1 constant amplitude LFM pulse signal
According to the fuzzy function, the wide pulse is modulated to improve its bandwidth. The modulated wide pulse signal passes through a matched filter when it is received. Its range resolution can be obtained by analyzing the fuzzy map. Constant amplitude LFM pulse signal is an example of widely used pulse compression waveform.
2.LFM pulse compression
Modulating a wide pulse can be thought of as setting different "marks" in phase or frequency along different parts of the pulse. For example, the frequency variation of LFM signal is distributed along the pulse, so that each short segment of the pulse corresponds to a different frequency. The modulated pulse passes through the dispersion delay line, and the delay time of the dispersion delay line is a function of frequency. Each segment of the pulse experiences different delays, so that in the dispersion delay line, the falling edge of the pulse may accelerate and the rising edge may slow down, so that they can "come together" and complete pulse compression.
Extended data:
Importance of pulse compression (requirements of radar detection on signal form);
In order to improve the detection ability, measurement accuracy and detection ability of radar system, radar signal is required to have a large product of time width, bandwidth and energy. However, the product of time width and bandwidth of single carrier frequency pulse signal is close to 1, and large time width and bandwidth cannot be both. Therefore, it is impossible to improve the range resolution and velocity resolution simultaneously by using the pulse signal generated by single carrier frequency.
(Principle of pulse compression and its high detection performance) From the formulas of equivalent time width and equivalent bandwidth of radar signal, it can be seen that modulating amplitude spectrum and phase spectrum can increase equivalent time width; Similarly, the equivalent bandwidth can be increased by amplitude modulation or phase modulation in the time domain. Pulse compression signal uses phase modulation in time domain to increase the equivalent bandwidth of the signal, thus increasing the product of the time width and bandwidth of the output signal.