Moving target angle tracking system

Claim 2

In a clutter-referenced moving target tracking employing a dual plane moNopulse range-tracking receiver having a range-gated intermediate frequency stage providing monopulse sum and difference channel outputs, means for reducing the system threshold of performance called the twilight clutter region where clutter signal strength approximates target signal strength, comprising: Means responsive to an early-received clutter sample of said sum channel output for providing a time-stretched and stored clutter reference signal, and Phase sensitive detection means interposed at each of said monopulse outputs for providing phase-detected clutterreferenced monopulse sum and difference signals.

Claim 3

The device of claim 1 in which there is further provided: high pass filter means responsive to each of said phase-detected, range-gated monopulse outputs for attentuating a clutter reference component in said clutter referenced monopulse signals to provide filtered monopulse signals, and phase-sensitive video detection means coupled to each of said filtered monopulse difference signals and having a phase-reference input commonly responsive to said filtered monopulse sum signal for providing bipolar video target angle tracking signals.

Claim 4

The device of claim 2 in which signal-normalizing means is included in said monopulse signal channels and comprising automatic gain controlled means interposed at the output of each of said high pass filters and having a gain-control input commonly responsive to the normalized monopulse sum channel output, said phase-reference inputs of said audio phase-detectors being responsive to the output of said normalized monopulse sum channel output.

Claim 5

The device of claim 2 in which said means for providing a clutter reference signal comprises: a one terminal roughened tapered delay line, and input of which is responsive to said early clutter sample; and a high-gain saturating amplifier responsive to the output of said delay line for providing a substantially constant amplitude phase reference.

Claim 6

In a dual-plane monopulse tracking system, including means for providing a first and second sum-channel-normalized, phase-detected, bipolar video, tracking angle signal, a combination for distinguishing a moving target signal from a marginal clutter reference, comprising: Means responsive to an early-received clutter sample of a monopulse sum channel of said receiver for providing a time-stretched and stored clutter reference; Phase-sensitive detection means interposed between each of a sum and two difference channel receiver outputs of said dual-plane monopulse tracking system and signal normalizing means thereof and having a phase-reference input responsive to said clutter reference for providing an associated clutter referenced moving target signal; and Band-pass filter means interposed at the output of each of said phase sensitive detection means for attenuating a clutter reference component in said clutter-referenced moving target signal.

Claim 7

In a dual-plane monopulse tracking system, including means for providing a first and second sum-channel-normalized, phase-detected, bipolar video, tracking angle signal, a combination for distinguishing a moving target signal from a marginal clutter reference, comprising: Means responsive to an early-received clutter sample of a monopulse sum channel of said receiver for providing a time-stretched and stored clutter reference; Phase-sensitive detection means interposed between each of a sum and two difference channel receiver outputs of said dual-plane monopulse tracking system and signal normalizing means thereof and having a phase-reference input responsive to said clutter reference for providing an associated clutter referenced moving target signal; and Band-pass filter means interposed at the output of each of said phase sensitive detection means for attenuating a clutter reference component in said clutter-referenced moving target signal.

Claim 8

The device of claim 5 in which said means for providing a clutter reference comprises: A tapered one-terminal delay line element; A duplexer coupled to the terminal of said delay line element, a receiving terminal of said duplexer being coupled to an early-gated output of a monopulse sum channel of said receiver; and A saturating amplifier intercoupling said phase reference inputs of said phase detection means and a transmitting terminal of said duplexer.