JPH10164460A - Audio signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an audio signal processor capable of conducting detection output, including no noise without requiring connection of a filter constituted by a capacitor. SOLUTION: The audio signal processor used for received, capable of receiver various television broadcasting systems is provided with a PLL-FM detection circuit 1, in which an audio intermediate frequency signal is inputted and output capable of judging the broadcasting system from DC voltage of the detection output is conducted and an amplifier 7, where the detection output of the PLL-FM detection circuit 1 is connected with one side 7b of an input terminal, reference voltage switched according to the judgment result of the broadcasting system is connected with the other side 7a and the detection output is amplified and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM detection circuit for an audio intermediate frequency signal used in a receiving apparatus such as a multi-mode television receiver for receiving various types of television broadcasts. The present invention relates to an improvement in FM detection of a multi-method audio intermediate frequency signal used.

[0002]

2. Description of the Related Art FIG. 7 shows an FM detection circuit for a multi-system audio intermediate frequency signal in a television receiver. In FIG. 7, 1 is a PLL-FM detection circuit,
7 is an amplifier, 8 is an IC composed of a semiconductor integrated circuit, and 9.1
Reference numerals 0 and 10a denote terminals of the IC 8, and 11A, 11B, and 11C denote bandpass filters (hereinafter, referred to as BPFs).

[0003] The audio intermediate frequency signals are BPF11A and 11B.
・ After only the desired signal component is selected by 11C, IC
8 and then to the FM detection circuit 1 of the PLL system.

The audio intermediate frequency signal has a television broadcasting system of B
Or 5.5 MHz for G system, 6.0 MH for I system
In the z, D or K system, the frequency is 6.5 MHz. To automatically receive these signals without switching, BPFs are connected in parallel, and the output is input to the PLL type FM detection circuit 1 inside the IC. The PLL is widely set so that its band covers from 5.5 MHz to 6.5 MHz, and all broadcasting from the B / G system to the D / K system is FM.
It can be detected.

Here, the FM detection circuit 1 of the PLL system will be described in detail with reference to FIG. The PLL-FM detection circuit 1 includes a voltage controlled oscillation (hereinafter, referred to as VCO) circuit 1A, a phase comparison circuit 1B, and a loop filter 1C. The input signal and the output of the VCO circuit 1A are input to a phase comparison circuit 1B and phase-compared.
After passing through, the oscillation output of the VCO circuit 1A follows the frequency of the input signal by being input as the oscillation frequency control voltage of the VCO circuit 1A. And the loop filter 1C
Since a voltage corresponding to the frequency of the input signal appears at the output of (1), this becomes the FM detection output.

FIG. 9 shows an example of the characteristics of the frequency of the input signal of the PLL circuit versus the output voltage of the loop filter. The pull-in range of the PLL is about 5 MHz to 7 MHz, and, for example, in an IC with a power supply voltage of 12 V, the output DC voltage is 4 V at 5.5 MHz, 6 V at 6.5 MHz, 6.5 MHz.
Is 8 V, and the maximum frequency displacement of the FM signal is + -50 kHz, so that the voltage is + -0.2 V. That is, the DC voltage of the FM detection output is 3.8 V in the B / G system, 5.8 to 6.2 V in the I system, and 7.8 to 8.2 V in the D / K system.

[0007] The detection output of an IC with a power supply voltage of 12 V is as small as 0.4 V at the maximum, and it is necessary to amplify the amplitude. After the AC component of the signal is removed by a filter using a resistor R and a capacitor C1 to amplify the AC signal, the DC signal becomes the same as the signal.
The signal is amplified by two inputs of the signal and an output signal having a desired amplitude is obtained. However, in this case, the capacitor needs to have a value of about 1 μF or more in order to achieve a sufficient effect on the frequency of the voice band. Therefore, such a capacitor of about 1 μF or more is required in addition to the IC. A terminal for the connection is required.

