Engineers who usually spend a significant amount of their time around test instruments are likely spending more of it at home these days. Those of us whose working life has been interrupted by the Covid-19 virus might well begin pondering about what goes into a test for human viruses rather than those confined to computers. […]
FAQ
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 […]
The therapeutic uses of RF energy
Discussions of the upcoming 5G technology sometimes focus on whether or not the millimeter-wave frequencies involved can damage human life. What gets less press is that radio frequency energy in other bands can be therapeutic. It can be useful to review a few of these uses to understand the beneficial role RF energy can play. […]
Testing transistors with a voltmeter
A bad transistor can sometimes be detected by its partly burned or distorted appearance, but more often there is no visible indication. One approach to troubleshooting is to substitute a known good component, but that is a costly way to go. Also, it is not reliable because an outside defective component can instantly destroy the […]
Will 5G make earth-bound radio telescopes impractical?
Though 5G is a promising technology, astronomers and Earth scientists are worried that 5G frequencies could interfere with the scientific use of previously quiet parts of the electromagnetic spectrum. The Federal Communications Commission recently came out with rules allowing experimental devices to use frequency bands between 95 GHz and 3 THz. Scientists see several problems […]
Measuring and abating jitter
Electronic noise results in spurious signals (spurs) or distortion in amplitude, frequency, or both. Jitter refers to unwanted variation in frequency, particularly in digital pulses and typically in the clock signal. Timing disruptions negatively impact system performance, particularly in ADCs, where sampling occurs, and in DACs. We’ll discuss causes of jitter, its detection and measurement […]
How to measure CCD and CMOS image sensor qualities
Today, about 95% of all digital cameras use CMOS image sensors with the rest employing CCDs. From the standpoint of sensor outputs, the main difference between CMOS and CCD sensors is that each pixel in a CMOS sensor has its own readout circuit next to the photosensitive area. In CCDs, charge collected in individual pixels […]
Setting input parameters in the Tektronix MDO3000 oscilloscope
Input parameters in the Tektronix MDO3000 Series Oscilloscope are determined by the user. This is done by pressing one or more of the channel menu buttons, causing the horizontal channel menu to appear. Menu items are: • Scale – Fine, Offset, Position, Probe setup and Deskew • Coupling – ac or dc • Termination – […]
Basics of flat screens in test equipment
Flat-screen technology has become ubiquitous. It has almost completely replaced CRTs in test instruments as well as in other appliances. Unfortunately, flat-screen tech can be a bit confusing because of vendors that use their own trade names to refer to their specific type of flat display technology. Here, we’ll try to clear up some of […]