First demonstration of correlation in a niobium superconductive programmable binary-analog matched filter

A complete prototype superconductive programmable binary-analog matched fil ter for a 2-Gchip/s spread-spectrum modem has been operated for the first t ime and has performed correlation. We had previously demonstrated functiona lity of each individual element of the filter. The analog samplers had capt ured signals with bandwidths in the order of 10 GHz; the binary-weighted ta ps, which utilize the unique quantum mechanical properties of superconducti ve circuits, had exhibited nondestructive readout as required; and the two digital shift registers, one that stores the binary code pattern and one th at controls sampling of the input analog signal in the bank of track-hold c ells, had functioned at 2 GHz, Now all of these elements have been operated together in low-frequency tests. A 7-bit (or "chip" in spread-spectrum ter minology) pseudo-noise (pn) code sequence was loaded into the reference shi ft register in each of the seven possible positions while an analog version of the pn code with its amplitude varied over the full bipolar dynamic ran ge of the filter was used as the incoming signal. The filter response peake d as expected when the analog signal and the binary reference were aligned. The peak and sidelobe responses agreed quantitatively with those predicted from calibration measurements made with uniform signals instead of pn code s.