Phase tracking correction scheme for high frequency modem
US4447910A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 2, 1981 |
| Grant date | May 8, 1984 |
| Priority date | — |
| Expiry date | Jun 2, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/03038
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An auxiliary phase tracking subsystem for compensating for fast phase changes in an adaptive transversal filter obtains a measure, from the received signal, of channel phase variations and corrects the phase of each received sample in accordance with this phase measure. The channel tracking weights are used in conjunction with the known transmitted symbols and the data decisions to "predict" the n received samples, PR.sub.i, for each frame. The average difference in phase, DP, between the predicted samples, PR.sub.i, and the actual received samples, R.sub.i, is then used to determine the phase correction for each received sample prior to using it for making estimates. The received samples, R.sub.0, R.sub.1, ------, R.sub.n-1, are then corrected to obtain the corrected samples, CR.sub.0, CR.sub.1, ------, CR.sub.n-1, as follows: ##EQU1## and K.sub.1 and K.sub.2 are constants. The result of this is to phase-correct each received sample by some constant phase, K.sub.1 DP, plus an additional correction which increases linearly with time during the frame. This latter correction is, in effect, a "frequency offset" correction and when accumulated from frame-to-frame serves the function of…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.