Patent ID: 7738537

Claim:
A pre-correlation filter for a receiver that receives spread-spectrum signals, the filter including: an array of complex accumulation registers that collect measurements that correspond to samples of a first channel of the received signal multiplied by a local version of a first pseudorandom number (PRN) code transmitted over the first channel, the samples taken over multiple code chips of the first PRN code transmitted at sample times that are asynchronous to code rate, the respective accumulation registers being associated with code chip ranges each of which is a fraction of a PRN code chip and corresponds to code phase angles that are included in the range that covers the fraction of the PRN code chip, the code chip ranges together covering all or a portion of a code chip of the first PRN code and all or a portion of a code chip of a second PRN code transmitted on a second signal channel that is in quadrature phase to the first channel; one or more code phase decoders that control the respective complex accumulation registers to direct respective measurements of the first signal channel of the received signal to the complex accumulation registers that are associated with the respective PRN code chip ranges from which the samples are taken, the one or more code phase decoders decoding values that correspond to the respective estimated code phase angles of the samples in the first PRN code to accumulate measurements that relate to chip transitions in the first PRN code and measurements that relate to chip transitions in the second PRN code.