Frequency-coded Pulse Signal

Radar waveforms design is an important aspect of modern radar theory. To detect invisible targets at low altitude drove research into designing such waveforms as to reject clutter, while anti-radiation missiles led to studying radar waveforms with low probability of intercept (LPI). Modern radar should not only detect and track objects, but also be able to obtain targets'information as much as possible to identify targets. The dissertation tries to develop such kind of signal and its designing method as to integrate targets detecting, targets identifying as well as LPI design into one task.The dissertation studied frequency-coded pulsed (FCP) signal which is spectrally agile in a probability way as well as FCP signal designing. This kind of signal was analyzed in a statistic manner. Results showed that there is no range-Doppler coupling, and that the signal PSD, equivalent bandwidth and resolution are all related to frequency hopping manner.A method was developed to design such kind of signal based on target signature to resonate with the target so as to strengthen the returns. For stable targets, design FCP signal matched to target impulse response. For random targets with no prior information, an adaptive learning method was proposed to get target steady response to design matched transmitted FCP signal. Simulations showed that this designing scheme enhanced SNR and improved LPI ability. Target steady impulse response can reflect target signature so it can be used to identify targets. That is, the adaptive method combines targets detecting, targets identifying as well as LPI design into one task.The work is organized as follows:1. Based on radar receiver machine response, cross ambiguity function and the target-signal interaction were derived. Analyzed characteristics of range profiles, based on concept of scattering center, performed range profile modeling to five different aircrafts by stepped frequency signals.2. FCP signal spectral is randomly agile, so the ambiguity function was analyzed in a statistic manner, measured by mean and variance. Studied the resolution, calculated and analyzed the power spectral density of the noise adding on FCP signal's return.3. Gave a sophisticated explanation on FCP signal designing approach and performed simulation.. Because target information usually wasn't prior, an adaptive approach was introduced to get target steady signature with it to design suboptimal FCP signal. Analyzed the SNR gain and LPI improvement brought by this kind of signal designing method4. Explained how to perform pulse compression by inverse Fourier transforming processing on FCP signal.