51–59 of 59 posts
Of course, on the RPI there is the good ole GPIO4 abuse: https://tutorials-raspberrypi.com/build-raspberry-pi-radio-t... Works a lot better and has been around a long time.
In college we had an I2C to ethernet adapter on our drone testbed that caused all sorts of RF interference for us. We eventually wrapped the whole fuselage in a farraday cage so that the datalink and flight controls wouldn't be overwhelmed. It was responsible for transmitting data at a 1 Hz rate, and we could visualize the interference on a spectrometer over a broad range of Rf at exactly 1 Hz. Anyway, we totally cou…
I thought i2c slowest clock was 100kb/s, how did this end up in a 1Hz rate?
Clever hack, but a lot of people are misinterpreting what’s going on here. These devices emit some very low level of 125MHz energy during normal operation. This software is simply turning that on and off, but not doing anything to increase the amount of emissions. Presumably the 125MHz emissions are within the FCC allowed envelope anyway, so this isn’t doing anything to exceed normal emissions limits. This only works…
From a regulatory perspective, there's a big difference between intentional and unintentional radiators.
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I've spent months and sleepless nights trying to get a product through the EMC certification. It's certainly possible but it's time consuming and expensive. With a shoestring engineering budget and a product that needs to be on the shelves in a month? Not really. I'm sure many devices on the market are not compliant. I follow lists of products removed from market for non-compliance and there are plenty each week. But…
Yeah, I remember in the early 2000s we had a wireless RCA audio/video transmitter, bought at a local electronics store, that played absolute havoc with the WiFi in our house as well as several neighbours. Another classic example is early cellphones that you would pick up on stereo systems etc. - "dat-dara-dat-dara-dat-dara-dat-dara-daaaaaa" going out in full blast.
Unlicensed equipment in the ISM WiFi band are operating under Part 15 (in USA) so must accept any interference.
And the phone interference to a stereo is caused by cheap and nasty design of the stereo. The phone itself cannot be blamed, and there's nothing which can be done to the phone to fix the interference (other than switching it off). Again the stereo is probably operating under Part 15, so must accept any interference.
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Yeah, I remember in the early 2000s we had a wireless RCA audio/video transmitter, bought at a local electronics store, that played absolute havoc with the WiFi in our house as well as several neighbours. Another classic example is early cellphones that you would pick up on stereo systems etc. - "dat-dara-dat-dara-dat-dara-dat-dara-daaaaaa" going out in full blast.
The effect of GSM phones on analog audio equipment was actually an oversight in defining the standard. Fully compliant equipment had that effect. Some years back when I had some small involvement in new EU regulations that case was actually given as an example of how, even after many reviews, some forms of harmful interference can only become apparent after a technology is already widely deployed.
The RF breakthrough is caused by the Amplitude Modulation in GSM, but then there's nothing fundamentally wrong with AM.
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https://en.m.wikipedia.org/wiki/Tempest_(codename)
I wanted to spin up a hardening service back in the mid-90s, based around what we knew of Tempest. I even named it Echelon Consulting (as in "upper echelon," but with a nod to ECHELON). My spouse wouldn't let me, they felt it'd be too risky to get involved with that environment, and we were just starting our family. But... yeah. You could tune into VGA monitors up to a mile a way using consumer hardware, and receptio…