through a wide-band-pass filter 22 and a variable band width filter 26, an AGC means 32 is provided in the reception system and the first demodulation signal is outputted as a low frequency through a tone adjustment means 38. Also, the other one is converted to a second demodulation signal through a narrow-band-pass filter 24. An interference condition is discriminated in an interference discrimination means 44 from the levels of the first and second modulation singles and signals passing through the wide-band-pass and narrow- band-pass filters 22 and 24 are subjected to fast Fourier transform in first and second Fourier transformation means 50 and 51. A central arithmetic means 52 discriminates the reception mode from the pattern of the Fourier-transformed signal in the condition without interference and controls the variable band width filter 26, the AGC means 32 and the tone adjustment means 38 corresponding to it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver which discriminates a reception mode of a reception signal and automatically controls an additional circuit means to a setting state optimal for the reception mode.

[0002]

2. Description of the Related Art CW, RTTY, SSB, AM and F
In a receiver operated in a plurality of reception modes such as M, it is necessary to switch the bandwidth of the IF band filter provided in the reception system according to the reception mode. Therefore, the applicant of the present patent has proposed, in Japanese Utility Model Application Laid-Open No. 2-141143, a technique in which the bandwidth of the IF band filter selected in advance corresponding to the reception mode is selected in association with the switching selection of the reception mode. . The operation of manually selecting the bandwidth of the IF band filter is omitted each time the reception mode is switched, and the operation of the receiver is simpler.

[0003]

[Problems to be Solved by the Invention]
In the technology proposed in No. 3, the setting state of the receiver can be switched according to the selection of the receiving mode of the receiver by the operator, but the receiving mode is changed from the received signal actually received by the receiver. From the viewpoint of simplifying the operation, it is also meaningful to judge the above and switch the additional circuit means of the receiver to the optimum setting state in accordance with this.

It is an object of the present invention to provide a receiver which discriminates a reception mode from a reception signal and automatically switches and controls the additional circuit means to an optimum setting state in accordance with the discrimination.

[0005]

To achieve the above object, in the receiver of the present invention, a reception signal received by an antenna is converted into a demodulation signal by a demodulation circuit through filters having different pass bandwidths. A first and a second receiving system,
Fourier transforming means for Fourier transforming the demodulated signal of the first and / or second receiving system, and a receiving mode is discriminated from the Fourier transformed signal so that the additional circuit means is set to an optimum setting state for the receiving mode. And a calculation means for controlling.

[0006]

[Operation] Both or one of the demodulated signals of the first and second receiving systems obtained through filters with different pass bandwidths is Fourier transformed, and the receiving mode is determined by the computing means from its spectrum distribution and its strength. You can Therefore, the additional circuit means can be controlled to the optimum setting state according to the determined reception mode.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the receiver of the present invention will be described below with reference to FIGS. FIG. 1 is a block circuit diagram of an embodiment of a receiver of the present invention, and FIG. 2 is a diagram showing the reception mode and the bandwidth of a variable bandwidth filter to be set to an optimum state as additional circuit means and the AGC means. It is a diagram showing the correspondence between the filter characteristics of the constant and the tone adjusting means,
3 is a diagram showing an example of the filter characteristic of the tone adjusting means, FIG. 4 is a flowchart showing the operation of the central processing means, and FIG. 5 is a flowchart showing the first operation of the interference determining means. 6 is a flowchart showing the second operation of the interference determination means.

First, the structure will be described with reference to FIG. 1
The received signal received by the antenna 10 of the book is amplified by the high frequency amplifier circuit 12 and given to the first mixer 14, and mixed with the first local oscillation signal from the first local oscillation circuit 16. The frequency-converted signal output from the first mixer 14 is supplied to the first intermediate frequency amplifier circuit 18, and the first intermediate frequency signal having a predetermined frequency is extracted and amplified and supplied to the distributor 20. The distributor 20 divides the first intermediate frequency signal into two, one of which is, for example, 30 KH.
a narrow band filter 2 provided to a wide band filter 22 having a bandwidth of z, the other having a bandwidth of 3 KHz, for example.
Given to 4. The bandwidth of the narrow band filter 24 is included in the bandwidth of the wide band filter 22.

