5. Special Issues on Radio Transmission Channel in C&T

The channel referred to in this chapter is the medium for information transmission. Radio transmission channel refers to the channel transmitting electromagnetic signals in free space (in a broad sense, it may include related components and links). Radio transmission channel may bring in many adverse impacts on C&T signals, such as orbit-determining error and signal attenuation caused by radio wave transmission characteristics, multipath interference caused by reflected wave, various types of noise and interference introduced by the channel, large Doppler frequency shift in high-dynamic radio channel, and the non-real time caused by the channel with time delay. The impacts of the last three transmission characteristics have been addressed in the early chapters.