Method and apparatus for tracking direct sequence spread spectrum signal in fractional fourier domain

A method for tracking a direct sequence spread spectrum (DSSS) signal in a fractional Fourier domain (FRFD), the method comprising the steps of:

• receiving an intermediate frequency (IF) DSSS signal;
• removing a Doppler frequency component from the received IF DSSS signal by mixing with local sine and cosine waveforms generated by a carrier numerically controlled oscillator (NCO) to obtain a plurality of in-phase (I) and quadra-phase (Q) carrier-stripped signal samples;
• performing code tracking and integration-and-dumping (I-and-D) implementations in the FRFD;
• discriminating carrier phase errors using I and Q prompt correlations and discriminating code chip errors using I and Q early and late correlations via carrier and code discriminators;
• processing the discriminated carrier phase errors and the discriminated code chip errors through a low-pass carrier and code loop filter;
• and
• using outputs of the low-pass carrier and code loop filter to generate carrier and code measurements and to adjust the carrier NCO and a code NCO in real time for tracking the received IF signals in a next epoch.