The model number on the Tektronix MDO3104 oscilloscope denotes that it is a 3000-Series Mixed-Domain Oscilloscope. The mixed domain moniker means it is capable of displaying a waveform simultaneously in the time domain and in the frequency domain. The time domain is more familiar, the way we envision a sine wave when amplitude is plotted […]
Is there such a thing as a catenary antenna?
A conic section is formed by the intersection of a plane that cuts though a cone, usually with the circle at the top and the hyperbola at the bottom. Between them lie the ellipse and the parabola. The parabola has distinctive properties when rotated in space to make a concave surface. The parabola can be […]
The ups and downs of bad DACs
A digital-to-analog converter (DAC) is more prone than an analog/digital converter to signal degradation. DACs are complex devices requiring precisely matched components. For this reason, with notable exceptions, DACs are implemented as mixed-signal ICs based on MOSFET technology. Discrete component DACs are found in radar systems and high-speed test equipment including digital sampling oscilloscopes. Digital […]
The up side of under sampling
A digital signal can be derived from the original time-varying, continuous analog signal by creating a sampled sequence of quantized values. It is intuitively evident that the fidelity and resolution of this quantized signal is based upon the number of samples taken per unit of time. Harry Nyquist published an early version, later further formalized […]
Measuring and using static electricity
Many moons ago, a future member of our editorial staff was playing with his very first multimeter. He was a farm kid. One of his first experiments was to put the negative lead of the meter on a ground rod and the positive lead on one of the metal bands used to reinforce the interlocking […]
Coaxial cable myths and misunderstandings
In this age of misinformation, you can add coaxial cable to the list of items for which it is easy to get steered wrong based on internet searches. Much of the bogus online commentary about coax relates to cable loss, cable impedance, and standing waves. Here are a few basics that may help sort the […]
Can something consume energy without emitting a field?
The editorial offices of Testandmeasurementtips.com recently received a letter from an individual who headed up a group of investigators of paranormal phenomenon. It was a serious letter. To summarize, the group had concluded there was no legitimate method to record the activity of an alleged haunting. But the writer did have a question for us, […]
How big is the band gap? A heated discussion
There’s a trick with a soldering iron that can be used to determine whether an unidentified semiconductor is n-type or p-type. In essence, it determines whether the majority carriers are holes (p-type) or electrons (n-type). Just as heat makes a gas expand (PV=nRT), the hot tip of a soldering iron makes carriers expand away from […]
The difference between signal under-sampling, aliasing, and folding
Most engineers today are sensitive to problems that arise when digital measurement instruments try to capture signals containing frequencies that are too high for the sampling circuitry to handle. Nevertheless, there are terms associated with sampling problems that sometimes get confused. Probably the three concepts most likely to cause issues are under-sampling, aliasing, and folding. […]
Difference between a waveguide and transmission line
As electronics migrates to higher and higher frequencies, the media routing electronic signals to their intended destinations grow increasingly exotic. This is particularly true as communication technology moves to 5G frequencies which are characterized by millimeter wave transmissions. In this frequency range, engineers are more likely to encounter waveguides and transmission lines rather than ordinary […]
