Two incompatible definitions of noise factor can lead to confusion, which you can alleviate by understanding where the differences lie.
FAQ
How to determine noise figure: part 3
Noise factor and noise figure as defined in an IEEE standard can be derived from a two-port device’s equivalent noise temperature. In part 1 and part 2 of this series we discussed several ways to indicate the noise performance of a device under test (DUT). We first introduced the concept of noise factor based on […]
How to determine noise figure: part 2
The relationship between noise and temperature prompted a precursor of the IEEE to promulgate an alternative definition of noise figure in 1959. In part 1 of this series, we described the work of the Danish-American radio engineer Harald Friis, who described noise factor F of a device or system as the ratio of the input-power […]
What information does an eye diagram depict?
An eye diagram is a powerful visualization tool in digital communications and high-speed electronics to assess signal quality and channel performance. This FAQ will briefly explain an eye diagram and the overall and specific metrics engineers should know to understand an eye diagram. When capturing signals from a digital bitstream such as Ethernet or USB, […]
How to determine noise figure: part 1
A noise figure consolidates the effects of various noise types to provide a single specification for the noise performance of a component or system. In electronic circuits and systems, noise is an undesirable, inevitable disturbance in currents and voltages. Noise has many underlying fundamental causes. Thermal noise, also known as Johnson–Nyquist noise, results from random […]
How to interpret a QAM display: part 3
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 […]
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, 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 […]
