Waveform Analysis And Design For High Frequency Ground Wave Radar

High Frequency ground wave RADAR can be used to detect ships and planes over the horizon, which is great advantage not to consider the restrict of earth curvature, but this advantage also calls for more strict waveform, ordinary waveforms can not function well because of energy or resolution problems.The transmit signal of radar is of great importance because it not only decides the method of signal processing, but also has great effect on resolution, measure precision and clutter rejection. Waveform design has different focus because of signal difference. Pulse signal usually has the problems of ambiguous range and transmitter power limitation, so we usually select large time-bandwidth product signal by frequency modulating or phase coded, in order to obtain sufficient energy on target for detection and the desired range resolution.Two kinds of signals are mainly discussed in this thesis: FMPCW (frequency modulated pulse continuous waveform) signal and phase coded signal based on P4 code. FMPCW sustains the large time-bandwidth product characteristic from FMICW signal, which can be used in HF radar. First we discuss the production and processing of FMPCW, and then gives a detailed description of the principle of the signal processing of the HF radar which uses the FMPCW. The processing is special and we use special method to get range processing result; then the doppler processing result. After that, we discuss the relationship of signal parameter and system parameter, and according to the given system parameter and different targets, we design the waveform and give the simulation.For phase coded signal with P4 code, it is also a kind of pulse compression signal which has large time-bandwidth product characteristic. First we introduce the characteristic of P4 code, especially the complementary characteristic, which attract us using P4 code in HF radar. After giving the echo waveform of phase coded signal, we analyse the information carried by the signal. The signal processing needs two steps: first, correlation in range, and using the complementary characteristic for accumulation; second, extracting doppler information. After that, according to the given system parameter and different target, we design the waveform and give the simulation result.At last, we make a discussion on the difference of FMPCW signal and phase coded signal with P4 code.