Adaptive depolarization-interference-compensator
US4757319A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 4, 1987 |
| Grant date | Jul 12, 1988 |
| Priority date | — |
| Expiry date | May 4, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B7/002
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An adaptive depolarization-interference-compensator for a digital radio relay system using multi-level quadrature amplitude modulation (QAM) with co-channel operation of the orthogonally polarized signals which is not necessarily synchronous with the clock frequency and/or carrier frequency and produces good compensation of depolarization effects. The receiving branch of the two receivers (3, 4), which use the same RF-local oscillator (5) or separate RF-local oscillators are synchronized for the differently polarized signals and each contain a quadrature demodulator (8, 14) for two signal components (I- and Q-channel). A canceller is provided which consists of two quadrature demodulators (20, 23) for the two polarization directions, which are each supplied at with an IF-received signal of one polarization and the IF-carrier (9, 15) of the respective other polarization, and which consist of complex transversal filters (21, 22, 24, 25) (I- and Q-channel) in the signal paths to the two quadrature demodulators (20, 23). The transversal filters (21, 22, 24, 25) have their outputs coupled into the receiving branch of the respective other polarization. The delay time .tau..sub.0 between t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.