Method and apparatus for measuring modulation accuracy

Abstract

A method and apparatus for determining the phase and amplitude accuracy of continuous-phase-modulated signals is described. A modulated RF signal generated by a transmitter is down converted to a relatively low intermediate frequency which is filtered and sampled by a high sampling rate analog-to-digital converter. A digital signal processor processes the digital signals to produce a measured phase function corresponding to the modulated RF signal. From the measured amplitude and phase functions, an estimate of the ideal reference phase function corresponding to the modulated RF signal is calculated and synthesized. The reference phase function is compared to the measured phase function to determine the phase function from which the modulated RF signal phase error and frequency error are computed.

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