Coherent signals processing by analog logical elements
The result of action of the matched linear filters that are optimal for detection of given signals is maximization of the signal-to-noise ratio SNRmax = P-Smax/P-N, where P-Smax is the peak power of the signal, and P-N is the average power of a noise. However, maximization of SNR, as a fraction, is obtained formally by the ratio SNRmax = P-S/P-Nmin, where (P) over bar (S) is the average power of the signal. P-Nmin is the minimum, in a certain sense, the power of the noise. When n coherent pulses are processed, it is proposed to suppose that P-Nmin is the minimum instantaneous power of available noise powers. In this case, the processing scheme represents the selector that constantly chooses the voltage with the minimum noise instantaneous power and transmits it to output. As shown in the paper, it is possible to perform this selection with acceptable accuracy and to improve SNR and, hence, probabilistic characteristics of detection in comparison with addition of coherent pulses. This improvement is obtained by using the adder input noises when their instantaneous powers are less than the instantaneous power of the adder output noise.
analog logical element signal-to-noise ratio minimum instantaneous power