I'm doing work comparing measurements of modulation from a DUT against a reference modulation source. The same instrument is used to generate the carrier for each. Both look a lot like square pulses at about 160 kHz around carriers near 900 MHz. For each modulation source, I'm measuring amplitude between the two states (e.g. (delta I)^2 + (delta Q)^2) with the Basic measurement personality on a PSA at 8 MHz. I'd like to think that this is nearly as simple as a modulation measurement could get My question is, if we can assume both the DUT and reference modulation are ideal square waves, does anyone know of a good way to estimate a relative accuracy of the measurement of the amplitude comparing these two signals?