JPH0690417A - Receiver - Google Patents

Abstract

PURPOSE:To simultaneously receive an arbitrary combination of respective TV signals by receiving signals regardless of a different transmission system (AM or FM) and a different TV system (MUSE or NTSC) at the time when TV, satellite, and CATV broadcast can be received and CATV broadcast is especially received. CONSTITUTION:At the time of BS and TV reception, demodulation is performed by a BS signal demodulating circuit 103 and a TV.CATV signal demodulating circuit 117. At the time of CATV reception, a BS.TV.CATV shared tuner circuit 102 is controlled by a local oscillation frequency switching control means 119 to perform demodulation in the BS signal demodulating circuit 103 in the case of the FM transmission system. In the case of the AM transmission system and the MUSE signal system, the reception performance is obtained by a demodulating circuit switching control means 118 and an AGC control circuit 130 using a keyed pulse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terrestrial television broadcasting signal (hereinafter sometimes referred to as TV signal), a satellite broadcasting signal (hereinafter sometimes referred to as BS signal), and a CATV broadcasting signal (hereinafter referred to as CATV signal). In some cases, the present invention relates to a receiving device which receives a video signal and outputs a video signal and an audio signal after signal processing.

[0002]

2. Description of the Related Art Conventionally, TV signals, BS signals, and CAT
In the case of receiving V signals all at once, it is necessary to combine devices that receive the respective broadcast signals or prepare a receiving device that individually includes a circuit that receives the respective broadcast signals.

In addition, the existing satellite broadcasting is broadcast by two systems of broadcasting by the NTSC system and high-definition broadcasting by the MUSE system. Therefore, MUSE system and NTSC
A means for discriminating the system is required, and a receiving device having the system discriminating means is described in JP-A-3-204287.

[0004]

However, the conventional TV signal, BS signal (MUSE system, NTSC system),
In the receiving device for receiving the CATV signal, the TV signal, BS
Since signals are received by the respective tuner circuits, it is necessary to perform TV signal selection and BS signal selection respectively, which complicates the operation and makes it difficult to reduce the circuit scale of the receiving device.

Further, in the above-mentioned conventional technique, the NTS based on the AM modulation system is used as a signal transmission system for CATV broadcasting.
Since the transmission of C signal is mainly considered, the NTSC signal is F
When transmitted by M modulation method or F by CATV broadcasting
MUS transmitted by M modulation method or AM modulation method
Receiving and signal processing the E signal is not considered.

The sync signal of an NTSC television signal has a negative polarity, and a method of performing AGC (automatic gain control) by a voltage proportional to the peak value of the sync signal is generally used. Since the signal uses a positive sync signal that does not cause sync loss in transmission, the peak value AG
When C is applied, it is considered to cause waveform distortion.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a receiving device capable of receiving a TV signal, a BS signal and a CATV signal, having a simple circuit configuration and excellent operability. It is in.

Another object of the present invention is that the BS signal is
It is an object of the present invention to provide a receiving device capable of receiving a television signal belonging to either the NTSC system or the MUSE system.

Another object of the present invention is to selectively perform signal processing through an AM demodulation system or an FM demodulation system regardless of whether the CATV signal transmission system is the AM modulation system or the FM modulation system. And can receive NTSC and MUSE television signals,
It is to provide a receiver and to obtain good reception performance.

In addition, the above-mentioned prior art does not sufficiently consider the case of receiving using two or more front ends, and the video and audio signal processing circuit system becomes complicated and the circuit scale becomes large. , BS signals, and CATV signals are received and distributed,
Circuit connection becomes complicated.

Therefore, another object of the present invention is to provide a TV signal, a BS signal, and a CATV signal in a case where the reception is performed by using two or more front ends capable of receiving the signals collectively.
It is an object of the present invention to provide a user-friendly receiving device that can easily input and output signals, BS signals, and CATV signals and has a simple circuit configuration.

[0012]

In order to achieve the above object, in the present invention, the B signal from the TV signal and CATV signal bands is used.
BS / TV / CA capable of variable continuous tuning up to S signal band
A tuner is provided for sharing the TV, and the channel selection circuit is a channel selection system in which the BS signal is received, the TV signal is received, and the CATV signal is received.

Further, since the two types of BS signals are received,
MUSE / NTSC system discriminating means for discriminating whether the BS signal is the NTSC system or the MUSE system is provided,
The receiver is a TV / CATV signal demodulation circuit, a BS signal processing circuit, a TV signal processing circuit, and a MUSE, which are equipped with a BS signal demodulation circuit, an NTSC demodulation circuit, and a MUSE demodulation circuit.
MUSE decoder (or MUSE-) that processes signals
(NTSC converter).

Further, an AM / FM system discriminating means for discriminating the signal transmission system of the CATV signal is provided.
AM demodulation processing from the discrimination result of the M / FM system discrimination means, F
A local oscillation frequency switching control means for selecting the M demodulation process is provided. Further, by using the MUSE / NTSC system discriminating means, it is possible to perform signal processing regardless of whether the CATV signal is of the NTSC system or the MUSE system, and particularly when the MUSE signal is the AM modulation system, a good reception characteristic is obtained. In order to obtain A
A GC control circuit and a demodulation circuit switching control means are provided.

Further, a TV signal processing circuit for receiving a TV / CATV demodulated signal and performing signal processing, a BS signal processing circuit for receiving a BS demodulated signal and performing signal processing, and a MUSE decoder (or a MUSE decoder for processing a MUSE signal). MUSE-N
BS / TV / CATV in which two or more systems of TSC converters are provided, respectively, and the tuning circuit is shared by BS signal reception, TV signal reception and CATV signal reception.
Shared tuner and its BS signal demodulation circuit and TV / CAT
Use two or more V signal demodulation circuits,

A TV / CATV demodulated signal or a BS demodulated signal output from these is switched and input to a TV signal processing circuit, a BS signal processing circuit, a MUSE decoder (or a MUSE-NTSC converter), and a TV signal is input. ,
Enables simultaneous or separate reception of CATV and BS signals,

Video signals and audio signals are output from two or more output terminals from each of the TV signal processing circuit, BS signal processing circuit, and MUSE decoder (or MUSE-NTSC converter). C
Common signal input terminal for inputting ATV signal and BS signal from the same terminal is a common channel for each BS / TV / CATV.
In this configuration, the TV signal, the CATV signal, and the BS signal are distributed to the respective tuners.

[0018]

According to the present invention, at least the BS signal, which has a simple circuit configuration and excellent operability, is used by sharing the channel selection circuit between BS signal reception, TV signal reception and CATV signal reception. It is possible to obtain a receiving device that can receive TV signals and CATV signals.

