Method and apparatus for determining the position of a mobile communication device using low accuracy clocks
US6453168B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 2, 1999 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Aug 2, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S2013/466
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A spread spectrum position location communication system determines the position of a mobile master radio using a round-trip messaging scheme in which the time of arrive (TOA) of ranging messages is accurately determined to yield the range estimates required to calculate the position of the mobile radio via trilateration. The master radio transmits outbound ranging messages to plural reference radios which respond by transmitting reply ranging messages. Upon reception of the reply ranging message, the master radio determines the range to the reference radio from the signal propagation time calculated by subtracting the far-end turn around time from the round-trip elapsed time. Any combination of fixed or mobile radios of known positions can be used as the reference radios for another mobile radio in the system, thereby providing adaptability under varying transmission conditions. The individual radios do not need to be synchronized to a common time reference, thereby eliminating the need for highly accurate system clocks. By performing internal delay calibration, errors caused by difficult-to-predict internal transmitter and receiver delay variations can be minimized. Leading-edge-…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.