The first intermediate frequency signal that has passed through the wide band filter 22 is given to the first Fourier transforming means 50 and also to the second intermediate frequency amplifying circuit 28 via the bandwidth variable filter 26. Is amplified. The output amplified by the second intermediate frequency amplifier circuit 28 is supplied to the second mixer 30, and a part of the output is AG
It is given to the C means 32. In this second mixer 30,
The second local oscillation signal from the second local oscillation circuit 34 is given, the second intermediate frequency signal obtained by frequency-converting the first intermediate frequency signal is given to the first demodulation circuit 36, and the first local oscillation signal is given. The demodulated signal is output. The tone quality of the first demodulated signal is adjusted by the tone adjusting means 38, and is amplified by the low frequency amplifier circuit 40 to be output from the speaker 42 as a low frequency signal. Further, a part of the first demodulated signal is given to the interference discrimination means 44.

The first signal passed through the narrow band filter 24
The intermediate frequency signal of 1 is given to the second Fourier transform means 51 and also given to the third intermediate frequency amplifying circuit 46 to be amplified, and the amplified output is given to the second demodulating circuit 48 to obtain the second The demodulated signal is output. This second demodulated signal is given to the interference discrimination means 44. Then, the interference determination means 44, the first Fourier transform means 50, and the second
The central processing means 52 to which signals are respectively applied from the Fourier transform means 51 of
C means 32, tone adjusting means 38, and first demodulation circuit 36
A signal is given to the second demodulation circuit 48 and the display means 54.

From the antenna 10 to the wide band filter 2
A first reception system is formed on a path from the antenna 10 to the first demodulation circuit 36, and a second reception system is formed on a path from the antenna 10 to the second demodulation circuit 48 via the narrow band filter 24. . Further, the bandwidth variable filter 26 is not limited to one in which a plurality of filters having different bandwidths are arranged in parallel and one of them is switched and selected by the signal of the central processing means 52, and a passband tuning circuit, an IFWIDTH circuit or the like is used. It may be the one you had. Furthermore, AGC means 3
Reference numeral 2 is a time constant based on the signal from the central processing means 52 according to the signal level of the second intermediate frequency signal, and controls the gain of the high frequency amplifier circuit 12 and the first and second intermediate frequency amplifier circuits 18 and 28. Apply AGC signal.

By the way, in the receiver shown in FIG.
In the W mode reception state, the bandwidth variable filter 26 as shown in FIG. 2 is 0.25 to 1 KH depending on the reception state.
z bandwidth, the time constant of the AGC means 32 is preferably FAST to MID according to the reception state, and the tone adjusting means 38 has an audio peak filter characteristic (FIG. 3A). Is desirable. Also,
In the reception state of the RTTY mode (FSK modulation method), the bandwidth of the bandwidth variable filter 26 is 1 to 2 KHz,
It is desirable that the time constant of the AGC means 32 is FAST to MID, and that the tone adjusting means 38 has a bandpass filter characteristic (FIG. 3B) in the higher band. Then, in the reception state of the SSB mode, the bandwidth variable filter 26 is 1.
5 to 3 KHz, AGC means 32 is MID to SLOW, and tone adjusting means 38 is flat filter characteristic (see FIG. 3).
(C)) is desirable. Furthermore, in the AM mode reception state, the bandwidth variable filter 26 has 3 to 10 bits.
KHz, AGC means 32 is FAST to MID, and tone adjusting means 38 is a high / low cut filter characteristic (see FIG. 3).
(D)) is desirable. Further, in the FM mode reception state, the bandwidth variable filter 26 has 8
˜30 KHz, AGC means 32 is FAST, tone adjusting means 38 is de-emphasis filter characteristic (see FIG. 3).
(E)) is desirable.

Next, the determination of the receiving mode necessary for automatically setting the setting state of the additional circuit means of the receiver to the optimum state as described above will be described. In the determination of the reception mode by the central processing means 52, the output signal of the wide band filter 22 whose main component is the signal of the target reception frequency is fast Fourier transformed by the first Fourier transformation means 50, and the spectrum distribution and intensity pattern Made by the difference. Here, the reception mode can be discriminated only by the fast Fourier transform by the first Fourier transform means 50, but in order to further improve the discrimination accuracy, the output signal of the narrow band filter 24 having a narrow bandwidth is changed to the second. The fast Fourier transform is performed by the Fourier transform means 51, and the spectrum distribution and the intensity pattern are referenced to make the determination. In order to reliably determine the reception mode, it is not desirable to have signals other than the target reception frequency such as interference signals or the presence of disturbance noise.

