# Robust Anti-Jamming Algorithm Based on Transmit/Receive Time-Sharing Technology
###### Abstract  
Transmit/Receive (T/R) time-sharing is a critical technology to ensure accurate space-time reference information of navigation signals, which solves the problem of co-channel interference between receiver and transmitter. The rapid development of the electronic information industry has led to severe frequency band conflicts between different electronic systems. Satellite navigation receivers must take measures to suppress interference to eliminate the effects of narrowband interference, mainly unintentional interference. Time-domain anti-jamming is widely used in navigation receivers for its simple and easy advantages in ensuring the validity and stability of navigation data. However, because the satellite-ground link receivers adopt transmit/receive time-sharing technology to realize the bidirectional measurement and communication function of the link, the stability of the data solution is greatly affected by anti-interference in the time domain. The anti-jamming filter of the traditional navigation receiver usually re-converges from the initial state in each signal-receiving time slot, which leads to the receiver losing high volume data due to repeated convergence. This paper proposes a robust time-domain anti-jamming technology based on transmit/receive time-sharing technology. The continuity and stability of the interference signal are used to obtain the preliminary information of the periodic transceiver. The results show that robust anti-jamming technology based on a T/R time-sharing navigation signal can effectively improve the carrier-to-noise ratio loss and data loss caused by traditional time-domain anti-jamming technology, reduce the convergence time to nanosecond level, and has bright prospects in the future application of other navigation systems. BeiDou Navigation Satellite System; transmit/receive time-sharing; time-domain anti-jamming; robust anti-jamming algorithm +
Footnote †: journal: _Machines_  
Time-domain anti-jamming technology is one of the most effective ways to suppress narrowband interference [11]. It is widely used in tiny navigation receivers such as hand-sets because of its simple and easy implementation [12; 13]. The anti-jamming module receives the digital signal through the radio-frequency front-end (RFFE) and transmits the processed data to the receiver back-end, suppressing narrowband interference and ensuring navigation signal availability [14; 15]. Compared to the recursive least square (RLS), Levinson-Durbin, and Burg algorithms, the least mean squares (LMS) algorithm has become one of navigation receivers' most commonly used NBI suppression techniques [16; 17]. Transmit/receive (T/R) time-sharing is a critical technology to provide precise space-time reference information for satellite-ground link receivers [18; 19]. The receiver alternately sends and receives signals in the T/R time-sharing period and performs bidirectional measurement and communication with the satellite receiver or the ground station [20]. The signal reception interval is usually shorter than the duration of narrowband interference. Therefore, in traditional BeiDou navigation receivers, there are multiple T/R time-sharing periods in the interference duration, and the anti-interference filter re-converges from the initial state whenever the T/R time-sharing cycle restarts. In the non-convergence stage of the anti-jamming filter, the navigation receiver cannot perform signal calculation, typically because the signal quality cannot reach the acquisition and tracking sensitivity of the receiver, resulting in the loss of information of the navigation signal [21; 22]. The classic navigation receiver usually receives a continuous signal directly, and the traditional anti-jamming algorithm is also designed for this kind of scenario. However, due to the emergence of T/R time-sharing technology, the navigation receiver sends and receives signals periodically.