Before inputting to the IC, three B
Because PFs are connected and they are not switched,
Frequency components other than the original signal are also included, and this becomes noise and is detected. For example, when receiving the D / K system, the audio intermediate frequency signal is 6.5 MHz, and the 5.5 MHz component of the video signal is also input to the PLL-FM detection circuit via the BPF into the 5.5 MHz BPF. .
The PLL-FM detection circuit also detects this unnecessary signal component at the same time, and may become a noise component mixed with the original audio signal.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an audio signal processing apparatus which can derive a detection output containing no noise without requiring connection of a filter constituted by a capacitor.

According to a first aspect of the present invention, a broadcast system is determined from a DC voltage of a detection output of a PLL-FM detection circuit, and a detection output is amplified according to the determination result. An object of the present invention is to provide an audio signal processing device capable of deriving a detection output that does not include noise without requiring connection.

According to a second aspect of the present invention, the detection output of the PLL-FM detection circuit is amplified and output in accordance with a reference voltage which is switched according to the result of the determination of the broadcast system, and the connection of a filter constituted by a capacitor is established. An object of the present invention is to provide an audio signal processing device that can derive a detection output that does not include noise and does not require it.

According to a third aspect of the present invention, the output of the band-pass filter switched according to the output of the judging means for judging the audio broadcasting system from the DC voltage of the detection output of the first PLL-FM detection circuit is inputted, and The second PLL- having a pull-in range in which the above-mentioned audio intermediate frequency signals of all the broadcasting systems can be detected.
It is an object of the present invention to provide an audio signal processing device which is provided with an FM detection circuit and can derive a detection output containing no noise without requiring connection of a filter constituted by a capacitor.

According to a fourth aspect of the present invention, a single bandpass filter is provided,
An object of the present invention is to provide an audio signal processing device capable of deriving a detection output that does not include noise without requiring connection of a filter constituted by a capacitor so that its center frequency can be switched according to the output of a determination unit. is there.

According to a fifth aspect of the present invention, an audio intermediate frequency signal is inputted, and audio from an output DC voltage of a first PLL-FM detection circuit having a pull-in range in which audio intermediate frequency signals of all desired broadcasting systems can be detected. A plurality of voltage-controlled oscillator circuits capable of pulling in only the band of the audio intermediate frequency signal for all broadcasting systems in accordance with the output of the determining means for determining the broadcasting method are selectively switched in accordance with the output of the determining means. Accordingly, it is an object of the present invention to provide an audio signal processing device capable of deriving a detection output that does not include noise without requiring connection of a filter constituted by a capacitor.

According to a sixth aspect of the present invention, a single voltage controlled oscillator circuit is used, the center frequency of which can be switched according to the result of the determination of the broadcast system, thereby eliminating noise without connecting a filter constituted by a capacitor. An object of the present invention is to obtain an audio signal processing device capable of deriving a detection output that does not include the detection output.

[0016]

According to a first aspect of the present invention, there is provided an audio signal processing apparatus capable of selectively processing a plurality of reception signals of a television broadcasting system, wherein the audio intermediate frequency signal of the broadcasting system is transmitted to an audio signal processing apparatus. By inputting the audio intermediate frequency signal to a PLL-FM detection circuit having a pull-in range that can be detected, the broadcast system is determined from the DC voltage of the detection output, and the FM detection output is amplified according to the determination result. It is characterized by.

According to a second aspect of the present invention, there is provided an audio signal processing apparatus for use in a receiving device capable of receiving various television broadcasting systems, wherein an audio intermediate frequency signal is inputted and a broadcast system is converted from a DC voltage of a detection output. A PLL-F having a pull-in range capable of detecting audio intermediate frequency signals of all desired broadcasting systems from which an output that can be determined is derived.
An M detection circuit, a detection output of the PLL-FM detection circuit is connected to one of the input terminals, and the other is connected to a reference voltage that is switched according to a result of determining the broadcast system,
An amplifier for amplifying and outputting the detection output.

