JP3743081B2 - Tuner device for satellite broadcasting reception - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a satellite broadcast receiving tuner device for receiving a signal from a broadcasting satellite and generating a video signal and an audio signal.
[0002]
[Prior art]
Conventionally, for example, a satellite broadcast receiving tuner device is configured as shown in FIG.
In other words, in FIG. 4, a satellite broadcast receiving tuner device 1 includes an RF tuning amplification unit 3, a mixer 4, an IF amplification unit 5, and an AGC control unit 6 to which a signal from an input terminal 2 to be connected to a BS converter is input. And an FM demodulator 7, a video processor 8 and an audio processor 9.
[0003]
Here, the RF tuning amplification unit 3 extracts a signal of a desired frequency component based on a signal from the input terminal 2 and amplifies it to generate an RF signal.
[0004]
The mixer 4 receives the local oscillation frequency from the local oscillation circuit 4a, and the local oscillation circuit 4a receives the reference frequency from the crystal oscillator 4b.
Further, a control signal from the AGC control unit 6 is input to the RF tuning amplification unit 3.
[0005]
The video processing unit 8 includes a video processing IC 8a and a SAW filter (not shown) adjacent thereto.
Here, as shown in FIG. 5, the video processing IC 8a includes a de-emphasis low-pass filter 8b, an energy spread signal removal circuit 8c, and a video amplification circuit 8d. Based on the demodulated signal from the FM demodulator 7, Generate a video signal.
[0006]
Furthermore, the audio processing unit 9 is constituted by an audio processing IC, and as shown in FIG. 6, is constituted by an audio bandpass filter 9a, a QPSK demodulating circuit 9b, a PCM demodulating circuit 9c, and an analog audio processing circuit 9d. An audio signal is generated based on the demodulated signal from the FM demodulator 7.
The QPSK demodulator circuit 9b includes an oscillation circuit 9e. The oscillation circuit 9e generates a reference frequency signal by a crystal oscillator (not shown).
[0007]
According to the satellite broadcast receiving tuner device 1 configured as described above, a signal from the BS converter is input to the RF tuning amplification unit 3 so that only a desired frequency component is input to the mixer 4 as an RF signal. The An oscillation signal having a predetermined local oscillation frequency determined by the crystal crystal of the oscillator 4b is input to the mixer 4 from the local oscillation circuit 4a. The mixer 4 receives the signal from the RF tuning amplification unit 3 and the oscillation signal. To produce an intermediate frequency (IF) signal.
[0008]
The IF signal is amplified by the IF amplifier 5, gain-controlled by the AGC controller 6, and then input to the FM demodulator 7. The FM demodulator 7 demodulates the input signal to output a television signal.
[0009]
Thus, the video signal is generated by the video processing unit 8 and the audio signal is generated by the audio processing unit 9 based on the television signal. The video signal and the audio signal are input to an input terminal of a television device or a video device (not shown) so that they can be displayed on a display device such as a cathode ray tube or recorded on a video tape.
[0010]
[Problems to be solved by the invention]
By the way, in the satellite broadcast receiving tuner device 1 configured as described above, both the RF tuning amplification unit 3 and the sound processing unit 9 are provided with crystal oscillators for generating reference frequencies for the oscillation circuits 4a and 9e, respectively. It has been. Accordingly, since the crystal oscillator itself is relatively expensive, there is a problem that the number of parts increases, and the part cost and the assembly cost increase.
[0011]
In view of the above, an object of the present invention is to provide a satellite broadcast receiving tuner device that can be reduced in cost with a simple configuration.
[0012]
[Means for Solving the Problems]
According to the present invention, the above-described object is achieved by sequentially connecting an RF tuning amplification unit, a mixer to which a local oscillation frequency from a local oscillation circuit is input, an AGC control unit and an FM demodulation unit, and a demodulated signal from the FM demodulation unit. based on the video processor and audio processing unit and a comprise that, satellite tuner device for generating respective video and audio signals, a local oscillator circuit for outputting a local oscillation frequency to the mixer, the audio processing The clock signal is connected to the local oscillation circuit via a buffer, and the buffer and the local oscillation circuit are connected in the mixer unit .
