Traceable GMSK vector modulation error based on analog PM

The paper addresses the problems about calibration of vector modulation error: first, signal generator calibrates VSA and vice versa, it forms a closed-loop, so it lacks traceability. Second, signal setting of vector modulation error has always been neglected in the VSA calibration This has exposed the shortcomings of the system level verification of VSA. To solve the problems for the GMSK, we propose new solutions to calibrate vector demodulation error, namely, use analog PM signal with certain paramters, to construct an “equivalent GMSK signals” with modulation error. The signals' EvmRms, EvmPeak, PhaseErrRms and PhaseErrPeak can trace to PM frequency, and thus traceable, calculatedly and also adjustable within a wide range. The above solutions have been proven through experiments.