In the audio signal processing apparatus according to the third aspect of the present invention, an audio intermediate frequency signal is input, and an output from which a broadcast system can be determined is derived from a DC voltage of a detection output thereof. A first PLL-FM detection circuit having a pull-in range in which a signal can be detected;
Determining means for determining the audio broadcasting system from the DC voltage of the detection output of the PLL-FM detection circuit, a plurality of bandpass filters corresponding to all the broadcasting methods and connected in parallel with each other; Switching means for selectively switching the band filter in response to the output of the band filter switched by the switching means, and having a pull-in range in which the audio intermediate frequency signals of all the desired broadcast systems can be detected. 2 PLL-FM detection circuit, and the output of the second PLL-FM detection circuit is introduced to one of the input terminals, and a reference voltage that is switched according to the output of the determination means is introduced to the other of the input terminals. An amplifier that amplifies the output of the determination means and outputs the amplified signal.

In the audio signal processing apparatus according to a fourth aspect of the present invention, an audio intermediate frequency signal is input, and an output from which a broadcast system can be determined is derived from a DC voltage of a detection output thereof. A first PLL-FM detection circuit having a pull-in range in which a signal can be detected;
Determining means for determining an audio broadcasting system from a DC voltage of a detection output of a PLL-FM detection circuit, a single band filter to which an audio intermediate frequency signal is input, and the band filter according to an output of the determining means Switching means for selectively switching the intermediate frequency of the, and input the output of the bandpass filter,
A second PLL-FM detection circuit having a pull-in range in which the audio intermediate frequency signals of all the desired broadcast systems can be detected, and an output of the second PLL-FM detection circuit introduced into one of input terminals; A reference voltage switched according to the output of the determining means is introduced to the other of the input terminals, and an amplifier for amplifying and outputting the output of the determining means is provided.

In the audio signal processing apparatus according to a fifth aspect of the present invention, a first PLL-FM detection circuit having a pull-in range in which an audio intermediate frequency signal is inputted and which can detect audio intermediate frequency signals of all desired broadcast systems, This first PLL-FM
Determining means for determining the audio broadcasting system from the DC voltage of the detection output of the detection circuit; and a plurality of voltage-controlled oscillation circuits capable of pulling in only the band of the audio intermediate frequency signal for each of the broadcasting systems. Is selectively switched according to the output of the determining means.

In the audio signal processing apparatus according to a sixth aspect of the present invention, a first PLL-FM detection circuit which receives an audio intermediate frequency signal and has a pull-in range in which audio intermediate frequency signals of all desired broadcast systems can be detected; This first PLL-FM
Determining means for determining the audio broadcasting system from the DC voltage of the detection output of the detection circuit, and a single voltage-controlled oscillation circuit that can pull in only the band of the audio intermediate frequency signal for each of the broadcasting systems, The center frequency of the voltage controlled oscillation circuit is selectively switched according to the output of the determination means.

The audio signal processing device according to the embodiment of the present invention has the following means for solving the problem. In an audio signal processing device used for a television receiver or the like that can receive various television broadcasting systems, the above-mentioned audio intermediate frequency is supplied to a PLL-FM detection circuit having a pull-in range capable of detecting audio intermediate frequency signals of all desired broadcasting systems. The broadcast system is determined from the DC voltage of the signal input and its detection output, the detection output is connected to one of the input terminals of the amplifier circuit, and the other is connected to a reference voltage that is switched according to the result of the determination of the broadcast method. The detection output is amplified and output.

In the audio signal processing apparatus according to the second embodiment of the present invention, the first PLL-PLL having a pull-in range in which audio intermediate frequency signals of all desired broadcast systems can be detected.
The audio intermediate frequency signal is input to an FM detection circuit, and the broadcast system of the audio is determined from the DC voltage of the detection output. At the same time, the audio intermediate frequency signals of all the broadcast systems can be passed, and At the time of the above, the audio intermediate frequency signal of the other system is connected in parallel to each band filter capable of removing the audio intermediate frequency signal, and after the output of each band filter is switched according to the result of determining the broadcast system, Is input to a second PLL-FM detection circuit having a pull-in range in which the audio intermediate frequency signal of the broadcasting system can be detected, and an output of the second PLL-FM detection circuit is connected to one of input terminals of an amplification circuit. The other is connected to a reference voltage that is switched according to the result of the determination of the broadcast system, and the detection output is amplified and output.

