JPH09298754A - Multi-system high frequency receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-system high frequency receiver in which an audio trap amount of a high attenuation is ensured and the circuit configuration is simplified. SOLUTION: In the case of NTSC or PAL control for audio trap changeover at a video image, a system changeover switch section 29 is turned on/off, either of an NTSC audio signal trap section 5 or a PAL 3 frequency audio signal trap section 7 acts like a trap so as to attenuate the audio signal of the undesired NTSC/PAL. Furthermore, in the case of PAL reception, an SIF signal outputted from an SIF signal output terminal 13 is passed through a PAL side SIF signal filter section 26 and in the case of NTSC reception, a switch section 25 is switched to pass an audio signal 27 to an NTSC side SIF signal filter section 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is effective when used in a terrestrial reception front-end device used for a video tape recorder (hereinafter referred to as VTR), a television receiver (hereinafter referred to as TV receiver), and the like. The present invention relates to a multi-system high frequency receiving device.

[0002]

2. Description of the Related Art In recent years, multi-system high frequency receivers for VTRs have an antenna distributor, a tuner, an RF modulator, and a demodulator constructed in a compact and integrated structure. A multi-system high frequency receiver is disclosed in US Pat. No. 4,689.
The one described in No. 825 is known.

A conventional multi-system high frequency receiver will be described below. A conventional multi-system high frequency receiver is shown in FIGS. 3 and 4. FIG. 3 is a block diagram of a conventional multi-system high frequency receiver. FIG. 4 (a) is a trap switching circuit diagram for attenuating an unnecessary audio signal in a video signal of a conventional multi-system high frequency receiver, and FIG. 4 (b) is an intermediate frequency audio signal and a reference oscillation signal of a video / audio demodulation unit. SI for extracting the audio signal (hereinafter referred to as SIF signal) after being multiplied by
It is an F signal filter switching circuit diagram.

In the figure, reference numeral 2 converts a TV signal received by an antenna (not shown) into an intermediate frequency signal and inputs a baseband video / audio signal into a high frequency signal of a specific channel of a television reception frequency signal. A tuner unit for conversion, 3 is an output terminal for outputting the intermediate frequency signal converted by the tuner unit, 1 is an input terminal provided in the tuner unit 2 for inputting a high frequency signal such as a TV broadcast signal, and 15 is an input terminal 1 An output terminal for outputting a high frequency signal input to the antenna through an antenna distributor and a switch section, and a terminal for outputting a high frequency signal from the RF modulator section configured in the tuner section 2, for example, a signal of a specific channel of a TV signal. Then, it is connected to a television receiver or the like through a coaxial cable. Reference numeral 16 is an input terminal to which a video / audio signal reproduced from a VTR recording section (not shown) is input, and 4 is an intermediate frequency video / audio signal extracted from the signal output from the tuner section 2 to obtain an intermediate frequency video signal and an intermediate frequency. A surface wave filter unit 10 for outputting an audio signal and an audio / video demodulator unit 10 for extracting a baseband video signal and an audio signal from the intermediate frequency video signal and the intermediate frequency audio signal output from the surface wave filter unit 4.
Reference numerals 1 and 32 denote first and second video side intermediate frequency balanced input terminals for inputting the intermediate frequency video signal output from the surface wave filter section 4, and 33 denotes an intermediate frequency audio signal output from the surface wave filter section 4. Input side intermediate frequency balanced input terminal, 12 is a video signal output terminal for outputting the video signal demodulated by the video / audio demodulation section 10, and 13 is an SI for outputting the SIF signal demodulated by the video / audio demodulation section 10.
F signal output terminals, 5 and 8 are NTSC audio signal trap units for attenuating NTSC audio signals in video signals, and 6 is NT
A switch unit for controlling ON / OFF of the SC audio signal trap unit 5, and a P for attenuating the PAL audio signal in the video signal.
AL3 frequency audio signal trap unit, 9 is baseband N
A switch unit for controlling ON / OFF of the TSC audio signal trap unit 8, 11 is a buffer unit for a baseband video signal output from the video signal output terminal 30, and 17 is a video signal output from the video signal output terminal 12. NTSC inter-carrier audio filter section for extracting NTSC inter-carrier audio, 14 is an NTSC inter-carrier S
IF signal buffer unit, 19 is a voice switch buffer unit, 18 is an SSC signal converter that inputs the NTSC intercarrier SIF signal output from the buffer unit 14 or the SIF signal output from the voice switch buffer unit 19 and performs frequency conversion Section, 20 is an SIF signal filter section of the SIF signal converted by the SIF signal converting section, 21 is a baseband video signal output from the buffer section 11, 22 is an audio signal, and 23 is an image to the audio / video demodulating section 10. A video signal input terminal for inputting a signal, 28 is a PAL / NTSC control signal input terminal, 30 is a video signal output terminal for outputting a baseband video signal after high frequency correction, and 34 is an output from the SIF signal filter section 20. An SIF signal input terminal for inputting the SIF signal to the video / audio demodulation unit 10, and 35 is a base signal. An audio signal output terminal for outputting the band of the audio signal.

