Amti radar system

Claim 3

Means adapted to be responsive to a non-coherent doppler signal processor for providing a substantially clutter-free target signal for display purposes and comprising a normally gated-on low-pass filter means; a normally gated-off high pass filter means; an input of each of said filter means commonly coupled to provide an input terminal; and notch filter means having a preselected center frequency corresponding to a frequency region intermediate the bandpass regions of said high-pass and low-pass filters, an input of said notch filter being coupled to said input terminal and an output thereof coupled to said gated filter means for providing gating signals for gating-off said low pass filter means and gating-on said high-pass filter means for the duration of said gating signals.

Claim 4

Means adapted to be responsive to a non-coherent doppler signal processor for providing a substantially clutter-free target signal for display purposes and comprising a normally gated-on low-pass filter means; a normally gated-off high pass filter means; an input of each of said filter means commonly coupled to provide an input terminal; and notch filter means having a preselected center frequency corresponding to a frequency region intermediate the bandpass regions of said high-pass and low-pass filters, an input of said notch filter being coupled to said input terminal and an output thereof coupled to said gated filter means for providing gating signals for gating-off said low pass filter means and gating-on said high-pass filter means for the duration of said gating signals.

Claim 5

The device of claim 2 in which there is further provided signal combining means having a first and second input respectively coupled to the gated output of said first and second gated filter and an output adapted to be connected to a display indicator.

Claim 6

The device of claim 2 in which the preselected bandpass of said notch filter corresponds to the speCtral edge of a clutter-referenced clutter signal component, and in which an upper corner frequency of said low pass filter is below said preselected bandpass.

Claim 7

The device of claim 2, in which there is further included radial extent discriminating means for gating said gated filter means, comprising OR logic output signalling means interposed between said gated filter means and the output of said notch filter, and AND logic output signalling means responsively coupled to an ungated output of said low pass filter for providing an output indicative of a clutter-referenced clutter return of at least three system pulsewidths in duration, an input of said OR logic means being responsively coupled to the output of said AND logic means.

Claim 8

In a non-coherent pulse type radar system for airborne use, including display means for displaying the situation of a detected target, means responsive to a non-coherent received signal for presenting a clutter-free signal for improved display of a detected target by said display means and comprising high-pass, low-pass and notch filter means, said filter means being commonly responsive to said non-coherently received signal, said low-pass filter means having a corner frequency substantially below a preselected upper corner-frequency of a clutter referenced clutter signal component, said high-pass filter means having a lower corner frequency above said preselected frequency, said notch filter means having a narrow bandpass, the center frequency of which is intermediate said upper and lower corner frequencies; and gating means coupled to the outputs of said low-pass and high-pass filters for normally gating-on the output of said low-pass filter and gating-off the output of said high-pass filter, and having a gating control input responsive to the output of said notch filter for gating-off the output of said low-pass filter and gating-on the output of the high-pass filter in response to output from said notch filter above a threshold level.

Claim 9

In a non-coherent pulse type radar system for airborne use, including display means for displaying the situation of a detected target, means responsive to a non-coherent received signal for presenting a clutter-free signal for improved display of a detected target by said display means and comprising high-pass, low-pass and notch filter means, said filter means being commonly responsive to said non-coherently received signal, said low-pass filter means having a corner frequency substantially below a preselected upper corner-frequency of a clutter referenced clutter signal component, said high-pass filter means having a lower corner frequency above said preselected frequency, said notch filter means having a narrow bandpass, the center frequency of which is intermediate said upper and lower corner frequencies; and gating means coupled to the outputs of said low-pass and high-pass filters for normally gating-on the output of said low-pass filter and gating-off the output of said high-pass filter, and having a gating control input responsive to the output of said notch filter for gating-off the output of said low-pass filter and gating-on the output of the high-pass filter in response to output from said notch filter above a threshold level.