Multi-rate signal processing that enables smart antenna, multi-channel communication, wideband intelligence gathering and data compression systems

Moore's Law continues to drive higher levels of processing capacity, and in doing so, processes that were once deemed too costly now find their way into newly fielded products. In particular, multi-rate systems that digitally decompose a wideband signal into a continuous set of sub-band signals are now coming into common use. To enable this technique an efficient set of multi-rate algorithms must be used. The algorithms described in this paper are polyphase decomposition (analysis) and reconstruction (synthesis) algorithms that possess the pseudo perfect reconstruction property. Examples of system designs are described that point out the design trades of prototype filter size and type, word sizes, multiple decimation and interpolation rates, and filter design to achieve a specified baseband equivalent filter. The resulting designs show the tremendous efficiencies in required compute capacity for applications such as radar, electronic warfare, and communications systems. The sub-bands of these systems are processed in many ways including Doppler processing, pulse compression and space-time adaptive processing for radar; signal detection, parameter estimation and techniques generation for EW; data demodulation, limiting and modulation for communications. Additionally, in each case, depending on the type of system, processing may perform receive and transmit beamforming or an angle of arrival interferometer within the sub-bands or subsets of the sub-bands allowing manipulation of distinct band portions of the wideband signal.