[0013]
According to the above configuration, the local oscillation circuit generates a local oscillation frequency based on the clock signal from the oscillation circuit in the audio processing unit and inputs the local oscillation frequency to the mixer. Therefore, it is necessary to provide a crystal oscillator in the local oscillation circuit. Therefore, the number of parts can be reduced and the cost can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.
1 to 3 show the configuration of an embodiment of a tuner for receiving satellite broadcast according to the present invention.
[0015]
In FIG. 1, a satellite broadcast receiving tuner apparatus 10 includes an RF tuning amplifying unit 12, a mixer 13, an IF amplifying unit 14, an AGC control unit 15 and an FM to which a signal from an input terminal 11 to be connected to a BS converter is input. The demodulator 16 further includes a video processor 17 and an audio processor 18 arranged in the same unit.
[0016]
The RF tuning amplifier 12 extracts a signal having a desired frequency component based on a signal from the input terminal 11 and amplifies it to generate an RF signal.
[0017]
The mixer 13 receives a local oscillation frequency from a local oscillation circuit 13a including a PLL circuit.
Further, a control signal from the AGC control unit 15 is input to the RF tuning amplification unit 12.
[0018]
As shown in FIG. 1, the video processing unit 17 includes a video processing IC 17a and adjacent SAW filters 17b and 17c.
Here, as shown in FIG. 2, the video processing IC 17a includes a de-emphasis low-pass filter 17d, an energy diffusion signal removal circuit 17e, and a video amplification circuit 17f. Based on the demodulated signal from the FM demodulation unit 16, Generate a video signal.
[0019]
Further, as shown in FIG. 1, the audio processing unit 18 is composed of an audio processing IC, and as shown in FIG. 3, the audio processing IC includes an audio bandpass filter 18a, a QPSK demodulation circuit 18b, The PCM demodulation circuit 18c and the analog audio processing circuit 18d are configured to generate an audio signal based on the demodulated signal from the FM demodulation unit 16.
Here, the four-phase DPSK demodulation circuit 18b includes an oscillation circuit 18e, and the oscillation circuit 18e generates a signal having a reference frequency by a crystal oscillator 18f.
[0020]
Further, the SAW filter 17b is configured to have a vibration frequency of, for example, 18.43 MHz for the clock of the audio processing IC, and the SAW filter 17b includes the clock of the video processing IC 17a, the video processing IC 17a, and the audio processing. It is configured to have a vibration frequency of, for example, 5.72 MHz for the digital filter clock of the IC.
[0021]
The above configuration is the same as that of the conventional satellite broadcast receiving tuner device 1 shown in FIGS. 4 to 6, but the satellite broadcast receiving tuner device 10 according to the embodiment of the present invention is different in the following points. It is configured.
[0022]
That is, the local oscillation circuit 13a for the mixer 13 of the satellite broadcast receiving tuner device 10 is the oscillation circuit 18e of the QPSK demodulation circuit 18b of the audio processing unit 18 (see FIG. 3), as indicated by an arrow in FIG. In order to eliminate interference, the clock signal is input via the buffer circuit 13b, and a local oscillation frequency is generated based on this clock signal.
[0023]
The satellite broadcast receiving tuner device 10 according to the embodiment of the present invention is configured as described above, and a desired frequency component is obtained by inputting a signal from the BS converter to the RF tuning amplifier 12 from the input terminal 11. Only is input to the mixer 13 as an RF signal. An oscillation signal having a predetermined local oscillation frequency generated by the local oscillation circuit 13a based on the clock signal from the oscillation circuit 18e of the audio processing unit 18 is input to the mixer 13, and the mixer 13 receives RF tuning. The signal from the amplifying unit 12 and the oscillation signal are mixed to generate an intermediate frequency signal IF.
