JP2006246000A - Radio broadcasting receiving circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio broadcasting receiving circuit for reducing the number of control ports of a microcomputer and the number of control lines from a computer. <P>SOLUTION: In the radio broadcasting receiving circuit 1, an AM/FM decoding part 15 switches an operation between an AM signal processing operation and an FM signal processing operation according to a control signal to be inputted from an input terminal 151, and an RDS decoding IC 17 switches a mode between an operation execution mode for executing a signal processing operation for an additional signal according to the control signal to be inputted from the input terminal 171 and an operation stop mode for stopping the operation. An output terminal 161 of a PLL/extended part 16 and an input terminal 151 of the AM/FM decoding part 15 are connected with each other through a control signal line 181, and an input terminal 171 of the RDS decoding IC 17 is connected to the control signal line 181. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio broadcast receiving circuit capable of receiving AM broadcast and FM multiplex broadcast in which an FM multiplex signal obtained by multiplexing an additional signal with an audio signal is transmitted.

2. Description of the Related Art Conventionally, as an FM multiplex broadcasting system, an RDS (Radio Data) that multiplexes an FM audio signal with an additional signal such as character data in a band different from the baseband of the audio signal, performs FM modulation on the multiplexed signal, and transmits the multiplexed signal. System) is known. The applicant has proposed an RDS receiver capable of receiving RDS FM multiplex broadcasting (see Patent Document 1).
On the other hand, in recent years, AV composite devices including a plurality of AV (audio / video) reproduction circuits such as a radio broadcast receiving circuit, a DVD reproduction circuit, a CD reproduction circuit, and an MD reproduction circuit have become widespread.
FIG. 2 shows a configuration of an AV composite device including a radio broadcast receiving circuit (5) capable of receiving FM multiplex broadcasting of RDS. In the AV composite device, the device is configured on a control board. A microcomputer (6) for controlling the operation of the plurality of AV playback circuits is mounted. The microcomputer (6) is connected to the plurality of AV playback circuits including the radio broadcast receiving circuit (5). The operation unit (3) and the display unit (4) are connected. In FIG. 2, the AV playback circuit other than the radio broadcast receiving circuit (5) is not shown.

The radio broadcast receiving circuit (5) includes an AM RF unit (52) connected to the AM receiving antenna (51) and an FM front end unit (54) connected to the FM receiving antenna (53). ), An AM / FM decoding unit (55) for demodulating the broadcast wave, a PLL / expansion unit (56) for changing the frequency division ratio of the PLL circuit (not shown) of the FM front end unit (54), and an addition An RDS decoding IC (57) for demodulating the signal is mounted.
Three control output terminals (560) (561) (562) provided in the PLL / expansion section (56), a control input terminal (540) provided in the FM front end section (54), and the AM / Two control input terminals (551) and (552) provided in the FM decoding unit (55) are connected to each other by control signal lines (580), (581) and (582).
Further, a control input terminal (563) provided in the PLL / extension unit (56), two control input terminals (571) (572) provided in the RDS decode IC (57), and a microcomputer (6) are provided. Three provided control ports (60), (61), and (62) are connected to each other by wires (70), (71), and (72), respectively.

The AM / FM decoding unit (55) can switch an operation between an AM decoding operation for demodulating an AM broadcast wave and an FM decoding operation for demodulating an FM broadcast wave. The operation is switched according to the operation switching control signal S3 supplied from (56). The operation switching control signal S3 is composed of, for example, a binary signal, and is switched to the AM decoding operation when taking a value of “0”, while being switched to the FM decoding operation when taking a value of “1”.
Further, the AM / FM decoding unit (55) sets the output sound to the silent state (mute state) or sets the silent state according to the mute control signal S4 supplied from the PLL / extension unit (56). Is released. The mute control signal S4 is composed of, for example, a binary signal. When the mute control signal S4 has a value of “0”, the output sound is set to a silent state, and when it takes a value of “1”, the silent state setting is canceled.

