Large Bandwidth Linear Fm Signal - Performance Evaluation And System Control

Waveform design and generation is one of the key techniques in the UWB-SAR system. The fundamentals of LFM(linear frequency modulation) signals, waveform parameter design, system control, quality analysis and pre-distortion calibration are discussed in this paper. The following are the four parts of this paper.In the first part, the fundamentals of LFM signals are introduced. The relationship between distance resolution and bandwidth, speed resolution and signal duration are the emphases to be discussed. It indicates the importance of using LFM signals with large duration and bandwidth in UWB-SAR system.In the second part, the relationship among signal parameters is discussed and reasonable parameters are designed. These parameters include bandwidth, carrier frequency, signal duration and signal repeat frequency. According to the parameters, we select the method direct reading the stored digital waveform to realize the waveform generationIn the third part, the waveform generator system control including communication control, timing control and address generation is designed.In the last part, signal quality is evaluated and pre-distortion calibration is applied to improve signal quality.The research achievements in this paper have been applied to the air-borne UWB-SAR experiment system successfully.