Quiet radar method and apparatus
AssigneeAlliedSignal Inc.
InventorsWilliam H. Chiles, Kenneth Raymond Moser
Life of this patent
Estimating the term…
Abstract
A random signal radar unit transmits a variable signal modulated by random noise (at 35). The return signal from the target area is correlated (at 61) with a sample of the transmitted signal, effectively compressing the spread spectrum waveform into a narrow band signal. The result is a covert high resolution radar which can be instrumented to operate in a number of single-or multi-mode configurations. By randomly varying biphase modulation (at 41, 35) and by, modulating (at 49) the echo signal with the modulation delayed by a time equivalent to that of a leakage delay, a random signal is produced (at 35, 39) in which leakage return signals are readily filtered (at 53, 59).
Claims10
Radar apparatus characterized by:
- a) means for providing a first modulated signal and for transmitting said signal;
- b) means for receiving an echo signal corresponding to the transmitted modulated signal, and responsive to said echo signal for providing a signal which includes a modulated echo component and a modulated leakage component;
- c) means for providing a signal corresponding to an anticipated modulation of the leakage component;
- d) time delay means for providing a time delayed signal representative of the transmitted signal and delayed by a variable amount of time;
- e) second modulated signal means including a first receiving mixer and connected to the echo signal receiving means and to the anticipated modulation means and responsive to the modulated echo component and the modulated leakage component of the signals from the echo signal receiving means for providing a second modulated signal;
- f) return signal means including a second receiving mixer connected to the second modulated signal means and to the time delay means and responsive to the signal therefrom for providing a return signal corresponding to the modulation of the modulated echo component, wherein the time delay means delays the signal representation of the transmitted signal prior to being provided to the second receiving mixer;
- g) the time delay means providing a signal representative of the modulation of the transmitted signal which thereby corresponds to the first modulated signal which is delayed by a variable interval;
- and
- h) means connected to the time delay means and to the return signal means for varying the interval of the delay of the signal representative of the modulation of the transmitted signal to provide a time delayed signal to match the return signal with the time delayed signal.
Method for obtaining range information, characterized by:
- a) providing a first modulated signal and transmitting said signal;
- b) receiving echo signals corresponding to the transmitted modulated signal, and responding to said echo signals by providing a response signal which includes a modulated echo component and a modulated leakage component;
- c) providing an anticipated modulation signal which includes an anticipated leakage signal delay component;
- d) varying the interval to match the return signal with the time delayed signal to provide an anticipated delay signal;
- e) modulating the anticipated delay signal to provide a signal corresponding to the first modulated signal which is delayed by a variable interval;
- f) modulating the response signal with the anticipated modulation signal to provide a second modulated signal in response to the modulated echo component and the modulated leakage component;
- and
- g) modulating the second modulated signal to provide a return signal corresponding to the modulation of the modulated echo component in response to the second modulated signal.
Dependencies are inferred from the claim text.