LFMCW SAR waveform generation with frequency nonlinearity suppression

Linearly frequency modulated (LFM) signals are desired in many electronic systems. For example, linearly frequency modulated continuous wave (LFMCW) radar has the good performance of lightweight, cost-effective, and high-resolution imaging. However, the presence of frequency nonlinearity in the transmitted signal will result in contrastand range-resolution degradation. In this paper, the impact of frequency nonlinearities on LFMCW synthetic aperture radar (SAR) system is addressed, and one parallel direct digital synthesizer (DDS)-driven phase locked loop (PLL) frequency synthesizer to synthesize wideband LFM signals is designed, and an adaptive system nonlinearity compensation technique is employed. In this way, an example wideband LFM synthesizer with good performance frequency linearity is designed.