The operation of the conventional multi-system high frequency receiving apparatus configured as described above will be described below.

First, the television signal (high frequency signal) from the antenna is input to the input terminal 1, and the high frequency signal distributed to the tuner side by the signal distributor in the tuner section 2 is intermediate frequency in the surface wave filter section 4. The video / audio signal is extracted. Of the intermediate frequency video and audio signals, the intermediate frequency video signal is input from the first and second video side intermediate frequency balanced input terminals 31 and 32 to the video and audio demodulation unit 10 and demodulated to a baseband video signal, It is output from the output terminal 12.

On the other hand, of the intermediate frequency video / audio signals, the intermediate frequency audio signal is input from the audio side intermediate frequency balanced input terminal 33 to the video / audio demodulation section 10, and the video / audio demodulation section 10 is supplied.
Then, it is demodulated into a baseband audio signal and is output from the SIF signal output terminal 13 as an SIF signal.

Video signal output terminal 1 of the video / audio demodulation section 10
2 and the operation of the video signal and the SIF signal output from the SIF signal output terminal 13 will be described with reference to FIG.

FIG. 4A is a circuit diagram showing the video side audio trap switching section. First, when an NTSC control signal is input from the PAL / NTSC control signal input terminal 28, the switch sections 6 and 9 are turned on. , Video signal output terminal 12
The video signal output from the NTSC audio signal trap unit 5 at the point A via the PAL3 frequency audio signal trap unit 7.
As a result, unnecessary NTSC audio signals in the video signal are attenuated. Thereafter, the video signal is input to the video / audio demodulation unit 10 from the video signal input terminal 23, is high-frequency emphasized, and is output from the video signal output terminal 30. The output video signal is
At the point B, by the NTSC voice signal trap unit 8,
An unnecessary NTSC audio signal in the slightly remaining video signal is attenuated and output via the buffer unit 11.

When the PAL control signal is input, the switch units 6 and 9 are turned off, and the PAL three-frequency audio signal trap unit 7 activates the PAL trap.
An unnecessary PAL audio signal in the video signal is attenuated and input to the video signal input terminal 23. After that, the video signal input to the video / audio demodulation unit 10 is high-frequency emphasized, and then output from the video signal output terminal 30 and output via the buffer unit 11.

FIG. 4 (b) is a circuit diagram of the audio side SIF signal filter switching section, which shows PAL /
When the PAL control signal is input from the NTSC control signal input terminal 28, the buffer unit 19 is turned on, the SIF signal filter unit 17 is turned off, and the SIF signal output from the SIF signal output terminal 13 is converted into the SIF signal. Input to the section 18. On the other hand, when the NTSC control signal is input, the buffer unit 19 is turned off and SI
NTSC included in the video signal output from the video signal output terminal 12 with the F signal filter unit 17 in the ON state
The intercarrier SIF signal is extracted by the NTSC intercarrier audio filter unit 17 and input to the SIF signal conversion unit 18 via the buffer unit 14.

After the SIF signal converted by the SIF signal converting section 18 is filtered by the SIF signal filtering section 20, the FM detecting section (not shown) in the video / audio demodulating section 10 is passed through the SIF signal input terminal 34. FM detection is performed with the baseband audio signal and the audio signal output terminal 3
5 is output.

[0013]

However, in the above-mentioned conventional configuration, in order to sufficiently attenuate the NTSC audio signal in the video signal at the time of NTSC reception, the attenuation amount of each NTSC audio signal trap is not sufficient. For the NTSC
The multi-stage circuit configuration of the audio signal trap unit 5 and the baseband NTSC audio signal trap unit 8 is required, which causes a problem that the circuit configuration becomes complicated.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a multi-system high-frequency receiver which secures a high amount of audio trapping and simplifies the circuit structure.

