基于LAS码的星群多目标测控技术研究

针对星群多目标同时测控问题,基于星群轨道根数的时延特性和多普勒频移特性分析可得,星群多目标测控的上行链路遥控与测距信号可实现S CDMA（Synchronous Code Division Multiple Access,同步码分多址）,由于星间距离较小,下行链路遥测与测距信号满足QS CDMA（Quasi synchronous code division multiple access,准同步码分多址）.上行链路遥控和测距信号形式设计为PCM BPSK CDMA（Pulse Code Modulation Binary Phase Shift Keying Code Division Multiple Access,脉冲编码调制二进制相移键控码分多址）,上行链路信号采用Gold序列扩频;下行链路遥测和测距信号形式设计为PCM BPSK CDMA,根据总的时延差,提出下行链路采用基于等长脉冲间隔法构造的LAS（Large Area Synchronous,大区域同步）码扩频.结果表明：比特信噪比Eb/N0为10.5 dB时,遥控误码率为1＆#215;10 6;Eb/N0为9.6 dB时,遥测误码率为1×10^5——与达到相同误码性能的Gold序列相比有1 dB改善,因此,LAS码相比于Gold码能够获得更好的误码性能.

On Multi-Object TT＆amp;C Technology for Formation Flying Satellites Based on LAS Code

Ground-based multi-object TT＆C （Tracking, Telemetry and Command） technology for clusters of forma tion flying satellites is analyzed. Propagation delay and Doppler frequency shift of formation flying satellites based on satellite ephemeris orbital parameters show that the uplink tracking and ranging signal is synchronous CDMA （Code Division Multiple Access） and it is designed as the form of PCM-BPSK-CDMA （Pulse Code Modulation-Binary Phase Shift Keying-Code Division Multiple Access）, which is spread by Gold sequence. The downlink telemetry and ranging signal is quasi-synchronous CDMA and is also designed as the form of PCM-BPSK-CDMA. Meanwhile, the downlink signal is spread by LAS （Large Area Synchronization） code, which is constructed by a new method of e- qual pulse interval according to downlink time delay error. When uplink Eb/No is more than 10.5 dB, the BER （Bit Error Rate） of tracking information is less than 1×10^-6. When downlink Eb/No is more than 9.6 dB, the BER of telemetry information is less than 1×10^-5, which is improved by 1 dB compared with Gold sequence. The BER per- formance applying LAS code is better than that using Gold sequence.