In the audio signal processing apparatus according to the third embodiment of the present invention, a single bandpass filter is used, but the center frequency thereof is switched according to the result of determining the broadcast system.

In the audio signal processing apparatus according to the second embodiment of the present invention, the first PLL-PLL having a pull-in range in which audio intermediate frequency signals of all desired broadcast systems can be detected.
The audio intermediate frequency signal is input to an FM detection circuit, and a broadcasting system of the audio is determined from a DC voltage of the detection output. At the same time, each VCO that can pull in only the band of the audio intermediate frequency signal for all the broadcasting systems , And each VCO can be switched according to the result of the determination of the broadcast system.

In the audio signal processing apparatus according to the fifth embodiment of the present invention, the VCO is single, but the center frequency is switched according to the result of determining the broadcasting system.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. First Embodiment FIG. 1 shows a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a PLL-FM detection circuit having the same configuration as a conventional PLL-FM detection circuit, 2 denotes a voltage determination circuit, 3 denotes a selector, 7 denotes an amplifier, 7a denotes a first input terminal of the amplifier 7, 7b is a second input terminal of the amplifier 7, 7c
Is an output terminal of the amplifier 7, and 8 is an I
C and 9 are input terminals of IC8, 10 is an output terminal of IC8,
11A, 11B and 11C are BPFs.

After the audio intermediate frequency signal is input to the input terminal 9 of the IC 8, it is input to the PLL-FM detection circuit 1 having the same configuration as the conventional PLL-FM detection circuit.

The output of the PLL-FM detection circuit 1 is input to a voltage determination circuit 2, and its DC voltage, that is, DC voltage, is compared between 5V and 7V to determine which of 4V, 6V and 8V is near. Thus, the frequency of the audio intermediate frequency signal, that is, the broadcast system is determined.

The output of the PLL-FM detection circuit 1 is an amplifier 7
Is input to one input terminal 7b. The input to the other input terminal 7a of the amplifier 7 is determined by the selector 3 using the output determination signal from the voltage determination circuit 2 and output from the selector 3 at 4V ·
It is controlled to select the same DC voltage as the FM detection output from the 6V / 8V reference voltage, and the signal is amplified normally without exceeding the dynamic range without using a capacitor outside the IC 8.

Embodiment 2 Embodiment 2 of the present invention
Is shown in FIG. In FIG. 2, 1 is a conventional PLL-F.
A first PLL-FM detection circuit having the same configuration as the M detection circuit, 2 is a voltage determination circuit, 3 is a first selector, 4A is a 5.5 MHz BPF, 4B is a 6.0 MHz BPF, 4C
Is a 6.5 MHz BPF, 5 is a second selector, and 6 is a second selector.
PLL-FM detection circuit, 7 is an amplifier, 7a is an amplifier 7
A first input terminal of the amplifier 7, 7b is a second input terminal of the amplifier 7,
7c is an output terminal of the amplifier 7, 8 is an IC formed of a semiconductor integrated circuit, 9 is an input terminal of the IC 8, 10 is an output terminal of the IC 8, and 11A, 11B and 11C are BPFs.

After the audio intermediate frequency signal is input to the input terminal 9 of the IC 8, the IC and the first PLL-FM detection circuit 1 having the same configuration as the conventional PLL-FM detection circuit are used together with the IC.
8, 5.5 MHz, 6.0 MHz, 6.5
MHz is input in parallel to BPFs 4A, 4B, and 4C.

The output of the first PLL-FM detection circuit 1 is
The DC voltage input to the voltage determination circuit 2
The voltage is compared between 5 V and 7 V, and the frequency of the audio intermediate frequency signal, that is, the broadcasting system is determined by determining which of the voltages is near 4 V, 6 V, and 8 V. B is determined by using the determination signal output from the voltage determination circuit 2 as the determination result.
The selector 5 controls which of the outputs of the PFs 4A, 4B, and 4C is selected, and outputs the selected output to the conventional PLL-FM.
Second PLL-FM having the same pull-in range as the detection circuit
The signal is input to the detection circuit 6 and subjected to FM detection.

