GMRS

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General Mobile Radio Service

GMRS (and by extension, FRS) evolved out of the original 465 MHz "Class A" CB service. Calling frequency 462.675 MHz CTCSS 141.3 Hz (sometimes referred to as the "travel channel" - FRS channel 20). See page for FRS for information about combined FRS/GMRS "bubble pack" radios. As of late 2017, the FCC legalized the 8 "GMRS only" 462 MHz frequencies as part of the FRS service, changing the number of shared frequencies from 7 to 15 and legalizing the use of all 22 channels for simplex use under the FRS rules. GMRS license holders are still granted higher transmit power privileges and use of repeaters under the new rules. See also, the FRS subpage for standardized calling channels, emergency channels, etc.

Maximum power 50 watts on GMRS is except on shared narrow band channels (FRS channels 1-7) where maximum power is 5 watts. Wide band FM (25 kHz or 20K0F3E, 16K0F3E or similar) or narrow band FM (11K2F3E, 11K0F3E and several other emissions with even narrower bandwidths) allowed on the 16 GMRS only frequencies for repeater or simplex use. Low power mobile and portable radios generally use narrow FM for compatibility with other handheld FRS radios aimed at the consumer market.

Like the FRS service, the FCC permits use of digital transmissions on the GMRS service. Digital transmissions are limited to text messages, requests for text messages, group chat messages, in-range location "ping" transmissions to verify that a radio is still within range of another radio (automatic range transponder capability), GPS location transmissions, GPS location requests, etc.

Contents

GMRS Frequencies GMRS Channels

  • Channel 01 - 462.5625 MHz - 5 watt power limit, simplex only
  • Channel 02 - 462.5875 MHz - 5 watt power limit, simplex only
  • Channel 03 - 462.6125 MHz - 5 watt power limit, simplex only
  • Channel 04 - 462.6375 MHz - 5 watt power limit, simplex only
  • Channel 05 - 462.6625 MHz - 5 watt power limit, simplex only
  • Channel 06 - 462.6875 MHz - 5 watt power limit, simplex only
  • Channel 07 - 462.7125 MHz - 5 watt power limit, simplex only
  • Channel 08 - 467.5625 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 09 - 467.5875 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 10 - 467.6125 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 11 - 467.6375 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 12 - 467.6625 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 13 - 467.6875 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 14 - 467.7125 MHz - 0.5 watt power limit, unlicensed FRS simplex
  • Channel 15 - 462.5500 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 16 - 462.5750 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 17 - 462.6000 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 18 - 462.6250 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 19 - 462.6500 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 20 - 462.6750 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 21 - 462.7000 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex
  • Channel 22 - 462.7250 MHz - 50 watt power limit, simplex or repeater output, shared with FRS simplex

Channels 1-22 are shared with the FRS service. FRS users may operate simplex only.

Channels 8-14 are simplex only and limited to 0.5 watt power output. GMRS users may transmit up to 5 watts on 462.5625 MHz, 462.5875 MHz, 462.6125 MHz, 462.6375 MHz, 462.6625 MHz, 462.6875 MHz and 462.7125 MHz (channels 1-7).

Licensed GMRS users and unlicensed FRS users are limited to 0.5 watts on 467.5625 MHz, 467.5875 MHz, 467.6125 MHz, 467.6375 MHz, 467.6625 MHz, 467.6875 MHz and 467.7125 MHz (channels 8-14).

Licensed GMRS users may transmit up to 50 watts on 462.550 MHz, 462.575 MHz, 462.600 MHz, 462.625 MHz, 462.650 MHz, 462.675 MHz, 462.700 MHz and 462.725 MHz (channels 15-22). GMRS users may use these frequencies for simplex (non-repeater) use or as repeater output frequencies. Because of the extensive simplex FRS use of all 22 channels, GMRS users are strongly encouraged to use CTCSS or DCS on any repeater pair and for simplex operations.


GMRS Bandwidth - Deviation "12.5 kHz" NFM and "25 kHz" FM

GMRS license holders (licensed GMRS users) are permitted to use regular 5 kHz deviation FM (16K0F3E emission or 20K0F3E emission - referred to as "25 kHz wideband" or "25 kHz channel" in Motorola literature) on channels 1-7, channels 15-22 and the 8 repeater pairs (output frequencies are, of course, channels 15-22). 5 kHz deviation is often referred to as wideband mode, "WIDE" mode or "FM". Narrowband (12.5 kHz channel) 2.5 kHz deviation - 11K3F3E, 11K2F3E, 11K0F3E emission - "NARROW", "NARR" or "NFM" mode on most radios use is required on channels 8-14 under FCC regulations. Use of narrow mode on channels 1-7 when communicating with FRS units is recommended. Use of narrow mode on all 22 channels is recommended when communicating with FRS units in the simplex (non-repeated) mode.