Therefore, first, the operation of the interference discriminating means 44 for discriminating the presence or absence of the interference signal will be described. Interference discrimination means 4
The first operation shown in FIG. 5 of FIG. 4 is to first set the variable bandwidth filter 26 to a predetermined bandwidth (step 1 in FIG. 5), and then perform the first demodulation obtained by passing through the filter having the predetermined bandwidth. It is determined whether or not the signal level is lower than the first reference value (step 2 in FIG. 5). Here, if the level of the first demodulated signal is smaller than the first reference value, it is recognized that signals other than the target reception frequency, disturbance noise, and the like are small. If the level of the first demodulated signal is lower than the first reference value, it is further determined whether or not the level of the second demodulated signal is higher than the second reference value (step 3 in FIG. 5). This step 3
If the level of the second demodulated signal is higher than the second reference value, the level of the received signal at the target reception frequency is high, the levels of the other received signals and disturbance noise are low, and there is no interference signal. It is possible to determine that the reception status is such that a sufficient S / N ratio is obtained. The level of the first demodulated signal is greater than the first reference value in step 2, or the second demodulated signal is in the second level in step 3.
If the level of the demodulated signal of is less than the second reference value,
It is possible to determine that the received signal at the target reception frequency is low and the level of the other received signals is high, and a sufficient S / N ratio cannot be obtained.

Another second operation of the interference discriminating means 44 will be described with reference to FIG. First, the bandwidth variable filter 26 is set to a predetermined bandwidth (step 1 in FIG. 6), and the level of the second demodulated signal is subtracted from the level of the first demodulated signal (step 2 in FIG. 6). The large difference obtained by this subtraction means that the level of the received signal or the disturbance noise other than the target received frequency is high. A small difference means that the level of the received signal other than the target receiving frequency is low. Therefore, it is judged whether or not the difference obtained by the subtraction is smaller than the reference value (see FIG. 6).
If the difference is smaller than the reference value, it can be determined that the interference signal does not exist, and if the difference is larger than the reference value, it can be determined that the interference signal exists.

As for the determination of the presence or absence of the interference signal, a ratio between the level of the first demodulated signal and the level of the second demodulated signal is calculated in addition to those shown in FIGS. 5 and 6, and this ratio is calculated. The presence or absence of the interference signal may be determined by comparing it with the reference value. Also, by subtracting the level of the second demodulated signal from the level of the first demodulated signal to obtain the difference, dividing the level of the second demodulated signal by this difference, and comparing the quotient with the reference value, The presence or absence of the interference signal may be determined.

Further, the discrimination of the receiving mode by the central processing means 52 from the spectrum distributions output from the first and second Fourier transforming means 50 and 51 and the patterns of the intensity thereof will be described. If the reception mode is the CW mode, there is a strong reception signal at one frequency within the reception band, and the characteristic that the reception signal is intermittent is recognized. Also,
In the RTTY mode, there is a strong reception signal at two frequencies within the reception band, and the characteristic that these two reception signals are alternately intermittent is recognized. Then, in the SSB mode, the characteristic that the peak of the received signal having a width of 2-3 KHz is formed in the reception band and the height of the peak is changed is recognized. Furthermore, in the AM mode, there is a strong reception signal at one frequency within the reception band, and it is recognized that a peak of the reception signal having a width of 2 to 3 kHz and lower than the reception signal at the center is formed on both sides thereof. Furthermore, in FM mode, there is a strong received signal at one frequency within the reception band, and 7
The characteristic that a received signal peak is lower than the received signal at the center in the range of -10 KHz is recognized. Therefore, the central processing unit 52 can determine the reception mode from the patterns of the signals which are Fourier-transformed and output. The first
If the central processing unit 52 cannot recognize and discriminate the receiving mode from the pattern of the signals output from the second Fourier transforming units 50 and 51, the receiving signal is a receiving mode other than the above, a radio wave beacon, or the like, or an interference signal. It is in a state strongly influenced by.

