Originally Posted by 1075guy
The wifi (no team-setup 802.11a/b/g/n networks allowed) rule has always perplexed me. It actually has existed for as long as I can remember in FRC (yes, it PREDATES the cRIO and robot control systems running on 802.11n.)
The old IFI controls ran on 900MHz radio modems (they run an RS-422 Serial link over a radio connection).
The current cRIO+wifi controls run using 802.11n in the 5GHz band, everywhere except Israel, where 5GHz is a restricted military frequency, so they use 802.11n@2.4GHz.
The rule has always been in place with the intent of preventing robot interference, and it USED to outlaw ALL wireless communication devices in ANY band, except for cell phones IIRC. (this meant teams couldn't use walkie talkies or similar devices)
I've always found it silly for several reasons.
Cell phones regularly make use of the 900MHz frequency band, especially historically during the era of the IFI controls. If interference was such a problem, the literally hundreds of cell phones at an FRC event should have caused some robot weirdness. None occured, to my knowledge. Fast forward to today, and smartphones are now equipped with Wifi abilities, simultaneously operating in several frequency bands. You could never outlaw bringing your cellphone to an FRC event. It would be impossible to police.
Event venues, and indeed, even FRC events themselves, frequently have Wifi running at, or within range of FRC events. Additionally, the 2.4GHz, and 5GHz bands are unlicensed bands, usable by anyone for anything, anywhere in North America. Many FRC events have residential, commercial, industrial, or institutional lands within range. Interference in this band comes from all over the place, whether or not teams are wilfully adding to it or not.
The 802.11 standard (in all flavors) has proven itself to be fairly resilient to interference, otherwise you and all your neighbors couldn't run your wifi routers in such close proximity to one another without causing problems. Furthermore, since FRC is using the comparitively unused 802.11n @ 5GHz, any interference in the 2.4GHz or 900MHz bands would cause no problems at all.
If interference were a true problem for FRC bots (its not), FRC could apply to the FCC and CRTC to use the licensed 3GHz band. I know of at least one company that makes 802.11 compliant devices using that band. This solution would surely eliminate any interference concerns, however, it would potentially be problematic in that each team might have to apply for a license, unless FIRST could convince both CRTC and FCC to grant the program a blanket license.
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