The Design of GNSS Anti-jamming Timing Terminal Under Complex Electromagnetic Environment
GNSS timing terminal is a device that can receive and calculate satellite navigation signals,obtain high-precision time information,and provide high-precision timing services such as NTP,B-code,PTP,and serial port.At present,the electromagnetic environment of battlefield and shooting ranges is becoming more and more complex,which leads to a decrease in the accuracy of GNSS timing terminal,even rendering unusable or obtaining false time,space,and velocity information.All of these pose severe challenges to the security application of GNSS.To address the susceptibility of GNSS signal interference under complex electromagnetic environment,a timing terminal with anti-jamming capability is de-signed in this paper.This terminal can provide continuous,accurate and stable timing services when GNSS navigation sig-nals are interfered.The GNSS anti-jamming timing terminal is designed based on the 7-array self-adaptive zero-adjusting antenna.The terminal integrity is monitored by reference signals including GNSS,long-wave and optical fiber IRIG-B code.High-precision time difference measurement and digital phase-locked control technology is conducted on the terminal built-in clock.A modular design is adopted on terminal output timing signals including 1PPS,IRIG-B,message and NTP.The terminal also supports various electric level interfaces including TTL,RS485,idle contact,RJ45,optical fiber and RS232.The performance test results show that the synchronization error of Beidou reference signal is about 15 ns,fiber B-code is about 40 ns,and long-wave reference source is about 150 ns,compared to the standard signal.The designed tim-ing terminal could provide high-precision timing service in a six band interference environment with a maximum dry flux ra-tio of 70 dB.
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