Itt Corporation

Itt Avionics, a Division of Itt Corporation

Charles R Ward

Ning H Lu

The present invention hybrid instantaneous frequency measurement (IFM) compressive receiver processes a wide bandwidth of incoming signals in two processing channels, where a small time delay is introduced to one of the two channels by a time delay stage. A comb generator provides for folding, or collapsing this wide input band into a much narrower bandwidth by overlapping sub-bands of the input band in the same frequency space. A compressive receiver is coupled to the spectrum folding circuitry for accurately measuring the frequency and amplitude of signals in this folded band, which have a sub-band ambiguity due to the folding. Logic circuitry is included for resolving the sub-band ambiguity in order to provide a unique description of the frequencies of input signals in the wide band input frequency range. The hybrid receiver overcomes the limitations of conventional IFM receivers by providing amplitude as well as frequency information for multiple time overlapped input signals with improved sensitivity. It also overcomes the limitations of a conventional compressive receiver by handling much wider input bandwidths than would otherwise be possible.

Hybrid instantaneous frequency measurement compressive receiver

There is described a zero IF receiver which affords to reduce offsets normally associated with quadrature mixers employed in such receivers. In order to reduce the effect of such offsets the local oscillator signal is modulated with a balanced pseudo-random phase code signal. This signal is then stripped off by means of additional mixers, one for each of the quadrature channels. The effect of the pseudo-random phase code signal is to spread the spectrum which is associated with the offsets so that the receiver can now respond to desired signals with a minimum of interference.

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Wayne, NJ, United States of America

Charles R Ward