Pulse compression waveforms design and Cross-ambiguity processing for Radar applications

2014 International Symposium on signal, Image, Video and Communications - ISIVC 2014, Marrakech, Maroc, 19-/11/2014 - 22/11/2014Radar waveforms design is an important step to design a hole radar system. In this paper, several waveforms based on modified Costas codes are used. The properties and performances are tested and compared. We propose a detection based on cross-ambiguity calculation for these waveforms. Indeed, such a processing is interesting when delay and Doppler should be estimated. The performances are evaluated in several scenarios in presence of noise and multiple targets. The waveforms are also tested on real experimentation hardware

Design and performances evaluation of new Costas-based radar waveforms with pulse coding diversity

Costas codes are a variant of pulse compression waveforms, largely studied for their attractive time-frequency properties. Their 'thumbtack-like' ambiguity function (AF) makes them highly suitable for delay and Doppler estimation, in radar and sonar applications. However, this behaviour depends heavily on the length of the code: the improvement in delay-Doppler resolutions and AF sidelobes level needs an increase in the size of the code. In this study, designs that allow good performance without increasing the size of the code are proposed. They are based on a modification of Costas codes by widening frequency separation between hops and replacing rectangular pulses by other waveforms. This will lead to a removal of autocorrelation function grating lobes that normally appear when frequency separation is increased. The originality of the work lies in the proposal of diversified pulse waveforms, such as phase codes, Slepian sequences, and other Costas codes, to encode main Costas pulses. A performance comparison of the proposed approaches is supplied. Such waveforms could also be of interest for applications where waveform diversity is desired

Doubly coded Costas signals for grating lobes mitigation

International audienceIn this paper, a novel design scheme for radar signal is proposed. It is based on a modification of Costas codes design by increasing the frequency separation of frequency hops beyond the orthogonality condition. Indeed, Costas codes are well known for their good range-doppler properties. Their orthogonality condition states that frequency separation between frequency hops should be at most equal to the inverse of bit duration of the code. Increasing frequency separation beyond this condition leads to the appearance of grating lobes near the main temporal lobe of the autocorrelation function. This paper proposes overcoming this problem using sub-pulse coding. The originality of the proposed approach consists in choosing for Costas sub-pulses other Costas codes instead of constant frequency ones in order to lower autocorrelation grating lobes that would normally appear when the orthogonality condition is not satisfied. In this paper, we show that under some conditions on Costas signal parameters in the sub-pulse, good elimination of grating lobes is achieved