Dual mode automatic frequency control
US5163159A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 1990 |
| Grant date | Nov 10, 1992 |
| Priority date | — |
| Expiry date | Jul 30, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2272
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A frequency control system for a dual-mode radiotelephone (152-238; 252-320) operative to receive either an FM signal or a DQPSK signal. In a first embodiment, when operative to receive the FM signal, the frequency of the reference oscillator (192) of the radiotelephone (152-222) is maintained in a fixed relation with the frequency of the FM signal. When operative to receive the DQPSK signal, the reference oscillator (192) is maintained in a fixed relation with the frequency of the DQPSK signal as determined by a digital signal processor (212). In a second embodiment, when operative to receive the FM signal, the frequency of an offset control oscillator (320) is maintained in a fixed relation with the frequency of the FM signal. When operative to receive the DQPSK signal, the reference oscillator (292) is maintained in a fixed relation with the frequency of the DQPSK signal as determined by a digital signal processor (312).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.