The article provides an in-depth view of keeping time and frequencies in case of satellite chain. When communicating over satellite system, it becomes important to keep the communication coherent as the space segment is usually above 36,000 Kilometers and there is a few seconds of delay between transmission and reception of the signals. By knowing exactly how much delay has happened, we can compensate for the same.

Spread Spectrum a kind of signal modulation, in which the signal frequency is spread over a very wide bandwidth. The band spread is achieved by chipping the signal with a code which is independent of signal. A code synchronized reception at the receiver is used for despreading and subsequent data recovery. Though started as a military application, it soon received applications in civilian communications.