DESIGN OF A SHORT RANGE CONTINUOUS WAVE COMPOUND PHASE CODED LINEAR FREQUENCY MODULATION RADAR SENSOR

The design of a low cost, short range radar sensor based upon a novel phase coded linear frequency waveform is discussed in this paper. The radar sensor utilizes a novel waveform that is produced using digital frequency synthesis techniques. Digital frequency synthesis techniques enable the generation of repeatable, highly linear frequency sweeps and provide a means for accurate application of phase codes to linear frequency modulations. The work presented contains analysis of the component linear frequency and phase code modulations that form the compound phase coded linear frequency modulation. The resulting compound phase coded linear frequency modulation is compared with the component modulations to demonstrate the performance improvement that can be achieved by the combining of radar waveform modulations enabled by modern digital frequency synthesis techniques. The compound phase coded linear frequency modulation waveform shows improved range resolution and suppression of range sidelobes over the individual component waveforms. The phase coded linear frequency modulation shows an improvement of 13 dB over the linear frequency modulation and is only 2 dB less than the phase code. It also achieves a 5 and 10 nanosecond narrower mainlobe autocorrelation peak than the phase code and linear frequency modulation, respectively. A notional signal processing architecture of the waveform is simulated to demonstrate the ability to process the compound waveform. Experimental data collected from a direct digital frequency synthesis based arbitrary waveform generator is compared with the simulated waveform. The compound waveform model and the experimental results show good agreement.