Quadrature amplitude modulation type digital radio communication device and method for preventing abnormal synchronization in demodulation system
US5438591A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 1992 |
| Grant date | Aug 1, 1995 |
| Priority date | — |
| Expiry date | Jul 30, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/3827
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
This invention relates to an abnormal synchronization preventing device used in a multiple value quadrature modulation type radio device and the abnormal synchronization preventing device includes a monitoring circuit for monitoring the carrier pull-out based on demodulated base band signals to output a carrier pull-out alarm signal, an abnormal synchronization detection circuit for sampling the reception signal level at a speed twice the transmission speed of reception data according to identification data and detecting abnormal synchronization according to whether or not the detection area of sampled data lies in a specified area, an abnormal synchronization preventing circuit for generating a signal for a preset period of time when abnormal synchronization is detected in a case where the carrier pull-out alarm signal is not output, and a selection circuit for receiving a reference signal used for generating a reference carrier frequency signal having a frequency close to the frequency of the carrier wave and a phase difference signal, selecting the phase difference signal as the control signal in the normal state, and selects the reference signal as the control signal while rece…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.