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The authors present a novel design of a wide bandwidth polyphase up-sampling filter bank formed by cascading external shaping filters, arbitrary interpolators and two stages of polyphase channelisation. The channeliser synthesises 160 channels with 6-MHz frequency centres and thus spans a two-sided baseband bandwidth of 960 MHz. The two stages of channelisation first form super channels from ten sets of 16-channels each in 32-path polyphase channelisers operating at an output sample rate of 192 MHz. These ten super channels are, in turn, channelised by a 16-path polyphase channeliser operating at an output sample rate of 1536 MHz. The two-stage approach permits the ten sets of first stage super channel channelisers to operate at an easy to implement medium sample rate. The complex baseband signal is further up-sampled 1-to-2 and translated to a digital intermediate frequency and pre-compensated for the sin(x)/x distortion of the output digitalto-analogue converter.

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A cognitive radio (CR) receiver should be able to filter and simultaneously down convert multiple signals having arbitrary bandwidths and randomly located center frequencies. In this paper we present an efficient structure, based on polyphase filter banks, for CR receivers. Its core, an analysis channelizer, is a variant of the standard M-path polyphase down converter channelizer. It is able to perform M/2-to-1 down sampling of the input time series while it shifts, by aliasing, all the M channels to base-band. A perfect reconstruction (PR) filter is selected as low-pass prototype for avoiding energy losses during the signal processing. A post analysis block is designed for extracting, when necessary, from the base-band aliased channels, the spectra, or their fragments, belonging to different signals. A selector commutes the output ports of the post analysis block that contain spectral fragments of the same bandwidths and properly delivers them to the up converter synthesis channelizers that reassemble them. The synthesis channelizers are P n -path polyphase up converter modified for performing 1-to-P n /2 up sampling of the input time series. Complex frequency rotators, placed at the output of the synthesizers, compensate the frequency offsets, applied in the transmitter, that are responsible for the arbitrary center frequency positioning of the received signals. At the end of the receiver chain, arbitrary interpolators resample the base-band centered signals to obtain two samples per symbol needed for the further processing stages.