The ambiguity functions of a kind of direct chaotic radar system are investigated. In this radar system, a microwave chaotic Colpitts oscillator is employed to generate the source signal that is directly transmitted through a wideband antenna without modulation. The auto-ambiguity function of this radar system shows many sidelobes which makes the unambiguous detection difficult. It is because the spectrum of the chaotic signal is not very flat and smooth, with pulsation peaks in it. The cross-ambiguity functions of the direct radar system have also been investigated to evaluate the electronic counter countermeasure (ECCM) performance and the "multi-user" characteristic. It is shown that rather excellent ECCM capability can be achieved in this radar system with transmitting chaotic signals generated by circuits with same parameters but at different time or with slightly different circuit parameters. In addition, several possible methods to reshape the spectrum of the chaotic signal from microwave Colpitts oscillators to improve the unambiguous detection performance are suggested at the end of this paper.
"Ambiguity Functions of Direct Chaotic Radar Employing Microwave Chaotic Colpitts Oscillator," ,
Vol. 77, 1-14, 2007. doi:10.2528/PIER07072001
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