초록 ▼

In a direct sequence spread spectrum communication receiver, a system and method for recovering the timing of a pseudo-random noise (PN) sequence used for despreading the received signals. In one embodiment of the method, the receiver waits for detection of a SYNC field to confirm at least a coarse

In a direct sequence spread spectrum communication receiver, a system and method for recovering the timing of a pseudo-random noise (PN) sequence used for despreading the received signals. In one embodiment of the method, the receiver waits for detection of a SYNC field to confirm at least a coarse synchronization or the receiver's local PN sequence with the received PN sequence (in the received signal). The receiver then performs a fast tracking to finely synchronize the receiver's PN sequence with the received PN sequence, preferably for a fixed duration of time. One embodiment of a system for performing the synchronization with the fast tracking includes an input for receiving a received spread-spectrum data stream, an ML detection logic, a receiver PN clock, a despreading mixer that generates a narrowband signal from the spread-spectrum data stream, a testing logic that generates a PASS output if it identifies a SYNC field in the narrowband signal, and a fast-tracking logic. The fast-tracking logic temporarily advances and temporarily delays the receiver PN clock by a small shift and measures the resulting correlations between the receiver's PN sequence and the received PN sequence. If the advanced correlation is greater or less than the delayed correlation, then the fast-tracking logic accordingly makes a small adjustment to advance or delay the receiver PN clock. This temporary advancing, temporary delaying, and adjusting of the receiver PN clock is preferably repeated a fixed number of times.

대표청구항 ▼

[ I claim:] [1.]1. A method for synchronizing a receiver PN (pseudo noise) sequence of a direct sequence spread spectrum communication receiver with a received PN sequence in a received data stream, wherein the received PN sequence comprises a repeated predetermined series of PN chips, wherein the r

[ I claim:] [1.]1. A method for synchronizing a receiver PN (pseudo noise) sequence of a direct sequence spread spectrum communication receiver with a received PN sequence in a received data stream, wherein the received PN sequence comprises a repeated predetermined series of PN chips, wherein the receiver PN sequence comprises the repeated predetermined series of PN chips, wherein each PN chip in the repeated predetermined series of PN chips persists for a predetermined PN chip duration Tc, wherein the received PN sequence has a received PN phase, wherein the receiver PN sequence has a receiver PN phase, wherein the data stream comprises a series of data frames, wherein the frames comprise a plurality of symbols, wherein the frames are received at substantially regular intervals, and wherein each frame in the series of frames includes a SYNC field at a predetermined location in the frame, the method comprising:performing an acquisition of the receiver PN phase, wherein said performing the acquisition comprises:setting the receiver PN phase so that the receiver PN sequence is synchronized with the received PN sequence; andconfirming the receiver PN phase after said setting the receiver PN phase, wherein said confirming the receiver PN phase comprises the receiver identifying one or more SYNC fields in the data stream; andperforming a fast tracking to finely synchronize the receiver PN sequence with the received PN sequence after said performing the acquisition.