CDMA geolocation system
US6665332B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1999 |
| Grant date | Dec 16, 2003 |
| Priority date | — |
| Expiry date | Sep 9, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2201/70715
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A geolocation system for geolocating a mobile transceiver operating in a CDMA communication system is disclosed having improved time of arrival extraction which allows the extracting of time of arrival information of weak CDMA emissions. The improved time of arrival extraction is accomplished by breaking the received CDMA emission into M identical processing stages. Each stage performs despreading/demodulating at over sampled chip offsets from the next processing stage. The P-point fast Fourier transform of the M stages is taken and in effect a two dimensional time versus frequency cross ambiguity function is created. The peak of the function may be interpolated to create an accurate estimate of the time of arrival of the emission from the mobile transceiver, thus improving the accuracy of time of arrival measurements and adjusting for doppler frequency shifts that may otherwise corrupt the measurements when integrating over a long period of time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.