Fast acquisition ringing filter MSK demodulator
US4622683A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 8, 1984 |
| Grant date | Nov 11, 1986 |
| Priority date | — |
| Expiry date | Nov 8, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/0278
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A clock and carrier recovery circuit, and a related method, for use in a minimum shift keying (MSK) receiver demodulator. The clock and carrier recovery circuit uses ringing filters to lock onto two frequency-doubled tone components of a received MSK signal. A signal having the same frequency as the clock is recovered by taking the difference of the outputs of the two filters. The output of each filter is then combined separately with a signal having a frequency to produce to signals, each having a frequency equal to twice the carrier frequency and having complementary amplitude modulation. These two signals are summed to cancel the amplitude modulation and the resulting sum signal, having constant amplitude and a frequency twice that of the carrier, is divided by two to recover the carrier signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.