Further, by providing the MUSE / NTSC system discriminating means, the NT currently being used for satellite broadcasting.
It is possible to obtain a receiving device compatible with two systems of broadcasting by SC system and high-definition broadcasting by MUSE system.

Further, an AM / FM system discrimination means, MUS
By using the E / NTSC system discrimination means, the local oscillation frequency switching control means, the AGC system switching circuit, and the demodulation circuit switching control means, whether the CATV signal transmission system is the AM modulation system or the FM modulation system. ,
MUS even if the television signal system is the NTSC system
Even with the E method, signal processing can be selectively performed,
Good reception performance can be obtained.

Further, two or more BS / TV / CATV shared tuners are used, and a TV signal processing circuit, a BS signal processing circuit, a MUSE decoder (or MUSE-NT) are used.
By providing and switching two or more separate SC converters), BS signals, TV signals,
It is possible to obtain a receiving device that can receive a CATV signal.

Further, a common signal input terminal for inputting a BS signal, a TV signal, and a CATV signal from the same terminal is provided in each tuner, and the BS signal, the TV signal, and the CATV signal are combined and then distributed to the respective tuners. Thus, the BS signal, the TV signal, and the CATV signal can be easily connected to each other by using one cable instead of connecting them by using different cables, so that the input device can be easily connected and the user-friendly receiver can be obtained.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show that, when combined along line AA,
It is a block diagram which shows the receiver as a 1st Example of this invention.

In the figure, 1 is a first front end, 2 is a second front end, 100 is a signal distributor,
101 is a signal input terminal for inputting a TV signal, a BS signal and a CATV signal, 102 is a first BS / TV / CATV common tuner circuit, 103 is a first BS signal demodulation circuit, 1
Reference numeral 04 is a first NTSC signal AM demodulation circuit, 105 is a first MUSE signal AM demodulation circuit, and 106 is a first BS.
A signal processing circuit, 107 is a first MUSE decoder (or MUSE-NTSC converter), 108 is a first TV signal processing circuit, 130 is a first AGC control circuit, 1
Reference numeral 12 is a first BS / TV / CATV shared channel selection means.

Reference numeral 202 designates a second BS / TV / CATV.
A shared tuner circuit, 203 is a second BS signal demodulation circuit,
Reference numeral 204 is a second NTSC signal AM demodulation circuit, 205 is a second MUSE signal AM demodulation circuit, and 206 is a second B demodulation circuit.
S signal processing circuit, 207 is a second MUSE decoder (or MUSE-NTSC converter), and 208 is a second
TV signal processing circuit, 230 is a second AGC control circuit,
212 is the second BS / TV / CATV shared channel selection means, 1
Reference numeral 13 is a keyed pulse output control circuit, 114 is a demodulation signal switching circuit, and 115 is a video and audio signal switching circuit.

Further, 24 is a first video signal output terminal, 25
Is a first audio signal output terminal, 26 is a second video signal output terminal, 27 is a second audio signal output terminal, 28 is a third video signal output terminal, 29 is a third audio signal output terminal, 48
Is a fourth video signal output terminal, 49 is a fourth audio signal output terminal, 70 is a channel selection keyboard, and 71 is a reception control circuit.

The 12 GHz BS signal is downconverted.
Is converted to a BS first intermediate frequency band (hereinafter referred to as BS-IF band) of about 1 to 2 GHz by a TV (not shown)
The signal and the CATV signal are input to the common input terminal 101. The signal is sent to the first BS / TV by the distributor 100.
CATV shared tuner circuit 102 and second BS / T
It is input to the V / CATV common tuner circuit 202.

In the first front end 1, the first shared tuner circuit 102 corresponds to the control signal output from the reception control circuit 71 in response to the input signal from the channel selection keyboard 70, and outputs the first common tuner circuit 102. If the signal selected by the BS / TV / CATV shared channel selection unit 112 of 1 is a BS signal, the BS-IF signal is referred to as an intermediate frequency signal (hereinafter referred to as an IF signal. 78 MH
z. ), And the TV / CATV signal is selected by the common channel selection unit 112, the TV / CATV signal is converted to I
F signal (in Japan, video carrier frequency 58.7
5 MHz. ).

Thereafter, the respective IF signals are converted into the BS signal demodulation circuit 103 and the first NTSC signal AM demodulation circuit 1
04 or first AM demodulation circuit 10 for MUSE signal
5 is input and demodulated. A video signal and a voice signal of the BS signal are collectively FM-modulated, and the first BS signal demodulation circuit 103 performs an FM demodulation operation and is an NTSC demodulation signal.
A baseband signal of the MUSE system or the MUSE system is output to the demodulation signal switching circuit 114.

Further, since the TV signal is transmitted after the video signal is AM-modulated and the audio signal is FM-modulated, the first NTS signal is transmitted.
The C signal AM demodulation circuit 104 performs the video signal AM demodulation operation and the audio signal FM demodulation operation, and outputs the video demodulation signal and the audio demodulation signal to the demodulation signal switching circuit 114.

Next, when the CATV signal is selected,
If the CATV signal has the same transmission method as the TV signal, the same signal processing as that when the above-mentioned TV signal is selected will be performed, and the description thereof will be omitted.

If the CATV signal selected next is the AM-modulated MUSE signal, the first AMUSE signal AM
The demodulation circuit 105 outputs the MUSE baseband signal to the demodulation signal switching circuit 114. In the AM-modulated MUSE signal, the video / audio signals are collectively AM-modulated, and the occupied bandwidth becomes about 12 MHz by adding the residual sideband to the base band bandwidth of 8.1 MHz, and the NTSC 1-channel AM transmission (6 MH)
A bandwidth twice as large as that of z) is required.

The polarity of the sync signal is different from that of the NTSC signal in the MUSE signal, and it is not suitable to use an AGC circuit using the horizontal sync signal of the NTSC signal, which is conventionally used in the AM demodulator for the NTSC signal. Therefore, the first M
In the USE signal AM demodulation circuit 105, the PLL synchronous detection method having a wide band demodulation characteristic is used.
A keyed AGC circuit using a keyed pulse output from the MUSE decoder 107 of FIG.

Next, if the selected CATV signal is the NTSC or MUSE FM transmission system, the demodulation circuit is switched to the first BS signal demodulation circuit 103, and NT is selected.
The baseband signal of the SC system or the MUSE system is output to the demodulation signal switching circuit 114. In the AGC control circuit 130, the AGC voltage input from the first BS signal demodulation circuit 103, the first NTSC signal AM demodulation circuit 104, and the first MUSE signal AM demodulation circuit 105 is switched to make the first shared tuner. -Apply to the AGC circuit in the internal circuit 102.

