PN Code Ranging System for Accurate and Long Distance Range Measurement

A ranging-sequence system is a system in which a periodic binary (±1) ranging sequence modulates an uplink carrier to produce a signal that is transmitted from an Earth station to a transponder in the spacecraft whose range from the Earth station is to be measured. This modulated uplink carrier is received and processed by the spacecraft transponder, either in a simple turnaround (non-regenerative) manner or by detection and regeneration to remove uplink noise, and then retransmitted to the Earth station where the transponder between the transmitted and received signals is measured. Regenerative ranging provides such a substantial power advantage over non-regenerative ranging, up to 30 dB in proposed systems that it can be expected to be the baseline in most of future deep space missions. The term ‘Pseudo-Noise (PN) ranging’ refers in a strict sense to the use of a ranging-sequence system in which the ranging sequence is a logical combination of the so-called range clock-sequence and several Pseudo-Noise (PN) sequences. The range clock sequence is the alternating +1 and –1 sequence of period2. A Pseudo-Noise (PN) sequence is a binary ±1 sequence of period L whose periodic autocorrelation function has peak value +L and all (L–1) off-peak values equal to –1.In this paper PN ranging system which has capability to measure accurately large distances for deep space satellite applications is simulated.