Performance analysis of curve-shaped NLFM against Doppler effect and background noise

Abstract

Linear Frequency Modulation (LFM) is a pulse compression method which is largely implemented in the radar applications. The high peak sidelobe is its main problem instead of its superiority on the simplicity and Doppler tolerance characteristics. The curve-shaped Nonlinear Frequency Modulation (NLFM) has been developed for overcoming this lack and prior investigation showed that this method provide lower sidelobe suppression than LFM. For obtaining the overall performance to be compared with LFM method, this research will investigate the curve-shaped NLFM in the case of Doppler effects and high level background noise. The Doppler effects considered in this research consist of two including center frequency shift and time dilation. Then, the background noise investigated is Gaussian distributed noise with signal to noise ratio (SNR) levels in range 0dB to −20dB. According to the simulation results, in the Doppler shift case, the curve-shaped NLFM is more sensitive than LFM as other NLFM drawbacks. However, this method is better than LFM in the time dilation scenario. Then, this pulse compression also has better detectability than LFM in the certain case of high level background noise condition.