JPH03220882A - All band television receiver - Google Patents

Abstract

PURPOSE:To make the receiver small in size and to reduce the manufacture cost by providing a mixer receiving a reception signal of a general television broadcast, a reception signal of a cable television broadcast and a reception signal of a satellite broadcast subject to frequency conversion by a BS converter in common and converting them into an intermediate frequency signal at a prescribed frequency. CONSTITUTION:A high frequency signal fed to an input terminal 52 is converted into a 1st intermediate frequency at a mixer 33 and only a 1st intermediate frequency signal of a desired channel is inputted to a double balanced mixer 57 via a band pass filter 34. When, e.g. a changeover switch 56 is thrown to the position of CATV by a switching signal Dsw, a tuner unit 51 acts like a CATV tuner. On the other hand when the changeover switch 56 is thrown to the position of BS by the switching signal Dsw, the tuner unit 51 acts like a BS tuner.

Description

Detailed Description of the Invention: “Industrial Application Field This invention relates to a television receiver, and more particularly, to an all-band television receiver capable of receiving general television broadcast signals, CATV (cable cable television broadcast) signals, and satellite broadcast signals. Regarding machines.

"Prior Art" In addition to general television broadcasting in the VHF band and UHF band, CATV and satellite broadcasting are also carried out.

If you want to receive all of these broadcasts, you can combine the devices that receive each broadcast to form an all-band reception system (see Figure 3), or you can use a device that is equipped with a circuit to receive each broadcast. An all-band television receiver (see Figure 4) is required.

FIG. 3 is a schematic diagram showing an example of the configuration of this all-band reception system. In this figure, 1 is a broadcasting satellite, and 2 is a parabolic antenna for receiving satellite broadcasting installed outdoors. 12 received by 311 parabolic antenna 2
This is a BS converter that amplifies a GHz band satellite broadcast signal and converts it into an IGHz band high frequency signal. A BS tuner 4 is provided indoors and converts the output signal of the BS converter 3 into an intermediate frequency signal, converts the intermediate frequency signal of a desired channel into a video signal and an audio signal, and outputs the signals. Further, numeral 5 is an antenna installed outdoors to receive the acid TV broadcast signal, 6 is a relay line installed outdoors to transmit the cable TV broadcast signal, and 7 is the cable TV broadcast signal to a second intermediate frequency signal. A CATV converter converts and outputs the data, and 8 is a television receiver.

Next, FIG. 4 shows the above-mentioned BS tuner 4 and CATV.
1 is a diagram showing an example of the configuration of an all-band television receiver 10 incorporating the function of a converter 7. FIG.

In this figure, 11 is an input terminal to which some TV broadcast signals and cable TV broadcast signals are supplied, and 2 is a controller that outputs a tuning signal representing the set channel, and is composed of a microprocessor or the like. . 13 is CAT
This is a VJ station circuit and outputs a tuning voltage corresponding to the supplied channel selection signal. 14 is a CATV tuner that converts the received signal into an intermediate frequency signal and outputs it; 15 is a video intermediate droplet wave amplifying section. 16 is an AFC circuit that detects a frequency deviation of an intermediate frequency signal and outputs an AFC voltage, and 17 is a video detection circuit. Next, 18 is an input terminal to which the output signal of the BS converter 3 is supplied, and 9 is the controller I2.
This is a BS tuning circuit that outputs a tuning voltage corresponding to a tuning signal supplied from the BS tuning circuit. 20 is a BS tuner that converts a high frequency signal into an intermediate frequency signal and selects and outputs the channel; 21 is a PLI and demodulator that performs FM demodulation of the intermediate frequency signal; and 22 is a video signal processing section that outputs a video signal.

23 is a band pass filter, 24 is a QPSK that demodulates and outputs the audio signal frequency division multiplexed with the video signal.
(4-phase differential phase) demodulator. In the all-band television receiver 10 having such a configuration, when a desired channel is set, the controller 12 selects CAT.
V tuner 14 or BS tuner 20 is selected,
The target channel is received by the selected CATv tuner I4 or BS tuner 20.

Next, FIG. 5 shows an example of the configuration of the CATV tuner 14 described above. In this figure, 30 is a high frequency amplifier;
1 is a tuning voltage input terminal, and 32 is a first local oscillator that oscillates a first local oscillation signal. 33 mixes the output signal of the high frequency amplifier 30 and the first local oscillation signal to generate the first local oscillation signal.
A first mixer for converting into an intermediate frequency signal. Also, 34
is a bandpass filter that passes the first intermediate frequency signal;
35 is AFCI! The pressure input terminal 36 is a second local oscillator that oscillates a second local oscillation signal. 37 mixes the first intermediate frequency signal and the output signal of the second local oscillator 36 to generate a second intermediate frequency signal.
38 is a second intermediate frequency amplifier that amplifies the second intermediate frequency signal; 39 is an output terminal to which the output signal of the second intermediate frequency amplifier 38 is output.