As a simple means, a first BS signal demodulation circuit 103, a first NTSC signal AM demodulation circuit 104,
Of the first AMUSE signal AM demodulation circuit 105, a normal AGC voltage is input from the demodulation circuit performing the demodulation operation, and a zero potential is input from the other demodulation circuits. The circuit 130 can be composed of a simple adder circuit.

The second front end 2 also performs a similar tuning operation. The demodulation signal switching circuit 114 to which the demodulation signals from the first and second front ends 1 and 2 are input corresponds to the control signal output from the reception control circuit 71 according to the input signal from the channel selection keyboard 70. Then, the first TV signal processing circuit 108, the second TV signal processing circuit 208, the first BS signal processing circuit 106, the second BS signal processing circuit 206, and the first MUSE decoder 10
7, output to the second MUSE decoder 207 as appropriate.

In the first TV signal processing circuit 108, of the TV demodulated signal (NTSC-AM), signal processing such as amplitude adjustment and audio signal carrier removal is performed on the video signal, and audio multiplexing is performed on the audio signal. Signal processing such as stereo demodulation of the signal is performed, and the video and audio signals of the TV are output to the video and audio signal switching circuit 115.

Similarly, the second TV signal processing circuit 208 also outputs TV video and audio signals to the video and audio signal switching circuit 115. On the other hand, the first BS signal processing circuit 10
In No. 6, in the BS demodulated signal (NTSC-FM), the video signal is subjected to signal processing such as removal of energy spread signal, de-emphasis of FM modulated signal, sync signal reproduction, amplitude amplification, etc. Extracts a digital audio signal in a certain frequency band from the BS demodulated signal and uses QPS
K (Quadrature Phase Shift Keying)
After the demodulation, the QPSK demodulated digital signal is subjected to PCM (pulse code modulation) decoding and converted into an analog voice signal.

The signal-processed BS video and audio signals are
It is output to the video / audio signal switching circuit 115. Similarly,
The second BS signal processing circuit 206 also outputs the video and audio signals to the video and audio signal switching circuit 115.

In the first MUSE decoder 107, the video signal is waveform equalization, synchronous reproduction, decoding, de-emphasis, still image, with respect to the MUSE signal (AM, FM) of the CATV demodulated signal and the BS demodulated signal. Signal processing such as video interpolation, inverse matrix, and gamma processing is performed, audio signals are subjected to signal processing such as waveform equalization, signal separation, time extension, and decoding, and video signals are output to the third video signal output terminal 2
8, the audio signal is output to the third audio signal output terminal 29.

Similarly, the second MUSE decoder 207 also performs the above signal processing, and outputs the video signal to the fourth video signal output terminal 48 and the audio signal to the fourth audio signal output terminal 49.

In the video / audio signal switching circuit 115, the input T signal corresponding to the control signal output from the reception control circuit 71 in response to the input signal from the channel selection keyboard 70.
The video and audio signals of V and BS are selected and switched to select the first video output terminal 24 and the first audio output terminal 25, and the second video output terminal 25.
The video output terminal 26 and the second audio output terminal 27 are output from two output terminals.

As described above, the receiving apparatus of this embodiment is not only capable of receiving the BS signal, the TV signal and the CATV signal, but also the tuner circuit 102 (when receiving the BS / TV / CATV signal). And 202), tuning means 112
Since (and 212) are shared, a receiver having a simple circuit configuration and excellent operability can be obtained.

The BS signal demodulation circuit 103 (and 2
03), the NTSC signal AM demodulation circuit 104 (and 2
04), AM demodulation circuit 105 for MUSE signal (and 2
05), the transmission method of CATV signal is
Reception is possible regardless of whether the television signal system is the NTSC system or the MUSE system, whether it is the AM modulation system or the FM modulation system.

Further, the first front end 1 and the second front end 2 can perform separate simultaneous channel selection operations for TV signals, CATV signals, and BS signals, and each has a signal processing circuit of two systems. Therefore, simultaneous reception of 2 systems of TV signals, simultaneous reception of 2 systems of BS signals, 2 systems of CAT
Various receiving forms such as simultaneous V signal reception, simultaneous TV and BS signal reception, simultaneous CATV and BS reception, simultaneous TV and CATV reception are possible.

In the signal format, NTSC-AM, N
From TSC-FM, MUSE-AM, and MUSE-FM, simultaneous reception is possible in any combination of two signal formats including the same format.

FIGS. 3 and 4 are block diagrams showing a receiving apparatus as a second embodiment of the present invention when combined along the line BB. In the figure, parts that perform the same operations as in FIGS. 1 and 2 are given the same numbers as in FIGS. 1 and 2 and their explanations are omitted.

In FIGS. 3 and 4, 117 is NTSC.
TV equipped with demodulation circuit for MUSE and demodulation circuit for MUSE
-CATV signal demodulation circuit, 116 is the first MUSEN
TSC discrimination means, 118 is a first demodulation circuit switching control means, 130 is a first AGC control circuit, and 119 is a first local oscillation frequency switching control means.

217 is a second TV / CATV signal demodulation circuit, 216 is a second MUSE / NTSC discriminating means,
218 is a second demodulation circuit switching control means, 230 is a second AGC control circuit, 219 is a second local oscillation frequency switching control means, 80 is a first changeover switch, 190 is a second changeover switch, 81, 82, 83, 191, 19
2, 193 are switch terminals.

In this embodiment, in the first front end 1, the first shared tuner circuit 102 has the first BS.
If the signal selected by the TV / CATV common channel selection means 112 is a BS signal, the BS-IF signal is converted into an intermediate frequency signal, and the TV / CATV signal is selected by the common channel selection means 112. In case of TV / CATV signal,
Convert to signal.

Thereafter, each IF signal is converted into the first B signal.
S signal demodulation circuit 103 or first TV / CATV
The signal is input to the signal demodulation circuit 117 and demodulated. First BS
The signal demodulation circuit 103 performs an FM demodulation operation and outputs a demodulated baseband signal such as NTSC or MUSE. Switch terminal 8 with the first changeover switch 80
1, 83 are connected, and the output BS demodulated signal is the first
The MUSE / NTSC discriminating means 116 discriminates and outputs the signal to the demodulation signal switching circuit 114. If it is an NTSC signal, the signal is processed by the first BS signal processing circuit 106, and if it is an MUSE signal, it is processed by the first MUSE decoder 107.

Further, since the TV signal is transmitted after the video signal is AM-modulated and the audio signal is FM-modulated, TV / CAT is transmitted.
The V signal demodulation circuit 117 performs a video signal AM demodulation operation and an audio signal FM demodulation operation, and outputs a video demodulation signal and an audio demodulation signal. The output TV demodulated signal is the first M
The signal is input to the demodulation signal switching circuit 114 through the USE / NTSC discriminating means 116, and the first TV signal processing circuit 10
Signal processing is performed at 8.

