Efficient Sample Rate Conversion in Software Radio Employing Folding Number System

In an ideal Software Radio, digitization of the received signal occurs immediately after receive antenna to enable channelization to be performed in the discrete time domain. However, this vision is still far from reality due to limitations of current analog to digital converter performance. In this paper, a novel number system called the Folding Number System (FNS) is proposed for use in Software Radio. We implement sample rate conversion immediately after the receive antenna using this number system thus providing an efficient solution to the above problem. By decomposing the input analog signal into separate channels in parallel, symmetrical residues are obtained with reduced number of comparators. These residues together with the folding information are processed in parallel in the FNS domain. The FNS has the same computational complexity as that in Residue Number System but the need for the intermediate steps such conversion of the analog data into binary and subsequently into residues is absent.