[0015]

In order to achieve this object, the present invention is a multi-system high frequency receiving apparatus capable of receiving a television signal of the first and second signal systems,
A tuner unit that converts a television signal received by an antenna into an intermediate frequency signal, a surface wave filter unit that extracts an intermediate frequency video / audio signal from the intermediate frequency signal output from the tuner unit, and an output from the surface wave filter unit A video / audio demodulation unit for demodulating the intermediate frequency video / audio signal into a baseband video / audio signal, and an unnecessary audio signal included in the video signal of the first signal system demodulated by the video / audio demodulation unit is attenuated. A first audio signal trap section, a second audio signal trap section for attenuating an unnecessary audio signal included in the video signal of the second signal system demodulated by the video / audio demodulation section, and the first audio signal trap section. And a first switch for switching the second audio signal trap unit, first and second audio filter units, and the first and second audio filters A second switch for switching the unit, and when receiving a television signal of the first signal system, the first switch is connected to the first audio signal trap unit and the second switch is connected to the first switch. Of the second signal system and the second switch is connected to the second audio signal trap section when the television signal of the second signal system is received. And a third switch for switching the first and second switches so as to be connected to the audio filter unit.

With such a configuration, a high attenuation amount of the voice trap amount is ensured, and the voice SIF signal filter is switched so that the buffer section is eliminated, thereby simplifying the circuit and greatly streamlining the circuit. It is intended.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The invention described in claims 1 to 3 of the present invention is a multi-system high-frequency receiving apparatus capable of receiving a television signal of the first and second signal systems, which is received by an antenna. A tuner unit for converting the television signal into an intermediate frequency signal, a surface wave filter unit for extracting an intermediate frequency video / audio signal from the intermediate frequency signal output from the tuner unit, and an intermediate unit output from the surface wave filter unit. A video / audio demodulation unit for demodulating a frequency video / audio signal into a baseband video / audio signal, and a first attenuating unnecessary audio signal included in the video signal of the first signal system demodulated by the video / audio demodulation unit And a second audio signal for attenuating an unnecessary audio signal included in the video signal of the second signal system demodulated by the audio / video demodulating unit. A trap section, a first switch for switching between the first and second audio signal trap sections, a first and second audio filter section, and a second switch for switching between the first and second audio filter sections And when receiving a television signal of the first signal system, the first switch is connected to the first audio signal trap section and the second switch is connected to the first audio filter section. At the same time, when the television signal of the second signal system is received, the first switch is connected to the second audio signal trap section and the second switch is connected to the second audio filter section. As described above, the third switch for switching the first and second switches is provided, and it has the effect of simplifying the circuit and achieving a significant rationalization.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram of a multi-system high frequency receiver of the present invention. FIG. 2 is a trap switching circuit diagram for attenuating an unnecessary audio signal in a video signal of the multi-system high frequency receiving apparatus of the present invention and an audio signal extracting step S.
It is a circuit diagram of an IF signal filter switching unit.

In FIG. 1, 2 is an antenna (not shown)
A tuner unit 3 for receiving a television signal from the TV and converting it to an intermediate frequency signal and for converting a received frequency signal of the TV into a high frequency signal of a specific channel by inputting a baseband video and audio signal The output terminal of the intermediate frequency signal converted by 1., 1 is an input terminal of the tuner unit 2 to which a high frequency signal such as a TV broadcast signal from the antenna is input, and 15 is an antenna distributor for the high frequency signal input to the input terminal 1. It is an output terminal that outputs through the switch unit, and is a high frequency signal from the RF modulator unit configured in the tuner unit 2.
For example, it is also a terminal for outputting a signal of a specific channel of a TV signal. The output terminal 15 is connected to a television receiver through a coaxial cable. Reference numeral 16 is an input terminal to which a video / audio signal reproduced from a recording / reproducing unit (not shown) is input, and 4 is an intermediate frequency video / audio signal extracted from the signal output from the tuner unit 2 to generate an intermediate frequency video signal and an intermediate frequency. Surface wave filter section for outputting audio signals, 10
31 is a video / audio demodulation unit for extracting the baseband video / audio signal from the video / audio intermediate frequency signal from the surface wave filter unit 4 via the video / audio demodulation unit 31;
Reference numerals 32 and 32 denote video side intermediate frequency balanced input terminals for inputting the intermediate frequency video signal output from the surface wave filter section 4 to the video / audio demodulation section 10. 33 denotes an image of the intermediate frequency audio signal output from the surface wave filter section 4. Voice demodulation unit 10
To the audio side intermediate frequency balanced input terminal, 12 is a video signal output terminal for outputting the video signal demodulated by the video / audio demodulation section 10, and 13 is an SIF signal demodulated by the video / audio demodulation section 10. SIF signal output terminal, 27 is an intercarrier SIF signal output terminal for outputting the NTSC intercarrier SIF signal switched by the video / audio demodulation section 10, and 5 is an NTSC audio signal trap section for attenuating the NTSC audio signal in the video signal, 7 Is P in the video signal
A PAL three-frequency audio signal trap unit for attenuating the AL audio signal, and 24 a PAL three-frequency audio signal trap unit 7 and NTS
A switch section for switching between the C audio signal trap section 5 and a switch 24a for switching the input side and a switch 24b for switching the output side. Reference numeral 23 is a video signal input terminal for inputting the output signal of the switch unit 24 into the video / audio demodulation unit 10 again. , A video signal output terminal for outputting the video signal of 11, a buffer portion of the video baseband signal output from the video signal output terminal 30, 21 a baseband video signal output from the buffer portion 11, and 17 an NTSC
Audio signal filter unit 26 is PAL side SIF signal filter unit 25 is PAL side SIF signal filter unit 26
And a switch unit for switching between the NTSC audio signal filter unit 17 and a diode switch 25a.
And 25b. 34 is NT
An SIF signal input terminal for inputting the SIF signal output from the SC audio signal filter section 17 and the PAL-side SIF signal filter section 26 to the video / audio demodulation section 10, 35 is a baseband audio signal output terminal, and 22 is a video / audio demodulation section. 1
0 is an audio signal output from 0, 28 is a PAL / NTSC control signal input terminal, and 29 is a system changeover switch section which operates by a control signal input from the PAL / NTSC control signal input terminal 28.

