Importance

Loading Importance Indicators...

Abstract

Apparatus is provided for decreasing the acquisition time for recovering spread spectrum codes. The transmitted spread spectrum code is preceeded by a sync signal to establish system time at the receiver. The received coded data signals are applied to a matched filter or a delay line such as a surface acoustic wave device. The number of chips in the delay line is made an integral fraction of the number of chips in the word to be detected. The signals stored in the delay line are detected chip by chip as the coded data passes through the delay line. The resultant output analog signals from the delay line is digitized and stored chip by chip in a digital memory, such as a shift register, having the same chip storage capacity as the sequence group being transmitted. The values of chips in the digital storage memory are recirculated back to the input of an adder. A new value for the same chip of the word is generated as a new digitized output in the delay line device, and is added in the adder to the value recirculated from the storage memory. In this manner, the peak outputs from the delay line, which are occurring at a unique or particular chip position, are enhanced so that the unique chip position in the coded data word is identified.

Loading the Abstract Image...

First Claim