Patent ID: 8599904

Claim:
A method of operating a receiver which synchronizes to a plurality of Direct-Sequence Spread Spectrum (DSSS) sources and receives a plurality of radio frequency (RF) signals conveyed at a substantially uniform carrier frequency as a superposition of individually Doppler-shifted signals due to a relative motion of each DSSS source and the receiver, each RF signal encoded with message data using a spreading code unique to its respective DSSS source, the method comprising acts of: (a) removing an intermediate carrier frequency from and subsequently low pass filtering a sequence of digitized samples to produce a filtered combined quasi-baseband signal; (b) reducing the sample rate of the filtered combined quasi-baseband signal down to a fixed rate equal to a chip rate of the spreading code and removing a variable Doppler time shift in the filtered combined quasi-base band signal in a single step by dynamically adjusting a sample stride of a down-sampler; and (c) removing a Doppler frequency shift from the fixed-rate signal to produce a baseband signal for each DSSS source.