Land-based local ranging signal methods and systems
US7339525B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 2004 |
| Grant date | Mar 4, 2008 |
| Priority date | — |
| Expiry date | Jun 15, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S19/37
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
To provide sub-meter accuracy in a local positioning system, ranging signals with a high modulation rate of code, such as 30 MHz, or more are transmitted. Code phase measurements may be used to obtain the accuracy without requiring relative motion or real time kinematic processing. The ISM or X-band is used for the carrier of the code to provide sufficient bandwidth within available spectrums. The length of codes used is less than or about a longest length across the region of operation, such as less than 15 kilometers in an open pit mine. The spread spectrum codes from different land-based transmitters are transmitted in time slots pursuant to a time division multiple access scheme for an increase in dynamic range. To avoid overlapping of code from different transmitters, each time slot includes or is separated by a blanking period. The blanking period is selected to allow the transmitted signal to traverse a region of operation. Differential measurements of signals received at a base station and a mobile receiver may improve accuracy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.