Narrowband channel extraction for wideband receivers

One of the most computationally intensive processing stages of a wideband digital receiver is the extraction of a narrowband channel from a wideband input signal. In implementations that compute the convolutional sum, the computation is proportional to the bandwidth of the input signal. This paper shows how to break this dependence, reducing the limiting factor to the requirement to maintain a sufficient output signal-to-noise ratio (SNR). This paper describes two complementary algorithms for efficient channel extraction in wideband receivers. The first allows the required frequency translation to be performed at the lower sample rate of the channel filter output. The second algorithm decouples the effect of interference rejection from SNR improvement and improves the computational efficiency of filtering by using only a subset of the input samples. Additionally, we present a simple model to quantify the effects of this technique and experimental verification using a wideband software radio receiver.