Next, when the CATV signal is selected,
If the CATV signal has the same transmission method as the TV signal, the same signal processing as that when the above-mentioned TV signal is selected will be performed, and the description thereof will be omitted.

Next, if the selected CATV signal is the MUSE AM transmission system, as shown in the embodiment of FIGS. 1 and 2, the demodulation circuit (for NTSC / MUSE) and A
It is necessary to switch the GC system, and the first TV / CAT
The signal demodulated by the V signal demodulation circuit 117 is converted into the first MUS.
The E / NTSC discriminating means 116 discriminates, the first demodulating circuit switching control means 118 switches the demodulating circuit, and the first AGC control circuit 130 controls the AGC system switching to demodulate the demodulated signal switching circuit 1.
14 and the signal is processed by the first MUSE decoder 107.

If the selected CATV signal is the NTSC or MUSE FM transmission system, the first
It is necessary to switch from the TV / CATV signal demodulation circuit 117 of the above to the first BS signal demodulation circuit 103.
First of the signals demodulated by the CATV signal demodulation circuit 117
The MUSE / NTSC discriminating means 116 determines the local oscillation frequency by the first local oscillation frequency switching control means 119 and controls the CATV signal of the FM transmission system as an IF signal.

Since the subsequent processing is the same signal processing as when the BS signal is selected, its explanation is omitted. The first
The MUSE / NTSC discriminating means 116 uses the separation of a specific signal such as a keyed pulse or a synchronizing signal output from the first MUSE decoder 107 for discrimination of the television system.

The second front end 2 also performs the same channel selection operation. The demodulated signals output from the first and second front ends 1 and 2 are input to the demodulated signal switching circuit 114. In the demodulation signal switching circuit 114, the first TV signal processing circuit 10 corresponds to the input signal.
8, second TV signal processing circuit 208, first BS signal processing circuit 106, second BS signal processing circuit 206, first MUSE decoder 107, second MUSE decoder 20
Output to 7 as appropriate.

The video and audio signal switching circuit 115 selects and switches the input video and audio signals of TV and BS, and outputs the first video output terminal 24 and the first audio output terminal 2.
5 and a second video output terminal 26 and a second audio output terminal 27.

As described above, in addition to the effects described in the embodiments of FIGS. 1 and 2, the receiving apparatus of this embodiment has the MU.
SE / NTSC discrimination means, demodulation circuit switching control means,
By using the AGC system switching circuit (AGC control circuit) and the local oscillation frequency switching control means, the demodulation circuit suitable for the signal format can be automatically selected.
Receiving is possible regardless of whether the signal transmission system is the AM modulation system, the FM modulation system, or the television signal system is the NTSC system or the MUSE system.

Further, the first front end 1 and the second front end 2 can perform the separate simultaneous channel selection operation of the TV signal, the CATV signal, and the BS signal, and each has a signal processing circuit of two systems. Therefore, simultaneous reception of 2 systems of TV signals, simultaneous reception of 2 systems of BS signals, 2 systems of CAT
V signal simultaneous reception, TV signal and BS signal simultaneous reception, CAT
Various reception forms such as simultaneous reception of V signal and BS signal and simultaneous reception of TV signal and CATV signal are possible. In terms of signal format, NTSC-AM, NTSC-FM, MUS
Simultaneous reception is possible from E-AM and MUSE-FM in any combination of two signal formats including the same format.

FIGS. 5 and 6 are block diagrams showing a receiving apparatus as a third embodiment of the present invention when combined along the line CC. In FIG. 1, FIG. 1, FIG. 2 and FIG.
Also, the same numbers are assigned to the parts that perform the same operations as in FIG. 4, and the description is omitted. 5 and 6, 109 is a first AM / FM discriminating means, and 209 is a second AM / FM discriminating means.

Considering that the receiving apparatus of the third embodiment shown in FIGS. 5 and 6 performs signal processing of the receiving channel at a higher speed than that of the second embodiment shown in FIGS. 3 and 4. ing. That is, in the first front end 1, the first B
When the CATV broadcast is tuned by the S / TV / CATV common channel selection means 112, in the second embodiment shown in FIGS. 3 and 4, the received signal is the first BS / TV / CATV shared channel. After receiving the signal processing by the analog circuit 102 and the first TV / CATV signal demodulation circuit 117, the control signal of the first local oscillation frequency switching control means 119 is output, but the first MUSE / NTSC discrimination means 116 is In the case of determining the television system, when the determination is made based on the separation of the key pulse output from the first MUSE decoder 107 or the specific signal (for example, the synchronizing signal), the processing takes time.

Therefore, in this embodiment, the first BS / TV /
CAT output from the tuner circuit 102 for shared use of CATV
Before the V signal is demodulated by the first TV / CATV signal demodulation circuit 117, the first AM / FM discriminating means 109 is provided.
The AM / FM system is discriminated by the above, and when the FM system is discriminated, the first local oscillation frequency switching control means 1
Unlike the second embodiment, a signal for controlling 19 is outputted to perform FM modulation before the signal processing in the first TV / CATV signal demodulation circuit 117 and the first MUSE / NTSC discriminating means 116. The system CATV signal can be discriminated and processed.

The same signal processing is also performed in the second front end 2. As described above, in addition to the effects described in the first and second embodiments, the receiving apparatus according to the present embodiment has a CAT when receiving a CATV signal as compared with the second embodiment.
Whether the V signal transmission method is AM modulation method or FM modulation method A
It is possible to perform the signal processing of the reception channel at high speed by discriminating by the M / FM discriminating means.

FIGS. 7 and 8 are block diagrams showing a receiving apparatus as a fourth embodiment of the present invention when combined along the line DD. In FIG. 1, FIG. 1, FIG. 2 and FIG.
Also, the parts performing the same operations as in FIG. 4, FIG. 5 and FIG.

The receiving apparatus of the fourth embodiment shown in FIGS. 7 and 8 has a simpler receiving apparatus configuration and can perform signal processing at a higher speed than those of the second and third embodiments described above. Are considering. That is, in the first front end 1, in the second and third embodiments described above, the first demodulation circuit switching control means 118 and the first AGC control circuit 13 are provided.
0, the control of the first local oscillation frequency switching control means 119 is controlled by the outputs from the first MUSE / NTSC discrimination means 116 and the first AM / FM discrimination means 109.

On the other hand, in the fourth embodiment shown in FIGS. 7 and 8, the first BS / TV / CATV shared channel selection means 1 is used.
The control signal from the first switch 80 causes the first switch 80
Demodulation circuit switching control means 118, first AGC control circuit 130, first local oscillation frequency switching control means 1
Control 19.

