Mti system having improved discrimination of targets displaying ambiguous doppler shifts

Claim 2

In a pulse doppler system having a doppler-filtered range trace output means for improving the discrimination between highspeed moving targets of interest displaying ambiguous doppler shifts and targets not of interest of lesser velocity, comprising means for operating said system for alternate periods of successive pluralities of pulse repetition intervals at a mutually exclusive one of two alternate pulse repetition rates; detector means responsive to a doppler-filtered output of said pulse doppler system for providing a clutter-suppressed video output; and logic means responsive to said detector means for comparing the doppler-filtered range trace output of said system for one of said alternate periods with a second successive one of said alternate periods for signalling the range-time occurrence of a high-speed moving target of interest displaying an ambiguous doppler shift.

Claim 3

The device of claim 1 in which said logic means comprises first storage means responsively coupled to said detector means for retrievably storing the response of said pulse doppler system to at least one of said two alternate periods of mutually exclusive pulse repetition rates; second storage means responsively coupled to an output of said first storage means; first NOT logic means responsively coupled to said detector means; second NOT logic means responsively coupled to an output of said second storage means; and AND logic means responsively coupled to the output of said first storage means and to an output of each of said first and second NOT logic means for indicating the occurrence of an ambiguous doppler shift of interest.

Claim 4

In an azimuthally scanning, pulsed-energy system employing doppler processing of clutter-reference received echoes of pulsed transmission, means for improving the discrimination between high-speed moving targets displaying ambiguous doppler shifts and targets of lesser velocity, comprising programming means for periodically alternating the pulse repetition rate of said pulsed energy system between two mutually exclusive rates, whereby a book of range trace data is provided for a plurality of successive pulse repetition intervals associated with each pulse repetition frequency; doppler-filtered detector means responsive to a video readout mode of said doppler processing for suppressing a clutter reference component of said video readout mode; and filter logic means responsive to the output of said detector means for successive data books for indicating the occurrence at a given range time within a range trace interval of the pulsed energy system, of a moving target having an ambiguous doppler shift of interest.

Claim 5

In an azimuthally scanning, pulsed-energy system employing doppler processing of clutter-reference received echoes of pulsed transmission, means for improving the discrimination between high-speed moving targets displaying ambiguous doppler shifts and targets of lesser velocity, comprising programming means for periodically alternating the pulse repetition rate of said pulsed energy system between two mutually exclusive rates, whereby a book of range trace data is provided for a plurality of successive pulse repetition intervals associated with each pulse repetition frequency; doppler-filtered detector means responsive to a video readout mode of said doppler processing for suppressing a clutter reference component of said video readout mode; and filter logic means responsive to the output of said detector means for successive data books for indicating the occurrence at a given range time within a range trace interval of the pulsed energy system, of a moving target having an ambiguous doppler shift of interest.

Claim 6

In pulsed energy system employing doppler processing of clutter-referenced received echoes of pulsed transmission, means for improving the discrimination between high-speed moving targets displaying ambiguous doppler shifts and targets of lesser velocity, comprising programming means for alternating the pulse repetition rate of said pulsed energy system between two mutually exclusive rates, whereby a book of range trace data is provided for a plurality of successive pulse repetition intervals associated with each pulse repetition frequency; doppler-filtered dEtector means responsive to a video readout mode of said doppler processing for suppressing a clutter reference component of said video output mode; and filter logic means responsive to the output of said detector means for successive data books for indicating the occurrence, at a given range time within a range trace interval of the pulsed energy system, of a moving target having an ambiguous doppler shift of interest.

Claim 7

In pulsed energy system employing doppler processing of clutter-referenced received echoes of pulsed transmission, means for improving the discrimination between high-speed moving targets displaying ambiguous doppler shifts and targets of lesser velocity, comprising programming means for alternating the pulse repetition rate of said pulsed energy system between two mutually exclusive rates, whereby a book of range trace data is provided for a plurality of successive pulse repetition intervals associated with each pulse repetition frequency; doppler-filtered dEtector means responsive to a video readout mode of said doppler processing for suppressing a clutter reference component of said video output mode; and filter logic means responsive to the output of said detector means for successive data books for indicating the occurrence, at a given range time within a range trace interval of the pulsed energy system, of a moving target having an ambiguous doppler shift of interest.

Claim 8

The device of claim 4, in which said logic means comprises means responsive to a clutter-suppressed video readout mode of said doppler processing for each of at least two successive data books for indicating a variation in the observed doppler shift of a moving target commonly observed in a common range bin in said data books.

Claim 9

The device of claim 4 in which said doppler-filtered detector means comprises a filter chain of at least two narrow band-pass doppler filters, the center frequencies of which are mutually exclusive, the bandpasses of successive filters being substantially mutually contiguous, an input of each of said filters being commonly responsive to said video readout, and a like plurality of threshold amplitude detectors as filters, each detector being responsive to an output of a mutually exclusive one of said filters, said filter logic means being responsive to a difference in the output state response of at least one of said filtered detector means to at least two successive data books, the range time occurrence of said response difference being indicative of a moving target of interest.

Claim 10

The device of claim 6 in which said filter logic means comprises storage means responsive to a preselected one of said detectors for retrievably storing the response of said detector to at least one of the two data books, gating means for providing an output signal in response to a difference in response states between corresponding range time portions of the detector responses to said two data books.

Claim 11

The device of claim 6 in which said logic means comprises first storage means responsively coupled to one of said detectors for retrievably storing the response of said pulse doppler system to at least one of said two alternate periods of mutually exclusive pulse repetition rates; second storage means responsively coupled to an output of said first storage means; first NOT logic means responsively coupled to said one detector; second NOT logic means responsively coupled to an output of said second storage means; and AND logic means responsively coupled to the output of said first storage means and to an output of each of said first and second NOT logic means for indicating the coincidence of an ambiguous doppler shift of interest.

Claim 14

The method of claim 9 in which said step of indicating comprises the steps of comparing the clutter-suppressed video readout mode of said doppler processing for data of one pulse repetition rate with that for data of another pulse repetition rate, and indicating the range time-occurrence of a spectral difference in the spectral states of said compared modes.