Research On Key Technology Of Robust Dual Antenna Telemetry System Based On Space-time Code

Continuous Phase Modulation(CPM)is a widely used modulation system in the field of aeronautical telemetry.The precoding characteristics of the Shaped Offset Quadrature Phase Shift Keying(SOQPSK)signal make its phase state can be uniquely determined according to the first two bits.The state grid is more intuitive when using the Viterbi algorithm.The multi-h continuous phase modulation signal(Multi-h CPM)uses a plurality of modulation indices to modulate the information symbols according to a certain rule.The time of similar path coincidence is prolonged,thereby improving the anti-interference ability of the signal.The introduction of Space Time Coding(STC)into the telemetry system using the CPM system can provide diversity gain and coding gain for the system,and the orthogonality of the code matrix can be used to solve the dual transmit antenna system.The "two antenna problem" caused by the mutual interference of the road signals simultaneously reaching the receiving end.This paper focuses on the joint detection technology of STC-CPM telemetry system.The research results are as follows:1.Based on the characteristics of the CPM signal,we derive the error lower bound of the CPM signal firstly.Then,the simplification algorithm such as Pulse-amplitude Modulation(PAM),Pulse Truncation(PT)and Cross-Correlated Trellis Coded Quadrature Modulation(XTCQM)are used for the SOQPSK-TG signal.As for the Multi-h CPM signals,the simplification algorithm called ‘Tilted Phase(TP)plus Frequency Pulse Truncation(FPT)’ is utilized to reduce complexity of detection.Compared with the derived error lower bound,the error performance of the above simplified algorithm is shown intuitively.And the analysis of the complexity reduction effect of each algorithm is also presented.2.The joint detection simplification algorithm based on PAM decomposition,modified PT and 32 waveform XTCQM is designed for Alamouti-SOQPSK-TG telemetry system.Considering that there are delays when two signals arrive at the receiving end,so the relevant formulas of joint detection should be discussed according to the situation where the delay difference is diverse.The simulation results of the joint detection using the above simplification algorithm provide a basis for selecting detection schemes with moderate detection complexity and good error performance.3.The design principle of the phase correction function involved in L~2 space-time code is combed,and the full-rate transmission characteristics and full diversity characteristics of L~2 space-time code are proved.The detection complexity of STC-Multi-h CPM telemetry system is simplified by TP+FPT algorithm.4.The principle of code matrix construction of Differential Unitary Space Time Code(DUSTC)is investigated.It is combined with Phase Shift Keying(PSK).The simulation of the error performance of the telemetry system is completed.In order to make full use of the design of L~2 STC which assures the waveforms of the transmitted signal is orthogonal,a non-coherent detection for L~2 STC-SOQPSK-TG telemetry system is designed.