[0024]
The intermediate frequency signal IF is amplified by the IF amplifier 14, gain-controlled by the AGC controller 15, and then input to the FM demodulator 16. The FM demodulator 16 demodulates the input signal to generate a television signal.
[0025]
The television signal is input to the video processing unit 17 and the audio processing unit 18. As a result, the video processing unit 17 generates a video signal, and the audio processing unit 18 generates an audio signal. Thus, the video signal and the audio signal can be displayed on a display device such as a cathode ray tube or recorded on a video tape by being input to an input terminal of a television device or a video device (not shown).
[0026]
In this case, the local oscillation circuit 13a of the mixer 13 of the satellite broadcast receiving tuner device 10 is supplied with the clock signal from the oscillation circuit 18e (see FIG. 3) of the QPSK demodulation circuit 18b of the audio processing unit 18, and the local oscillation circuit. 13a generates a local oscillation frequency based on this clock signal, so that a crystal oscillator for the local oscillation circuit 13a becomes unnecessary. Accordingly, the number of parts can be reduced, the parts cost and the assembly cost can be reduced, and the space for mounting the crystal oscillator for the local oscillation circuit 13a becomes unnecessary, so that the whole can be made compact.
[0027]
In the above embodiment, the clock signal from the audio processing unit 18 is input to the local oscillation circuit 13a of the mixer 13 via the buffer 13b in order to eliminate interference, but instead of the buffer 13b. Isolation may be achieved by connecting a resistor and a capacitor in series.
[0028]
The satellite broadcast receiving tuner device 10 may be provided with a BS distributor 19 on the input side. In this case, the BS signal from the input terminal 11 is input to the BS distributor 19, and one of the two distribution outputs is output from the output terminal 20 to the outside, and the other distribution output is Input to the RF tuning amplifier 12.
As a result, it is possible to distribute the BS signal to other devices such as a television receiver and a video device without the need for an external distributor.
[0029]
【The invention's effect】
As described above, according to the present invention, the local oscillation circuit generates the local oscillation frequency based on the clock signal from the oscillation circuit in the audio processing unit and inputs the local oscillation frequency to the mixer. Since there is no need to provide a crystal oscillator, the number of parts can be reduced and the cost can be reduced.
[0030]
Thus, according to the present invention, it is possible to provide an extremely excellent satellite broadcast receiving tuner device that can reduce the cost with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of an embodiment of a satellite broadcast receiving tuner device according to the present invention.
2 is a block diagram showing a configuration of a video processing unit of the satellite broadcast receiving tuner device of FIG. 1;
3 is a block diagram showing a configuration of an audio processing unit of the satellite broadcast receiving tuner device of FIG. 1;
FIG. 4 is a block diagram showing an example of a conventional satellite broadcast receiving tuner device.
5 is a block diagram showing a configuration of a video processing unit of the satellite broadcast receiving tuner device of FIG. 4;
6 is a block diagram showing a configuration of an audio processing unit of the satellite broadcast receiving tuner device of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Satellite broadcast reception tuner apparatus 11 Input terminal 12 RF tuning amplification part 13 Mixer 13a Local oscillation circuit 13b Buffer 14 IF amplification part 15 AGC control part 16 FM demodulation part 17 Video processing part 18 Audio processing part 18e Oscillation circuit 18f Crystal oscillator

Claims (1)

A video signal and an audio signal based on the demodulated signals from the RF tuning amplification unit, the mixer to which the local oscillation frequency from the local oscillation circuit is input, the AGC control unit and the FM demodulation unit, and the FM demodulation unit, respectively. a video processor and audio processor for generating includes, in a satellite broadcast receiving tuner, the local oscillation circuit outputting a local oscillation frequency to the mixer, which operates based on the clock signal from the audio processing unit The satellite broadcast receiving tuner device , wherein the clock signal is connected to the local oscillation circuit via a buffer, and the buffer and the local oscillation circuit are connected in the mixer unit .

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