When using a repeater, generally 5 kHz deviation (wide mode) is used. Check with the repeater owner/operator to see if their repeater is operating in 5 kHz deviation or 2.5 kHz narrowband deviation. There are some advantages to running a GMRS repeater in narrow mode (2.5 kHz deviation). This is especially true in urbanized areas and other locations where the GMRS repeater input frequency is subject to large amounts of adjacent channel interference from simplex activity on channels 8-14.

  • Channel 01 - 462.5625 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 02 - 462.5875 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 03 - 462.6125 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 04 - 462.6375 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 05 - 462.6625 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 06 - 462.6875 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 07 - 462.7125 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 08 - 467.5625 MHz - NFM mode (narrowband) required for all users
  • Channel 09 - 467.5875 MHz - NFM mode (narrowband) required for all users
  • Channel 10 - 467.6125 MHz - NFM mode (narrowband) required for all users
  • Channel 11 - 467.6375 MHz - NFM mode (narrowband) required for all users
  • Channel 12 - 467.6625 MHz - NFM mode (narrowband) required for all users
  • Channel 13 - 467.6875 MHz - NFM mode (narrowband) required for all users
  • Channel 14 - 467.7125 MHz - NFM mode (narrowband) required for all users
  • Channel 15 - 462.5500 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 16 - 462.5750 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 17 - 462.6000 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 18 - 462.6250 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 19 - 462.6500 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 20 - 462.6750 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 21 - 462.7000 MHz - NFM or FM allowed for licensed GMRS users
  • Channel 22 - 462.7250 MHz - NFM or FM allowed for licensed GMRS users

GMRS Repeaters

Ch Output MHz Input MHz
15 462.550 467.550
16 462.575 467.575
17 462.600 467.600
18 462.625 467.625
19 462.650 467.650
20 462.675 467.675
21 462.700 467.700
22 462.725 467.725


GMRS Repeater Tones

Many GMRS repeaters require a CTCSS tone or DCS code to "open" the repeater. The majority of the time, the repeater will transmit that same tone/code on the repeater output, allowing for use of full tone squelch by mobile/portable units associated with the repeater and the added benefit of not having to hear interference from simplex users of the same frequency as the repeater output.

The 141.3 Hz "GMRS travel tone" (associated with GMRS 675 / FRS channel 20 - the GMRS "road channel" and GMRS calling channel is frequently used, as many GMRS users have this tone set by default. However, use of 141.3 Hz by GMRS repeaters is by no means standardized.

Just like with simplex-only FRS, there are some tone/frequency combinations which should be avoided to reduce the chance of interference from FRS simplex users on the same frequency. See the FRS page for more detailed information.


GMRS Channel Names Frequency Designators

Many GMRS users refer to the wide band GMRS frequencies by the three digits after the frequency in MHz notation:

  • GMRS 550 - 462.5500 MHz
  • GMRS 575 - 462.5750 MHz
  • GMRS 600 - 462.6000 MHz
  • GMRS 625 - 462.6250 MHz
  • GMRS 650 - 462.6500 MHz
  • GMRS 675 - 462.6750 MHz
  • GMRS 700 - 462.7000 MHz
  • GMRS 725 - 462.7250 MHz

However, the FRS channel numbers are also frequently used, since all 22 channels may be used in simplex mode:

  • 462.5500 MHz - Channel 15
  • 462.5750 MHz - Channel 16
  • 462.6000 MHz - Channel 17
  • 462.6250 MHz - Channel 18
  • 462.6500 MHz - Channel 19
  • 462.6750 MHz - Channel 20
  • 462.7000 MHz - Channel 21
  • 462.7250 MHz - Channel 22

Resources and Further Reading:

List of Grandfathered GMRS Users Licenses - Grandfathered GMRS Entities by Zip Code

MyGMRS.com GMRS user resource

MyGMRS.com GMRS repeater listing - GMRS repeaters nationwide

ArtSci Publications - nationwide amateur and GMRS repeater listing



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