Receiving circuit for demodulating an angle modulated signal
US5260671A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 1992 |
| Grant date | Nov 9, 1993 |
| Priority date | — |
| Expiry date | May 15, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2331
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A receiving circuit is designed for an MSK (Minimum Shift Keying) receiver and a QPSK (Quadrature Phase Shift Keying) receiver. The circuit provides a synchronous state determining device and a control voltage sweeping device for sweeping the output of a voltage oscillator. In the asynchronous state, a switch is turned off for interrupting a reproducing phase error signal so that the output of the voltage oscillator may be swept for causing the synchronous state. Then, the sweeping operation is stopped and the switch is turned on for controlling the voltage of the voltage controlled oscillator so that the low-frequency error component is removed from the phase error signal of the demodulating circuit. This results in implementing the simply-arranged demodulating circuit which keeps the proper demodulating performance against the shifted carrier frequency without any degrade and demodulates the input signal stably if the signal has a low C/N ratio. This circuit is capable of stably demodulating an MSK signal from a broadcasting satellite or a communication satellite.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.