Apparatus for estimating the frequency difference existing between the carrier frequency of a digital signal and the frequency of a receiver local oscillator
US6181750A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 1997 |
| Grant date | Jan 30, 2001 |
| Priority date | — |
| Expiry date | Dec 29, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D3/007
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An apparatus estimates the frequency difference existing between the carrier frequency of a received digital signal and the frequency of a signal from a local oscillator contained in a receiver of the received signal. The receiver performs quadrature demodulation on the received signal. The apparatus includes a detector that detects the noise level received in the band of the receive filters, a processor for computing discrete Fourier transforms on the received signal transposed into baseband, a summer for summing the energy levels detected on either side of the center frequency of the receive filters, a subtractor for subtracting the noise level from the energy bands, and a comparator for comparing the resultant energy levels and delivering an estimate .epsilon. of the frequency difference.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.