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Abstract

A zero IF receiver which is capable of detecting short duration or CW signals and of operating over a large dynamic range includes an input terminal for receiving an input signal, a quadrature down-converter coupled to the input terminal for producing quadrature related, frequency down-converted signals in a pair of signal paths. These signal paths each include an amplifier having a substantially sinh.sup.-1 transfer characteristic so that the pair of signal paths produce substantially logarithmic quadrature related output signals which are coupled to a demodulator. The demodulator converts the quadrature related output signals into amplitude and frequency descriptions of the input signal relative to a center frequency of the receiver. The amplitude description is determined by selecting the one of the quadrature related output signals having the larger absolute value and applying an amplitude correction thereto. The frequency description is determined by forming an indication of the phase angle of the input signal from the difference between the quadrature related output signals, applying a phase correction thereto, and determining the rate of change of the corrected phase angle indication.

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First Claim