JP3136031B2 - Receiving machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for judging a reception mode of a reception signal and automatically controlling 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 an IF band filter provided in a reception system according to the reception mode. In view of this, the present applicant has proposed, according to Japanese Utility Model Application Laid-Open No. 2-141143, a technique in which the bandwidth of an IF band filter previously selected according to the reception mode is selected in conjunction with the selection of the switching of the reception mode. . Every time the reception mode is switched, the operation of manually selecting the bandwidth of the IF band filter is omitted, and the operation of the receiver is simplified accordingly.

[0003]

Problems to be Solved by the Invention
In the technique proposed in No. 3, the setting state of the receiver is 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. It is also significant from the viewpoint of simplification of operation that the additional circuit means of the receiver be switched to the optimum setting state in accordance with this.

SUMMARY OF THE INVENTION 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 an additional circuit means to an optimum setting state in accordance with the reception mode.

[0005]

In order to achieve the above object, a receiver according to the present invention converts a received signal received by an antenna into a demodulated signal by a demodulation circuit through filters having different pass bandwidths. First and second receiving systems;
Fourier transform means for performing a Fourier transform on the demodulated signal of the first and / or the second receiving system, and a receiving mode is determined from the Fourier-transformed signal so that the additional circuit means is set to an optimal setting for the receiving mode. And a calculating means for controlling.

[0006]

[Function] Fourier transform is performed on both or one of the demodulated signals of the first and second receiving systems obtained through filters having different passbands, and the receiving mode is determined by the calculating means from the spectrum distribution and the intensity thereof. I can do it. Therefore, the additional circuit means can be controlled to an optimal setting state according to the determined reception mode.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a receiver according to the present invention will be described below with reference to FIGS. FIG. 1 is a block circuit diagram of an embodiment of a receiver according to the present invention. FIG. 2 is a diagram showing each reception mode, the bandwidth of a bandwidth variable filter to be set to an optimum state as an additional circuit means, and the AGC means. It is a diagram showing the correspondence between the constant and the filter characteristics of the tone adjustment means,
FIG. 3 is a diagram showing an example of a filter characteristic of the tone adjusting unit. FIG. 4 is a flowchart showing an operation of the central processing unit. FIG. 5 is a flowchart showing a first operation of the interference determination unit. FIG. 6 is a flowchart showing a 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 is amplified by the high frequency amplifier circuit 12 and provided to the first mixer 14, where it is 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 a first intermediate frequency amplification circuit 18, and a first intermediate frequency signal having a predetermined frequency is extracted and amplified, and supplied to a distributor 20. The divider 20 divides the first intermediate frequency signal into two, one of which is, for example, 30 KH
z is applied to a broadband filter 22 having a bandwidth of z, the other being a narrowband filter 2 having a bandwidth of, for example, 3 KHz.
4 given. Note that 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 wideband filter 22 is supplied to a first Fourier transform means 50 and to a second intermediate frequency amplifier circuit 28 via a variable bandwidth filter 26. Amplified. The output amplified by the second intermediate frequency amplifying circuit 28 is supplied to a second mixer 30 and a part of the output is supplied to the AG.
C means 32. This second mixer 30 includes:
The second local oscillation signal from the second local oscillation circuit 34 is supplied, the second intermediate frequency signal obtained by frequency-converting the first intermediate frequency signal is supplied to the first demodulation circuit 36, and the first A demodulated signal is output. The tone quality of the first demodulated signal is adjusted by the tone adjusting means 38, further amplified by the low frequency amplifier circuit 40, and output as a low frequency from the speaker 42. Further, a part of the first demodulated signal is provided to the interference determination means 44.

Further, the first signal having passed through the narrow band filter
Is supplied to the second Fourier transform means 51 and is also supplied to the third intermediate frequency amplifying circuit 46 to be amplified. The amplified output is supplied to the second demodulation circuit 48 and the second A demodulated signal is output. The second demodulated signal is provided to the interference determination means 44. Then, the interference determination means 44, the first Fourier transform means 50 and the second
From the central processing means 52 to which signals are respectively given from the Fourier transform means 51,
C means 32, tone adjusting means 38, and first demodulation circuit 36
Then, a signal is given to the second demodulation circuit 48 and the display means 54.

