Zero intermediate frequency receiver
US5715281A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 21, 1996 |
| Grant date | Feb 3, 1998 |
| Priority date | — |
| Expiry date | Feb 21, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J7/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A zero intermediate frequency radio receiver that comprises mixing stages, an A to D converter, a digital demodulator, a carrier tracking system and a carrier nulling system is disclosed. The mixing stages receive FM or PM signals and produce analogue in-phase and quadrature baseband signal which are in turn converted to digital baseband signals by the A to D convertor. DC offsets in the baseband signals are removed by high pass filtering prior to demodulation. Tracking enables the baseband signals to be maintained at a centre frequency of substantially zero hertz, while signal strength at this frequency is minimized or mulled before the DC offset filtering. Information which might otherwise be removed by the filtering is thereby retained in the baseband signals, which are relatively less distorted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.