Method and apparatus for filtering interference in a modem receiver
US6240150A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 12, 1998 |
| Grant date | May 29, 2001 |
| Priority date | — |
| Expiry date | May 12, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/10
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for filtering interference (e.g. transmitter feed-through and RF) in a modem receiver. The method of reducing transmitter feed-through (Tx-FT) interference at a receiver of a modem to obtain a desired receive (Rx) signal having a spectrum at a carrier frequency for input into a QAM demodulator includes attenuating the Tx-FT interference and passing the Rx signal at the carrier frequency using an analog filter. The output signal from the analog filter is converted to a digital representation by a analog-to-digital (ADC) converter. A digital band pass filter is used to pass the Rx signal at the carrier frequency and to attenuate the Tx-FT interference further. A mixer is then used to shift the carrier frequency of the spectrum of the Rx signal to an intermediate frequency. The mixer introduces at least one spectral transmitter feed-through image Tx-FT(I) and a receive signal image Rx(I). A digital low pass filter is used to pass the Rx signal at the intermediate frequency and attenuating the image spectrums Tx-FT(I) and Rx(I). A final decimation function is performed to downsample the Rx signal at a downsampling rate from the second digital filter to match the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.