One of the most basic satellite television receivers, usually should include the following parts: Electronic tuner selector, if amplification and demodulator, signal processor, sound signal
demodulator, front panel indicator, power circuit. Card digital machine also includes card interface circuit.
1. Electronic tuned selector. Its main function is to select the frequency of a TV channel to be received from the 950-1450m input signal and transform it into a fixed second-rate (usually $number. 5MHz), given if amplification and demodulator.
2. Medium-frequency AGC amplification and demodulator. This will be the input of the fixed second-if signal filtering, amplification, and then frequency demodulation, the inclusion of the image and sound signal, including the composite baseband signal, but also output a signal can be characterized by the size of the DC component to the level indicating circuit.
3. Image signal processor. It separates the video signal from the composite baseband signal and restores and outputs the image signal after a series of processing, such as aggravation, energy diffusion and polarity transformation.
4. Audio demodulator. It separates the sound subcarrier signal from the composite baseband signal and amplifies it and demodulation it to obtain the sound signal.
5. Panel indicator. It will amplify the DC level signal sent by the intermediate frequency amplifier, use the pointer level meter, light-emitting diode display level meter or digital display to show the strength and quality of the receiver input signal.
6. Power supply circuit. It will be the power supply by pressure, rectification, voltage regulator after the many groups of low-voltage DC voltage source, for the local parts and outdoor units (high-frequency head) power supply.