Editing General Mobile Radio Service (section)

== Frequency assignments ==
GMRS is allotted 30 frequency channels in the vicinity of 462&nbsp;MHz and 467&nbsp;MHz.  They are divided into 16 main channels and 14 interstitial channels.<ref>{{CodeFedReg|47|95|1763}}</ref>

Licensees may use the eight main 462&nbsp;MHz channels for [[simplex communication]] or [[repeater]] outputs.<ref>{{CodeFedReg|47|95|1763|a}}</ref>

The eight main 467&nbsp;MHz channels may only be used as repeater inputs,<ref>{{CodeFedReg|47|95|1763|c}}</ref> in conjunction with the 462&nbsp;MHz channels as outputs.  The repeater input frequencies are exclusive to GMRS, and may be used only by licensed GMRS operators.

GMRS operators are permitted to transmit at up to 50&nbsp;[[watt]]s [[transmitter power output]], on the 16 main channels,<ref>{{CodeFedReg|47|95|1767}}</ref> but transmitting 1 to 5&nbsp;watts is more common in practice.

The interstitial frequencies are in-between the main channels, and the 462&nbsp;MHz interstitial frequencies may be used for simplex as long as the [[effective radiated power]] (ERP) does not exceed 5&nbsp;watts.<ref>{{CodeFedReg|47|95|1767|b}}</ref>  The 467&nbsp;MHz interstitial frequencies have a power limit of 500&nbsp;milliwatts ERP,<ref>{{CodeFedReg|47|95|1767|c}}</ref> and only hand-held portable units may transmit on these channels.<ref>{{CodeFedReg|47|95|1763|d}}</ref>

=== Sharing with FRS ===
All 22 [[Family Radio Service]] (FRS) frequencies are shared with GMRS, and users of the two services may communicate with each other.  With the exception of FRS channels 8 through 14, GMRS licensees may use higher power radios with detachable or external antennas.

=== Frequency table ===
{| class="wikitable sortable"
|-
! Frequency !! Channel !! FRS power !! FRS<br>bandwidth !! GMRS power !! GMRS<br>bandwidth !! Notes
|-
| 462.5625&nbsp;MHz || 1 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W ||25&nbsp;kHz || (1)(4)(5)
|-
| 462.5875&nbsp;MHz || 2 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W || 25&nbsp;kHz || (1)(4)(5)
|-
| 462.6125&nbsp;MHz || 3 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W || 25&nbsp;kHz || (1)(4)(5)
|-
| 462.6375&nbsp;MHz || 4 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W || 25&nbsp;kHz || (1)(4)(5)
|-
| 462.6625&nbsp;MHz || 5 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W || 25&nbsp;kHz || (1)(4)(5)
|-
| 462.6875&nbsp;MHz || 6 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W || 25&nbsp;kHz || (1)(4)(5)
|-
| 462.7125&nbsp;MHz || 7 || 2&nbsp;W || 12.5&nbsp;kHz || 5&nbsp;W || 25&nbsp;kHz || (1)(4)(5)
|-
| 467.5625&nbsp;MHz || 8 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 467.5875&nbsp;MHz || 9 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 467.6125&nbsp;MHz || 10 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 467.6375&nbsp;MHz || 11 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 467.6625&nbsp;MHz || 12 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 467.6875&nbsp;MHz || 13 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 467.7125&nbsp;MHz || 14 || 0.5&nbsp;W || 12.5&nbsp;kHz || 0.5&nbsp;W || 12.5&nbsp;kHz || (1)(4)(6)
|-
| 462.5500&nbsp;MHz || 15 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 462.5750&nbsp;MHz || 16 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 462.6000&nbsp;MHz || 17 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 462.6250&nbsp;MHz || 18 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 462.6500&nbsp;MHz || 19 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 462.6750&nbsp;MHz || 20 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)(7)
|-
| 462.7000&nbsp;MHz || 21 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 462.7250&nbsp;MHz || 22 || 2&nbsp;W || 12.5&nbsp;kHz || 50&nbsp;W || 25&nbsp;kHz || (2)(5)
|-
| 467.5500&nbsp;MHz || 15R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.5750&nbsp;MHz || 16R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.6000&nbsp;MHz || 17R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.6250&nbsp;MHz || 18R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.6500&nbsp;MHz || 19R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.6750&nbsp;MHz || 20R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.7000&nbsp;MHz || 21R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|-
| 467.7250&nbsp;MHz || 22R || {{n/a}} || {{n/a}} || 50&nbsp;W || 25&nbsp;kHz || (3)(5)
|}

;<!-- Table notes require wikifying with ref tag -->Table notes:(1) Shared FRS and GMRS simplex.<br>(2) Shared FRS and GMRS simplex; GMRS repeater output.<br>(3) GMRS repeater input. The output frequency of this repeater input is the input frequency minus 5 MHz.<br>(4) FRS transmissions are limited to bandwidth of 11 kHz with a transmitter deviation of +/- 2.5 kHz. Channels are on 12.5 kHz centers. <br> (5) GMRS transmissions may have a bandwidth of 16 kHz with a transmitter deviation of +/- 5.0 kHz. Channels are on 25 kHz centers. <br> (6) GMRS transmissions are limited to a bandwidth of 11 kHz with a transmitter deviation of +/- 2.5 kHz. Channels are on 12.5 kHz centers. <br> (7) National GMRS calling channel (CTCSS tone 141.3 Hz).

'''Note:''' Some inexpensive GMRS mobiles and portables do not fully comply with FCC permissible modulation bandwidth for GMRS and thus have weak transmitter audio and reduced range.

'''Conditions:''' Effective February 16, 1999, the GMRS rules have been amended and one may operate on any of the primary or interstitial channels shown in section 95.1763.  Exception: Licensees who operate North of Line A and East of Line C may not operate on channels 462.6500 MHz (channel 19), 467.6500 MHz (channel 19R), 462.7000 MHz (channel 21) and 467.7000 MHz (channel 21R), unless one's previous license authorized such operations.

[[File:GMRS and FRS Frequency Spectrum Chart.svg|thumb|GMRS and FRS radio frequency and power limitations]]

====Bandwidth vs channel spacing====
The FCC stipulates a specific channel bandwidth for FRS and GMRS. The bandwidth is constrained by the modulation which is FM deviation (GMRS = +/- 5.0 kHz, FRS = +/- 2.5 kHz) plus the uncertainties of the filtering of the transmitter and receiver. Additionally receivers and transmitters may drift over time or temperature so the bandwidth is further constrained to prevent interference to the adjacent channel. Channel spacing is 25 kHz for GMRS and so a 20 kHz bandwidth fits into that channel with protection on each side. FRS channels are spaced within a 12.5 kHz space directly between two GMRS channels. FRS radios generally utilize an 11 kHz transmitter bandwidth and a power lower than GMRS so the interference to an adjacent GMRS channel is minimized.