Ultra-Wideband Radar Waveform Generation Technology

Recently, with the fast development of multi-targets identification and high resolution microwave imaging technologies, ultra-wide band radar has been more and more widely used in object imaging and object detection field. Waveform design and generation is a key component of ultra-wide band radar, whose qualification and performance directly influence the performance of the whole radar system. So research of the ultra-wide band radar waveform generation technology is very important.LFM signal is a classic pulse compression signal and it is one of the ultra-wideband radar waveforms, there is sophisticated theoretical basis of its generating, receiving and processing. Because of the inherent imperfections of the analog system, such as the sensitivity to the environment temperature, the nonagile waveforms, or bad repetitions, the performance improvement of radar system is restricted. With the development of digital technology, getting pulse compression signals with direct digital synthesis has been in general use these days. It is widely used to generate pulse compression signal using DDS method.After comparing several analog and digital generation methods of LFM signal, this paper confirms the system scheme as direct digital synthesis plus quadrature modulation. Combined with Agilent Arbitrary Waveform Generator and Phasor Signal Generator, a generation system is established and a ultra-wideband signal, whose bandwidth is 1GHz and carrier frequency is 4GHz, is generated. According to the carrier wave leakage and mirror wave interference in the signal generation, this paper analyzes the source of waveform distortion and its influence to signal spectrum and pulse compression result. As the distortions have severe influence on the performance of ultra-wideband radar waveform, this paper focuses on the correction of waveform distortion, and approaches the correction of carrier wave leakage distortion. In order to suppress the mirror wave interference, this paper brings forward a predistortion correction method. Utilizing the predistortion property of DDWS, it directly modifies the original inputs with time domain information of the output distortion waveform, which...