The Application of Same-frequency Sine Wave Compound Modulation in an Azimuth Measurement System
Z-Y. Yang, X.X. Huang, Z-F. Zhou and Z-L. Zhang
The same-frequency sine wave compound modulation was introduced into the azimuth measurement system for the first time in the paper. The principle of azimuth measurement system was analysed, according to Stokes parameters and Miller matrix transformation, the model of the output modulated signal from modulator was present. After the components analysis on the modulated signal, the relationship between azimuth and the alternating current (AC) signal of modulated signal was detected, then the azimuth measurement model was established. In order to widen the system measurement range, the azimuth region judgment rule based on the variety trend of extreme points was present. Simulation results show that, the constant in the model is more accurate to express, the amplitude of extreme points increase clearly, they help to improve the precision effectively. It also shows that, with the help of azimuth region judgment rule, the system measurement range is widened to -90 to 90°.
Keywords: Laser beam, azimuth measurement, sine wave, compound modulation, magneto-optic modulation, extreme point, Stokes parameters, Miller matrix transformation