Hello,
I’m experiencing frequency interference between UHF radios and my Jetson Xavier board. Whenever I turn on the radio, a 1.6V voltage is induced on the GPIO pins of the Jetson Xavier. Even when I continuously execute GPIO.output(33, GPIO.LOW) in a while loop, the voltage interference persists. Is there a solution to mitigate this RF interference between the radio and Jetson board? I would appreciate any suggestions or guidance on how to resolve this issue.
Thank you.
Hi milad72,
Are you using the devkit or custom board for Xavier NX?
What’s your Jetpack version in use?
Have you tried to use sysfs to control any pin at this moment?
What’s the frequency of your UHF radio?
Does the specific frequency affect the board?
Please describe in detail about your whole settings. It is not normal that a GPIO pin voltage level is affected by RF interference. Where is the UHF radio device? Is it connected to Xavier or not? What’s its max TX power? What’s the distance between it and Xavier board? Which GPIO pins are affectec?
We are using the Jetson Xavier NX with Jetpack 4.6 (rev3) installed on it. We have tested pins 31 and 33 at the moment, and the voltage level interference occurs on both of these pins and we have observed this problem both on the Devkit and our custom manufactured board.
The radio device is not connected to the Jetson board. It is physically located at a distance of about 1 to 5 meters from the Xavier NX board.
We have tested the radios in frequencies ranging from 400 to 520 MHz. However, the interference does not occur at all frequencies in this range (in some channels, there is no interference). The UHF radio’s maximum transmitter power is 45W at 11A.
When we disable Wi-Fi and Bluetooth connections of the board and remove the network card, the problem still persists.
Currently, we have not tried using sysfs to control any pin.
Please let me know if you require further information or if you have any additional suggestions for troubleshooting this issue.
Devkit is for development only and a bare board without metal box or other shielding and so might be interfered by radio. If custom product needs to work in wireless environment that might cause interference, then shielding design might be necessary. We don’t have recommendation on this kind of use case, maybe you can check with the vendors in ecosystem.
Just some comments on the topic, not necessarily a solution…
If you look at the square waves used in any computer, interference gets really complicated in a hurry. A square wave is equivalent to the sum of infinite odd harmonics (the sine waves used to add together to create a square wave). One can never truly have a pure square wave, as the infinite sum of odd harmonics means infinite power requirements (think of black holes/singularities type of not possible). So there is always a slew rate on a square wave.
Sometimes interference occurs over power wires shared by a computer and a radio. In that case you can add filtering to the wires, e.g., ferrite beads or low pass filters.
More often we are talking about EM problems, and there is a need to isolate the hardware with a Faraday cage. I’m guessing that you’re basically going to need to wrap something like a screen mesh wire cage around the Jetson (something that lets air through, but the holes are small enough that the relevant wavelength is significantly larger). I’m guessing that all wavelengths you are concerned with are at least 50 cm in length, so finding a cage material which has small enough holes, while allowing air to pass through, won’t be too difficult. The trick is that it has to be grounded. That’s the nature of RF.
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