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The General Mobile Radio Service (GMRS) is a land-mobile UHF radio service in the United States available for short-distance two-way communications to facilitate the activities of an adult individual who possesses a valid GMRS license, as well his or her immediate family members, including a spouse, children, parents, grandparents, aunts, uncles, nephews, nieces, and in-laws (47 CFR 95.179). Immediate relatives of the GMRS system licensee are entitled to communicate among themselves over the general area of their residence or during recreational group outings, such as camping or hiking.
GMRS radios are typically handheld portable devices much like Family Radio Service (FRS) radios, and share some frequencies. Mobile and base station-style radios are available as well, but these are normally commercial UHF radios often used in the public service and commercial land mobile bands. These are perfectly legal and their use is encouraged as long as they are GMRS type-approved. They are more expensive than the walkie talkies typically found in discount electronics stores, but are higher quality.
Interstitial Frequencies
There are 7 "interstitial" channels shared with Family Radio Service, and 8 channels exclusively for GMRS. GMRS use requires an FCC license in the US, and licensees are permitted to transmit at up to 50 watts on GMRS frequencies (1 to 4 is more common), as well as have detachable antennas. GMRS licensees are also able to use the first 7 FRS frequencies (the "interstitial" frequencies), but at the lower 5 watt maximum power output, for a total of 15 channels. Radios programmed for GMRS may also use repeater systems. FRS channels 8 through 14 are not available for GMRS use; use of these frequencies requires an FRS transceiver.
Recently, hybrid FRS/GMRS consumer radios have been introduced that have 22 channels, instead of the 14 channels associated with FRS. On this type of radio, only channels 8-14 are strictly license-free FRS channels: Transmitting on all channels above channel 14 requires a license, and transmitting on the shared FRS/GMRS channels 1-7 also requires a license if, as is the usual case, the effective radiated power of the radio is greater than 500 milliwatts (1/2 watt). It is the responsibility of the radio user to read and understand all applicable rules and regulations regarding GMRS.
The requirement for GMRS licensing in the USA is not followed by many users of these frequencies. Nonetheless, there are over 80,000 GMRS licensees. Reports of GMRS enforcement are encouraging. However, enforcement against individuals is rare, if ever attempted. This has led to a lot of consternation among the "non-bubble-pack" segment of the GMRS user population, who have significantly more expensive equipment, and have paid approximately $80 for a license. Online communities such as www.gmrs.net.tc and www.popularwireless.com are working to solve this problem by encouraging GMRS enforcement.
Frequency Chart
The "Friendly Name" of a frequency is the portion of the frequency to the right of the decimal.
This first set of frequencies shows the split frequency pairs used in duplex operational mode, often used with repeaters. Simplex (talk-around) mode only utilizes the 'Lower Freq' values.
| Name | Lower Frequency (MHz) | Upper Frequency | Motorola convention |
|---|---|---|---|
| "550" | 462.550 | 467.550 | ch 15 |
| "575" | 462.575 | 467.575 | ch 16 |
| "600" | 462.600 | 467.600 | ch 17 |
| "625" | 462.625 | 467.625 | ch 18 |
| "650" | 462.650 | 467.650 | ch 19 |
| "675" | 462.675 | 467.675 | ch 20 |
| "700" | 462.700 | 467.700 | ch 21 |
| "725" | 462.725 | 467.725 | ch 22 |
This second set of frequencies shows the interstitial ranges shared with the Family Radio Service services. These frequencies can only be used for simplex operations.
| Name | Frequency (MHz) | Motorola convention |
|---|---|---|
| "5625" or "FRS 1" | 462.5625 | ch 1 |
| "5875" or "FRS 2" | 462.5875 | ch 2 |
| "6125" or "FRS 3" | 462.6125 | ch 3 |
| "6375" or "FRS 4" | 462.6375 | ch 4 |
| "6625" or "FRS 5" | 462.6625 | ch 5 |
| "6875" or "FRS 6" | 462.6875 | ch 6 |
| "7125" or "FRS 7" | 462.7125 | ch 7 |
GMRS in Canada
In Canada, hand-held GMRS radios up to 2 watts have been approved for use since September 2004. Typically these are dual FRS and GMRS units, with fixed antennas, and operating at 2 watts on GMRS and 0.5 watts on the FRS-only channels. A licence is not required in Canada for operation at 2 watts on the GMRS channels. Mobile units, base stations and repeaters are not currently permitted on the GMRS channels in Canada.
See also
External links
- FCC: GMRS Specifications and U.S. Licensing Info
- FRS Band Plan
- GMRS Band Plan
- The Personal Radio Steering Group
- Basic information about GMRS for the average consumer.
- Personal Radio Association.
- Canadian GMRS Information.
- Popularwireless.com GMRS Discussion
- GMRS Radio Information and Forums
"General Mobile Radio Service"