In this paper, a method of reducing cochannel FM interference with adaptive tracking notch filters, first proposed by E. Baghdady (1959), is refined and extended. Analytical descriptions and computer simulations of a novel adaptive notch filter are presented. The new form of adaptive notch filter is useful for suppressing strong cochannel FM and CW signals and allows simple, practical realizations of very high and adaptive notch filters in either analog or digital technologies. The analysis demonstrates that when the instantaneous frequency of the stronger interfering FM carrier signal is known precisely, the stronger signal can be completely eliminated. In some cases, placing an additional adaptive notch filter in front of the stronger signal demodulator to suppress the weaker desired cochannel signal improves the estimate of the stronger signal.>

Techniques of storing multiple bits of information in a single memory location are reviewed. Any of several states can be stored in ROM's by adjusting the threshold voltage or the size of a particular memory device. In dynamic RAM's, this can be achieved by varying the charge stored on the cell capacitor. The peripheral circuitry required to distinguish between the states stored in the memory areas is discussed.