Further, the output of the PLL-FM detection circuit 6 is input to one input terminal 7b of the amplifier 7. The input to the other input terminal 7 a of the amplifier 7 is determined by the selector 3 by using the output determination signal from the voltage determination circuit 2.
The same D as FM detection output from 4V, 6V, 8V reference voltage
The C voltage is controlled so as to be selected, and the signal is normally amplified without exceeding the dynamic range without using a capacitor outside the IC 8.

It should be noted that 5.5 MHz and 6.0 M in the IC 8 are used.
Since the BPFs 4A, 4B, and 4C at the frequency of 6.5 Hz are high frequency, the 5.5 MHz, 6.0 MHz,
The frequency accuracy of the 6.5 MHz BPFs 4A, 4B, and 4C may be loose enough to select only one frequency component among the three frequency components selected by the precise BPFs 11A, 11B, and 11C outside the IC 8. And this IC
By the BPFs 4A, 4B, and 4C in 8, the frequency components other than the audio intermediate frequency signal input at that time are accurately removed, so that noise is surely reduced.

Embodiment 3 In the recent IC circuit technology, it is easy to electrically change the center frequency of the BPF by using an active filter. In this case, the frequency may be changed by one BPF. FIG. 3 shows an example of a BPF IC circuit, and the frequency characteristics are set by C3, C4, I2, and I3. Therefore, the center frequency of the BPF can be changed by changing the control voltage.

The BPF of FIG. 3 corresponds to the second embodiment shown in FIG.
Can be used in place of the BPFs 4A, 4B, and 4C. By changing the control voltage of the BPF according to the output of the voltage determination circuit 2, the center frequency of the BPF can be changed, whereby the passband can be selectively switched.

Embodiment 4 FIG. The embodiment shown in FIG.
Compared to the second embodiment shown in FIG.
By switching the O circuit, the function of the BPF and the amplification effect are provided.

In FIG. 4, reference numeral 1 denotes a first PLL-FM detection circuit having a configuration similar to that of a conventional PLL-FM detection circuit, 2 denotes a voltage judgment circuit, and 8 denotes a semiconductor integrated circuit.
C and 9 are input terminals of IC8, 10 is an output terminal of IC8,
12 is a phase comparison circuit, 13 is a loop filter, 14A is a 5.5 MHz VCO circuit, 14B is a 6.0 MHz VCO
The circuit, 14C is a 6.5 MHz VCO circuit, and 15 is a selector.

According to the output of the voltage judgment circuit 2, the selector 1
5, the 5.5 MHz VCO circuit 14A
6.0MHz VCO circuits 14B and 14C are 6.5MHZ
The zVCO circuit 14C is selectively connected. The selected VCO circuit 14A, 14B or 14C performs a voltage oscillation control operation in a loop circuit including the phase comparison circuit 12 and the loop filter 13, and outputs its output to the output terminal 1 of the IC circuit 8.
Derived to 0. VCO circuits 14A, 14B, 14 in FIG.
C is BPF4A · 4 in the second embodiment shown in FIG.
B · 4C and the amplifier 7 can be used as a substitute. According to the output of the voltage judgment circuit 2, the selector 15 causes the VCO circuits 14A and 14B or 1
By selectively connecting 4C, a function similar to that of switching the BPF can be achieved, and thereby the passband can be selectively switched.

Embodiment 5 FIG. The embodiment shown in FIG.
By switching the center frequency of the VCO circuit, a function of a BPF for selectively switching a pass band and an amplification effect are provided. FIG. 5 is an example of an IC circuit of a VCO. The oscillation frequency is determined by the value of C2 and the amount of current I1, but the value of I1 is changed by changing the control voltage. However, by optimizing the value of C2 and the control voltage, the input frequency versus output voltage characteristics of the entire PLL can be set freely. That is, V
CO has a center frequency of 5.5 MHz and 6.0 MH respectively.
z · 6.5 MHz, and the pull-in range at that time is narrow, about + −0.2 MHz. The input frequency vs. output voltage characteristic is as shown in FIG.
Since the pull-in range of L is narrow, it has an effect of removing frequency components other than the audio intermediate frequency signal, and has the same effect as the BPF.

