[chirp_users] GMRS Channel Locking

Chris Romp chrisromp+chirp at gmail.com
Mon Feb 21 14:59:29 PST 2022

Oops, broke my hyperlinks:

47 CFR Part 95B §95.563 "FRS Channels" (link
47 CFR Part 95E §95.1763 "GMRS Channels" (link

On Mon, Feb 21, 2022 at 1:43 PM Chris Romp <chrisromp at gmail.com> wrote:

> Hello,
> I have a question about how CHIRP handles GMRS radios, e.g. BTech GMRS V1
> and Retevis RB26. I've noticed that CHIRP enforces that GMRS channels
> follow the FRS channel number and frequency pairings, e.g. Channel 1 is
> 462.5625, Channel 18 is 462.625, etc.  I've been trying to find in the FCC
> regs if this mapping is a requirement of GMRS operation. The only place
> I've found the channels spelled out is on 47 CFR Part 95B §95.563 "FRS
> Channels" (link
> <https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-B/section-95.563>),
> but GMRS seems only to specify the frequencies and bandwidth which may be
> used via Part 95E §95.1763 "GMRS Channels" (link
> <https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-95/subpart-E/section-95.1763>).
> It's entirely possible that I've missed the clause requiring this mapping,
> and I am not a lawyer, so apologies if I've overlooked it.
> When I am programming a GMRS radio, I don't always want what my family
> refers to as our "channel 1" to be 462.5625.  Likewise I may want to set up
> different repeaters that may use the same frequencies, but different tones
> (especially on radios where I cannot edit the tone from the radio itself)
> I am able to program the RB26 to accept an alternate GMRS-legal frequency
> with a little trickery, so there does not seem to be a firmware restriction
> enforcing this and it hasn't bricked my radio (yet).
> Would it be possible for CHIRP to accept GMRS-legal frequencies in any
> channel slot, and not require the FRS channel-frequency mapping?
> Thank you,
> Chris Romp
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