We describe a method of traceably calibrating source or receiver Error Vector Magnitude (EVM) contributions for Wideband Code Division Multiple Access (WCDMA) waveform using a Real-Time Digital Oscilloscope as the reference receiver. We present the results and uncertainties for a receiver calibrated using four WCDMA sources from different manufacturers.

The objective was to provide a sound manufacturer independent traceable method, with an uncertainty budget, to calibrate the modulation fidelity of communications test equipment. This is important because if the communications receiver can only decode a communications waveform, there is a severe risk of circular traceability where the source is traceable to the receiver and vice-versa.