Coherent detection system
US5586148A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 1995 |
| Grant date | Dec 17, 1996 |
| Priority date | — |
| Expiry date | May 31, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2275
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A coherent detection system synchronously detects a received wave involving a Doppler shift. To realize a stable demodulation performance, the system has a memory for storing in advance Doppler shifts to be related to an input signal and corresponding pass bands to reduce the bit error rate of restored information to below an allowable maximum when the corresponding Doppler shifts are present; an estimating unit for finding levels of the input signal or instantaneous values R of the input signal that form an envelope, counting the number N per unit time of points where the envelope crosses a threshold, and estimating a Doppler shift fD according to an expression that indicates the ratio of the number N to the Doppler shift fD and involves the in-phase and orthogonal components of the input signal, a distribution of the temporal differentiation of these components, a distribution of power spectra, and the instantaneous values normalized by the threshold; and a band controller for retrieving a pass band corresponding to the estimated Doppler shift fD from the memory and setting the pass band to a filter of the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.