Space-Time-Frequency Processing For Multicarrier Polyphase-Coded Signal

Firstly, this paper shows the principle of phase-coded signals. Combined with multicarrier technology, it researches a new class of radar signal:Multicarrier polyphase-coded signal. Here, orthogonal frequency division multiplexing technology is used to get large time-bandwidth product and improve the frequency band efficiency. Multicarrier polyphase-coded signal not only has the advantage of large time-bandwidth product but also provides the freedom degree to design phase-coded sequence. The first design is based on using an identical sequence(IS)to modulate all carriers. The second design is based on using consecutive ordered cyclic shifts(COCS)of a chirplike ideal sequence to modulate all carriers to lower sidelobe.A major drawback of the multicarrier signal is its varying amplitude. If the signal generator contains a power amplifier, it becomes desirable to reduce the peak-to-mean envelope power ratio(PMEPR)as much as possible to avoid operating the power amplifier at a large backoff. To be able to use multicarrier signal in real radar systems, it is necessary to find multicarrier signal that has favorable PMEPR and attractable Range-Doppler behavior. In this paper, some efficiency design methods are studied to lower PMEPR.It discusses the effect of signal parameters on autocorrelation, power spectra and ambiguity function in forms of single pulse and compares different kinds of single pulse signals.Genetic algorithm is a practical, efficient and strong robustness of the optimization technique. Its applications of multicarrier phase-coded signal design are discussed in this paper. The first application is design optimization weighting according to peak-to-average power ratio requirements of the system. The other one is to optimize polyphase code based on ambiguity function.Finally, Based the characteristics of multicarrier phase-coded signal, it studies space-time-frequency processing and designs a new space-time-frequency steering vector to obtain better anti-interference properties.