The RDS decode IC (57) can switch between a normal operation mode for executing a demodulation processing operation for an additional signal and a low power consumption mode for stopping the demodulation processing operation. The mode is switched in accordance with the mode switching control signal S5 supplied from (1). The mode switching control signal S5 is composed of, for example, a binary signal and is switched to the low power consumption mode when taking a value of “0”, while being switched to the normal operation mode when taking a value of “1”. The RDS decode IC (57) is low when receiving an AM broadcast in which an additional signal cannot be obtained from the AM / FM decode unit (55), when turning off the power of the apparatus body, and when selecting an AV playback function other than the radio broadcast reception function. The power consumption mode is set.
The RDS decode IC (57) receives the reset control signal S6 supplied from the microcomputer (6) and starts the demodulation process for the additional signal. The reset control signal S6 is composed of a binary signal, for example, and takes either “0” or “1”.

In the radio broadcast receiving circuit (5), when an operation for switching the received broadcast from FM multiplex broadcast to AM broadcast is performed, the microcomputer (6) detects this, and the PLL / expansion section (56). The PLL / extension unit (56) receives the control signal, supplies the mute control signal S4 and the operation switching control signal S3 to the AM / FM decoding unit (55), and then mutes again. The control signal S4 is supplied to the AM / FM decoding unit (55). As a result, the operation of the AM / FM decoding unit (55) is switched from the FM decoding operation to the AM decoding operation in a state where the output sound of the AM / FM decoding unit (55) is set to the silent state, and then the silent state is set. Is released.
The microcomputer (6) supplies a mode switching control signal S5 to the RDS decode IC (57). As a result, the RDS decode IC (57) is switched from the normal operation mode to the low power consumption mode.
The AM broadcast wave received by the AM receiving antenna (51) is supplied to the AM / FM decoding unit (55) through the AM RF unit (52) and demodulated. It is supplied to a subsequent audio signal amplifier (not shown).

On the other hand, when an operation for switching the received broadcast from the AM broadcast to the FM multiplex broadcast is performed, the microcomputer (6) detects this and outputs a broadcast switching control signal to the PLL / extension unit (56). The PLL / extension unit (56) receives the control signal, supplies the mute control signal S4 and the operation switching control signal S3 to the AM / FM decoding unit (55), and then AM / FM decodes the mute control signal S4 again. Part (55). As a result, the operation of the AM / FM decoding unit (55) is switched from the AM decoding operation to the FM decoding operation in a state where the output sound of the AM / FM decoding unit (55) is set to the silent state, and then the silent state is set. Is released.
The microcomputer (6) supplies the mode switching control signal S5 and the reset control signal S6 to the RDS decoding IC (57). As a result, the RDS decoding IC (57) is switched from the operation stop mode to the normal operation mode, and the demodulation processing for the additional signal obtained from the AM / FM decoding unit (55) is started.
The FM multiplex broadcast wave received by the FM receiving antenna (53) is supplied to the FM front end unit (54) to select a broadcast wave of a specific frequency, and the broadcast wave is transmitted to the AM / FM decoding unit (55). ) To be demodulated. The FM audio signal and the additional signal obtained in this way are respectively supplied to the subsequent audio signal amplification unit and the RDS decoding IC (57). In the RDS decoding IC (57), the additional signal is demodulated, and the additional data obtained thereby is supplied to the microcomputer (6).

Thereafter, when an operation for changing the reception frequency of FM multiplex broadcasting is performed, the microcomputer (6) detects this and outputs a frequency control signal to the PLL / expansion unit (56), and the PLL / extension The unit (56) receives the control signal, supplies the mute control signal S4 to the AM / FM decoding unit (55), changes the frequency division ratio of the FM front end unit (54), and then performs mute control again. The signal S4 is supplied to the AM / FM decoding unit (55). As a result, the reception frequency is changed in a state where the output sound of the AM / FM decoding unit (55) is set to the silent state, and thereafter, the setting of the silent state is canceled.
The microcomputer (6) supplies the reset control signal S6 to the RDS decode IC (57). As a result, demodulation processing for the additional signal obtained from the AM / FM decoding unit (15) is started.

JP-A-10-163901 [H04L 1/00]

However, in the conventional AV composite device, as shown in FIG. 2, a dedicated control port (61 for outputting the mode switching control signal S5 and the reset control signal S6 to the RDS decoding IC (57) to the microcomputer (6). ) (62) must be provided, and the number of control ports of the microcomputer (6) increases. Further, wires (71) and (72) for connecting the microcomputer (6) and the RDS decode IC (57) are required, and there is a problem that the number of control lines from the microcomputer (6) increases.
An object of the present invention is to provide a radio broadcast receiving circuit capable of reducing the number of control ports of a control circuit such as a microcomputer and the number of control lines from the control circuit as compared with the conventional one.

