Direct conversion receiver
US5640428A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 9, 1995 |
| Grant date | Jun 17, 1997 |
| Priority date | — |
| Expiry date | Nov 9, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/1525
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a first direct conversion receiver for demodulating I and Q signals, having a quadrature relation therebetween, obtained from a received FSK signal through a direct conversion, a first D FF latches a level of the I signal when a sign condition of I and Q signals moves from the same to different sign conditions, a second D FF latches a level of the Q signal when the sign condition of the I and Q signals moves from the different to same sign condition and EXCLUSIVE OR operations are made among the I and Q signals and the outputs of the first and second D FFs to provide a frequent data judgement to improve a receiving sensitivity of an FSK signal having a relative low modulation index. In a second direct conversion receiver, a sign change in the Q signal is detected by a first edge detection circuit 17, a first D FF holds the level of the I signal, and an EXCLUSIVE OR circuit provides a first demodulation result. A sign change in the I signal is detected by a second edge detection circuit 17, a second D FF holds the level of the Q signal, an EXCLUSIVE OR circuit provides a second demodulation result and a subtracting circuit combines the first and second demodulation results. An ea…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.