What are Digital Satellite Systems?
Digital satellite system is a digital satellite television receiver system based on MPEG compression technology. A complete digital satellite system includes both outdoor and indoor parts. The outdoor part consists of a receiving antenna, a high-frequency head, a feed source, and a first intermediate frequency cable. The indoor part is mainly composed of a tuner, a demodulator, a power divider, a digital satellite receiver, and a light transmitter.
- Digital satellite system (DSS) is one of the fastest growing consumer electronics products. In foreign countries, DSS
- Digital satellite system is a digital satellite TV receiver system based on MPEG compression technology. It is developed by Thomson Multimedia. It refers to a type of 18-inch diameter roof dish antenna to receive video signals to obtain high-quality digital video at home. Method of delivery.
- The method uses communication satellites at HUB stations and multiple
- Digital satellite system composition diagram
- The figure is a block diagram of a typical satellite receiving system, which includes two parts of horizontal polarization and vertical polarization.
- As a collective receiving system, the output of the satellite receiver is the signal source of the cable television, so it is directly connected to the radio frequency modulator; when receiving individually, the satellite receiver is directly connected to the television. [2]
Digital Satellite System Outdoor
- (1) Satellite receiving antenna. The position of the satellite receiving antenna in the entire satellite receiving system is obvious. Its role is to effectively receive the electromagnetic waves radiated by the satellite to the ground and transmit it to the high frequency head.
- (2) Tuner. The role of the high frequency head is: low noise amplification; down conversion; intermediate frequency amplification. Commonly used are C-band and Ku-band.
- (3) Feed. The feed is also called a radiator or irradiator. It consists of a feed head, a polarizer, and a round pitch converter. It mainly provides effective radiation to the antenna.
- (4) The first intermediate frequency cable. The function of the first IF cable is to transmit satellite signals from outdoor to indoor. At the same time, the satellite receiver provides 18V DC power voltage to the high-frequency head and is also transmitted through the first IF cable. If the distance between the satellite antenna and the front end is relatively long, in order to compensate for the attenuation of the cable, a line amplifier needs to be installed in the middle of the cable. Line amplifiers are also powered by cables. [2]
Digital satellite system indoor part
- (1) Tuner: It is used to receive the satellite signal input by the outdoor tweeter, and amplify, filter and re-convert it to convert it into a suitable signal. Simply put, it is to convert digital signals into analog signals.
- (2) Demodulator: The demodulator includes D / A converter, QPSK demodulator, decoder and forward error correction unit. Its role is to convert analog signals into digital signals.
- (3) Power divider: The power divider is referred to as the power divider. The function of the power divider is: The first intermediate frequency signal transmitted by the cable to the room is evenly distributed into several channels and provided to each satellite receiver; Effective isolation of each satellite receiver to minimize the interference.
- (4) Digital satellite receiver: Digital satellite television receiver, also known as integrated receiving decoder, mainly completes channel tuning, QPSK demodulation, channel decoding, demultiplexing, MPEG-2 decompression, and PAL encoding. Conditional access also requires system control and user smart cards. The digital satellite receiver inputs the first intermediate frequency signal, outputs the audio signal and the video signal, and at the same time the receiver outputs the data signal.
- (5) Optical transmitter: Optical transmission is the technology of transmitting optical signals between the sender and receiver. The working process of the optical transmission signal is performed between the optical transmitter, the optical fiber, and the optical receiver. The most important optical device in an optical transmitter is a semiconductor laser. Its function is to convert electrical signals into optical signals. [2]