  Therefore, as a result of intensive studies to solve the above problems, the present inventor has made AM from the PLL / expansion unit (56) at the same timing as a mode switching control signal for switching the mode of the RDS decode IC (57). It came to the idea that the operation switching control signal S3 supplied to the / FM decoding unit (55) is also used, and the first radio broadcast receiving circuit according to the present invention was completed.

The first radio broadcast receiving circuit according to the present invention is capable of receiving AM broadcast and FM multiplex broadcast in which an FM multiplex signal obtained by multiplexing an additional signal with an audio signal is transmitted,
An AM broadcast receiving circuit for receiving AM broadcast;
An FM multiplex broadcast receiving circuit for receiving FM multiplex broadcast;
An AM signal processing operation for providing an audio signal by performing signal processing on an AM broadcast reception signal according to a control signal input from the control input terminal, and an FM multiplex broadcast reception signal. An AM / FM signal processing circuit that switches between an FM signal processing operation that performs signal processing on the output and outputs an audio signal and an additional signal;
An operation execution mode that includes a control input terminal and that performs a signal processing operation on an additional signal obtained from the AM / FM signal processing circuit and stops the signal processing operation according to a control signal input from the control input terminal An additional signal processing circuit for switching the mode between the operation stop mode and
A signal output circuit connected to the control circuit and outputting a control signal in response to a command from the control circuit; The signal output circuit includes a control output terminal to output a control signal to the AM / FM signal processing circuit and the additional signal processing circuit, and the control output terminal and the control input of the AM / FM signal processing circuit. Terminals are connected to each other by a control signal line, and a control input terminal of the additional signal processing circuit is connected to the control signal line.

In the first radio broadcast receiving circuit according to the present invention, the control signal output from the control output terminal of the signal output circuit in response to a command from the control circuit is input to the AM / FM signal processing circuit and the additional signal processing circuit. The AM / FM signal processing circuit switches the operation between the AM signal processing operation and the FM signal processing operation in accordance with the control signal, while the additional signal processing circuit has an operation execution mode in accordance with the control signal. Switches the mode between the operation stop modes.
As described above, the control signal output from the control output terminal of the signal output circuit is used as an operation switching control signal for switching the operation of the AM / FM signal processing circuit and a mode switching control signal for switching the mode of the additional signal processing circuit. By sharing this, the control port (61) for outputting the mode switching control signal provided in the conventional microcomputer (6) can be omitted. Further, the wire (71) connected to the control port (61) is not necessary.

  The inventor also provides a mute that is supplied from the PLL / extension unit (56) to the AM / FM decoding unit (55) at the same timing as a reset control signal for causing the RDS decoding IC (57) to start demodulation processing. As a result, the second radio broadcast receiving circuit according to the present invention was completed.

The second radio broadcast receiving circuit according to the present invention is capable of receiving AM broadcast and FM multiplex broadcast in which an FM multiplex signal obtained by multiplexing an additional signal with an audio signal is transmitted,
An AM broadcast receiving circuit for receiving AM broadcast;
An FM multiplex broadcast receiving circuit for receiving FM multiplex broadcast;
An AM signal processing operation for performing signal processing on an AM broadcast reception signal and outputting an audio signal, and an FM signal processing operation for performing signal processing on an FM multiplex broadcast reception signal and outputting an audio signal and an additional signal An AM / FM signal processing circuit that includes a control input terminal and sets the output sound to a silent state or cancels the setting according to a control signal input from the control input terminal;
An additional signal that performs signal processing on an additional signal obtained from the AM / FM signal processing circuit, includes a control input terminal, and starts the signal processing in response to the control signal input from the control input terminal A processing circuit;
A signal output circuit connected to the control circuit and outputting a control signal in response to a command from the control circuit; The signal output circuit includes a control output terminal to output a control signal to the AM / FM signal processing circuit and the additional signal processing circuit, and the control output terminal and the control input of the AM / FM signal processing circuit. Terminals are connected to each other by a control signal line, and a control input terminal of the additional signal processing circuit is connected to the control signal line.

