Interference in the 900 MHz band appears to produce random errors in a gas station price sign. Spectrum analyzers help track it down. I received a call recently from a former client who manufactures electronic signs. A gas station was experiencing intermittent loss of wireless control of its signs, which displayed the price of various […]
How to separate differential and common-mode harmonic noise currents
Differential-mode and common-mode currents can cause your product to produce radiated and conducted emissions. These three techniques can help you measure them.
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 […]
TinySA Ultra: A low-cost spectrum analyzer that fits in your pocket
This palm-sized, battery operated instrument can help you diagnose EMC problems.
How to use simple antennas for EMI troubleshooting
For general troubleshooting, you can use consumer-grade antennas such as for TV. Pre-compliance tests require calibrated antennas. Antennas are important for capturing radiated harmonic emissions from electronic products. You can use them for simple troubleshooting or for calibrated pre-compliance testing. For troubleshooting purposes, you can use almost any uncalibrated antenna. I’ve even seen engineers use […]
How to use RF current probes for EMI: Part 2
In Part 2, you will learn how to use an RF current probe to calculate E-fields and troubleshoot EMI emissions from cables. Free and low-cost software tools let you customize the calculations based on your current probe’s data. As I mentioned in Part 1, RF current probes are one of my most useful troubleshooting tools. […]
How to use RF current probes for EMI: Part 1
DIY and commercial RF current probes let you find which cables act as EMI-emitting antennas. RF current probes are one of my most useful troubleshooting tools. Because most radiated emissions failures are due to attached cables acting as transmitting antennas, clamping an RF current probe around a wire or cable will measure the common mode […]
How to locate EMI emissions with near-field probes: Part 3
Part 3 of a series on using near-field probes for detecting EMI sources shows you how to set up a spectrum analyzer and how to detect emissions problems. Now that we’ve discussed the theory of measuring near-field emissions (Part 1) and how to use near-field probes (Part 2) to make the measurements let’s discuss how to […]
How to locate EMI emissions with near-field probes: Part 2
Now that you know a little theory of near-field measurements, how do you use near-field probes and a spectrum analyzer to help you troubleshoot and mitigate emissions issues? Remember, as mentioned in Part 1, that deciding whether to use an H-field or E-field probe depends on whether you’ll be probing high switching currents — di/dt […]
How to locate EMI emissions with near-field probes: Part 1
Near-field probes let you find the sources of near-field and far-field EMI that ruin your design, and your day. You don’t need to know Maxwell’s Equations to troubleshoot your designs.