Apparatus and method for finding location of a mobile unit
US6567486B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1999 |
| Grant date | May 20, 2003 |
| Priority date | — |
| Expiry date | Jul 26, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S1/045
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A phase-modulated signal such as a quadrature phase-shift-keyed (QPSK) signal in a wireless communication system is demodulated by frequency demodulating the phase-modulated signal. The phase-modulated signal is separated into first and second copies, the first copy is phase demodulated to generate demodulated symbols, and the second copy is frequency demodulated to generate, e.g., a measure of the instantaneous frequency of the phase-modulated signal. The instantaneous frequency measure is processed to identify one or more symbol transitions, and the identified transitions are used to generate event signals having signature properties (signature events). These signature events are used in traditional Time Difference of Arrival tdoa algorithms to accurately determine position of a mobile unit in the wireless communication system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.