Comment by threemux | Hacker News Reader

Comment by threemux | Hacker News Reader

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While I highly doubt you'd ever get in trouble, data transmissions on GMRS are severely restricted by the FCC. You obviously need the license (though it's just a fee and covers your whole family).

In any case, I'm pretty sure this device is illegal to use for short text messages. It doesn't appear to comply with several of the restrictions on digital emissions in 47 CFR 95.1787(a), namely it appears to have a removable antenna. Removable antennas are fine for regular GMRS use, but not when the device can send digital emissions.

https://www.ecfr.gov/current/title-47/part-95/subpart-E#p-95...

Also I'd be shocked if it enforced the time limits for digital transmissions in software. This leads me to believe it's not actually type-certified for use which then calls into question anything else it does. Caveat emptor.

The antennas on mine don't appear to come off, at least not easily. I read somewhere that they came off on the early models but are now glued.

It does enforce time limits. If I send a message or something that uses digital communication (like gps coordinates), it won't let me send another one immediately after.

Wow I'm surprised - I based my message of the manual on their site which pretty clearly shows a detachable antenna and says nothing about time limits. I wonder if they received something from the FCC saying they can't market a GMRS radio that isn't type-accepted.

Why wouldn’t they comply with tx duration? You don’t want excessively long tx as you can’t rx at the same time. You’ll lose messages.

There is no amount of time that guarantees you won't interfere with another user on a shared channel without time division. Any protocol used has to account for it no matter what.

But discussion of that is irrelevant because the regulation is no more than one every 30 seconds and each one can't be longer than 1 second in duration. This necessarily limits the length of messages you can send or requires more efficient modulation and/or weaker error correction at the tradeoff of worse weak-signal performance.

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