Note that the antenna 10 receives the broadband filter 2
A first receiving system is formed on a path from the antenna 10 to the first demodulation circuit 36, and a second receiving 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 a signal of the central processing unit 52, but a passband tuning circuit, an IFWIDTH circuit, or the like is used. It may be what was. AGC means 3
Numeral 2 controls the gain of the high-frequency amplifier circuit 12 and the first and second intermediate frequency amplifier circuits 18 and 28 with a time constant based on the signal from the central processing unit 52 according to the signal level of the second intermediate frequency signal. Apply AGC signal.

By the way, in the receiver shown in FIG.
In the W mode reception state, as shown in FIG.
z, the time constant of the AGC means 32 is desirably FAST to MID according to the reception state, and the tone adjusting means 38 is an audio peak filter characteristic (FIG. 3A). Is desirable. Also,
In the receiving state of the RTTY mode (FSK modulation system), the bandwidth of the bandwidth variable filter 26 is 1 to 2 KHz,
The time constant of the AGC means 32 is desirably FAST to MID, and the tone adjustment means 38 is desirably a bandpass filter characteristic (FIG. 3B) for a higher band. If the reception state is the SSB mode, the bandwidth variable filter 26 is set to 1.
5 to 3 KHz, the AGC means 32 has MID to SLOW, and the tone adjustment means 38 has a flat filter characteristic (FIG. 3).
(C)) is desirable. Further, in the AM mode reception state, the bandwidth variable filter 26
KHz, AGC means 32 is FAST-MID, and tone adjustment means 38 is a high-low cut filter characteristic (FIG. 3).
(D)) is desirable. Further, in the FM mode reception state, the bandwidth variable filter 26
-30 KHz, AGC means 32 is FAST, tone adjustment means 38 is a de-emphasis filter characteristic (FIG. 3).
(E)) is desirable.

Next, the determination of the reception mode necessary for automatically setting the setting state of the additional circuit means of the receiver as described above will be described. The determination of the reception mode by the central processing means 52 is performed by performing a fast Fourier transform on the output signal of the wideband filter 22 having a signal of the target reception frequency as a main component by the first Fourier transform means 50 and obtaining a spectrum distribution and intensity pattern thereof. Made by difference. Here, although the reception mode can be determined only by the fast Fourier transform by the first Fourier transform means 50, the output signal of the narrow-band filter 24 having a narrow bandwidth is converted into the second signal in order to further improve the determination accuracy. The Fourier transform means 51 performs a fast Fourier transform, and makes a determination with reference to the spectrum distribution and intensity pattern. In order to reliably determine the reception mode, the presence of a signal other than the target reception frequency such as an interference signal or the presence of disturbance noise is not desirable.

First, the operation of the interference determining means 44 for determining the presence or absence of an interference signal will be described. Interference determination means 4
In the first operation shown in FIG. 5 of FIG. 4, first, the bandwidth variable filter 26 is set to a predetermined bandwidth (step 1 in FIG. 5), and the first demodulation obtained through the filter of the predetermined bandwidth is obtained. It is determined whether the signal level is smaller 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 and disturbance noise 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 other received signals and disturbance noise are low, and no interference signal exists. Can be determined as a reception state in which a sufficient S / N ratio can be obtained. Note that the level of the first demodulated signal is higher than the first reference value in step 2 or the second demodulated signal is higher in step 3
If the level of the demodulated signal is smaller than the second reference value,
Since the received signal of the target reception frequency is low and the level of the other received signals is high, it can be determined that a reception state in which a sufficient S / N ratio cannot be obtained.

