Pulse or digital communications – Repeaters – Testing
Patent
1998-09-04
1999-12-14
Chin, Stephen
Pulse or digital communications
Repeaters
Testing
375208, 375359, 375362, 375365, 375367, 375371, 375373, 370350, 370503, 370514, 370515, 370516, H04B 1500, H04K 100, H04L 2730, H04L 700
Patent
active
060027096
ABSTRACT:
In a direct sequence spread spectrum digital communication receiver, a system and method for recovering and verifying the timing or phase of a pseudo-random noise (PN) sequence used for despreading received signals. In one embodiment, the method includes steps of: (a) determining an initial value of a received PN phase, (b) setting the receiver's PN phase equal to the initial value of the received PN phase, (c) a first testing to verify that the receiver identifies a SYNC field within a testing time of predetermined duration, (d) a second testing, to verify that temporarily shifting the receiver's PN phase results in a degraded correlation between the receiver's PN sequence and the received signal, and (e) repeating steps (a)-(d) if either of the testings indicate that the receiver's PN sequence is not correct. One embodiment of a system for recovering and verfying the PN timing includes an input for receiving a received spread-spectrum data stream, a maximal likelihood detection logic, a receiver PN clock, a despreading mixer that generates a narrowband signal from the spread-spectrum data stream, a first testing logic that generates a PASS output if it identifies a SYNC field in the narrowband signal during a testing period, and a second testing logic that temporarily shifts the receiver PN clock and generates a PASS output if the temporary shifting degrades the correlation between the receiver's PN sequence and the received signal.
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Bharucha Cyrus F.
Chin Stephen
DSP Group Inc.
Hood Jeffrey C.
Maddox Michael W.
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