Synchronization in severe-fading environments

A system identifying and synchronizing radio communications from an authorized sender, the system comprising:

• a Radio-Frequency (RF) receiver that receives a RF signal within a predetermined frequency band;
• a processor;
• and computer-readable memory encoded with instructions that, when executed by the processor, causes the system to:
• auto-correlate a first portion of the RF signal received with a second portion of the RF signal received so as to generate an auto-correlation signal, the first and second portions time-separated by a predetermined time delay separating first and second code-sequences of an expected sync-sequence;
• sync-correlate the first and second portions of the RF signal received with the expected sync-sequence so as to generate a sync-correlation signal, the first and second portions of the RF signal received together with a ward band being of same length as a predetermined length LSYNC of the expected sync-sequence;
• wherein the sync-correlating further comprises convolving a conjugated version of the first and second code sequences of the expected sync-sequence with an unconjugated version of the first and second portions of the RF signal received;
• multiply the auto-correlation signal and the sync-correlation signal so as to generate a combined synchronization signal;
• identify a peak in the combined synchronization signal;
• and
• determine a synchronization time of an authorized communication based on the peak identified.