Apparatus for demodulating differential phase shift keyed signals
US4634990A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 25, 1985 |
| Grant date | Jan 6, 1987 |
| Priority date | — |
| Expiry date | Jun 25, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY04S40/121
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A demodulating apparatus receives a differential phase shift keyed analog signal which is coupled to the input of a voltage controlled oscillator. The voltage controlled oscillator generates a plurality of pulses at a frequency which is proportional to the amplitude of the analog signal. The pulses are counted during in-phase intervals and intervals which are quadrature phase related to the in-phase intervals. The signs of the differences between (i) the number of in-phase and quadrature phase interval pulses counted during a first bit rate interval and (ii) a reference pulse count number, are determined. The signs of the differences between (i) the in-phase and quadrature phase pulses counted during a second bit rate interval, which follows the first bit rate interval, and (ii) the reference count number, are also determined. A phase change is indicated when the signs of the second in-phase and quadrature phase differences are different from the signs of the first in-phase and quadrature phase differences respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.