A Study on High Precision Calibration of Zero Value for Navigation Signal Simulator

摘要

As a high precision source, the navigation signal simulator is possible to simulate the navigation signal which arrived at the antenna of receivers in all kinds of dynamic or static scene, providing a realistic and controllable environment for receiver performance testing. It not only needs higher signal simulation accuracy, but also needs methods and means of high-precision test measurement for itself. The measurement of zero value which is a key indicator has an important effect on its testing as well as the correctness and reliability of receiver's measurement. The traditional measurement of zero value is to make use of an oscilloscope to observe the measured waveform and manually measure the time delay between of flip point and the rising edge of 1PPS signal, and average the measurements. This method will not only introduce measurement errors, but also difficult to locate the flip point accurately due to the low power signal. In this paper, the analysis of the measurement principle of zero value was first introduced, and then a new method was proposed which oscilloscope was used to store the measurement data. In this method, interpolation was first applied to the sampled data, and then the Hilbert transform and polynomial interpolation fitting were used to extract the envelope to find the zero value. The actual results show that the method can improve work efficiency, and is capable to raise the zero value measurement accuracy up to 1 cm.