Wireless USB cable

I was wondering if anyone had come across a wireless USB solution (aka wireless tether) for use at competitions.

Gonna stop you right there before you get stopped by a CSA at a comp.

There is a very, very, very low chance that’s going to go over well. IIRC there may be a way that is legal, or at least follows the intent of the competition rules, but anything on the WiFi spectrum is right out.


I presume you mean in the pit or on the practice field. Even if it’s not wifi, enabling this in the ARENA would violate H303 V and R707. Just connecting it to the robot at the event could potentially be construed as violating R707.


Technically speaking, I believe R707 can only apply for configurations that are inspected for match use, so it wouldn’t automatically be against the rules to attach something between matches as long as it never saw the field.

That said, I imagine the rules would simply be rewritten if someone tried to skirt them. The GDC holds on to what little control they have of the wireless spectrum for good reason. It wouldn’t be long before one team doing it turns into thirty at a single event, and then it’s probably not working for anyone.

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Good grief, NO, NOT in the arena. Pit/practice field only! Times you want to be tethered, but not risk running out of cable.

I have been to events where the pit area and the competition field were separated by cloth curtains so they were really the same space in terms of radio propagation.

I’d argue this is probably the setup for MOST events

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To be clear, my answer was with respect to the pits/practice field.

The short of it is that unless your event provides practice radios, you’re out of luck.

I believe this would violate E301-E304, specifically E304:

*Practice FIELD wireless via event radios only. If operating wirelessly on the Practice FIELD,
ROBOTS must use one of the provided Practice FIELD radios for communication.

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Ah, there it is. I always forget there’s a separate event rules PDF.

E303 also requires you to tether everywhere that’s not the field/practice field, and it’s pretty clear that ‘tether’ in this case means ‘wired’, as otherwise the rule isn’t saying anything at all. ‘Wireless tether’ as it appears in the OP is somewhat of an oxymoron.

Just to play devils advocate- only 802.11 stations are prohibited. Bluetooth uses the 2.4GHz band and is not prohibited. I believe VEXnet also uses 2.4GHz.

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If you are just trying to work around length limitations of USB cables, https://www.amazon.com/dp/B003L14ZTC exists.


I don’t know about MOST overall, but yes, in my experience. Arkansas 2019-2020, Tallahassee 2022 there was nothing but a curtain between the ARENA and practice field, and not a lot of distance. Bayou 2012-2022: there wasn’t much more (a “half wall”), but a bit more distance. CMP 2022: cloth and distance. CMP 2015: they were in separate buildings - yay for wireless separation, but a bummer otherwise. I don’t seem to recall practice fields at off season events, but from these, I suspect that many events at high schools have the field and the pits/practice field separated by necessity.

Pending an official ruling otherwise, I’d call it that way as well, but most of us have seen, um, interesting interpretations of the rules over the years, especially at events, but sometimes on Q&A. If you want to blaze this trail, I have three recommendations:

  1. Don’t use wifi frequencies. When combined with wifi protocols, that’s a event rule, E301. Using wifi frequencies with different protocols could easily fall afoul of E302.
  2. Decide up front how you’ll play it. I see two obvious ways - either ask a Q&A that asks whether your “wireless tether” is considered part of the ROBOT for R rules if it is removed/disabled for matches, or keep it quiet - don’t invite an at-event forced decision. I’m sure some of you can come up with subtler strategies, but I still recommend that you make your strategy decision well before the Q&A window closes on your next event.
  3. Have a traditional wire tether handy. Just in case. And if you’re using a subtle strategy, make contingency plans.

Ours was probably separated by at least 100 feet with two walls between. No chance of leakage. And with the new rules, wireless is intended to be used on the practice field.

To which new rules are you referring?

Someone quoted E304 above.

Which requires you to use a DIFFERENT radio than the one you already have on your robot.

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“Most” may be a bit hyperbolic, but nearly every regional event I’ve been to (and I’ve run volunteer schedules that have nearly rivaled that of the great @Koko_Ed) have had some/all of the pits on the opposite side of a production curtain from the field. District events are hit or miss due to the (typically) smaller venues.

There are a number of solutions but most would not be suitable in an FRC environment. Here are some options that I looked into for other projects. You might be able to get a LoRa system to work and maybe be legal. There is also the idea of using a 4G router/hub and VPNing into the robot but that does not sound like a good idea. I would consider all of these solutions to not be ideal and would need work just to be able to test. Hopefully, it is a decent starting point (if you want to make it a project).

Let me restate none of these ideas are tested or even good ideas. Just wanted to add to the discussion. To directly answer your question, No. No one has found a good way of communicating with the robot wirelessly when restricted by the rules at a competition.

As pointed out by bovlb, the rules restrict it completely. Take E303 and E304 in conjunction:

Tethered operation outside FIELDS/Practice FIELDS. ROBOTS may only be operated by tether when outside the FIELD or Practice FIELD.

Practice FIELD wireless via event radios only. If operating wirelessly on the Practice FIELD, ROBOTS must use one of the provided Practice FIELD radios for communication.

There’s no provision here made about spectrum, protocol, etc. When not on a field, you must be wired. When on the practice field, you must use an event-provided practice field radio or be wired. There’s no room to lawyer it.