The operation of the central processing means 52 will be further described with reference to FIG. First, the presence / absence of the interference signal is determined by the presence / absence of the signal from the interference determination means 44 (step 1 in FIG. 4). If the interference signal is present, the presence of the interference signal is displayed on the display means 54 without determining the reception mode. Display (step 2 in FIG. 4) and return to step 1. If there is no interference signal in step 1, the pattern of the signals output from the first and second Fourier transforming means 50 and 51 is C.
Whether or not it is the W mode is determined (step 3 in FIG. 4), and if it is the CW mode, the bandwidth of the bandwidth variable filter 26 is set to 1 kHz.
, The time constant of the AGC means 32 is MID, and the tone adjusting means 38 is an audio peak filter characteristic (see FIG. 4).
Then, the CW mode is displayed on the display means 54 (step 4) (step 5 in FIG. 4) and the process returns to step 1. The determination of the CW mode in step 3 is made under the condition that there is no interference signal, and the variable bandwidth filter 26 is used so as to correspond to a good reception condition in which a sufficient S / N ratio is obtained.
And the time constant of the AGC means 32 are set. The same applies to the reception modes determined below. If the CW mode cannot be discriminated in step 3, it is then discriminated whether or not it is the RTTY mode (step 6 in FIG. 4). In the RTTY mode, the bandwidth of the bandwidth variable filter 26 is set to 2 kHz.
Then, the time constant of the AGC means 32 is set to MID, the tone adjusting means 38 is set to a bandpass filter characteristic from a high band (step 7 in FIG. 4), and the RTTY mode is displayed on the display means 54 (step 8 in FIG. 4). , Return to step 1. If the RTTY mode cannot be discriminated in step 6, it is then discriminated whether or not it is the SSB mode (step 9 in FIG. 4), and if it is the SSB mode, the bandwidth variable filter 26.
Is 3 KHz, the AGC means 32 has SLOW, and the tone adjusting means 38 has flat filter characteristics (see step 1 in FIG. 4).
0), display the SSB mode (step 11 in FIG. 4),
Return to step 1. Furthermore, if the SSB mode cannot be discriminated in step 9, then it is discriminated whether or not it is the AM mode (step 12 in FIG. 4). If it is the AM mode, the bandwidth variable filter is 10 KHz, the AGC means 32 is the MID, and the tone is adjusted. The means 38 has a high / low cut filter characteristic (step 13 in FIG. 4), the AM mode is displayed (step 14 in FIG. 4), and the process returns to step 1. And again, step 1
If the AM mode cannot be discriminated in 2, it is then discriminated whether or not it is the FM mode (step 15 in FIG. 4). If it is the FM mode, the bandwidth variable filter 26 is set to 30 KHz and the AGC means 3 is used.
2 is FAST, the tone adjusting means 38 is a de-emphasis filter characteristic (step 16 in FIG. 4), the FM mode is displayed (step 17 in FIG. 4), and the process returns to step 1. If the FM mode cannot be discriminated in step 15, the display means 54 displays that the reception mode cannot be discriminated (step 18 in FIG. 4), and the process returns to step 1. It should be noted that in the operation of the central processing means 52 shown in FIG. 4, the order of each step for determining whether each receiving mode is performed may be changed, and the step for determining a certain receiving mode may be deleted or added. Of course.

With the above configuration and operation, in the receiver of the present invention, the additional circuit means is automatically controlled to the optimum setting state according to the reception mode of the received signal actually received, and the manual operation by the operator is possible. It is not necessary and the operation of the receiver is extremely simple.

Further, another embodiment of the receiver of the present invention will be described with reference to FIG. In FIG. 7, circuit blocks that are the same as or equivalent to those in FIG. 1 are assigned the same reference numerals and redundant description is omitted.

In FIG. 7, the first intermediate frequency amplifier circuit 1
The output of 8 is given to the first Fourier transforming means 50 and the noise blanker 60. In the noise blanker 60, the first intermediate frequency signal is given to the noise gate 64 and the noise amplifier 66. The noise amplifier 66 amplifies the first intermediate frequency signal and supplies it to the noise detector 62, and the noise detector 62 outputs the noise detection signal. Then, this noise detection signal is given to the interference discrimination means 44 and also given to the gate control circuit 70 via the switch 68. Then, the gate control circuit 70 extracts the pulse noise included in the noise detection signal, and the noise gate 64 is turned on / off according to the extracted pulse noise, and the noise gate 6
The first intermediate frequency signal, which has passed through 4 and is free of pulse noise, is supplied to the variable bandwidth filter 26. The switch 68 is turned on by a signal from the central processing means 52.
/ OFF, the operation of the noise blanker 60 is turned ON / OF
F control.