In the second radio broadcast receiving circuit according to the present invention, the control signal output from the control output terminal of the signal output circuit in response to a command from the control circuit is input to the AM / FM signal processing circuit and the additional signal processing circuit. The AM / FM signal processing circuit sets / cancels the silence state of the output sound according to the control signal, while the additional signal processing circuit starts signal processing for the additional signal according to the control signal.
In this way, the control signal output from the control output terminal of the signal output circuit starts signal processing for the mute control signal and additional signal processing circuit for setting / releasing the silence state of the output sound of the AM / FM signal processing circuit. The control port (62) for outputting the reset control signal provided in the conventional microcomputer (6) can be omitted by using the reset control signal as well. Further, the wire (72) connected to the control port (62) is not necessary.

  According to the first and second radio broadcast receiving circuits according to the present invention, the number of control ports of a control circuit such as a microcomputer and the number of control lines from the control circuit can be reduced as compared with the prior art.

Hereinafter, the embodiment of the present invention implemented in the radio broadcast receiving circuit (1) of the AV composite device shown in FIG. 1 will be described in detail with reference to the drawings.
In the AV composite device according to the present invention, a microcomputer (2) for controlling the operation of a plurality of AV playback circuits constituting the device is mounted on the control board, and the microcomputer (2) includes a radio. The plurality of AV circuits including the broadcast receiving circuit (1) are connected, and the operation unit (3) and the display unit (4) are connected. In FIG. 1, the AV playback circuit other than the radio broadcast receiving circuit (1) is not shown.
Similarly to the conventional radio broadcast receiving circuit (5) shown in FIG. 2, the radio broadcast receiving circuit (1) has an AM RF unit (12) connected to the AM receiving antenna (11) on the substrate, and an FM. FM front end (14) connected to the receiving antenna (13), AM / FM decoding unit (15) for demodulating broadcast waves, and PLL circuit (not shown) of the FM front end (14) A PLL / extension unit (16) for changing the frequency division ratio and an RDS decoding IC (17) for demodulating the additional signal are mounted.
A first control output terminal (160) provided in the PLL / expansion section (16) and a control input terminal (140) provided in the FM front end section (14) are connected to a control signal line (180). Are connected to each other.
A second control output terminal (161) provided in the PLL / extension unit (16) and a first control input terminal (151) provided in the AM / FM decoding unit (15) are control signals. The control signal line (181) is connected to the first control input terminal (171) provided in the RDS decode IC (17) via the control signal line (183). It is connected.
A third control output terminal (162) provided in the PLL / extension unit (16) and a second control input terminal (152) provided in the AM / FM decoding unit (15) are control signals. The control signal line (182) is connected to a second control input terminal (172) provided in the RDS decode IC (17) via the control signal line (184). It is connected.
Further, a control input terminal (163) provided in the PLL / extension unit (16) and a control port (20) provided in the microcomputer (2) are connected to each other by a wire (70).

The AM / FM decoding unit (15) can switch an operation between an AM decoding operation for demodulating an AM broadcast wave and an FM decoding operation for demodulating an FM broadcast wave. The operation is switched according to an operation / mode switching control signal S1 input from the second control output terminal (161) (16) via the control signal line (181) and the first control input terminal (151). In the present embodiment, the operation / mode switching control signal S1 is composed of a binary signal, and is switched to the AM decoding operation when taking a value of “0”, while being switched to the FM decoding operation when taking a value of “1”. Can be switched.
The AM / FM decoding unit (15) is input from the third control output terminal (162) of the PLL / expansion unit (16) via the control signal line (182) and the second control input terminal (152). In response to the mute / reset control signal S2, the output sound is set to the silent state or the silent state setting is canceled. In this embodiment, the mute / reset control signal S2 is composed of a binary signal, and when the value “0” is taken, the output sound is set to the silent state, whereas when the value “1” is taken, the silent state is set. The setting is canceled.

