Amateur radio
General Mobile Radio Service
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 for personal or business purposes, but employees of the licensee, who are not family members, may not use this service.
GMRS radios are typically handheld portable devices much like Family Radio Service (FRS) radios, and share some frequencies with FRS. 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 legal for use in this service 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.
Other countries have personal radio services with somewhat similar characteristics, but technical details and operating conditions vary according to national rules. Many European countries use a similar 8 channel system near 446MHz known as PMR446
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 (same frequency for receiving and Transmitting) mode only utilizes the 'Lower Freq' values.
| Name | Lower Frequency/Repeater Output (MHz) | Upper Frequency/Repeater Input | Motorola convention | Icom F21-GM convention |
|---|---|---|---|---|
| "550" | 462.550 | 467.550 | Ch. 15 | Ch. 1 |
| "575" | 462.575 | 467.575 | Ch. 16 | Ch. 2 |
| "600" | 462.600 | 467.600 | Ch. 17 | Ch. 3 |
| "625" | 462.625 | 467.625 | Ch. 18 | Ch. 4 |
| "650" | 462.650 | 467.650 | Ch. 19 | Ch. 5 |
| "675" | 462.675 | 467.675 | Ch. 20 | Ch. 6 |
| "700" | 462.700 | 467.700 | Ch. 21 | Ch. 7 |
| "725" | 462.725 | 467.725 | Ch. 22 | Ch. 8 |
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 | Icom F21-GM convention |
|---|---|---|---|
| "5625" or "FRS 1" | 462.5625 | Ch. 1 | Ch. 9 |
| "5875" or "FRS 2" | 462.5875 | Ch. 2 | Ch. 10 |
| "6125" or "FRS 3" | 462.6125 | Ch. 3 | Ch. 11 |
| "6375" or "FRS 4" | 462.6375 | Ch. 4 | Ch. 12 |
| "6625" or "FRS 5" | 462.6625 | Ch. 5 | Ch. 13 |
| "6875" or "FRS 6" | 462.6875 | Ch. 6 | Ch. 14 |
| "7125" or "FRS 7" | 462.7125 | Ch. 7 | Ch. 15 |
Note: The Personal Radio Steering Group (PRSG) and Popular Wireless Magazines adopted CTCSS 141.3 Hz as the national travel tone for use on all GMRS channels. It is not known how many GMRS licensees have adopted the standard. You can make the travel tone system work by setting one or more of your base-station frequencies to the 141.3 Hz tone.
Some groups have been pushing FRS channel 1 as an emergency/calling channel. FRS radios operate with very little power.
