YD/T 828.29-1997
Methods of measurement for equipment used in digital microwave transmission systems.Part 2: Measurements on terrestrial redio-relay systems.Section 9: Service channels (English Version)
- Standard No.
- YD/T 828.29-1997
- Language
- Chinese, Available in English version
- Release Date
- 1997
- Published By
- Professional Standard - Post and Telecommunication
- Latest
- YD/T 828.29-1997
- Scope
- This standard specifies measurements related to official channels used in digital microwave wireless relay systems. In digital wireless relay systems, there are usually two basic methods used to transmit official channel signals (i.e., voice signals, monitoring signals). The first transmission method uses analog transmission technology, that is, using analog business channel signals to directly frequency modulate the intermediate frequency or radio frequency carrier signal of the digital modulator, and then using the FM demodulator to restore it at the receiving end (for example, in the coherent digital demodulator) in the carrier recovery circuit). The second transmission method is digital transmission, which uses a multiplexer to insert the service channel signal into the main bit stream in the form of a separate bit stream for transmission (possibly transmitted together with a bit stream carrying additional information). For digital transmission, the service channel signal may be an analog signal that is digitally encoded for bit insertion, or it may be a digital signal. In this case, in order to change the line code into a code pattern suitable for the wireless device, appropriate code conversion is generally required. At the receiving end, a tap is used to restore the service channel bits, and after appropriate decoding or code conversion, the service channel output signal is provided. Usually, there is more than one service channel to be transmitted. Sometimes additional bit streams can be transmitted (for example, alarm control signals for protection switching and monitoring equipment). Therefore, appropriate multiplexing and tapping equipment should be used, such as frequency division multiplexing for analog transmission and time division multiplexing for digital transmission. Using time division multiplexing, analog business channel signals and digital business channel signals can be digitally transmitted at the same time.
YD/T 828.29-1997 history
- 1997 YD/T 828.29-1997 Methods of measurement for equipment used in digital microwave transmission systems.Part 2: Measurements on terrestrial redio-relay systems.Section 9: Service channels
