General Mobile Radio Service

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GMRS capable handheld radio

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 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.

Although the introductory paragraph (as taken from the FCC website) would seem to exclude communications with others that are not part of one's immediate family, the license actually extends privileges of the primary licensee to include communications with the licensee's immediate family members, and authorizes immediate family members to use the licensees station(s) to conduct the activities of the licensee.

Additionally, the FCC rules for GMRS state: "A GMRS license authorizes a GMRS station to transmit messages to other GMRS stations at any geographical location within or over the territorial limits of any area where radio services are regulated by the FCC". This means that GMRS licensees are also allowed to communicate with other licensees in the wider GMRS community. Futher, the FCC has clarified that GMRS licensees are allowed to communicate with FRS users on those frequencies that are shared between the two services.

Other countries have personal radio services with somewhat similar characteristics, but technical details and operating conditions vary according to national rules.

1 Interstitial Frequencies
2 Frequency Chart
3 History
4 GMRS in Canada
5 See also
6 External links

[edit] 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 (although 1 to 4 watts 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. http://www.provide.net/~prsg/part95ae.htm

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 http://www.popularwireless.com are working to solve this problem by encouraging GMRS enforcement.

[edit] 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	Icom F21-GM convention	Notes
"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	Use not permitted near the Canadian border.
"675"	462.675	467.675	Ch. 20	Ch. 6	Nationwide emergency and road information calling. Nationally recognized coded squelch for 675 emergency repeater operation is 141.3 Hz.
"700"	462.700	467.700	Ch. 21	Ch. 7	Use not permitted near the Canadian border.
"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: 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 but you are more likely to attract attention on more frequencies. You can make the travel tone system work by setting one or more of your base-station frequencies to the 141.3 Hz tone. Remember when people use a Travel Tone, they don't necessarily go alone.

Some groups have been pushing FRS channel 1 as an emergency/calling channel. FRS radios operate with very little power and FRS in urban areas is nothing but congested anarchy.

[edit] History

GMRS, General Mobile Radio Service, was originally named Class A Citizens Radio Service when it was rolled out in the 1960s. Tube type transceivers were used and output power was limited to 60 watts plate input power to the final amplifier tube. The original service ran wideband FM with ±15 kHz transmitter deviation and 50 kHz channel spacing. At the time, this was the norm for all U.S. land mobile services. There was also a Class B Citizens Radio Service which used a different set of 461 MHz channels and was limited to 5 watts output. Business users were permitted to license in this radio service. Radios were built by consumer electronics firms and commercial two-way radio vendors.

In the 1960s, the UHF 450-470 MHz band was ordered reallocated to 25 kHz channels. This meant transmitter deviation was reduced to ±5 kHz. This doubled the number of channels available across the entire 450-470 MHz band. Class B Citizens Radio Service channels were re-allocated to other radio services.

In the 1970s, allowed power was again changed to 50 watts across the output terminals of the transmitter. In the 1980s, licensing of business users was discontinued and businesses were allowed to continue operating until their licenses expired. There was congestion on all channels in larger metropolitan statistical areas and moving businesses to Business Radio Service channels would provide some relief. The radio service was changed to its present name. Repeaters began to proliferate in the 1980s after the prevalence of unlicenced operations in the Class D Citizens Band made HF CB radios unusable in many applications.

[edit] 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 (permanently mounted in vehicles), base stations and repeaters are not currently permitted on the GMRS channels in Canada.