The VCO circuit of FIG. 5 can be used in place of the BPFs 4A, 4B, 4C and the amplifier 7 in the second embodiment shown in FIG. By changing the control voltage of the VCO circuit in accordance with the output of the voltage determination circuit 2, the same function as switching the center frequency of the BPF can be performed, and thereby the passband can be selectively switched.

Further, as the frequency width becomes narrower,
The amount of change in the output voltage with respect to the change in the frequency of the PLL characteristic can be increased. For example, in FIG.
+ -1 V vs. Hz, that is, 2
An output of V amplitude is obtained. As a result, a large output can be obtained for each broadcasting system, and the DC voltage of the detection output can be substantially the same, so that subsequent signal processing is also easy.

Further, if the output of the loop filter of the PLL is optimally converted to the VCO control voltage, the center frequency can be switched by one VCO circuit.

[0045]

According to the present invention, the number of IC terminals and the capacitors connected to them are reduced, and frequency components other than the audio intermediate frequency signal input in each broadcasting system are removed. Is reduced.

According to the first aspect of the present invention, the broadcast system is determined from the DC voltage of the detection output of the PLL-FM detection circuit, and the FM detection output is amplified according to the result of the determination. It is possible to obtain an audio signal processing device that can derive a detection output that does not include noise without requiring connection of a filter.

According to the second aspect of the present invention, the detection output of the PLL-FM detection circuit is amplified and output according to the reference voltage which is switched according to the result of the determination of the broadcasting system, so that the output of the filter constituted by the capacitor is reduced. An audio signal processing device that can derive a detection output that does not include noise without requiring connection can be obtained.

According to the third invention, the first PLL-FM
The output of the band-pass filter switched according to the output of the judging means for judging the audio broadcasting system from the DC voltage of the detection output of the detection circuit is inputted, so that the above-mentioned audio intermediate frequency signals of all desired broadcasting systems can be detected. Second P with range
By providing the LL-FM detection circuit, it is possible to obtain an audio signal processing device capable of deriving a detection output that does not include noise without requiring connection of a filter constituted by a capacitor.

According to the fourth aspect of the present invention, a single bandpass filter is used, and its center frequency can be switched according to the output of the determination means, so that noise can be reduced without the necessity of connecting a filter composed of a capacitor. It is possible to obtain an audio signal processing device capable of deriving a detection output that does not include the detection output.

According to the fifth invention, the DC voltage of the detection output of the first PLL-FM detection circuit having the pull-in range in which the audio intermediate frequency signal is inputted and the audio intermediate frequency signals of all desired broadcasting systems can be detected. A plurality of voltage-controlled oscillators capable of pulling in only the band of the audio intermediate frequency signal for each broadcasting method in accordance with the output of the judging means for judging the audio broadcasting system are selectively provided in accordance with the output of the judging means. By performing the switching, it is possible to obtain an audio signal processing device that can derive a detection output that does not include noise without requiring connection of a filter constituted by a capacitor.

According to the sixth aspect of the present invention, a single voltage controlled oscillation circuit is used, and the center frequency thereof can be switched according to the result of determining the broadcasting system, thereby eliminating the need for connecting a filter composed of a capacitor. An audio signal processing device capable of deriving a detection output that does not include noise can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 6 is a characteristic diagram showing Embodiment 5 of the present invention.

FIG. 7 is a configuration diagram showing a conventional technique.

FIG. 8 is a partial configuration diagram showing a conventional technique.

FIG. 9 is a characteristic diagram showing a conventional technique.

[Explanation of symbols]

1 first PLL-FM detection circuit, 2 voltage judgment circuit,
3 First selector, 4A / 4B / 4C BPF, 5
Second selector, 6 second PLL-FM detection circuit, 7
Amplifier, 7a first input terminal of amplifier 7, 7b second input terminal of amplifier 7, 7c output terminal of amplifier 7,
8 IC, 9 Input terminal of IC8, Output terminal of 10IC8, 11A, 11B, 11C BPF, C1, C2, C
3 Capacitor, I1, I2, I3 current amount.