BS signal of NTSC system (NTSC-F
M) and the BS signal of the MUSE system (MUSE-FM) are selected, a control signal is output from the first BS / TV / CATV shared channel selection means 112 and the first switch 80.
Connects terminals 81 and 83 and inputs the BS demodulated signal to the demodulated signal switching circuit 114.

In the demodulation signal switching circuit 114, the first BS signal processing circuit 106 in the case of an NTSC BS signal.
Alternatively, the signal is output to the second BS signal processing circuit 206 and the MU
In the case of the SE BS signal, the signal is output to the first MUSE decoder 107 or the second MUSE decoder 207 and signal processing is performed.

When the TV signal (NTSC-AM) is selected, a control signal is output from the first BS / TV / CATV common channel selection means 112 and input to the first demodulation circuit switching control means 118. , The first TV / CATV demodulation circuit 117 is a circuit for demodulating an NTSC signal, the switch 80 connects the terminals 82 and 83, and inputs the TV demodulation signal to the demodulation signal switching circuit 114.

When a CATV signal of AM modulation system is selected, the first BS / TV / CATV shared channel selection means 11 is selected.
2 outputs the control signal and the television signal is NTSC.
In the case of the system (NTSC-AM), the same processing as that at the time of receiving the TV signal is performed, and therefore description thereof will be omitted, but in the case of the MUSE system (MUSE-AM), the first BS / TV / CATV shared channel selection means 112. The control signal is output from the first TV-C and is input to the first demodulation circuit switching control means 118.
The ATV demodulation circuit 117 is a circuit that demodulates a MUSE signal, controls the first AGC control circuit, and further,
The first switch 80 connects the terminals 82 and 83 and inputs it to the demodulation signal switching circuit 114.

In the demodulation signal switching circuit 114, the NTSC-
It outputs to the first TV signal processing circuit 108 or the second TV signal processing circuit 208 for the AM system input signal, and outputs the first M signal for the MUSE-AM system input signal.
The signal is output to the USE decoder 107 or the second MUSE decoder 207 for signal processing.

FM system CATV signal (NTSC-FM
And MUSE-FM), the first BS
A control signal is output from the TV / CATV common channel selection unit 112 and input to the first local oscillation frequency switching control unit 119, and the description is omitted because it is the same as the case where the BS signal is selected. The same signal processing is performed in the second front end 2 as well.

As described above, since the signal processing path of the receiving apparatus of this embodiment is determined at the same time as the channel selection, in addition to the effects described in the first, second and third embodiments, the second and third embodiments are also provided. Compared with the above embodiment, all the switching controls are BS / TV / CAT.
By performing the output from the V shared channel selection means, the configuration of the receiving device is simple and the signal processing can be performed at high speed.

FIG. 9 shows N in FIG. 3, FIG. 5, and FIG.
First equipped with TSC demodulation circuit and MUSE demodulation circuit
And second TV / CATV signal demodulation circuits 117 and 2
17 is a circuit diagram showing a specific example in which the circuit configuration of 17 is simplified. The TV / CATV signal demodulation circuit described above is based on NTSC.
It had a demodulation circuit for MUSE and a demodulation circuit for MUSE.
Since the video signal of the TSC signal and the MUSE signal have the same AM modulation, the detection circuit can be commonly used.

In FIG. 9, 75, 76, 77 and 78 are changeover switches, 120 is an IF signal input terminal, 121
Is an AM detection output terminal, 122 is a voice detection output terminal, 12
3 is a control signal input terminal, 140, 141, 142, 14
3, 144 and 145 are switch terminals, 180 is a wideband surface acoustic wave (hereinafter referred to as SAW) filter, 181 is a narrowband SAW filter, 182 is an IF amplifier circuit, 18
3 is an AM detection circuit, 184 is a voice detection circuit, 185 is a peaking adjustment circuit, and 186 is a 4.5 MHz trap.

The TV / CATV signal demodulation circuit 117 shown in FIG.
a indicates that the IF signal input from the input terminal 120 is NTS.
In the case of the C method, the switch 75 causes the switch 142 to switch to the terminal 142 and the switch 7 in response to a control signal from the demodulation circuit switching control means 109.
6 is connected to the terminal 145 and has a narrow band SAW filter 18
1 is selected, the switch 77 is connected to operate the voice detection (FM demodulation) circuit 184, the switch 78 is connected to operate the 4.5 MHz trap circuit 186, and the peaking adjustment circuit 185 is controlled. To do. as a result,
The terminal 121 outputs an AM detection signal and the terminal 122 outputs a voice detection signal.

Next, in the case of the MUSE system, the switch 75 has the terminal 140 and the switch 76 has the terminal 1 according to the control signal from the demodulation circuit switching control means 118 or 218.
The wide band SAW filter 180 connected to the switch 43 is selected, the switch 77 is disconnected, and the voice detection circuit 184 is connected.
Does not work, and the switch 78 is disconnected and 4.5M
The Hz trap circuit 186 also does not operate, and the peaking adjustment circuit 185 is controlled so as to compensate for the high frequency side of the output from the AM detection circuit 183. As a result, from the terminal 121 to the MU
It outputs a SE-based baseband signal.

As described above, the circuit of FIG.
Wide-band and narrow-band SAW filters that share the detection circuit,
By controlling the voice detection circuit, the peaking adjustment circuit, and the 4.5 MHz trap, signal processing can be performed regardless of whether the CATV signal of the AM transmission system is the NTSC system or the MUSE system.

In the embodiment of the present invention, the case where the television signal is the NTSC system and the MUSE system has been described. However, even if the NTSC system is replaced by the PAL system or the SECAM system, the HDTV signal is not the MUSE system but the US digital system. HDTV system or European HD-MAC
Even in the system, the same effect can be obtained with the same configuration by changing the bandwidth, the frequency of the IF signal or the local oscillation signal, the type of the decoder, and the like.

Next, FIG. 10 shows a specific example of the AGC voltage generator for AM-modulated MUSE signal in the AGC control circuit of the embodiment shown in FIGS. 3, 5, and 7. Figure 10
50, a demodulated signal input terminal, 51 a keyed pulse input terminal, 52 a demodulated signal noise elimination filter, and 53
Is a gate circuit by a keyed pulse, 54 is an AGC voltage generation detection circuit, 55 is a smoothing low-pass filter, 56,
57 is an AGC voltage amplifier circuit.

The demodulated MUSE signal is input from the demodulated signal input terminal 50, and after noise is removed by the noise removal filter 52, it is passed through a gate circuit 53 that passes the demodulated signal during the keyed pulse period input from the keyed pulse input terminal 51. Input to the AGC detection circuit 54.

