Modeling and simulation of higher-order PLL rotation tracking system in GNSS receiver

A higher-order rotation tracking PLL (Phase-Locked Loop) is proposed and studied for automatic trajectory correction of spinning projectile in a GNSS (Global Navigation Satellite System) receiver. Firstly, a whole GNSS receiver solution is put forward. This system consists of a rotation demodulation loop, a carrier tracking loop, and a PRN code capture loop. In this paper, the rotation demodulation loop is specially designed and added ahead of the carrier loop and PRN code demodulation loop to demodulate the rotation-modulated signals. The rotation demodulation loop is composed of an LPF (low pass filter), a switch, a counter, and a VCO (Voltage-Controlled Oscillator). The LPF is a key component and is designed by a 4th-order PLL which is discussed in detail. In addition, the modeling and simulation of carrier tracking loop via SIMULINK are implemented. Focusing on the design solution, the simulation experiments results are given here. The simulation results show that range from +40 Hz to -40 Hz could be tracked at 200 Hz of center frequency by 4th-order PLL. In another word, it could meet the needs of tracking 200 revolutions per second. Meanwhile, the test results of true satellite data are obtained, which support a good platform for design of GNSS receiver under spinning conditions.