Low Latency Self Calibrating Digital Filter Equalizer

The Army is looking to research and develop a programmable multichannel radio frequency filter-equalizer having a programmable number of channels, each programmable with potentially unequal spacing, bandwidth, and equalization. What is needed is a digitally programmable multichannel filter-equalizer that can perform a complex filtering function tailored to multiple applications. Bedford Signals proposes to solve this problem by combining our capabilities in high precision high bandwidth custom DSP hardware with our expertise in digital filtering and calibration. Specifically, we completed a comprehensive study of hardware architectures, FPGA building blocks, filter architectures, filter design algorithms, and calibration/equalization algorithms. The result is a preliminary design for a 6U-160 Eurocard that can implement 8 low latency programmable filters covering 0.3 to 370 MHz center frequency, and 12.5 KHz to 100 MHz bandwidth with a 0.5 dB passband, a 70 dB stopband rejection, and a transition bandwidth less than 1 passband width. Minimum latency of the preliminary design is estimated at approximately 100 nS, but design optimization can reduce this further. Successful algorithm development was followed by leveraging Bedford Signals'high precision high isolation DSP board to provide a GUI controlled laboratory demonstration.