Flexible digital ranging system and method

A ranging system for determining the distance between a satellite and a ground station, comprising:

• a master clock divider circuit that generates clock signals derived from a master clock;
• a transmit code generation circuit that is operative to receive clock signals from the master clock divider circuit, generate three pseudo-random number codes and process the pseudo-random number codes to produce a composite signal having positive and negative correlation peaks that is transmitted to the satellite as an analog signal;
• a digitizing circuit that is operative to receive clock signals from the master clock divider circuit, receive the analog signal comprising the composite signal having positive and negative correlation peaks from the satellite, and digitize the analog signal comprising the composite signal;
• a frequency domain matched filter that is operative to receive clock signals from the master clock divider circuit and match filter the digitized analog signal to produce correlation peaks contained in the digitized analog signal;
• and
• a central processing unit that comprises a middle code software matched filter that generates an outer code bit, that computes the distance from the ground station to the satellite by calculating the difference between the time that the composite signal was received compared to the time that the composite signal was transmitted and dividing the difference value by the speed of light, and that comprises an outer code software matched filter that produces a bit error rate signal indicative of the validity of the computed range value.