The phrase and concept “orthogonal” is widely used in engineering, but it is also often misunderstood. The formal definition of orthogonal signals does not necessarily mean that they are unrelated or uncorrelated, although that is how the term is often used in casual “engineering speak.” Formally, two vectors are orthogonal if their dot product is […]
FAQ
What is “orthogonal”? (Part 1): mechanical design
The phrase and concept “orthogonal” is widely used in engineering, but it is also often misunderstood. I was chatting the other day with a non-technical friend and said something like, “Oh, that won’t happen. Those two things are orthogonal.” My friend looked at me and replied with a “huh?” and he was right to do […]
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 […]
How does a precision rectifier work?
A precision rectifier, sometimes called a super diode, is an op amp circuit designed to behave like an ideal diode and is used in high-precision signal processing applications. It’s not a synchronous rectifier. The op-amp-based precision rectifier should not be confused with power MOSFET-based synchronous rectification. Because there is no diode voltage drop between the […]
What’s the difference between equalizers?
Equalizers are used to alter the performance of signal chains. In some cases, that means linearizing signal chain performance. In other cases, equalizers are used to introduce nonlinearities. As a result, equalizer designs vary widely from simple passive circuits to complex multi-stage designs and active circuits. This FAQ reviews equalizer basics, looks at equalizers for […]
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, […]
What do you do with a bucket brigade device?
A bucket brigade device (BBD) is a discrete-time analog delay line using capacitors that has been replaced in most digital signal processing applications. But it continues to be used in some specialty applications such as guitar and audio sound effects and some types of sensors. It consists of a series of capacitance sections where a […]
What’s a logarithmic resistor ladder good for?
A logarithmic resistor ladder consists of a resistor string and switches designed to attenuate a signal. The state of the switches can be considered to represent a digital code proportional to the logarithm of the attenuation ratio. Logarithmic attenuation is useful when a large dynamic range is needed. Audio volume control and fading/balancing audio signals […]
Where do you use A, B, AB, D, G, DG and H circuits?
This selection of power amplifier classes is used to strengthen AC signals. The letter symbols differentiate between amplifier types and indicate the expected performance and characteristics. Basic amplifier classes such as A, B, AB, and C relate to the time that the amplifier is operating, or conducting, expressed as a fraction of the period of […]
Teardown: Inside an industrial absolute encoder
If you go to the Wikipedia page on absolute encoders, you’ll find descriptions of these devices mentioning multiple code rings, glass or plastic discs, and configurations of sliding contacts arranged so each contact wipes against a metal disc at a different distance from a turning shaft. Actually, you’d be hard pressed to find any of […]