Mechanism for deriving accurate frequency reference for satellite communications burst demodulator
US4932070A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 1988 |
| Grant date | Jun 5, 1990 |
| Priority date | — |
| Expiry date | Aug 22, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2271
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Accurate tuning of a satellite system's burst demodulator to a signal which is subject to frequency offset in the course of its transmission over the satellite link is achieved without the use of high precision oscillators at remote sites, or the transmission of a dedicated pilot tone. Instead, a dedicated high precision clock is used for the purpose of establishing both the outlink carrier and the return channel carrier. The modulation of the data on the outlink carrier is also derived from the precision clock source. At each remote station, the outlink channel is monitored to recover the high precision clock. This recovered clock is then used as a reference for generating the return channel carrier. The burst demodulator equipment at the master station monitors both the outlink channel continuous carrier and burst mode transmissions from the remote stations. Each of the continuous and burst mode carriers, having been transmitted through the satellite, will undergo the same frequency offset or modification, so that the frequency difference between the outlink channel carrier and the return link channel carrier will always be constant. The outlink channel carrier, which is availabl…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.