By the way, the CATV tuner 14 with such a configuration
In this case, the second local oscillation signal output from the second local oscillator 36 is required to always have a constant frequency. However, since the second local oscillator 36 usually uses an LC oscillation circuit, its oscillation frequency tends to drift due to temperature changes, etc. Therefore, the oscillator 36
The oscillation frequency is kept constant by the AFC voltage output from the circuit 16 (see FIG. 4).

FIG. 6 shows a circuit example of this second local oscillator 36. In this figure, T1 is a terminal to which power supply voltage Vcc is supplied;
T2 is an input terminal to which an AFC voltage is supplied, R1-R5 are resistors, and C and -C are capacitors. Further, Tr is a transistor, L is a coil, and Dvc is a variable capacitance diode. The Colpitts-type LC oscillation circuit having such a configuration is controlled so that the oscillation frequency is constant by supplying the AFCI pressure to the variable capacitance diode Dvc, which is a part of the tuning capacitance of the @ path.

Next, an example of the configuration of the BS tuner 20 is shown in FIG. In this figure, 40 is a high frequency amplifier, 41 is a tuning voltage input terminal, and 42 is a local oscillator that oscillates a local oscillation signal. 43 is a mixer that mixes the output signal of the high frequency amplifier 40 and the local oscillator signal and converts it into an intermediate frequency signal;
44 is a band pass filter that passes the intermediate frequency signal.

Further, 45 converts the output signal of the bandpass filter 44 into an FM
This is a PLL demodulator that demodulates and outputs the signal. This PLL!
[The m unit 45 includes a VCO (voltage controlled oscillator) 45a, a phase comparator 45b, a loop filter 45c, and a video amplifier 45d.

The VCO 45a outputs an oscillation signal fc having a frequency corresponding to the input oscillation frequency control signal Vc.

The phase comparator 45b outputs a phase difference signal obtained by comparing the phase of the intermediate frequency signal input from the previous stage with the phase of the oscillation signal rc. A double balanced mixer (DBM) is generally used for this phase comparator 45b. The loop filter 45c removes high frequency components and noise components from the phase difference signal. The video amplifier 45d amplifies and outputs the output signal of the loop filter 45c. 46 is a demodulation output terminal, and the output signal of the video amplifier 45d is output from this demodulation output terminal 46 as a demodulation signal, and is also inputted to vCO.45a as an oscillation frequency control signal Vc.

In such a configuration, the high frequency signal supplied to the input terminal 18 is converted into an intermediate frequency signal of a desired channel via the mixer 43 and the bandpass filter 44.

In the PLL demodulator 45, the oscillation signal rc of the VCO 45m changes to lock onto this intermediate frequency signal, so the oscillation frequency control signal Vc input to the VCo 45a becomes an FM (! modulation signal). .

``Problem to be solved by the invention'' By the way, the above-mentioned conventional all-band TV reception! 1
10 does not share the receiving circuit and is simply a collection of conventional receiving equipment, so the manufacturing cost cannot be reduced and the receiver has no choice but to have a complicated circuit configuration. There is a problem of inviting larger scale.

This invention was made against this background, and an object of the present invention is to provide an all-band television receiver that can reduce the number of component parts, downsize the receiver, and reduce manufacturing costs. .

"Means for Solving the Problem" In the invention according to claim 1, a received signal of general television broadcasting, a received signal of cable television broadcasting, and a received signal of satellite broadcasting whose frequency has been converted by a BS converter. It is characterized by comprising a mixer that commonly inputs the signals and converts them into intermediate frequency signals of a predetermined frequency.

In addition, in the invention according to claim 2, the device is used as a frequency mixer when receiving a television signal whose amplitude is modulated by a video signal, and when receiving a television signal whose frequency is modulated by a video signal. is characterized by having a double balanced mixer used as a phase comparator for PLL111.

"Function" According to the invention described in claim 1, the mixer can receive a common television broadcast reception signal, a cable television broadcast reception signal, and a satellite broadcast reception signal frequency-converted by a BS converter. and converts it into an intermediate frequency signal of a predetermined frequency.

Further, according to the invention described in claim 2, the double balanced mixer is used as a frequency mixer when receiving a television signal whose amplitude is modulated by a video signal, When receiving the signal, it is used as a phase comparator for PLL demodulation.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a tuner unit 5I of an all-band television receiver according to an embodiment of the present invention. In this figure, parts corresponding to those in FIG. 5 or 7 are given the same reference numerals, and their explanations will be omitted.