The operation of the multi-system high frequency receiver of the present embodiment configured as described above will be described below with reference to FIGS. 1 and 2.

First, the television signal (high frequency signal) from the antenna is input to the input terminal 1, and the high frequency signal distributed to the tuner side by the signal distributor in the tuner section 2 is intermediate frequency in the surface wave filter section 4. The video / audio signal is extracted. Of the intermediate frequency video and audio signals, the intermediate frequency video signal is input from the first and second video side intermediate frequency balanced input terminals 31 and 32 to the video and audio demodulation unit 10 and demodulated to a baseband video signal, It is output from the output terminal 12. The NTSC intercarrier SIF signal in the video signal is output from the intercarrier SIF signal output terminal 27.

On the other hand, of the intermediate frequency video / audio signals, the intermediate frequency audio signal is input from the audio side intermediate frequency balanced input terminal 33 to the video / audio demodulation section 10, and the video / audio demodulation section 10 is supplied.
Then, it is demodulated into a baseband audio signal and is output from the SIF signal output terminal 13 as an SIF signal.

At this time, when the NTSC control signal is input from the PAL / NTSC control signal input terminal 28, the system changeover switch unit 29 controls the switches 24a and 24b in the switch unit 24 to be connected to the terminal a. The switch 25a in the switch unit 25 is turned on and the switch 25b is turned off. Then, the video signal output from the video signal output terminal 12 is input to the NTSC audio signal trap unit 5, and the unnecessary NTSC audio signal is attenuated. The video signal in which the unnecessary NTSC audio signal is attenuated is input to the video signal input terminal 23 of the video / audio demodulation unit 10 via the switch unit 24. Video signal input terminal 2
The video signal input to 3 is high-frequency emphasized in the video / audio demodulation unit 10, and then output from the video signal output terminal 30 and output via the buffer unit 11.

When the PAL control signal is input from the PAL / NTSC control signal input terminal 28, the system changeover switch unit 29 controls the switches 24a and 24b in the switch unit 24 to be connected to the terminal b. Then, the video signal output from the video signal output terminal 12 is input to the PAL three-frequency audio signal trap unit 7, and the unnecessary PAL audio signal is attenuated. The video signal in which the unnecessary PAL audio signal is attenuated is input to the video signal input terminal 23 of the video / audio demodulation unit 10 via the switch unit 24. The video signal input to the video signal input terminal 23 is high-frequency emphasized in the video / audio demodulation unit 10, and then the video signal output terminal 30
And is output via the buffer unit 11.

With this configuration, PAL / NTS
A high attenuation type voice trap can be realized in both C. For example, one trap attenuation amount in the present embodiment has an attenuation amount of 30 dB, whereas one trap attenuation amount of the conventional multistage configuration is 15 dB.

On the other hand, the switch section 25 of the SIF signal filter section on the audio side switches when the PAL control signal is input from the PAL / NTSC control signal input terminal 28.
Switch 25a in 5 is turned off and switch 25b is turned on.
Control to N. Then, the SIF signal output terminal 13
The SIF signal output from the
It is input to the AL side SIF signal filter unit 26.

