Communication system and method for acquiring pseudonoise codes or carrier signals under conditions of relatively large chip rate uncertainty
US7221696B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 2003 |
| Grant date | May 22, 2007 |
| Priority date | — |
| Expiry date | Aug 23, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0053
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A Spread Spectrum system acquires signals with frequency uncertainty. The present invention independently computes the number of frequency bands necessary to cover the carrier frequency uncertainty and the chip rate uncertainty and uses the largest of the two quantities in the acquisition process. A receiver cycles through pseudonoise code phases until a matched filter output exceeds a threshold. The local code is adjusted based on that code phase and the signal is processed for carrier acquisition, where an FFT estimates the carrier frequency. The code phase and nearest neighbors are used to determine the presence of a false alarm. When a false alarm is absent, the detection is examined for an alias or noise spur. If an alias is absent, the signal search is complete. Otherwise, processing continues to search for a pseudonoise code. The process continues by examining all code phases for each band until a signal is detected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.