Smart sweep apparatus for data rate receivers
US4916405A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 1988 |
| Grant date | Apr 10, 1990 |
| Priority date | — |
| Expiry date | Oct 27, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0051
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Apparatus is provided for locking onto a severe doppler shifted data modulated carrier signal. A phase lock loop of the type having a data detection branch, a carrier tracking branch and a voltage controlled oscillator branch is modified to provide a summing circuit at the input of the voltage control oscillator in the voltage controlled oscillator branch. A sweep control circuit is connected to the input of the summing circuit for sweeping the voltage controlled oscillator through a range of frequencies which encompass the doppler shifted carrier frequency. An automatic frequency control circuit is connected to the input of the summing circuit for automatically disconnecting the sweep control circuit from the summing circuit when the frequency of the voltage controlled oscillator reaches a predetermined value defining a window which encompasses only the center frequency of the doppler shifted carrier frequency. The automatic frequency control circuit is adapted to drive the output of the voltage controlled oscillator to the center frequency of the doppler shifted carrier frequency without overshoot and then enable the phase lock loop to phase lock onto the phase of the doppler shi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.