In the paper, a fast initial alignment of strapdown MIMU used in the two-dimension trajectory correction fuze was
analyzed. According to the situation that MIMU can't work normally because of high shock on shrapnel of Compound
Extended Range by Base Bleed and Rocket at firing, the MIMU in initial alignment with Bar-Itzhack and Berman's error
model is presented and the observability was analyzed. It shows that the observability of MIMU on stationary base is
poor. The selection of unobservable states was discussed. A Kalman filter estimation algorithm was provided, but the
azimuth error converges very slowly in initial alignment. A fast estimation method of the azimuth error was proposed. It
reveals that the azimuth error can be entirely estimated from the estimates of leveling error and leveling error rate
without gyro output signal. It shows that the method can realize the rapid initial alignment of MIMU.
In trajectory correction fuze of spinning projectiles, the rotating rate experienced by fuze GNSS(Global Navigation
Satellite System) receiver causes it positioning inaccurately for the amplitude or phase of signal from them are
modulated by rotation. With multi-antenna array, this GNSS Receiver could improve signal-to-noise and anti-interference
ability of the system. In addition, the special rotation demodulation loop with three channels helped the
GNSS receiver demodulate rotation-modulated signals and thus provided correct position and attitude information.
Besides, the quick searching and parallel algorithm realization based on SDR and FPGA were given here. At last, the effect of magnitude and phase modulation and roll rates were simulated, and primary data were obtained. The results show that it can capture and track the rotating projectiles effectively.