When an NTSC control signal is input from the PAL / NTSC control signal input terminal 28, the switch 25a in the switch section 25 is turned on and the switch 25b is turned on.
Control is performed to set to FF. Then, the inter-carrier S
The NTSC intercarrier SIF signal output from the IF signal output terminal 27 is input to the NTSC side SIF signal filter unit 17.

The SIF signals that have passed through the respective filter sections are input to the video / audio demodulation section 10 from the audio signal input terminal 34, FM detection is performed in the video / audio demodulation section 10, and the SIF signals are output via the audio signal output terminal 35. It is output from the output terminal 22.

As described above, according to the present embodiment, in the video / audio demodulation section 10, a high attenuation sound trap amount is ensured, and the audio SIF signal filter section is switched by a diode switch which does not have a buffer section. With this circuit configuration, it is possible to realize a multi-system high frequency receiving device that can simplify the circuit and greatly streamline the circuit.

[0030]

As described above, according to the present invention, the video / audio demodulation section secures a high attenuation audio trap amount at the time of NTSC reception and PAL reception, and the audio SIF signal filter switching does not have a buffer section. By adopting a diode switching circuit configuration, the circuit can be significantly rationalized, and for example, a printed circuit board configuration of a multi-system circuit including the NTSC system can be handled with a single one-sided small printed circuit board configuration, and a high attenuation trap characteristic. An excellent effect that a multi-system high frequency receiver having the above can be realized is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-system high frequency receiver according to an embodiment of the present invention.

FIG. 2 (a) is a circuit diagram of an audio trap switching unit on the video side of the multi-system high frequency receiving device in the same embodiment; and (b) is a circuit diagram of an SIF signal filter switching unit on the audio side.

FIG. 3 is a block diagram of a conventional multi-system high frequency receiving device.

FIG. 4A is a circuit diagram of an audio trap switching unit on the video side of a conventional multi-system high-frequency receiving device. FIG. 4B is a circuit diagram of an SIF signal filter switching unit on the audio side.

[Explanation of symbols]

 2 Tuner section 4 Surface wave filter section 5 NTSC audio signal trap section 7 PAL 3 frequency audio signal trap section 8 NTSC audio signal trap section 10 Video and audio demodulation section 17 NTSC audio signal filter section 24 Switch section 25 Switch section 26 PAL side SIF signal filter 29 System changeover switch

Claims (3)

[Claims] 1. A multi-system high frequency receiving device capable of receiving a television signal of a first and a second signal system, the tuner unit converting a television signal received by an antenna into an intermediate frequency signal, A surface wave filter unit for extracting an intermediate frequency video / audio signal from the intermediate frequency signal output from the tuner unit, and an audio / video for demodulating the intermediate frequency video / audio signal output from the surface wave filter unit into a baseband video / audio signal. A demodulation unit, a first audio signal trap unit for attenuating unnecessary audio signals included in the video signal of the first signal system demodulated by the video and audio demodulation unit, and demodulated by the video and audio demodulation unit A second audio signal trap unit for attenuating an unnecessary audio signal contained in a video signal of the second signal system, and the first and second audio signal traps. A first switch for switching the switching section, a first and a second audio filter section, a second switch for switching the first and the second audio filter sections, and a television having the first signal system. When a signal is received, the first switch is connected to the first audio signal trap unit, the second switch is connected to the first audio filter unit, and the television of the second signal system is used. Switching the first and second switches to connect the first switch to the second audio signal trap section and connect the second switch to the second audio filter section when receiving a signal; A multi-system high-frequency receiver, comprising: 3 switches. 2. The multi-system high frequency receiving apparatus according to claim 1, wherein the first switch comprises a buffer transistor section, a diode switch section, a voice trap section, and a system changeover switch section. 3. A multi-system high frequency receiving apparatus capable of receiving a television signal of the first and second signal systems, the television signal received by an antenna is converted into an intermediate frequency signal, and the intermediate frequency signal is converted from the intermediate frequency signal. The intermediate frequency video / audio signal is extracted, the intermediate frequency signal is demodulated to a baseband video / audio signal, and unnecessary audio signals included in the demodulated video signals of the first and second signal systems are respectively converted into first and second unnecessary audio signals. Attenuating by switching with a switch, switching the first and second voice filter parts with a second switch, and switching the first and second switches with a third switch, the amount of attenuation in a voice trap is greatly improved. A multi-system high-frequency receiving device characterized by: