The best plan to curtail measurement errors is to modulate the input signal before it enters a sensor. As far as linear directional sensors are concerned, VMM (the vector modulation method) can make the earliest modulation and appropriate demodulation to curtail measurement errors and then improve the precision of measurement. According to the modulation–demodulation principle and the linear system theory, especially the frequency-remaining character and the superposition theorem of linear systems, a precise response to the input signal will be resolved by means of demodulation. VMM curtails the main elements of errors, including quantization error and bias of a measurement system, along with bias, drift, noise and disturbance of sensors. Experiments measuring ERR (the Earth's rate of rotation) are presented, and a design for an experiment measuring gravitational acceleration with VMM is presented. The preliminary experiments have given positive support. VMM, which can remarkably get rid of errors, is much clearer in theory and easier to implement in engineering practice.

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