The RDS decoding IC (17) is capable of switching between a normal operation mode for executing a demodulation processing operation for an additional signal and a low power consumption mode for stopping the demodulation processing operation, and includes a PLL / extension unit. The mode is switched in accordance with the operation / mode switching control signal S1 input from the second control output terminal 161 of (16) through the control signal lines 181 and 183 and the first control input terminal 171. . In this embodiment, when the operation / mode switching control signal S1 takes a value of “0”, the mode is switched to the low power consumption mode, whereas when it takes the value of “1”, the mode is switched to the normal operation mode. The RDS decoding IC (17) is used when receiving an AM broadcast in which an additional signal cannot be obtained from the AM / FM decoding unit (55), when turning off the power of the device body, and when selecting an AV playback function other than the radio broadcast receiving function. Low power consumption mode is set.
The RDS decode IC (17) is input from the third control output terminal (162) of the PLL / expansion section (16) via the control signal lines (182) (184) and the second control input terminal (172). In response to the mute / reset control signal S2, the demodulation process for the additional signal is started. In the present embodiment, the demodulation process is started when the mute / reset control signal S2 has a value of “1”.

尚、“０”と“１”の値を入れ替えることも可能である。 Table 1 below shows the relationship between the value of the operation / mode switching control signal S1, the operation of the AM / FM decoding unit (15) and the mode of the RDS decoding IC (17).

It is also possible to exchange the values of “0” and “1”.

尚、“０”と“１”の値を入れ替えることも可能である。 Table 2 below shows the value of the mute / reset control signal S2 and the setting / canceling of the silent state of the AM / FM decoding unit (15) and the start / absence of the demodulation processing of the RDS decoding IC (17). Represents a relationship.

It is also possible to exchange the values of “0” and “1”.

In the radio broadcast receiving circuit (1), when an operation for switching the received broadcast from FM multiplex broadcast to AM broadcast is performed, the microcomputer (2) detects this, and the PLL / expansion section (16). A broadcast switching control signal is output to the PLL / expansion unit 16 in response to the control signal, and an operation / mode switching control signal S1 that takes a value of “0” and a mute / reset that takes a value of “0”. The control signal S2 is output from the second control output terminal (161) and the third control output terminal (162), respectively. The operation / mode switching control signal S1 and the mute / reset control signal S2 output in this way are input to the AM / FM decoding unit (15). As a result, the output sound of the AM / FM decoding unit (15) is silent. In the state set to the state, the operation of the AM / FM decoding unit (15) is switched from the FM decoding operation to the AM decoding operation.
Further, the operation / mode switching control signal S1 and the mute / reset control signal S2 output as described above are input to the RDS decode IC (17), and as a result, the RDS decode IC (57) is reduced in power consumption from the normal operation mode. Switch to mode. Since the mute / reset control signal S2 has a value of “0”, the demodulation process is not started.

  Thereafter, the PLL / expansion unit (16) outputs a mute / reset control signal S2 having a value of “1” from the third control output terminal (162). The mute / reset control signal S2 is input to the AM / FM decoding unit (15). As a result, the silent state of the output sound is canceled. The mute / reset control signal S2 is also input to the RDS decode IC (17). Since the IC (17) is set to the low power consumption mode as described above, the demodulation process starts. It will never be done.

  The AM broadcast wave received by the AM receiving antenna (11) is supplied to the AM / FM decoding unit (15) via the AM RF unit (12) and demodulated. It is supplied to a subsequent audio signal amplifier (not shown).

On the other hand, when an operation for switching the received broadcast from the AM broadcast to the FM multiplex broadcast is performed, the microcomputer (2) detects this and outputs a broadcast switching control signal to the PLL / extension unit (16). Upon receiving the control signal, the PLL / expansion unit (16) receives an operation / mode switching control signal S1 and a mute / reset control signal S2, respectively, as a second control output terminal (161) and a third control output terminal (162). Output from. The operation / mode switching control signal S1 and the mute / reset control signal S2 output in this way are input to the AM / FM decoding unit (15). As a result, the output sound of the AM / FM decoding unit (15) is silent. In the state set to the state, the operation of the AM / FM decoding unit (15) is switched from the AM decoding operation to the FM decoding operation.
The operation / mode switching control signal S1 and the mute / reset control signal S2 output as described above are input to the RDS decode IC (17). As a result, the RDS decode IC (57) operates normally from the low power consumption mode. Switch to mode. Since the mute / reset control signal S2 has a value of “0”, the demodulation process is not started.
Thereafter, the PLL / expansion unit (16) outputs a mute / reset control signal S2 having a value of “1” from the second control output terminal (162). The mute / reset control signal S2 is input to the AM / FM decoding unit (15). As a result, the silent state of the output sound is canceled. The mute / reset control signal S2 is input to the RDS decode IC (17), and as a result, the demodulation process for the additional signal obtained from the AM / FM decode unit (15) is started.

