Study On Radar Waveform Compatible With Communication

Air Early Warning(AEW),born in the United States in World War II,has become more and more important in the national defense security.With the high degree of automation,the large capacity of the target processing,the distance of communication and the strong anti-interference ability,the early-warning machine is more prominent in the operation of the modern joint system.In order to meet the strong operational requirements,there are a wide variety of early-warning electronic devices.Therefore,many problems are brought about:one is that the transmission power of the communication equipment is limited,the transmission distance is limited,the transmission speed is slow,the direction is poor,and it is easily intercepted,so it can not satisfy the high speed and large capacity of the modern war transmission secrecy.The high demand is required;two is the serious electromagnetic interference between the enemy and the enemy,the mutual interference between the systems,the complex electromagnetic environment,and the difficulty in realizing the communication transmission under high power interference;three,it is difficult to implement a new communication system because of the small number of antenna units.The use of airborne phased array radar has the characteristics of good direction,low sidelobe and high pulse pressure ratio.It is an effective way to solve the problem by integrating the communication unit and radar unit effectively and realizing the sharing of each unit.With the rapid development of radar digital technology,it provides an important technical guarantee for waveform design of radar communication integration.In this paper,the main works are as follows:1.The advantages and disadvantages of three common integrated waveforms are analyzed,and the reasons for selecting continuous phase shift keying signal(CPFSK)as modulated signal are explained from the following two aspects:continuous phase shift keying has the characteristics of constant amplitude and continuous phase,and continuous phase shift keying signal has better error rate and lower sidelobe;The phase frequency shift keying signal modulates the phase of the linear frequency modulation signal(LFM).The integrated signal has the characteristics similar to the continuous phase shift keying signal.The envelope is constant,the phase is continuous and the sidelobe is low.2.In view of the energy leakage caused by the expansion of the integrated waveform spectrum,the time-frequency characteristics of the integrated waveform are analyzed in detail from the time frequency angle.The time frequency of the integrated waveform along the line LFM frequency distribution with the different modulation symbols is obtained.The reasons for the energy leakage of the integrated waveform are analyzed,and the release of energy leakage is analyzed.The method of reducing spectrum expansion is verified,and the correctness of theoretical analysis is verified by experimental simulation.3.The ambiguity function of the performance of the integrated waveform radar is simulated and analyzed.The Doppler resolution and time delay resolution of the integrated waveform are analyzed respectively.It is concluded that the integrated waveform has the same Doppler resolution as the simple continuous phase shift keying signal,which is related to the product of the number of modulation symbols and the product width product.It is related to the pulse width of the radar and is independent of the modulation of specific random communication symbols.The time-delay resolution of the integrated waveform in two extreme cases is analyzed.The delay resolution is a range,which is related to the communication code,the radar pulse width and the system bandwidth in a single radar pulse.4.The influence of integrated waveform on radar performance is analyzed.The false alarm probability of the integrated waveform is the same as the false alarm probability of the LFM signal.Under the same condition,it is only related to the noise,that is,the signal to noise ratio of the signal.After the modulation of the data,the energy leakage problem can not be completely solved.It can only be effectively relieved,or some energy leakage,resulting in the reduction of signal energy compared with the LFM signal,resulting in the detection probability of radar detection will be reduced.