Claims
- 1. A satellite television broadcasting receiver comprising:
- a channel selecting circuit for receiving, as an input signal, a first intermediate frequency signal obtained by frequency converting a plural channel of radio waves received from a satellite and for frequency converting said first intermediate frequency signal into a second intermediate frequency signal such that a selected channel of the second intermediate frequency signal has a predetermined frequency;
- a band-pass filter for receiving said second intermediate frequency signal and for passing therethrough only a desired FM signal of said selected channel of said second intermediate frequency signal;
- an FM demodulator for demodulating the desired FM signal so as to obtain a pre-emphasized video signal which has been pre-emphasized at a transmitter;
- a de-emphasis circuit for de-emphasizing the pre-emphasized video signal;
- a low-pass filter, receiving an output signal of said de-emphasis circuit, for passing therethrough only a video signal;
- a first amplifier for amplifying said video signal from said low-pass filter and outputting an amplified video signal;
- a first clamping circuit for clamping the amplified video signal and outputting a clamped video signal;
- a second amplifier for amplifying the clamped video signal and outputting a second amplified video signal; and
- a second clamping circuit for clamping the second amplified video signal and outputting a second clamped video signal,
- wherein each of said first clamping circuit and said second clamping circuit has an input terminal and an output terminal and each comprises:
- a capacitor connected at a first end to said input terminal and connected at a second end to said output terminal;
- a DC power source; and
- a transistor having an emitter connected to said output terminal and a base connected to said DC power source.
- 2. A satellite television broadcasting receiver comprising:
- a channel selecting circuit for receiving, as an input signal, a first intermediate frequency signal obtained by frequency converting a plural channel of radio waves received from a satellite and for frequency converting said first intermediate frequency signal into a second intermediate frequency signal such that a selected channel of the second intermediate frequency signal has a predetermined frequency;
- a band-pass filter for receiving said second intermediate frequency signal and for passing therethrough only a desired FM signal of said selected channel of said second intermediate frequency signal;
- an FM demodulator for demodulating the desired FM signal so as to obtain a pre-emphasized video signal which has been pre-emphasized at a transmitter;
- a de-emphasis circuit for de-emphasizing the pre-emphasized video signal;
- a low-pass filter, receiving an output signal of said de-emphasis circuit, for passing therethrough only a video signal;
- a first amplifier for amplifying said video signal from said low-pass filter and outputting an amplified video signal;
- a pulse clamping circuit comprising:
- an input terminal receiving said amplified video signal from said first amplifier and an output terminal,
- a switching circuit connected to said input terminal and selectively providing a constant voltage to said amplified video signal that is input to said input terminal, in accordance with a control signal,
- an inversion amplifier receiving said amplified video signal and providing an output based on inversion amplifying the amplified video signal,
- a peak holder circuit for receiving said output of said inversion amplifier and providing an output representing a peak of said output of said inversion amplifier,
- a level shifter circuit for receiving said output of said peak holder circuit and shifting a level thereof by a given amount to obtain a level shifted output, and
- a comparator for comparing said level shifted output of said level shifter circuit to the output of said inversion amplifier and generating said control signal in response thereto;
- a second amplifier for amplifying the video signal clamped by said switching circuit and outputting a second amplified video signal; and
- a clamping circuit for clamping the second amplified video signal output from said second amplifier so as to output a clamped video signal.
Priority Claims (2)
Number |
Date |
Country |
Kind |
3-145822 |
Jun 1991 |
JPX |
|
4-013521 |
Jan 1992 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 08/286,226, filed Aug. 5, 1994 (abandoned), which is a continuation of application Ser. No. 07/897,676, filed Jun. 12, 1992 (abandoned).
US Referenced Citations (5)
Foreign Referenced Citations (5)
Number |
Date |
Country |
2615680A1 |
Nov 1988 |
FRX |
2311230B2 |
Jul 1974 |
DEX |
1213074 |
Aug 1989 |
JPX |
3289876 |
Dec 1991 |
JPX |
451674 |
Feb 1992 |
JPX |
Non-Patent Literature Citations (1)
Entry |
A Satellite Broadcasting Receiver (Part 2, desirable performance; The Radio Technical Association. |
Continuations (2)
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Number |
Date |
Country |
Parent |
286226 |
Aug 1994 |
|
Parent |
897676 |
Jun 1992 |
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