A method of processing a Direct Sequence Spread Spectrum DSSS signal, the method comprising: performing DSSS acquisition to obtain estimates of a frequency offset and a spreading code phase; and performing DSSS carrier tracking based on the estimated frequency offset and the spreading code phase by: using a time and frequency transform based correlation method to sequentially obtain a complex correlation function between a DSSS signal segment and a replica of a spreading code, for each one of a plurality of segments of a received DSSS signal, based on the estimated frequency offset and the spreading code phase for coarse Doppler compensation; determining a spreading code carrier phase corresponding to a correlation peak in the complex correlation function; phase-aligning the complex correlation functions by applying a phase rotation to one or more of the complex correlation functions using the determined spreading code carrier phase, to compensate for a Doppler frequency offset between successive ones of the complex correlation functions; summing the phase-aligned complex correlation functions over a data symbol; and estimating a polarity of the data symbol based on the summed complex correlation functions, wherein the time and frequency transform based correlation method involves, for each one of the plurality of segments of the received DSSS signal, obtaining a plurality of samples, performing a time to frequency transformation, multiplying the transformed samples by a complex conjugate of the time to frequency-transformed replica of the spreading code, and performing an inverse time to frequency transformation. performing DSSS acquisition to obtain estimates of a frequency offset and a spreading code phase; and performing DSSS carrier tracking based on the estimated frequency offset and the spreading code phase by: using a time and frequency transform based correlation method to sequentially obtain a complex correlation function between a DSSS signal segment and a replica of a spreading code, for each one of a plurality of segments of a received DSSS signal, based on the estimated frequency offset and the spreading code phase for coarse Doppler compensation; determining a spreading code carrier phase corresponding to a correlation peak in the complex correlation function; phase-aligning the complex correlation functions by applying a phase rotation to one or more of the complex correlation functions using the determined spreading code carrier phase, to compensate for a Doppler frequency offset between successive ones of the complex correlation functions; summing the phase-aligned complex correlation functions over a data symbol; and estimating a polarity of the data symbol based on the summed complex correlation functions, using a time and frequency transform based correlation method to sequentially obtain a complex correlation function between a DSSS signal segment and a replica of a spreading code, for each one of a plurality of segments of a received DSSS signal, based on the estimated frequency offset and the spreading code phase for coarse Doppler compensation; determining a spreading code carrier phase corresponding to a correlation peak in the complex correlation function; phase-aligning the complex correlation functions by applying a phase rotation to one or more of the complex correlation functions using the determined spreading code carrier phase, to compensate for a Doppler frequency offset between successive ones of the complex correlation functions; summing the phase-aligned complex correlation functions over a data symbol; and estimating a polarity of the data symbol based on the summed complex correlation functions, wherein the time and frequency transform based correlation method involves, for each one of the plurality of segments of the received DSSS signal, obtaining a plurality of samples, performing a time to frequency transformation, multiplying the transformed samples by a complex conjugate of the time to frequency-transformed replica of the spreading code, and performing an inverse time to frequency transformation.