  The FM multiplex broadcast wave received by the FM receiving antenna (13) is supplied to the FM front end unit (14) to select a broadcast wave of a specific frequency, and the broadcast wave is supplied to the AM / FM decoding unit (15 ) To be demodulated. The FM audio signal and the additional signal obtained in this way are respectively supplied to the subsequent audio signal amplification unit and the RDS decode IC (17). In the RDS decoding IC (17), the additional signal is demodulated, and the additional data obtained thereby is supplied to the microcomputer (2).

Thereafter, when an operation for changing the reception frequency of FM multiplex broadcasting is performed, the microcomputer (2) detects this and outputs a frequency control signal to the PLL / expansion unit (16), and the PLL / extension The unit (16) receives the control signal and outputs a mute / reset control signal S2 having a value of “0” from the third control output terminal (162). The mute / reset control signal S2 output in this way is input to the AM / FM decoding unit (15), and as a result, the output sound of the AM / FM decoding unit (15) is set to a silent state. The mute / reset control signal S2 is also input to the RDS decoding IC (17), but takes a value of “0”, so that the demodulation process is not started.
The PLL / expansion unit (16) changes the frequency division ratio of the FM front end unit (14) based on the frequency control signal. As a result, the reception frequency is changed.
Thereafter, the PLL / expansion unit (16) outputs a mute / reset control signal S2 having a value of “1” from the second control output terminal (162). The mute / reset control signal S2 is input to the AM / FM decoding unit (15). As a result, the silent state of the output sound is canceled. The mute / reset control signal S2 is input to the RDS decode IC (17), and as a result, the demodulation process for the additional signal obtained from the AM / FM decode unit (15) is started.

  When the device main unit is turned off and when an AV playback function other than the radio broadcast reception function is selected, “0” is sent from the PLL / expansion unit (16) to the AM / FM decoding unit (15) and the RDS decoding unit (17). When the operation / mode switching control signal S1 taking the value of is supplied, the operation of the AM / FM decoding unit (15) is switched to the AM decoding operation, and the RDS decoding IC (17) is switched to the low power consumption mode.

In the AV composite device, as described above, the operation / mode switching control signal S1 output from the second control output terminal (161) of the PLL / extension unit (16) switches the operation of the PLL / extension unit (16). 2 is used as a mode switching control signal for switching the mode of the RDS decoding IC (17) and the mode switching control signal provided in the conventional microcomputer (6) shown in FIG. The control port (61) for outputting S5 can be omitted. The mute / reset control signal S2 output from the third control output terminal (162) of the PLL / expansion unit (16) is used to set / cancel the silence state of the output sound of the PLL / extension unit (16). A control port for outputting the reset control signal S6 provided in the conventional microcomputer (6) because the control signal and the RDS decode IC (17) are also used as a reset control signal for starting demodulation processing. (62) can be omitted. As a result, the number of control ports of the microcomputer (2) can be reduced as compared with the prior art.
Further, a socket, a plug, a wire and the like for connecting the microcomputer (2) and the RDS decode IC (17) become unnecessary, and the number of parts can be reduced and the cost can be reduced.

In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim.
For example, it is also possible to mount the microcomputer (2) on the substrate constituting the radio broadcast receiving circuit (1).

It is a block diagram showing the structure of AV compound apparatus provided with the radio broadcast receiving circuit which concerns on this invention. It is a block diagram showing the structure of the conventional AV compound apparatus.

