Windowing functions account for mismatches between an input signal and FFT sample size. We concluded part 2 of this series with a look at fast Fourier transforms (FFTs) of 39.1-Hz and 38.12-Hz cosine waves, with our sample size N = 512 and our sample interval Δt = 1 ms (Figure 1). Shouldn’t the amplitudes of […]
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Why does the Fourier transform provide apparently inaccurate results, and what can I do about it? part 2
A bare-bones implementation of the Fast Fourier Transform helps illuminate how to extract frequency information from input data samples. In part 1 of this series, we reviewed the discrete Fourier transform (DFT) and manually calculated one DFT shown in Table 1. Table 1. Manual DFT results DFT input Complex DFT |DFT| 3 12 + j0 […]
Review: Electronic bug and hidden camera detectors
Do you want assurance that cameras embedded in everyday devices don’t spy on you? Then you should check for cameras, SD card slots, and Wi-Fi-connections. We reviewed two devices that help you find those lurking spies. While discovering a hidden camera in an Airbnb, VRBO, or hotel is rare, there have been reports of travelers […]
Why does the Fourier Transform provide apparently inaccurate results, and what can I do about it? part 1
This multipart series will review the discrete Fourier Transform and describe how to avoid common problems when transitioning from the time to frequency domain. A recent post on phase noise discussed expressing a function of time as a function of frequency. The Fourier Transform is the well-known road from the time domain to the frequency […]
How to use remote sensing for DC programmable power supplies
In this FAQ, you’ll learn how to know if your test application needs sensing and how to properly wire a power supply to a load. Calibrating certain sensing circuits, such as those used in electric vehicles (EVs), is critical to get right. An inaccurate calibration of an automotive battery monitoring circuit could, for example, allow […]
What is phase noise and how can I measure it? part 2
Phase noise requires more than one instrument unless you use a phase-noise analyzer.
AOC 2023: Exhibits show the latest in military wireless
Washington — The Association of Old Crows (AOC) held its 60th annual convention in Washington during the week of December 11, 2023. EE World was there on December 12. Here is some of what we saw in the exhibit hall. AOC is a defense-oriented conference that focuses on military wireless communications. In addition to product […]
TinySA Ultra: A low-cost spectrum analyzer that fits in your pocket
This palm-sized, battery operated instrument can help you diagnose EMC problems.
Product tryout: Tektronix 4 Series B oscilloscope
EE World gets its hands dirty on the latest Tektronix oscilloscope. So many features, so little time. When Tektronix gave the press a preview of the 4 Series B 12-bit mixed-signal oscilloscope and TekScope software, I asked to try the software. Days later, the real thing arrived in a transit case. Fortunately and unfortunately, today’s […]
What is phase noise, and how can I measure it? part 1
Phase noise is an artifact of a nonideal oscillator and is best investigated in the frequency domain. Phase noise accompanies the generation of any real-world sinusoidal signal. You can think of it as the analog equivalent of digital jitter, which we covered in an earlier series (read part 1 and part 2). Recall that jitter […]
