The Acceleration Sensitive Coefficient Calibration of the Crystal Oscillator Based on the GPS Carrier Control Principle

Abstract

In acceleration and vibration environment, to weaken frequency instability influence of the crystal oscillator on GPS carrier loop and rectify frequency compensation, researchers usually adopt the solution of crystal oscillator frequency acceleration compensation. The vital basis of compensating frequency errors is how to obtain accurately corresponding sensitive parameters of crystal oscillator. In the traditional calibration approach of acceleration sensitivity coefficient, indispensably using precise frequency reference and measurement equipment makes the calibration process expensive and complex, that fails to be widely applied in GPS navigation system. Combined a precise frequency reference of GPS satellites with the carrier tracking loop principle, the paper analyzes the acceleration frequency errors transmission mechanism of crystal oscillator in the carrier tracking loop, and designs an adaptive weighted EKF to handle frequency bias observed values synchronously in multiple tracking loops, which reduces frequency bias estimating noise and separates frequency offset and frequency drift rate, from the receiver’s frequency bias observation in the crystal oscillator. And on this basis, acceleration sensitivity coefficients of crystal oscillator calibrate on the super tight combination navigation board by 2g flipping calibration method. The experiments show that the method is able to effectively calibrate acceleration sensitivity coefficients of crystal oscillator, which is the solution base of compensating crystal oscillator acceleration frequency errors on related GPS technology research.