DS/SS predictive PN code tracking loop using a Kalman filter

We present a new code tracking loop, which is stable and has high capability of tracking, for DS/SS communication systems between aircraft and ground base stations. The proposed loop uses delay estimators combining the modified code tracking loop (MCTL) with the Kalman filter, which is usually used to track the position of an aircraft, but is used to estimate the propagation delay of the spreading sequence in our loop. We call the proposed loop the predictive PN code tracking loop (PCTL). The estimated delay-controlled device transforms the propagation delay obtained by the Kalman filter to the adaptive signal and inputs it to the MCTL discretely through the operational circuit. The PCTL can revise the degradation in the tracking performance of the MCTL under the constraint of Doppler effects and the channel noise. The tracking performance of the PCTL is investigated and compared with that of the MCTL by computer simulations. It is shown that our proposed system has a higher code tracking performance than the MCTL from the viewpoint of tracking jitter.