Here, in addition to the reception signal of the target reception frequency, the noise detection signal may include a reception signal due to the broadcast frequency of another nearby station and disturbance noise. Therefore, based on the level of the noise detection signal and the level of the first demodulation signal which is the reception signal of the target reception frequency after passing through the variable bandwidth filter 26, the interference determination unit 44 determines whether or not the interference signal exists. The same is possible as in FIG. Further, since the reception mode is determined under the condition that there is no interference signal, the first demodulation signal at this time is mainly the reception signal of the target reception frequency, and other reception signals and disturbance noise are extremely small. Or not included. Therefore, the central processing unit 52 can determine the reception mode from the pattern of the signal obtained by performing the fast Fourier transform on the first intermediate frequency signal by the first Fourier transform unit 50, as in the case of FIG.

Further, when the central processing means 52 determines that the reception mode is the FM mode, the switch of the noise blanker 60 is set in the same manner as the setting of the variable bandwidth filter 26, the AGC means 32 and the tone adjusting means 38. 68 for O
If FF is performed and the operation of the noise blanker 60 is controlled to be OFF, generation of a click sound due to ON / OFF operation of the noise gate 64 can be prevented while receiving the FM mode.

In another embodiment of the receiver of the present invention shown in FIG. 7, the noise blanker 60 is used instead of the wide band filter 22 of the receiver shown in FIG. It is suitable to be applied to a receiver equipped with.

In the description of the above embodiment, the interference discriminating means 44 and the first and second Fourier transforming means 50, 5 are used.
Although the 1 and the central processing means 52 are composed of separate blocks,
Of course, it may be incorporated in a one-chip microcomputer or the like as software. In addition, these are DSP
(Digital signal processor) may be used for processing.

Further, the discrimination of the reception mode is executed even in the reception condition in which the interference signal is somewhat present, and the interference discrimination means 44
From the central processing means 52
The bandwidth of the bandwidth variable filter 26 and the time constant of the AGC means 32 may be appropriately adjusted and set within the range shown in FIG. 2 in the determined reception mode.

[0027]

As is apparent from the above description, the receiver of the present invention has the following special effects.

In the receiver according to the first aspect, the received signal is Fourier transformed, the receiving mode is discriminated from the pattern, and the additional circuit means is controlled. Therefore, the receiver is automatically switched to the optimum setting state. Therefore, it is not necessary to manually set the additional circuit means, and the operation is extremely simple.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an embodiment of a receiver of the present invention.

FIG. 2 is a diagram showing the correspondence between each reception mode, the bandwidth of the variable bandwidth filter to be set, the time constant of the AGC means, and the filter characteristic of the tone adjusting means.

FIG. 3 is a diagram showing an example of filter characteristics of a tone adjusting means.

FIG. 4 is a flowchart showing the operation of the central processing means.

FIG. 5 is a flowchart showing a first operation of the interference determination means.

FIG. 6 is a flowchart showing a second operation of the interference determination means.

FIG. 7 is a block circuit diagram of another embodiment of the receiver of the invention.

[Explanation of symbols]

 10 Antenna 12 High Frequency Amplifier Circuit 14 First Mixer 18 First Intermediate Frequency Amplifier Circuit 20 Distributor 22 Wideband Filter 24 Narrow Band Filter 26 Bandwidth Variable Filter 28 Second Intermediate Frequency Amplifier Circuit 30 Second Mixer 32 AGC Means 36 First Demodulation Circuit 38 Tone Adjusting Means 40 Low Frequency Amplifying Circuit 42 Speaker 44 Interference Discriminating Means 46 Third Intermediate Frequency Amplifying Circuit 48 Second Demodulating Circuit 50 First Fourier Transforming Means 51 Second Fourier Transforming Means 52 Central processing means 60 Noise blanker 62 Noise detector 64 Noise gate 68 Switch

Claims (1)

[Claims] 1. A first and a second reception system for converting a reception signal received by an antenna into a demodulation signal by a demodulation circuit through filters having different pass bandwidths, and the first and / or the second reception system. Fourier transforming means for Fourier transforming the demodulated signal of the receiving system, and computing means for discriminating the receiving mode from the Fourier transformed signal and controlling the additional circuit means to the optimum setting state for the receiving mode. A receiver characterized in that.