Measuring EVM in a WLAN device under test with two spectrum analyzers
Measuring the error vector magnitude (EVM) in WLAN receiver tests under challenging conditions such as wider modulation bandwidths that push the signals closer to the noise floor, requires a test system that can remove the noise contribution of the analyzer. The test system needs to isolate the noise coming from the device under test (DUT) from the rest of the measurement system, including the analyzer.
Two spectrum analyzers used as receivers in the cross-correlated EVM (ccEVM) technique capture and demodulate the same signal independently and cancel out uncorrelated noise added by the receivers to get a much lower EVM. This method provides accurate and reliable DUT EVM measurement in WLAN receiver tests, especially at higher-frequency and wider-bandwidth applications.
WLAN cross-correlated EVM test solution
Measuring the EVM in WLAN receiver tests requires canceling the uncorrelated noise contribution from the receivers, to get a much lower EVM for the DUT. The Keysight WLAN ccEVM test solution comprises two N9032B PXA X-Series signal analyzers (spectrum analyzers) with N9077EM2E PathWave X-Series multi-touch applications software. The test system isolates the DUT noise from the rest of the measurement system by comparing the measured EVM on both signal analyzers to compute the true EVM caused by the DUT-generated noise and impairments. This provides highly accurate WLAN EVM measurements than previously possible with a single receiver.
