Method and apparatus for detecting an interleaved code

Details Method and apparatus for detecting an interleaved code Method and apparatus for detecting an interleaved code

2005-03-29

2005-03-29

Chin, Stephen (Department: 2634)

Pulse or digital communications

Receivers

Particular pulse demodulator or detector

C375S148000, C375S222000, C375S141000, C375S142000, C375S152000, C375S150000, C370S335000, C370S342000, C370S332000, C455S502000

Reexamination Certificate

active

06873664

ABSTRACT:
A receiver that receives a long pseudonoise (PN) code signal composed of two shorter codes interleaved with one another, includes a correlator unit that correlates the received signal with one or more reference codes corresponding to the two interleaved codes, respectively, and generates correlation signals. The receiver also includes an even code detector coupled to the correlator unit, for detecting from the correlation signals one of the two shorter codes, and an odd code detector coupled to the correlator unit, for detecting from the correlation signals the short code that is not detected by the even detector. A delay unit is coupled to the even and odd code detectors, and delays the even or the odd correlation signals so as to align the correlation signals. The aligned signals are combined and evaluated by a merit function. If the combined signals exceed a threshold value the short codes are determined to be aligned, the phase of each code can be determined, and the phase of the longer code can be determined from the determined phases of the shorter codes. The receiver can detect two short PN codes that have been combined, such as by interleaving the short codes, to create a long PN code. Hence, the receiver can inexpensively detect the two short codes which allows the receiver to detect the long code with high gain.

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