TEST & MEASUREMENT
signal analysis software also records error vector spectrum, error vector time, common pilot error, channel frequency response, and more.
Figure 1 is an example of software that allows engineers to view an unlimited number of simultaneous traces, showing results such as EVM versus frequency or time, equaliser channel frequency response, common pilot error, and phase noise spectrum.
The software can also assist with the new MIMO regulations, such as modulation quality measurement because the IEEE 802.11 specifi cation requires a spectral emission mask (SEM). SEM is mainly a measure of interference within the wireless band. The software can provide SEM measurements with a quick setup for 802.11be 40 MHz (shared), 160 MHz, and 320 MHz bandwidth. Software solutions are an all-important diagnostic tool for wireless connectivity testing, especially for Wi-Fi 7. The software enables more advanced testing features such as cross-correlated EVM (ccEVM) to improve EVM performance.
ccEVM is a technique used to extend the dynamic range of a receiver for best EVM
“
Phase noise is often the dominant cause of EVM issues in OFDM systems. Vector signal analysis software enables users to characterise phase noise within the
802.11be demodulation measurement using an OFDM channel called phase noise spectrum trace.
from the signal source and the device under test.
Figure 2 is an example of using ccEVM software. In this example, engineers use a signal generator and two receivers along with ccEVM to result in a 6 dB EVM improvement to the 802.11be WLAN signal.
Conclusion
performance by using two receivers to capture and demodulate the same signal independently. This process also performs cross-correlation on the error vectors to cancel out uncorrelated noise added by the receivers, resulting in a much lower EVM. This method primarily causes the ccEVM value to contain the noise from the device under test, or in the case of an amplifi er, noise coming
48 MARCH 2024 | ELECTRONICS FOR ENGINEERS ”
We can continue to go through all the features that software brings to a wireless connectivity testing world, but the list is extensive, and the result is the same. Software is critical in helping engineers test standards such as Wi-Fi 7 and any newly released wireless standards. Remember, society cannot go a day without wireless devices because it is part of our daily life. High-performance solutions enable easier testing and evaluation to ensure wireless devices meet regulations. Software enables engineers to analyse, test, and resolve critical issues in wireless connectivity.
About the Author
Andrew Herrera, product marketing manager, RF test software at Keysight Technologies.
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