JPH08340492A - High frequency receiving converter - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a high-frequency receiving and converting device that improves receiving sensitivity even in an area where the TV signal level is weak and realizes highly sensitive receiving image quality. [Arrangement] Depending on the level of the input signal, whether to pass the high frequency amplifier 4 or not to pass the high frequency amplifier 4 is arbitrarily selected on the on-screen display (not shown),
The system microcomputer 20 transmits serial data to the timer microcomputer 21, and the timer microcomputer 21 transmits serial data to the PLL circuit 23. PLL
One of the BAND output ports 7 from the circuit 23 is used as a control signal for the high frequency amplifier circuit section 8 to switch the first and second switches 3 and 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency receiving and converting apparatus which is effective for use in receiving front end means including a video tape recorder (hereinafter referred to as VTR).

[0002]

2. Description of the Related Art An example of a conventional high frequency receiving and converting device will be described with reference to FIG.

FIG. 2 shows recording of a VTR and an antenna / tuner for receiving a conventional television (hereinafter referred to as TV) broadcast, a video / audio demodulation circuit for demodulating an intermediate frequency signal from the tuner into a baseband signal of video / audio. RF that converts the video and audio signals reproduced and output from the unit to high-frequency signals
FIG. 3 is a block diagram showing an example of a high-frequency reception conversion device including a modulator. In FIG. 2, 1 is an antenna input terminal to which a high frequency signal such as a TV broadcast signal is input from the antenna, 2 is an antenna output terminal, and this antenna output terminal 2 is connected to a television receiver (not shown) through a coaxial cable. It is connected. Further, the high frequency modulation signal from the RF modulator 11 is output to the antenna output terminal 2 through the switch circuit 10 and connected to the television receiver via the coaxial cable. At this time, the high frequency signal output from the RF demodulator 11 is output by switching the switch circuit 10 by a control signal from the outside, that is, an antenna switching control signal. Reference numeral 9 denotes an antenna distributor, which distributes a high frequency signal from the antenna input terminal 1 to the tuner 14 and the antenna output terminal 2 through the switch circuit 10. An RF modulator 11 RF-modulates the baseband video / audio signal obtained from the video / audio processing circuit from the recording / recording unit of the VTR to extract a high frequency signal, and switches the antenna input from the switching signal input terminal 7. The switch circuit 10 is switched by the control signal and is output to the antenna output 2.
Generally, domestic VTRs output signals of 1-channel or 2-channel video and audio carrier frequencies, which can be connected to a television receiver via a coaxial cable for reception. A switch circuit 10 switches a TV signal from the distributor 9 and a video / audio carrier frequency signal from the RF modulator 11 by an antenna switching control signal, which is generally switched by a transistor or a diode circuit. An antenna switching control terminal 7 is a control signal input terminal for outputting a TV signal from the antenna input terminal 1 or a high frequency signal from the RF modulator 11 to the antenna output terminal 2 as required. A tuner 14 receives and selects a TV signal and converts it into an intermediate frequency signal. Reference numeral 15 is an antenna tuner having an antenna section and a tuner section. Reference numeral 16 denotes a video / audio demodulation circuit that demodulates the selected video / audio intermediate wave number signal into a baseband signal. 1
Reference numeral 7 is a video output terminal for outputting the demodulated base band video signal to a recording / reproducing means (not shown). Reference numeral 18 denotes an audio output terminal from which the audio demodulated baseband audio signal is taken out. The signals extracted from 17 and 18 are input to the video / audio signal processing circuit of the VTR.

[0004]

However, in the above structure, the TV input from the antenna input terminal 1 is used.
Since the signal is directly input to the distributor 9, the reception sensitivity is poor in a region where the TV signal level is weak (weak electric field region), which causes a problem that the TV reception image quality deteriorates.

The present invention solves the above problems, and
Improves reception sensitivity even in areas with weak V signal levels,
It is an object of the present invention to provide a high-frequency reception conversion device that realizes highly sensitive reception image quality.