Another second operation of the interference determination 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). A large difference obtained by this subtraction means that the level of a received signal or disturbance noise other than the target reception frequency is high. Also, a small difference means that the level of a received signal other than the target reception frequency is low. Therefore, it is determined whether or not the difference obtained by the subtraction is smaller than the reference value (see FIG. 6).
Step 3) If the difference is smaller than the reference value, it can be determined that no interference signal exists, and if the difference is larger than the reference value, it can be determined that the interference signal exists.

To determine 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 other than 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 with a reference value. Further, by subtracting the level of the second demodulated signal from the level of the first demodulated signal to obtain a difference, dividing the level of the second demodulated signal by the difference, and comparing the quotient with a reference value, The presence or absence of the interference signal may be determined.

The determination of the reception mode by the central processing unit 52 based on the spectrum distribution output from the first and second Fourier transform units 50 and 51 and the pattern of its intensity 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 case of the RTTY mode, there is a strong reception signal at two frequencies in the reception band, and a characteristic that these two reception signals are intermittently alternated is recognized. In the SSB mode, a peak of a received signal having a width of 2 to 3 KHz is formed in the reception band, and the feature that the height of the peak changes is recognized. Further, in the AM mode, there is a feature that a strong reception signal is present at one frequency within the reception band, and a peak of a reception signal having a width of 2 to 3 KHz lower than the center reception signal is formed on both sides thereof. Further, in the FM mode, there is a strong reception signal at one frequency within the reception band, and 7
The characteristic that the peak of the received signal is lower than the central received signal in the width of 10 to 10 KHz is recognized. Accordingly, the central processing unit 52 can determine the reception mode from the pattern of the signal output after the Fourier transform. The first
If the central processing means 52 cannot recognize and determine the reception mode from the pattern of the signal output from the second Fourier transform means 50, 51, the reception signal is in a reception mode other than the above, a radio signal, or the like. Is strongly influenced by

Further, the operation of the central processing means 52 will be described with reference to FIG. First, the presence / absence of an interference signal is determined based on the presence / absence of a signal from the interference determination means 44 (step 1 in FIG. 4). If an interference signal is present, the presence of the interference signal is determined by the display means 54 without determining the reception mode. It is displayed (Step 2 in FIG. 4), and the process returns to Step 1. If there is no interference signal in step 1, the signal pattern output from the first and second Fourier transform means 50 and 51 is C
It is determined whether or not the mode is the W mode (step 3 in FIG. 4). If the mode 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 (FIG. 4).
Step 4) Further, the CW mode is displayed on the display means 54 (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 bandwidth variable filter 26 is adjusted so as to correspond to a good reception situation in which a sufficient S / N ratio can be obtained.
And the time constant of the AGC means 32 are set. The same applies to the reception mode determined below. If the CW mode cannot be determined in step 3, it is next determined whether or not the mode is the RTTY mode (step 6 in FIG. 4). If the mode is the RTTY mode, the bandwidth of the bandwidth variable filter 26 is set to 2 kHz.
The time constant of the AGC means 32 is set to MID, the tone adjusting means 38 is set to a band-pass 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 determined in step 6, it is next determined whether or not the mode is the SSB mode (step 9 in FIG. 4).
Is set to 3 kHz, the AGC means 32 is set to SLOW, and the tone adjusting means 38 is set to a flat filter characteristic (step 1 in FIG. 4).
0), display the SSB mode (step 11 in FIG. 4),
Return to step 1. Further, if the SSB mode cannot be determined in step 9, it is next determined whether or not the mode is the AM mode (step 12 in FIG. 4). If the mode is the AM mode, the bandwidth variable filter is set to 10 KHz, the AGC means 32 is set to MID and tone adjustment. The means 38 is set to 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 also Step 1
If the AM mode cannot be discriminated in step 2, then it is discriminated whether the mode is the FM mode (step 15 in FIG. 4). If the mode is the FM mode, the bandwidth variable filter 26 is set to 30 KHz and the AGC means 3
2 is set to FAST, the tone adjusting means 38 is set to 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. Further, if the FM mode cannot be determined in step 15, the display means 54 indicates that the reception mode cannot be determined (step 18 in FIG. 4), and the process returns to step 1. In the operation of the central processing unit 52 shown in FIG. 4, the order of the steps for determining whether or not each reception mode is performed may be changed, and the step for determining a certain reception mode may be deleted or added. Of course.

With this configuration and operation, in the receiver of the present invention, the additional circuit means is automatically controlled to the optimum setting state in accordance with the reception mode of the actually received signal, and the manual operation by the operator can be performed. There is no need and the operation of the receiver is extremely simple.

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

In FIG. 7, a first intermediate frequency amplifying circuit 1
8 is provided to the first Fourier transform means 50 and to the noise blanker 60. The noise blanker 60 supplies the first intermediate frequency signal to the noise gate 64 and the noise amplifier 66. The noise amplifier 66 amplifies the first intermediate frequency signal and supplies the amplified signal to the noise detector 62, which outputs a noise detection signal. Then, the noise detection signal is provided to the interference determination means 44 and also to the gate control circuit 70 via the switch 68. Then, the pulse noise included in the noise detection signal is extracted by the gate control circuit 70, and the noise gate 64 is turned on / off according to the extracted pulse noise, and the noise gate 6 is turned off.
4, the first intermediate frequency signal from which the pulse noise has been removed is applied to the variable bandwidth filter 26. The switch 68 is turned on by a signal from the central processing unit 52.
/ OFF, turns on / off the operation of the noise blanker 60
Perform F control.

Here, the noise detection signal may include, in addition to the reception signal of the target reception frequency, a reception signal due to a 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 demodulated signal composed of the reception signal of the target reception frequency via the bandwidth variable filter 26, the interference determination means 44 determines whether or not an interference signal exists. This is possible as in FIG. Since the reception mode is determined under the condition that no interference signal exists, the first demodulated signal at this time is mainly a reception signal of the target reception frequency, and other reception signals and disturbance noise are extremely small. Or not included. Therefore, the central processing means 52 can determine the reception mode from the pattern of the signal obtained by subjecting the first intermediate frequency signal to the fast Fourier transform by the first Fourier transform means 50, as in the case of FIG.

Further, when the central processing unit 52 determines that the reception mode is the FM mode, the switch of the noise blanker 60 is switched similarly to the setting of the variable bandwidth filter 26, the AGC unit 32, and the tone adjustment unit 38. 68 to O
If the operation of the noise blanker 60 is turned off by performing FF, the generation of a click sound due to the ON / OFF operation of the noise gate 64 can be prevented while the FM mode is being received.

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

In the description of the above embodiment, the interference discriminating means 44 and the first and second Fourier transform means 50 and 5 are used.
1 and the central processing means 52 are constituted by separate blocks,
Needless to say, it may be incorporated in a one-chip microcomputer or the like as software. In addition, these
(Digital signal processor).

Further, the determination of the reception mode is performed even in a reception situation where some interference signal exists, and the interference determination means 44
From the central processing means 52
Thus, 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 clear 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 determined from the pattern, and the additional circuit means is controlled, so that the receiver is automatically switched to the optimum setting state. In addition, there is no need to manually set the additional circuit means, and the operation is extremely simple.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating an example of a filter characteristic of a tone adjusting unit.

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 present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Antenna 12 High frequency amplifier circuit 14 1st mixer 18 1st intermediate frequency amplifier circuit 20 Divider 22 Broadband filter 24 Narrow band filter 26 Bandwidth variable filter 28 2nd intermediate frequency amplifier circuit 30 2nd 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 transform means 51 Second Fourier transform means 52 Central processing means 60 Noise blanker 62 Noise detector 64 Noise gate 68 Switch

Claims (1)

(57) [Claims] 1. A first and / or second receiving system for converting a received signal received by an antenna into a demodulated signal by a demodulation circuit via filters having different pass bandwidths, and the first and / or the second system. Fourier transform means for performing a Fourier transform on the demodulated signal of the receiving system, and arithmetic means for determining a receiving mode from the Fourier-transformed signal and controlling the additional circuit means to a setting state optimal for the receiving mode. A receiver characterized in that: