General Mobile Radio Service
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(Redirected from GMRS)
The FCC Personal Radio Service rules changed effective September 28, 2017 and some of the information in this article is now obsolete. For more information see:
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. 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 most of the 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 FCC Part 95 certified. They are more expensive than the walkie talkies typically found in discount electronics stores, but are higher quality.
- See FRS/GMRS combined channel chart for power and bandwidth limits.
The "Friendly Name" of a frequency is the portion of the frequency to the right of the decimal. Here is the raw listing of frequencies from the database.
|462.55000||467.55000||RM||GMRS 462.5500||462.5500 Simplex/Repeater||FM||Other|
|462.57500||467.57500||RM||GMRS 462.5750||462.5750 Simplex/Repeater||FM||Other|
|462.60000||467.60000||RM||GMRS 462.6000||462.6000 Simplex/Repeater||FM||Other|
|462.62500||467.62500||RM||GMRS 462.6250||462.6250 Simplex/Repeater||FM||Other|
|462.65000||467.65000||RM||GMRS 462.6500||462.6500 Simplex/Repeater||FM||Other|
|462.67500||467.67500||RM||GMRS 462.6750||462.6750 Simplex/Repeater||FM||Other|
|462.70000||467.70000||RM||GMRS 462.7000||462.7000 Simplex/Repeater||FM||Other|
|462.72500||467.72500||RM||GMRS 462.7250||462.7250 Simplex/Repeater||FM||Other|
Recognized Channel Usage
The now-defunct PRSG and Popular Wireless Magazine adopted CTCSS 141.3 Hz as the national travel tone for use on all GMRS channels. We have no idea 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 and calling channel. FRS radios operate with very little power and FRS in urban areas is nothing but congested anarchy.
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.
In the 2000s, the proliferation of "hybrid" FRS/GMRS radios has created a serious problem for GMRS licensees. These mass-marketed radios have wreaked havoc on the frequencies. Most purchasers of these cheap, low-quality radios have disregarded the license requirements. Many licensees believe this will create a similar situation to that of 27 MHz CB radio. FCC enforcement actions against unlicensed users is common, however, the sheer numbers of illegal operations has proved overwhelming.
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. For more information see RSS-210 Annex E and SP 462/467 MHz.
Use of GMRS equipment in other countries
The use of radio transmitters is regulated by national laws and international agreements. Often radio equipment accepted for use in one part of the world may not be operated in other parts due to conflicts with frequency assignments and technical standards. Some of the roles that the licensed GMRS service fills in the United States are, in other countries, filled by unlicensed or class-licensed services. Generally these services have strict technical standards for equipment to prevent interference with licensed transmitters and systems.
Other countries have personal radio services with somewhat similar characteristics, but technical details and operating conditions vary according to national rules. For more information see the wikipedia.com article Personal radio service.
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