[0006]

In order to achieve this object, a high frequency receiving and converting device of the present invention is a high frequency receiving device built in a video tape recorder used by being connected to a television receiver. Connected to an antenna input terminal for inputting a television signal to be received at, a first switch for receiving a television signal from the antenna input terminal and switching to two output terminals, respectively, and one output terminal of the first switch High-frequency amplifier,
A second switch that is connected to the high-frequency amplifier and the other output terminal of the first switch and is switchable;
A distributor for distributing the television signal output from the switch, a third switch for switching and outputting one output signal of the distributor and an input signal from the recording / reproducing means of the video tape recorder, and the distributor. A tuner for receiving and selecting a desired broadcast signal from the other output signal of
A video / audio demodulation circuit that demodulates the broadcast signal received and selected by the tuner into video and audio signals, a timer microcomputer that outputs serial control data, and the first and second switches are switched by serial control data output from the timer microcomputer. And a PLL circuit for controlling the above.

[0007]

According to the above means, the control of the signal path of the amplifier circuit section is controlled by the serial data from the timer microcomputer.
By supplying the signal to the LL circuit and enabling the switching by the control signal from the BAND output port, the switching control can be completed only by the high frequency receiving device, the cost does not increase, and the dedicated external control circuit can be reduced. Is.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a high frequency receiving and converting apparatus of this embodiment. In FIG. 1, the same components as those of the conventional technique are designated by the same reference numerals and the description thereof will be omitted. 3 is a first switch circuit connected to the output of the antenna input terminal 1, 4 is a high frequency amplifier for amplifying the signal output from the first switch circuit 3, and 5 is the output signal of the high frequency amplifier 4 or the first switch. A second switch for switching the output signal of 3 and a signal path 6 for connecting the output of the first switch circuit 3 to the second switch circuit 5. Two
0 is an RF / AGC voltage generated in the video / audio demodulation circuit section 16 and is a voltage that changes in accordance with the electric field strength of the TV signal input to the antenna input terminal 1. 21 is RF
It is a voltage detector that detects the AGC voltage 20 and outputs a LOW or HIGH control signal. This voltage detector 21
Is composed of a comparator circuit, but is not limited to this. The first switch circuit 3 is switched by a control signal output from the voltage detector 21. Reference numeral 8 is a high-frequency amplifier circuit section including the first switch circuit 3, the second switch circuit 5, the high-frequency amplifier 4, and the signal path 6. Reference numeral 20 is a system microcomputer for controlling the operation of the VTR in which the present apparatus is incorporated, and 21 is a timer microcomputer. Each of 20 and 21 is controlled by serial data. Reference numeral 22 is serial data for controlling the PLL circuit. This data is composed of the system microcomputer 20 and the timer microcomputer 21, but is not limited to this. Reference numeral 23 is a PLL circuit provided in the tuner 14, and 7 is a BAN from the PLL circuit 23.
D output port. Reference numeral 24 is a high-frequency amplifier circuit control unit including a system microcomputer 20, a timer microcomputer 21, and a tuner 14.

The operation of the high-frequency receiving and converting apparatus of the present invention constructed as above will be described below.

First, depending on the level of the input signal, it is arbitrarily selected on the on-screen display (not shown) whether the high-frequency amplifier 4 is passed or not, and the system microcomputer 20 causes the timer microcomputer 2 to operate.
1 is transmitted as serial data, and further, the timer microcomputer 21 transmits it as serial data to the PLL circuit 23. One of the BAND output ports 7 from the PLL circuit 23 is used as a control signal for the high frequency amplification circuit section 8 to switch the high frequency amplification circuit section 8.

Next, the operation of the high frequency amplifier circuit section 8 will be described. A TV signal is input to the antenna input terminal 1 from the external antenna. By applying the control signal 7 arbitrarily according to the level of this input signal, the first and second switch circuits 3 and 5 are switched to pass the high frequency amplifier 4 or the high frequency amplifier 4 is not passed. 6
To switch to Generally, when the input level is low (weak electric field level), the first switch 3 and the second switch 3
The switch 5 is switched to the a side, and the input signal is input to the distributor 9 via the high frequency amplifier 4. When the input level is high, the first switch 3 and the third switch 5
Are switched to the b side, and the input signal is input to the distributor 9 via the signal path 6.

The TV signal thus controlled is distributed by the distributor 9
, And one of the TV signals is input to the tuner 14 and received and selected as a desired signal. Then, it is converted into an intermediate frequency signal and input to the video / audio demodulation circuit 16.
The intermediate frequency signal input to the video / audio demodulation circuit 16 is demodulated into a baseband video and audio signal, and the VTR video / audio signal is output via the video signal terminal 17 and the audio signal terminal 18.
It is transmitted to the audio signal processing circuit.

The other TV signal of the distributor 9 is input to the antenna switch circuit 10. In the antenna switch circuit 10, the control signal input from the antenna switching control signal input unit 10 switches between the a terminal on the distributor 9 side and the b terminal on the RF modulator 11 side. Usually, when the TV signal received by the antenna is directly displayed on the TV receiver, the antenna switch circuit 10 is connected to the a side, and the output signal of the distributor 9 is transmitted from the antenna output terminal 2 to the TV receiver via the coaxial cable. Is output to. Also, VT
When the video / audio signal reproduced by R is input to the TV receiver, the antenna switch circuit 10 is connected to the b side, and the video / audio signal input to the video input terminal 12 and the audio input terminal 13 is the RF modulator. The signal is output from the antenna output terminal 2 via 11 to the TV receiver via the coaxial cable.

As described above, according to this embodiment, when the TV signal level input to the antenna input terminal 1 is weak, the output of the first switch circuit 3 is amplified via the high frequency amplifier 4. , The reception sensitivity can be improved even when the TV signal level is weak.

[0016]

As described above, according to the present invention, the first and second switch circuits, the high frequency amplifier and the like are provided in front of the distributor of the antenna tuner section, and the high frequency signal from the antenna input is supplied to the first switch circuit and the high frequency circuit. An amplifier circuit section having a signal path that passes through the amplifier and the second switch circuit and a signal path that does not pass the high-frequency amplifier through the first and second switch circuits is configured, and the control of the signal path of the amplifier circuit section is controlled by the serial from the timer microcomputer. PLL provided in the tuner with data
It is possible to control whether or not the input TV signal is passed through the high frequency amplifier by supplying the signal to the circuit and the control signal from the BAND output port, so that the receiving sensitivity is improved even in the area where the TV signal level is weak (weak electric field area). It has an excellent effect of good distortion characteristics.

[Brief description of drawings]

FIG. 1 is a block diagram of a high frequency reception conversion apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional high frequency receiving and converting device.

[Explanation of symbols]

 1 Antenna Input Terminal 2 Antenna Output Terminal 3 First Switch Circuit 4 High Frequency Amplifier 5 Second Switch Circuit 6 Signal Path 7 Control Signal 8 Amplification Circuit Section 9 Antenna Distributor 10 Antenna Switch Circuit 11 RF Modulator 20 System Microcomputer 21 Timer Microcomputer 23 PLL circuit

Claims (1)

[Claims] 1. A high-frequency receiving device built in a video tape recorder used by connecting to a television receiver, the antenna input terminal for inputting a television signal received by an antenna, and the television from the antenna input terminal. A John signal is input to the two output terminals and can be switched to each of the two output terminals, a high frequency amplifier connected to one output terminal of the first switch, and the other of the high frequency amplifier and the first switch. A second switch that is connected to an output terminal and can be switched respectively, a distributor that distributes the television signal output from the second switch, one output signal of the distributor, and recording of a video tape recorder. A third switch for switching and outputting the input signal from the reproducing means, and the other output signal of the distributor. A tuner for receiving and selecting a desired broadcast signal from the TV, a video / audio demodulation circuit for demodulating the broadcast signal received and selected by the tuner into video and audio signals, a timer microcomputer for outputting serial control data, and the timer microcomputer for outputting. And a PLL circuit that controls to switch the first and second switches according to serial control data.