In the AGC detection circuit 54, since the keyed pulse corresponds to the clamp period of the MUSE signal, the AGC detection circuit 54 performs detection at a clamp level that does not depend on the image content and outputs a detection voltage. The detected voltage is smoothed by the low pass filter 55. Since the frequency of the keyed pulse is 60 Hz,
The time constant of the low pass filter 55 needs to be set to several tens of seconds.

In this case, although it is not possible to follow high-speed level fluctuations such as flutter caused by airplanes, which are seen in terrestrial broadcasting of NTSC signals, the signal level of CATV signals is relatively stable and high-speed fluctuations such as flutter occur. There is little fluctuation in level, so there is no practical problem. The AGC voltage smoothed by the low-pass filter 55 is amplified by the AGC voltage amplification circuit 56 and then output as a gain control voltage of the IF amplification circuit in the demodulation circuit. Further, the AGC voltage amplifier circuit 57 performs amplification and voltage shift, and outputs as a gain control voltage for the RF amplifier circuit or the like in the tuner section.

According to this example, AM-modulated MUS
Since the E-signal AGC voltage generator is configured to detect the demodulated signal in the keyed pulse period, the AGC voltage is generated in the clamp period that does not depend on the image content, so that a stable AGC voltage can be obtained even when the APL changes, which is excellent. Demodulation characteristics can be obtained.

Another specific example of the AGC voltage generator is shown in FIG. In the figure, parts that operate in the same manner as in FIG. 10 are assigned the same numbers and explanations thereof are omitted. Figure 11
58 is a low-pass filter whose time constant can be switched, and 59
Are MUSE and NTSC switching signal input terminals.

In this example, the purpose is to share the AM-modulated NTSC signal and MUSE signal AGC voltage generators and to simplify the circuit. Demodulated NTS
After the C signal or MUSE signal is input from the demodulation signal input terminal 50 and noise is removed by the noise removal filter 52,
Input to the AGC detection circuit 54. At the time of receiving the MUSE signal, the AGC detection circuit 54 performs the peak value AGC detection using the frame pulse that is in the MUSE signal and does not depend on the image content, as in the clamp period described above.

The frame pulse of the MUSE signal has a relatively high signal level, so that the control sensitivity of the AGC can be improved as compared with the detection using the clamp level. When the NTSC signal is received, the peak value AGC detection using the horizontal synchronizing signal of the NTSC signal is performed. With this configuration, the AGC voltage generator can be shared by the MUSE signal and the NTSC signal.

The detected voltage is smoothed by the low pass filter 55. Since the frame pulse cycle is 30 Hz,
The time constant of the low-pass filter 55 still needs to be set to several tens of seconds or more. Also in this case, similar to the specific example of FIG. 10, it is not possible to follow high-speed level fluctuations such as flutter caused by airplanes, which are seen in terrestrial broadcasting of NTSC signals,
In the CATV signal, the signal level is relatively stable,
There are few high-speed level fluctuations such as flutter, so there is no practical problem.

The AGC voltage smoothed by the low pass filter 55 is amplified by the AGC voltage amplifier circuit 56 and then output as a gain control voltage of the IF amplifier circuit in the demodulation circuit. Further, the AGC voltage amplifier circuit 57 performs amplification and voltage shift, and outputs as a gain control voltage for the RF amplifier circuit or the like in the tuner section.

According to this example, AM-modulated MUS
Since the E-signal AGC voltage generator is configured to detect using a frame pulse, the AGC voltage is generated in the frame pulse period that does not depend on the image content, so that a stable AGC voltage can be obtained even when the APL fluctuates. By obtaining the demodulation characteristics and controlling the switching of the time constant of the low-pass filter, it becomes possible to share the same with the AGC voltage generating section for the AM modulated NTSC signal using the horizontal synchronizing signal, and the circuit of the AGC voltage generating section can be used. It can be simplified.

When the AGC voltage generator of this example is used, the A of the embodiment shown in FIGS. 3, 5 and 7 is used.
The GC control circuits 130 and 230 are the AG control circuits shown in FIG.
This is the same as the C control circuits 130 and 230, and the AGC control circuit can be simplified.

[0093]

According to the present invention, not only is it possible to receive BS signals, TV signals, and CATV signals, but also BS.T.
Since the tuner circuit and the channel selection means are shared when the V / CATV signal is received, a receiver having a simple circuit configuration and excellent operability can be obtained.

By using the BS signal demodulation circuit, the NTSC signal AM demodulation circuit, and the MUSE signal AM demodulation circuit, whether the CATV signal transmission system is the AM modulation system or the FM modulation system, Reception is possible regardless of whether the television signal system is the NTSC system or the MUSE system.

Further, by providing the local oscillation frequency switching control means, even if the CATV signal transmission system is the AM transmission system or the FM transmission system, the BS signal demodulation process or the TV / CATV signal demodulation process is selected to perform the signal processing. Has the effect that is possible.

Also, by providing the MUSE / NTSC discriminating means, it is possible to receive high-definition broadcasts. In addition, by providing an AGC system switching circuit (AGC control circuit) and demodulation circuit switching control means, CAT
Even if the V broadcast is an AM modulation MUSE signal, good reception performance is obtained, and it is possible to receive multi-channel high-definition broadcast by CATV.

Further, according to the present invention, a TV signal, a CAT
In a receiving device that receives a V signal and a BS signal, and switches and outputs two or more sets of video and audio signals, outputs a TV demodulation signal, a CATV demodulation signal, and a BS demodulation signal by sharing a channel selection circuit, a frequency conversion circuit, and the like. Together with TV signal, CA
The TV signal and the BS signal are input from the same terminal. The demodulated signal from the front end with a simple structure is switched to the demodulated signal processing circuit of two or more systems and input to output the signals, thereby receiving two systems of TV signals and two systems. Various reception forms such as CATV signal reception, two-system TV signal reception, simultaneous TV and BS signal reception, simultaneous CATV and BS signal reception, simultaneous TV and CATV signal reception are possible.

Moreover, by using a front end having a simple structure for inputting a TV signal, a CATV signal, and a BS signal from the same terminal, connection of a high frequency signal input terminal becomes simple, and a small circuit structure which is easy to use is provided. A receiver is obtained.

Furthermore, in TV / CATV signal demodulation, by using a keyed pulse or a frame pulse in the AGC voltage generator, a stable AG can be achieved even when the APL changes.
The C voltage is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a left half of a first embodiment of the present invention.

FIG. 2 is a block diagram showing the right half of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a left half of a second embodiment of the present invention.

FIG. 4 is a block diagram showing the right half of the second embodiment of the present invention.

FIG. 5 is a block diagram showing a left half of a third embodiment of the present invention.

FIG. 6 is a block diagram showing the right half of the third embodiment of the present invention.

FIG. 7 is a block diagram showing a left half of a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing the right half of the fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a specific example in which the circuit configuration of the TV / CATV signal demodulation circuit in FIGS. 3, 5, and 7 is simplified.

10 is a block diagram showing an AGC voltage generator for AM-modulated MUSE signal in the AGC control circuits of FIGS. 3, 5 and 7. FIG.

FIG. 11 is a block diagram showing an AGC voltage generator for an AM-modulated NTSC signal and a MUSE signal.

[Explanation of symbols]

1 ... 1st front end, 2 ... 2nd front end, 24 ... 1st video signal output terminal (current television broadcasting), 26 ... 2nd video signal output terminal (current television broadcasting), 28 ... 1st Video signal output terminal (high-definition broadcasting), 48 ... second video signal output terminal (high-definition broadcasting), 25 ... first audio output terminal (current television broadcasting),
27 ... Second audio output terminal (current television broadcast), 29 ...
First audio output terminal (high-definition broadcasting), 49 ... Second
Audio output terminal (high-definition broadcasting), 101 ... Signal input terminal, 100 ... Signal distributor, 102 ... First BS / T
V / CATV shared tuner circuit, 202 ... second BS /
TV / CATV shared tuner circuit, 103 ... First BS
Signal demodulation circuit, 203 ... second BS signal demodulation circuit, 10
4 ... First AM demodulator for NTSC signal, 204 ... Second
AM demodulator circuit for NTSC signals, 117 ... First TV
CATV signal demodulation circuit 217 ... second TV / CATV
Signal demodulation circuit, 105 ... First NTSC signal AM demodulation circuit, 205 ... Second NTSC signal AM demodulation circuit, 1
16 ... First MUSE / NTSC discriminating means, 216 ... Second MUSE / NTSC discriminating means, 106 ... First BS
Signal processing circuit, 206 ... Second BS signal processing circuit, 10
7 ... 1st MUSE decoder, 207 ... 2nd MUSE
Decoder, 108 ... First TV signal processing circuit, 208 ...
Second TV signal processing circuit, 118 ... First demodulation circuit switching control means, 218 ... Second demodulation circuit switching control means, 119 ... First local oscillation frequency switching control means,
219 ... Second local oscillation frequency switching control means, 11
2 ... First BS / TV / CATV shared channel selection means, 130
... first AGC circuit, 230 ... second AGC circuit, 21
2 ... Second BS / TV / CATV shared channel selection means, 109
... first AM / FM discriminating means 209 ... second AM / F
M discrimination means, 113 ... Keyed pulse control circuit, 114 ...
Demodulation signal switching circuit, 115 ... Video and audio signal switching circuit, 180 ... Wide band SAW filter, 181 ... Narrow band SAW filter.

Claims (6)