Explanation of symbols

(1) Radio broadcast receiving circuit
(11) AM receiving antenna
(13) FM receiving antenna
(15) AM / FM decoding section
(151) (152) Control input terminal
(16) PLL / expansion section
(160) to (162) Control output terminal
(17) RDS decoding IC
(171) (172) Control input terminal
(181) to (184) Control signal line
(2) Microcomputer
(3) Operation part
(4) Display section

Claims (6)

In a radio broadcast receiving circuit capable of receiving AM broadcast and FM multiplex broadcast in which an FM multiplex signal obtained by multiplexing an additional signal with an audio signal is transmitted,
An AM broadcast receiving circuit for receiving AM broadcast;
An FM multiplex broadcast receiving circuit for receiving FM multiplex broadcast;
An AM signal processing operation for providing an audio signal by performing signal processing on an AM broadcast reception signal according to a control signal input from the control input terminal, and an FM multiplex broadcast reception signal. An AM / FM signal processing circuit that switches between an FM signal processing operation that performs signal processing on the output and outputs an audio signal and an additional signal;
An operation execution mode that includes a control input terminal and that performs a signal processing operation on an additional signal obtained from the AM / FM signal processing circuit and stops the signal processing operation according to a control signal input from the control input terminal An additional signal processing circuit for switching the mode between the operation stop mode and
A signal output circuit connected to the control circuit and outputting a control signal in response to a command from the control circuit. The signal output circuit sends a control signal to the AM / FM signal processing circuit and the additional signal processing circuit. A control output terminal to be output is provided, and the control output terminal and the control input terminal of the AM / FM signal processing circuit are connected to each other by a control signal line, and the control of the additional signal processing circuit is connected to the control signal line. A radio broadcast receiving circuit, wherein an input terminal is connected.   The control signal is composed of a binary signal, and the AM / FM signal processing circuit switches the operation to the AM signal processing operation when the input control signal takes the first value, while the input control signal is When taking the second value, the operation is switched to the FM signal processing operation, and the additional signal processing circuit switches the mode to the operation stop mode when the inputted control signal takes the first value, The radio broadcast receiving circuit according to claim 1, wherein the mode is switched to an operation execution mode when the control signal thus obtained takes the second value.   The AM / FM signal processing circuit includes a second control input terminal, and sets the output sound to a silent state or cancels the setting according to the second control signal input from the control input terminal. The additional signal processing circuit includes a second control input terminal, and starts signal processing for the additional signal in response to a second control signal input from the control input terminal. The output circuit includes a second control output terminal to output a second control signal to the AM / FM signal processing circuit and the additional signal processing circuit. The second control output terminal and the AM / FM signal processing The second control input terminal of the circuit is connected to each other by a control signal line, and the second control input terminal of the additional signal processing circuit is connected to the control signal line. Radio broadcast reception described in Road.   The second control signal is composed of a binary signal, and the AM / FM signal processing circuit sets the output sound to a silent state when the input second control signal takes the first value, When the input second control signal takes the second value, the silent state setting is canceled, and the additional signal processing circuit determines that the input second control signal is the first value or the first value. The radio broadcast receiving circuit according to claim 3, wherein signal processing for the additional signal is started when any one of the values of 2 is taken. In a radio broadcast receiving circuit capable of receiving AM broadcast and FM multiplex broadcast in which an FM multiplex signal obtained by multiplexing an additional signal with an audio signal is transmitted,
An AM broadcast receiving circuit for receiving AM broadcast;
An FM multiplex broadcast receiving circuit for receiving FM multiplex broadcast;
An AM signal processing operation for performing signal processing on an AM broadcast reception signal and outputting an audio signal, and an FM signal processing operation for performing signal processing on an FM multiplex broadcast reception signal and outputting an audio signal and an additional signal An AM / FM signal processing circuit that includes a control input terminal and sets the output sound to a silent state or cancels the setting according to a control signal input from the control input terminal;
An additional signal that performs signal processing on an additional signal obtained from the AM / FM signal processing circuit, includes a control input terminal, and starts the signal processing in response to the control signal input from the control input terminal A processing circuit;
A signal output circuit connected to the control circuit and outputting a control signal in response to a command from the control circuit. The signal output circuit sends a control signal to the AM / FM signal processing circuit and the additional signal processing circuit. A control output terminal to be output is provided, and the control output terminal and the control input terminal of the AM / FM signal processing circuit are connected to each other by a control signal line, and the control of the additional signal processing circuit is connected to the control signal line. A radio broadcast receiving circuit, wherein an input terminal is connected.   The control signal is composed of a binary signal, and the AM / FM signal processing circuit sets the output sound to a silent state when the input control signal takes the first value, while the input control signal When the second value is taken, the silent state setting is canceled, and the additional signal processing circuit causes the input control signal to take either the first value or the second value. The radio broadcast receiving circuit according to claim 5, wherein signal processing for the additional signal is started.

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