In this figure, 52 is an input terminal to which a general television broadcast signal, a cable television broadcast signal, and an output signal of the BS converter 3 (see FIG. 3) are commonly input. 53 is a high frequency amplifier that amplifies the signal input to the input terminal 52, and its signal bandwidth is 50 MHz to 1.86 GHz. 54 is a channel selection voltage input terminal to which a channel selection voltage Vt is supplied; 55 is a switching signal input terminal to which a switching signal D SW (described later) is input; 56 is a switching signal input terminal on the BS side in response to the switching signal D SW (described later). Alternatively, it is a changeover switch set on the CATV side. Reference numeral 57 denotes a double balanced mixer (DBM) which is constituted by a multiplication circuit and can obtain the sum and difference of frequencies of two input signals.

According to such a configuration, the high frequency signal supplied to the input terminal 52 is converted to the first intermediate frequency in the mixer 33, and only the first intermediate frequency signal of the desired channel is converted into a double balance mixer 5
7 will be powered by humans. Now, for example, when the changeover switch 56 is set to the CATV side by the changeover signal Dsw, the tuner unit 51 operates as a CATV tuner. That is, the VCo 45a receives the input A
The double balanced mixer 57 operates as a second local oscillator whose oscillation frequency is controlled to be constant by the PC 14 pressure, and the double balanced mixer 57 operates as a second mixer. As a result, the output of the double balanced mixer 57 becomes a second intermediate frequency signal, which is outputted to the output terminal 39 via the second intermediate frequency amplifier 38. On the other hand, when the changeover switch 56 is set to the BS side by the changeover signal Dsw, the tuner unit 51 operates as a BS tuner. In this case, since the double balanced mixer 57 operates as a phase comparator, the circuit elements 57.45c, 45d, and 45a are
LL demodulator (see FIG. 7) is formed. As a result, P
The M demodulated signal is output to output terminal 46.

Next, FIG. 2 is a block diagram showing a partial configuration example of an all-band television receiver 50 that employs this tuner unit 51. In this figure, parts corresponding to those in FIG. 4 are given the same reference numerals, and their explanations will be omitted. In this figure, 58 is a control circuit composed of a microprocessor or the like.

This control circuit 58 outputs a channel selection signal Dc representing the set channel, and also outputs a switching signal Dsw for controlling the switching of the switch 56 shown in FIG. 1 depending on whether the set channel is for satellite broadcasting or not. Output. 59 is a tuning circuit that converts the tuning signal Da into a tuning voltage Vt and outputs it.

All-band TV reception #150 with such a configuration
First, when the power is turned on and a channel for general television broadcasting or cable television broadcasting is set, the control circuit 58 sends a switching signal Dsw to control the switching of the changeover switch 56 shown in FIG. A channel selection signal Dc corresponding to the selected channel is output. As a result, the tuner unit 51 is set to CATV tuner operation, and the desired channel of general television broadcasting or cable television broadcasting is received. Next, when the satellite broadcasting channel is set, the control circuit 58 switches the changeover switch 5 shown in FIG.
Since the switching signal Dsw for controlling the switching of 6 to the BS side and the tuning signal DC for instructing the satellite channel are output, the desired channel of satellite broadcasting can be received.

As explained above, according to this embodiment, CATV
The functions of a tuner, a BS tuner, and a PLL demodulator can be realized by a single tuner, and only one channel selection circuit is required for tuning the tuner.

"Effects of the Invention" As explained above, the all-band television receiver according to the present invention has a simplified circuit configuration, so it is possible to reduce the number of component parts, downsize the receiver, and reduce manufacturing costs. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tuner unit 51 of an all-band television receiver according to an embodiment of the present invention, and FIG. 2 is a block diagram of an all-band television receiver 5 according to an embodiment of the present invention.
0, FIG. 3 is a schematic diagram of an all-band reception system, and FIG. 4 is a conventional all-band TV receiver IO.
5 is a block diagram of the CATV tuner 14, FIG. 6 is a circuit diagram of the second local oscillator 36, and FIG. 7 is a block diagram of the BS tuner 20. 33...First mixer, 57...Double balance mixer, 55...Switching signal input terminal, 56...Switching switch.

Claims (2)

[Claims] (1) A mixer that commonly inputs the reception signal of general television broadcasting, the reception signal of cable television broadcasting, and the reception signal of satellite broadcasting frequency-converted by a BS converter and converts it into an intermediate frequency signal of a predetermined frequency. An all-band television receiver comprising: (2) Used as a frequency mixer when receiving a television signal amplitude modulated by a video signal, and used as a phase comparator for PLL demodulation when receiving a television signal frequency modulated by a video signal. An all-band television receiver characterized by being equipped with a double-balanced mixer.