Keywords: PID (program identification), digital satellite TV, decoder
When receiving digital satellite TV programs, it is often necessary to set the parameters of the programs to be received. For most general-purpose digital satellite decoders, generally only need to set LNB parameters (including receiving frequency, local oscillator frequency, polarization mode), digital signal transmission symbol rate (symbol-rate), FEC, and then find through automatic search The program to be received. The setting of some professional digital satellites is more complicated. In addition to setting the parameters of the general decoder, the PID parameters of the receiving satellite programs must also be set. For satellite signals of multiple programs with a single frequency, the difference between each program is only the difference in PID. To receive a certain program, the PID of its program must be set. For professional program departments such as TV stations, a decoder can receive a certain program for a long period of time, which requires simplicity, safety and reliability. The fewer other programs that are not related to the need to receive the program, the better. It is best to receive only the desired TV. Programs; This is different from the requirements of general household satellite decoders, which require one machine to receive as many programs as possible.
The following introduces the relevant knowledge of PID and General Instrument (GI)
How to set up the SR-3200 Professional Satellite Receiver.
1. Basic knowledge of PID
PID is the abbreviation of English Program IdenTIficaTIon, meaning program identification, including video identification VID, audio identification AID, clock reference signal identification PCR, and graphic signal identification. They are used as identification codes for the decoder to identify the type of data packet signals in the transmission code stream and the distinction between multiple sets of program data packets. For VID, AID and graphic identification codes, as the name suggests, it is easy to understand the meaning. Here mainly introduces the concept of PCR for reference.
There is no concept of synchronization pulse in the digital code stream. In the digital compression system, since the data of each image is different (image-based encoding method and complexity), it is impossible to obtain timing directly from the beginning of the image data information. The solution is to select some headers to transmit data packets to transmit time information. This is a 27MHz clock transmitted in the PCR (Program-Clock_refernece) field, which indicates the expected time for the decoder to read this field from the code stream. The phase of the local clock during decoding is compared with this instantaneous PCR to determine whether the decoding process is synchronized. Usually, PCR from the code stream does not directly change the phase of the local clock, but only serves as an input to adjust the clock frequency. In other words, the PCR parameters input in the decoder are used by the decoder to correctly decode the synchronization and timing signals of the program signal. If the PCR setting is incorrect, the decoder will "freeze", and it must be powered off and restarted to continue operation.
2. PID data related to satellite TV programs (Table 1)
Note: The above program PID is not suitable for Xinnuo No. 1 Ku band CBTV, and it changes with satellite, frequency, etc., for reference only.
3. SR-3000 professional digital satellite TV decoder settings
The SR-3000 decoder can complete all settings for receiving satellite TV programs through the front panel display and a set of buttons. Press the MAIN key to display one screen. Due to the large number of main menu items, it is displayed in 4 screens. By pressing the NEXT key, you can select a certain screen. There are 4 options on the main menu of the first screen: PIDs, Prog, Status, Next. Select a certain option.
You can press one of the four keys (F1, F2, F3, F4) on the left and right sides of the display. After selecting PIDs (that is, pressing the F1 key), enter the PIDs submenu, which has 3 options: VID, AUD, PCR. After selecting an item, view the current settings or modify the settings. In addition, the main menu of 1 screen has Tune, Vol, Language, Next 4 items, among them TUNE contains frequency, symbol rate (SRATE), FEC setting.
It is known that on the Asia 2 satellite, the IF signal of Inner Mongolia Satellite TV is: 1 ~ 320GHz; the symbol rate is: 8.400Msymbols; FEC is 3/4; offset: 0? 0000GHz; the PIDs of the first set of programs are: VID is 511, AUD is 512, PCR is 512. The process of receiving the first set of programs of Inner Mongolia Satellite TV is as follows:
MAIN → Press F4 to select Enter Menu → Press F4 to select Next → Tune → Freq. → 1? 2255GHZ → Enter SRate → 6? 000Msymb → Enter
FEC → 3 ï¼ ï¼” → Enter
TUNE → LNB → Offset → 0.00000GHz → Enter
Menu → PIDs → PCR → 512 → Enter
VID → 511 → Enter
AID → 512 → Enter
After the above settings, the satellite decoder can receive the program. When setting PIDs, you must set PCR first, and then set VID. Otherwise, there will be a crash during the setting process. At this time, you can only continue the operation by turning off the power and then turning it back on. The reason for analysis is that when the VID is changed first, after entering the identification code and pressing the ENTER key, the decoder starts MPEG, and the PCR at this time is still the original program, thus causing a crash
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