[Claims] 1. A receiving device for receiving a terrestrial television broadcast signal (hereinafter, referred to as a TV signal), a satellite broadcast signal (hereinafter, referred to as a BS signal), and a CATV broadcast signal (hereinafter, referred to as a CATV signal). BS / TV / CATV shared tuner circuit (102, 202) for selecting and receiving a signal, a BS signal, or a CATV signal, and a BS / TV for sending a channel selection command to the shared tuner circuit CATV shared channel selection means (112, 212) and an NTSC-AM demodulation circuit (104, 204) that takes in an IF signal from the shared tuner circuit and demodulates it if it is an NTSC-AM modulated signal. If it is a MUSE-AM modulated signal, it is demodulated and the MUSE-AM demodulation circuit (1
05, 205), which is an NTSC-FM modulated signal or M
BS for demodulating USE-FM modulated signal
A signal demodulation circuit (103, 203) and a gain control (hereinafter referred to as AG) for the common tuner circuit from each of the demodulation circuits.
AGC control circuit (130, 23) for fetching and selectively switching a voltage (referred to as C) and supplying it to the common tuner circuit.
0) and at least two front-ends (1, 2) including the demodulated signal output from each of the demodulation circuits in the front-end, and at least two systems of TV signal processing circuits (108, 208), at least two BSs
A signal processing circuit (106, 206) and a MUSE decoder (or M) for at least two systems of MUSE signal processing.
USE-NTSC converter) (107, 207) to selectively output the demodulation signal switching circuit (114), the two-system TV signal processing circuit, and two-system BS signal processing circuit output signals. A signal switching circuit that captures and switches the video signal and the audio signal (or the data signal), which are the output signals, to the video signal output terminals (24, 26) and the audio signal output terminals (25, 27) of at least two systems and outputs them. 115) and, which enables simultaneous or independent signal reception of TV signals, BS signals, and CATV signals. 2. A receiving device for receiving a terrestrial television broadcast signal (hereinafter, referred to as a TV signal), a satellite broadcast signal (hereinafter, referred to as a BS signal), and a CATV broadcast signal (hereinafter, referred to as a CATV signal), from the input signal to the TV. BS / TV / CATV shared tuner circuit (102, 202) for selecting and receiving a signal, a BS signal, or a CATV signal, and a BS / TV for sending a channel selection command to the shared tuner circuit CATV shared channel selection means (112, 212) and a TV / CATV signal demodulation circuit (117, 217) that takes in the IF signal from the shared tuner circuit and demodulates it if it is a TV signal or a CATV signal. , BS signal demodulation circuit (103, 203) for demodulating the BS signal when it is a BS signal
And MUSE / NTSC for determining which television system the input signal at that time belongs to
Discriminating means (116, 216) and A as a CATV signal
Whether the TV / CATV signal demodulation circuit is an NTSC system demodulation circuit depends on the determination result by the determination means whether the signal transmitted by the M modulation system belongs to the NTSC system or the MUSE system. Demodulation circuit switching control means for switching to the MUSE demodulation circuit (11
8, 218) and whether the signal transmitted as the CATV signal is a signal according to the AM modulation method or a signal according to the FM modulation method, depending on the discrimination result by the discrimination means. Local oscillation frequency switching control means (11) for switching the local oscillation frequency of the circuit
9, 219), and when receiving an AM-modulated MUSE signal, the MUSE described later
By generating the AGC voltage using the keyed pulse from the decoder (107, 207), the tuner AGC voltage to be output from the BS signal demodulation circuit and the TV / C when the AM-modulated NTSC signal is received.
The tuner / AGC voltage to be output from the ATV signal demodulation circuit is selectively switched to the BS / TV /
At least two front ends (1, 2) including an AGC control circuit (130, 230) for outputting to a CATV shared tuner circuit are provided, and output from each of the demodulation circuits in the front end. At least two systems of TV signal processing circuits (108, 208) that capture demodulated signals, at least two systems of BS
A signal processing circuit (106, 206) and a MUSE decoder (or M) for at least two systems of MUSE signal processing.
USE-NTSC converter) (107, 207) to selectively output the demodulation signal switching circuit (114), the two-system TV signal processing circuit, and two-system BS signal processing circuit output signals. A signal switching circuit that captures and switches the video signal and the audio signal (or the data signal), which are the output signals, to the video signal output terminals (24, 26) and the audio signal output terminals (25, 27) of at least two systems and outputs them. 115) and, which enables simultaneous or independent signal reception of TV signals, BS signals, and CATV signals. 3. A receiving device for receiving a terrestrial television broadcast signal (hereinafter, referred to as a TV signal), a satellite broadcast signal (hereinafter, referred to as a BS signal), and a CATV broadcast signal (hereinafter, referred to as a CATV signal), from the input signal to the TV. BS / TV / CATV shared tuner circuit (102, 202) for selecting and receiving a signal, a BS signal, or a CATV signal, and a BS / TV for sending a channel selection command to the shared tuner circuit CATV shared channel selection means (112, 212) and a TV / CATV signal demodulation circuit (117, 217) that takes in the IF signal from the shared tuner circuit and demodulates it if it is a TV signal or a CATV signal. , BS signal demodulation circuit (103, 203) for demodulating the BS signal when it is a BS signal
And MUSE / NTSC for determining which television system the input signal at that time belongs to
Discriminating means (116, 216) and A as a CATV signal
Whether the TV / CATV signal demodulation circuit is an NTSC system demodulation circuit depends on the determination result by the determination means whether the signal transmitted by the M modulation system belongs to the NTSC system or the MUSE system. Demodulation circuit switching control means for switching to the MUSE demodulation circuit (11
8, 218), and when receiving an AM-modulated MUSE signal,
By generating the AGC voltage using the keyed pulse from the decoder (107, 207), the tuner AGC voltage to be output from the BS signal demodulation circuit and the TV / C when the AM-modulated NTSC signal is received.
The tuner / AGC voltage to be output from the ATV signal demodulation circuit is selectively switched to the BS / TV /
An AGC control circuit (130, 230) that outputs to the CATV shared tuner circuit, and a CATV signal that is taken into the TV / CATV signal demodulation circuit from the shared tuner circuit by an AM modulation method or an FM modulation method. AM that distinguishes whether it is a signal
/ FM discrimination means (109, 209) and local oscillation frequency switching control means (119, 219) for switching the local oscillation frequency of the BS / TV / CATV shared tuner circuit depending on the discrimination result by the discrimination means. And at least two front-ends (1, 2) including: and a demodulation signal output from each demodulation circuit in the front-end, and at least two systems of TV signal processing circuits (108, 208) , At least 2 BSs
A signal processing circuit (106, 206) and a MUSE decoder (or M) for at least two systems of MUSE signal processing.
USE-NTSC converter) (107, 207) to selectively output the demodulation signal switching circuit (114), the two-system TV signal processing circuit, and two-system BS signal processing circuit output signals. A signal switching circuit that captures and switches the video signal and the audio signal (or the data signal), which are the output signals, to the video signal output terminals (24, 26) and the audio signal output terminals (25, 27) of at least two systems and outputs them. 115) and, which enables simultaneous or independent signal reception of TV signals, BS signals, and CATV signals. 4. A receiving device for receiving a terrestrial television broadcast signal (hereinafter, referred to as a TV signal), a satellite broadcast signal (hereinafter, referred to as a BS signal), and a CATV broadcast signal (hereinafter, referred to as a CATV signal). BS / TV / CATV shared tuner circuit (102, 202) for selecting and receiving a signal, a BS signal, or a CATV signal, and a BS / TV for sending a channel selection command to the shared tuner circuit CATV shared channel selection means (112, 212) and a TV / CATV signal demodulation circuit (117, 217) that takes in the IF signal from the shared tuner circuit and demodulates it if it is a TV signal or a CATV signal. , BS signal demodulation circuit (103, 203) for demodulating the BS signal when it is a BS signal
And whether the signal transmitted by the AM modulation method as the CATV signal at that time belongs to the NTSC method, or MUS
The discrimination information as to whether it belongs to the E system is the BS / TV /
Obtained from the CATV common channel selection means, and depending on it, demodulation circuit switching control means (118, 218) for switching the TV / CATV signal demodulation circuit to the NTSC system demodulation circuit or the MUSE system demodulation circuit, and AM modulated When receiving the MUSE signal, the MUSE described later
By generating the AGC voltage using the keyed pulse from the decoder (107, 207), the tuner AGC voltage to be output from the BS signal demodulation circuit and the TV / C when the AM-modulated NTSC signal is received.
The tuner / AGC voltage to be output from the ATV signal demodulation circuit is selectively switched to the BS / TV /
An AGC control circuit (130, 230) that outputs to the CATV shared tuner circuit, and a CATV signal that is taken into the TV / CATV signal demodulation circuit from the shared tuner circuit by an AM modulation method or an FM modulation method. The BS / TV / CATV common channel selection means receives the discrimination information as to whether it is a signal or not, and depending on it, the local oscillation frequency switching control means (119) for switching the local oscillation frequency of the BS / TV / CATV shared tuner circuit. , 219) and at least two front-ends (1, 2) including, and capturing the demodulated signals output from the respective demodulation circuits in the front-end, and at least two systems of TV signal processing circuits (108). , 208), at least two BSs
A signal processing circuit (106, 206) and a MUSE decoder (or M) for at least two systems of MUSE signal processing.
USE-NTSC converter) (107, 207) to selectively output the demodulation signal switching circuit (114), the two-system TV signal processing circuit, and two-system BS signal processing circuit output signals. A signal switching circuit that captures and switches the video signal and the audio signal (or the data signal), which are the output signals, to the video signal output terminals (24, 26) and the audio signal output terminals (25, 27) of at least two systems and outputs them. 115) and, which enables simultaneous or independent signal reception of TV signals, BS signals, and CATV signals. 5. The receiving device according to claim 1, 2, 3 or 4, wherein at least two of the front ends are
A receiving device characterized in that a TV signal, a BS signal, and a CATV signal are taken in through a common input terminal (101). 6. The receiving device according to claim 2, 3 or 4, wherein in the TV / CATV signal demodulating circuit,
An AGC voltage generator for generating the tuner AGC voltage includes a noise removal filter (52) that receives a demodulated signal and removes noise to output, and an AGC detection that receives the output of the noise removal filter. A circuit (54), a low-pass filter capable of switching its time constant when receiving a MUSE signal and when receiving an NTSC signal, the AGC of said detection circuit
The low-pass filter (55) to which the detection output is input,
A receiver, comprising: an AGC voltage amplifier circuit (56, 57) for inputting, amplifying and outputting the output of the low-pass filter.