Digital phase detector
US3956623A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1974 |
| Grant date | May 11, 1976 |
| Priority date | — |
| Expiry date | Oct 21, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2338
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital phase detector which periodically detects the phase angle .theta..sub.k of a carrier signal in which data are encoded as discrete phase changes. A coherent or differential phase-modulated carrier signal is split into its in-phase and quadrature phase components R.sub.o Sin.theta.(t) and R.sub.o Cos.theta. (t). Each signal component is sampled at a predetermined modulation interval and converted into a digital word having the form R.sub.o Cos.theta..sub.k and R.sub.o Sin.theta..sub.k. In one configuration, the two signal components are applied to a digital divider network which forms the quotient .PSI. of the two digital words such that .vertline..PSI..vertline..ltoreq. 1. The quotient .PSI.is applied to a data look-up ROM, programmed for Tan.sup.-.sup.1 operation, which forms a digital reference phase angle .PHI.limited to an angle .ltoreq. 45.degree. is corrected by selection logic to form the desired phase angle .theta..sub.k. Once .theta..sub.k is known for each modulation interval, the encoded data may be readily extracted, since .theta..sub.k is proportional to the encoded data.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.