Patent ID: 8514979
Filing Date: 2013-08-20
Classification: H03D,H04B

Abstract:
1. A method for use in a radio receiver, comprising the steps of: translating a received radio frequency (RF) signal to an intermediate frequency (IF) signal; converting the IF signal to a stream of digital samples using a sampling frequency that is four times the IF; dividing the stream of digital samples into a first set of even samples and a second set of odd samples; digitally demodulating the stream of digital samples to produce a complex signal with real (I) and imaginary (Q) components at one half of the sampling frequency using two parallel quadrature demodulators with a first quadrature demodulator demodulating only the first set of even samples and a second quadrature demodulator only demodulating the second set of odd samples; delaying the second set of odd samples by one time period of the sampling frequency; and filtering the demodulated first set of even samples using a first set of coefficients of a digital filter and the delayed demodulated second set of odd samples using a second set of coefficients of the digital filter to produce a baseband complex signal, the filtering implementing an N-tap finite impulse response (FIR) filter, where N is a positive integer, using block digital filtering with two parallel filtering paths with one of the filtering paths operating at one half of the sampling frequency on the first set of even samples using even coefficients of the N-tap FIR filter and the other of the filtering paths operating at one half of the sampling frequency on the second set of odd samples using odd coefficients of the N-tap FIR filter.