The concepts of signal phase modulation and signal frequency modulation, and the difference between them, are often a source of confusion. Ditto for the related idea of phase distortion. Here, we’ll try to clarify things. To understand phase distortion, recall that any waveform can be considered to be a sum of sine waves of different […]
Difference between signal jitter and frequency modulation
Jitter and frequency modulation both involve a change in the frequency of an underlying signal. It’s worth investigating how the two phenomenon differ. Jitter is usually defined as an undesired deviation in timing of a signal from its original periodicity. It can take the form of variations in phase, period, or duty cycle. And jitter […]
Basics of amplitude distortion
Amplitude distortion is the unintended modification of a signal, typically while undergoing amplification. Amplitude modulation, in contrast, is the intended modification of a carrier wave in response to a varying audio, video or other information-bearing signal. Sources of amplitude distortion include noise and interference, but the main source is non-linear amplification. Amplitude distortion can include […]
Overview of electrical measuring instruments, part three
In recent columns, we’ve given a quick review of some basic instrumentation common to most engineering work benches. Here are a few more instruments found in many engineering labs. Signal generator Signal Generator is a generic term describing various instruments, all sharing a single rationale, which is that a device under test (DUT) requires a […]
Overview of electrical measuring instruments – Part 2
In a recent column, we gave a quick review of some basic instrumentation common to most engineering work benches. Here are a few more instruments found in many engineering labs. Curve Tracer The curve tracer is a member of the oscilloscope family of measuring instruments. In its CRT or flat screen display, the user sees […]
Overview of electrical measuring instruments
Here’s a quick review of some basic instrumentation common to most engineering work benches. Ammeter The ammeter is the basis for many other electrical measuring instruments. Whether you are measuring volts or ohms, essentially inside the instrument you are measuring current. Measurement of current in a circuit is somewhat problematic because all the electrical energy […]
Another Covid causality: The James Webb telescope
NASA has announced it will pause work on the James Webb Space Telescope because of the ongoing COVID-19 pandemic. The launch is still currently on the books for 2021, but there are questions about whether that date will hold. The James Webb Space Telescope, successor to the Hubble and Spitzer instruments, was originally scheduled to […]
The difference between instrumentation and differential amps
Many of the test instruments used in industry today have inputs based on instrumentation amplifiers. This kind of amplifier, sometimes abbreviated as InAmp, is itself based on a more fundamental amplifier setup, the differential amplifier. It can be helpful to understand how these two devices differ. A differential amplifier ideally amplifies the difference two input […]
The difference between SWR and TDR meters
In setting up transmission lines, it is often desirable to measure the amount of signal reflection. The relevant metric is the standing wave ratio (SWR). SWR is defined as the ratio between the amplitude of a partial standing wave at antinodes [max] to the amplitude of the adjacent mode [min]. Thus a ratio of 1.5:1 […]
Do you really need a VNA when a scalar network analyzer might do?
Network analyzers measure network parameters of electrical networks, such as two-port amplifiers and filters. The instruments characteristically operate at 5 Hz to 1.05 THz, mostly at the higher end, though some models are sensitive down to 1 Hz. These instruments are available in two varieties: scalar network analyzers, which measure only the amplitude of the […]