Error vector magnitude characterizes actual QAM signals’ deviations from their ideal locations due to nonlinearity and phase noise. In part 1 of this series, we discussed quadrature amplitude modulation (QAM), which results from summing orthogonal amplitude-modulated cosine and sine waves of the same frequency. In part 2, we looked at assigning bit sequences to QAM […]
FAQ
How to interpret a QAM display: part 2
Sixteen unique 16-QAM symbols can each convey a unique 4-bit sequence. In part 1 of this series, we discussed quadrature amplitude modulation (QAM), which results from summing amplitude-modulated cosine and sine waves of the same frequency. We also looked at the constellation diagram, which a test instrument such as an oscilloscope or vector signal analyzer […]
How to interpret a QAM display: part 1
A constellation diagram plots a quadrature amplitude modulation (QAM) signal’s in-phase and quadrature components. The EE World article “Should I use a spectrum, signal, or vector network analyzer?” in part 3 mentioned that vector-signal analyzers (VSAs) can display modulation-domain and frequency-domain information. Other instruments incorporating digital signal processing (DSP) capabilities, including oscilloscopes, can provide insights into […]
Verify, test, and troubleshoot 5G Wi-Fi FWA gateways
By Xiang Li, Keysight Technologies Follow these three steps to ensure your fixed-wireless access designs will be compatible with the Wi-Fi fronthaul and 5G backhaul. Many areas lack the wired infrastructure to bring residential broadband access. Making those connections has become costly and inefficient. Fixed Wireless Access (FWA) has emerged as a compelling alternative to […]
Should I use a spectrum analyzer, signal analyzer, or vector network analyzer? Part 4
A vector network analyzer can fully characterize components by deriving their scattering parameters. In earlier parts of this series, we looked at analog spectrum analyzers (part 1 and part 2) and vector signal analyzers (part 3), both of which monitor unknown signals, whether emanating from a system, device under test (DUT), or an enemy’s transmitter […]
Should I use a spectrum, signal, or vector network analyzer? part 3
In part 2 of this series, we looked at a swept-tuned spectrum analyzer and how it could sweep a frequency span of interest from 1 MHz to 1.1 MHz with a sweep time of 50 msec. As Figure 1 shows, the analyzer readily identifies a signal at 1.03 MHz but misses the intermittent signals shown […]
Should I use a spectrum, signal, or vector network analyzer? part 2
An analog spectrum analyzer’s sweep time can hide intermittent unwanted signals. In part 1 of this series, we examined a simplified block diagram of a traditional analog spectrum analyzer, which includes an RF frontend, mixer, voltage-controlled oscillator (VCO), intermediate-frequency (IF) stage, sweep generator, envelope detector, and display. We also looked at resolution bandwidth (RBW), the […]
Should I use a spectrum, signal, or vector network analyzer? part 1
Signal analysis is invaluable for applications ranging from amplifier characterization to signal intelligence. In a recent series, we discussed specs such as 1-dB compression and third-order intercept points. At the end, I pointed to some application notes that explain how to use specific spectrum, signal, and vector network analyzers to make these measurements. These instruments’ […]
New products at the EMC & Compliance International Conference
At the annual UK event, Tekbox, Y.I.C. Technologies, and Harogic Technologies were among the companies exhibiting new EMC measurement equipment. The EMC & Compliance International conference and training was held again in Newbury, UK, from May 22 to 23 this year (Reference 1). This was my first opportunity to attend this annual conference hosted by […]
How can I quantify a device’s nonlinearity? part 3
A higher third-order intercept point results in lower intermodulation products at any given input power level below compression. In part 1 of this series, we discussed the 1-dB compression point as a figure of merit for device linearity. In part 2, we examined a circuit that adds two fundamental input signals of frequencies f1 = […]