Claims (6)

[Claims] An audio signal processing apparatus capable of selectively processing a plurality of received signals of a television broadcasting system, wherein said audio intermediate frequency signal is supplied to a PLL-FM detection circuit having a pull-in range capable of detecting an audio intermediate frequency signal of said broadcasting system. An audio signal processing apparatus characterized by receiving a signal, determining a broadcast system from a DC voltage of the detection output, and amplifying the detection output according to the determination result. 2. An audio signal processing apparatus for use in a receiving device capable of receiving various television broadcasting systems, wherein an audio intermediate frequency signal is input, and an output from which a broadcasting system can be determined is derived from a DC voltage of a detection output. And a PLL-FM detection circuit having a pull-in range capable of detecting audio intermediate frequency signals of all broadcasting systems, and a detection output of the PLL-FM detection circuit connected to one of input terminals, and the other to determine the broadcasting system. An audio signal processing apparatus, comprising: an amplifier connected to a reference voltage switched according to a result and amplifying and outputting the detection output. 3. An audio intermediate frequency signal is input, and an output from which a broadcast system can be determined is derived from a DC voltage of a detection output of the audio intermediate frequency signal. PLL-FM detection circuit, determination means for determining the audio broadcasting system from the DC voltage of the detection output of the first PLL-FM detection circuit, and a plurality of parallelly connected ones corresponding to all the broadcasting systems A bandpass filter, switching means for selectively switching the bandpass filter according to the output of the determination means, and input the output of the bandpass filter switched by the switching means,
A second PLL-FM detection circuit having a pull-in range in which the audio intermediate frequency signals of all the desired broadcast systems can be detected, and an output of the second PLL-FM detection circuit introduced into one of input terminals; 3. The audio signal according to claim 2, wherein a reference voltage switched according to the output of the determination unit is introduced to the other of the input terminals, and an amplifier that amplifies and outputs the output of the determination unit is provided. Processing equipment. 4. An audio intermediate frequency signal is inputted, and an output from which a broadcast system can be determined is derived from a DC voltage of a detection output thereof. A first audio signal having a pull-in range in which audio intermediate frequency signals of all desired broadcast systems can be detected. A PLL-FM detection circuit, determination means for determining the audio broadcasting system from the DC voltage of the detection output of the first PLL-FM detection circuit, and a single band-pass filter to which an audio intermediate frequency signal is input; Switching means for selectively switching the intermediate frequency of the bandpass filter in accordance with the output of the determination means; and a pull-in range in which the output of the bandpass filter is input and the audio intermediate frequency signals of all the desired broadcast systems can be detected. The second PLL with
An FM detection circuit and an output of the second PLL-FM detection circuit are introduced into one of the input terminals, and a reference voltage switched according to the output of the determination means is introduced into the other of the input terminals, 3. The audio signal processing device according to claim 2, further comprising an amplifier for amplifying the output and outputting the amplified signal. 5. A first PLL-FM detection circuit which receives an audio intermediate frequency signal and has a pull-in range in which audio intermediate frequency signals of all desired broadcast systems can be detected;
Determining means for judging an audio broadcasting system from a DC voltage of a detection output of the LL-FM detection circuit; and a plurality of voltage controlled oscillation circuits capable of pulling in only a band of the audio intermediate frequency signal for each of the broadcasting systems. 3. The audio signal processing device according to claim 2, wherein the plurality of voltage controlled oscillation circuits are selectively switched in accordance with an output of the determination unit. 6. A first PLL-FM detection circuit which receives an audio intermediate frequency signal and has a pull-in range in which audio intermediate frequency signals of all desired broadcast systems can be detected.
Determining means for determining the audio broadcasting system from the DC voltage of the detection output of the LL-FM detection circuit; and a single voltage-controlled oscillation circuit capable of pulling in only the band of the audio intermediate frequency signal for each of the broadcasting systems. 3. The audio signal processing apparatus according to claim 2, wherein a center frequency of the voltage controlled oscillation circuit is selectively switched according to an output of the determination unit.