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I've always wondered what sort of devices would actually break the FCC regulations on interference. I'd imagine the only things that might do that are radio dev
by AUmrysh 15y ago
I've always wondered what sort of devices would actually break the FCC regulations on interference. I'd imagine the only things that might do that are radio devices and jammers. Does anyone have experience with such devices?
- sophacles 15y agoI presume those regulations exist for a few reasons: 1) In any wireless device, it is not hard to imagine a bug causing problems 2) In any electronic device carrying oscillating currents, there is EM emission, therefore it is possible for unintended leakage on bad frequencies (e.g. this trace is just the right length to be a broadcast antenna at frequency Y, given normal modes of operation. 3) Some devices may individually not cause problems, even though they are low power emissions on certain bands, but cumulatively they may cause signal degradation in those bands. 4) Having and enforcing them forces engineers to ensure they are met up front, resulting in better, nicer playing devices to begin with, as it is cheaper to engineer it right, than to deal with the consequences of doing it poorly.
- Retric 15y agoIt's also something of a hold over from larger electric devices. A poorly designed laptop can mess with your local radio reception and networking equipment, but a poorly designed 50KW electric motor can disrupt radio transmission over a much larger area.
- paxswill 15y agoFirst thing I thought of: http://www.ladyada.net/make/wavebubble/index.html http://www.ladyada.net/make/wavebubble/index.html
- BorgHunter 15y agoIt's rare, but possible, even in devices which should have nothing to do with wireless signals at all: http://dansdata.com/gz128.htm http://dansdata.com/gz128.htm
- tezmc 15y agoI had a small remote control toy car when I was a child. One day I got freaked out when I heard voices coming out of it. It turned out I wasn't going mad, the thing was picking up local CB radio.
- bandy 15y agoFind someone with a running TRS-80. Bring your favorite portable AM radio with you. Have your friend run a program, and while that's occurring, put your radio next to the machine and start tuning it around. It won't take long before you find one of the (many) harmonics emitted by the computer.
- HeyLaughingBoy 15y agoA crappy $1 brush DC motor running from a 9V battery does a pretty good job of generating tons of interference all across the spectrum.
- 69_years_and 15y agoYup, and the common universal motor (used in vacuum cleaners to power drills) is a big offender too.
- dfox 15y agoPerfect example of such devices are cheap Chinese replacement chargers for just about anything. Anything that contains oscillator radiates RF and when the device switches relatively large currents periodically (like for example switched mode power supply) it becomes pretty good transmitter unless adequately shielded and filtered. Another significant source of EMI is almost any kind of digital sequential logic which contains signals with very sharp edges, which are mostly synchronized with each other.
- rcxdude 15y agowell, the rasberry pi didn't pass on the first go due to a misconfigured HDMI interface, so it seems it's not too hard to accidently breach the rules.