What is GMRS radio?

The General Mobile Radio Service (GMRS) is a land-mobile FM UHF radio service designed for short-distance two-way communication. It requires a license but there is no test.  The licensee, as well as their immediate family members, are allowed to communicate among themselves for personal or business purposes. (Employees of the licensee who are not family members are not covered by the license.)

GMRS radios come in a variety of forms including handheld portable devices like Family Radio Service (FRS) radios. GMRS share a frequency band with FRS near 462 and 467 MHz. Mobile and base station-style radios are available as well. GMRS licensees are allowed to use "Repeaters" to extend the range of their communications.

Any individual in the United States who is at least 18 years of age and not a representative of a foreign government may apply for a GMRS license by completing the application form, online through the FCC's Universal Licensing System. No exam is required! A GMRS license is issued for a 10–year term. The fee is $35.

A single GMRS license covers you and your immediate family (spouse, children, grandchildren, stepchildren, parents, grandparents, stepparents, brothers, sisters, aunts, uncles, nieces, nephews, and in-laws). The family members do not need to live in the same household to be covered by your GMRS License. GMRS license holders are allowed to communicate with FRS users on those frequencies that are shared between the two services. GMRS individual licenses do not extend to employees.

When you get a license, you will be given a callsign consisting of four letters and threee numbers (for example: "WABC123"). Each GMRS station must be identified by the transmission of its FCC-assigned call sign at the end of a transmission or a series of transmissions, and at least once every 15 minutes for a series lasting more than 15 minutes. The call sign may be spoken or sent with audible tones using Morse code. 

As with other UHF radio services, the reliable range is considered to be "line-of-sight" and the distance can be estimated based on antenna height and power. Theoretically, the range between two hand-held units would be about one or two miles; mobile units have higher antennas with more power and a range of around 5 miles. A GMRS Repeater with an antenna that is high above the surrounding area can extend the usable range over a wide area – for example, up to a 40–mile radius or more around the repeater station. Obstructions such as trees, hills and buildings can reduce the range. Higher power does not necessarily give a proportional increase in range, although it may improve the reliability of communication at the limits of line-of-sight distance.

Frequency Assignments:
GMRS is allotted 30 frequency channels in the vicinity of 462 MHz and 467 MHz. They are divided into 16 main channels and 14 interstitial channels.

  • Licensees may use the eight main 462 MHz channels for simplex (talking directly radio to radio) communication or repeater outputs.
  • The eight main 467 MHz channels may only be used as repeater inputs, in conjunction with the 462 MHz channels as outputs. The repeater input frequencies are exclusive to GMRS, and may only be used by licensed GMRS operators.
  • GMRS operators are permitted to transmit at up to 50 watts on the 16 main channels, but transmitting 1 to 5 watts is more common in practice.
  • The interstitial frequencies are in-between the main channels, and they may be used for simplex as long as the transmitter power output does not exceed 5 watts. The 467 MHz interstitial frequencies have a power limit of 500 milliwatts ERP, and they may only be used by hand-held portable units.

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.

(Courtesy, Wikipedia)