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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 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.

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

Contents

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. Part95 Rules on Provide net

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 GMRS.net and Popular Wireless.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. Here is the raw listing of frequencies from the database;


Frequency  Type  Alpha Tag  Description  Mode  Tag 
462.55000  BM  GMRS462.5500 Common Use or Repeater Output  FM  Other 
462.56250  BM  GMRS462.5625 Common Use (shared with FRS)  FM  Other 
462.57500  BM  GMRS462.5750 Common or Repeater Output  FM  Other 
462.58750  BM  GMRS462.5875 Common Use (shared with FRS)  FM  Other 
462.60000  BM  GMRS462.6000 Common or Repeater Output  FM  Other 
462.61250  BM  GMRS462.6125 Common Use (shared with FRS)  FM  Other 
462.62500  BM  GMRS462.6250 Common or Repeater Output  FM  Other 
462.63750  BM  GMRS462.6375 Common Use (shared with FRS)  FM  Other 
462.65000  BM  GMRS462.6500 Common or Repeater Output  FM  Other 
462.66250  BM  GMRS462.6625 Common Use (shared with FRS)  FM  Other 
462.67500  BM  GMRS462.6750 Common or Repeater Output  FM  Other 
462.68750  BM  GMRS462.6875 Common Use (shared with FRS)  FM  Other 
462.70000  BM  GMRS462.7000 Common or Repeater Output  FM  Other 
462.71250  BM  GMRS462.7125 Common Use (shared with FRS)  FM  Other 
462.72500  BM  GMRS462.7250 Common or Repeater Output  FM  Other 
467.55000  BM  GMRS467.5500 Common Use and/or Repeater Input  FM  Other 
467.57500  BM  GMRS467.5750 Common Use and/or Repeater Input  FM  Other 
467.60000  BM  GMRS467.6000 Common Use and/or Repeater Input  FM  Other 
467.62500  BM  GMRS467.6250 Common Use and/or Repeater Input  FM  Other 
467.65000  BM  GMRS467.6500 Common Use and/or Repeater Input  FM  Other 
467.67500  BM  GMRS467.6750 Common Use and/or Repeater Input  FM  Other 
467.70000  BM  GMRS467.7000 Common Use and/or Repeater Input  FM  Other 
467.72500  BM  GMRS467.7250 Common Use and/or Repeater Input  FM  Other 


The following is an applications use chart. Channels 15-20 show the split frequency pairs used in duplex operational mode, often used with repeaters. Simplex or so-called talk-around mode only utilizes the 'Lower Freq' values.

Name Lower Frequency (MHz) Upper Frequency Motorola convention Notes
"550" 462.5500467.5500 Ch. 15
"5625" or "FRS 1" 462.5625 467.5500 Ch. 1 shared with FRS, simplex only
"575" 462.5750467.5750 Ch. 16
"5875" or "FRS 2" 462.5875 467.5876 Ch. 2 shared with FRS, simplex only
"600" 462.6000467.6000 Ch. 17
"6125" or "FRS 3" 462.6125 467.6125 Ch. 3 shared with FRS, simplex only
"625" 462.6250467.6250 Ch. 18
"6375" or "FRS 4" 462.6375 467.6375 Ch. 4 shared with FRS, simplex only
"650" 462.6500467.6500 Ch. 19 Use not permitted near the Canadian border.
"6625" or "FRS 5" 462.6625 467.6625 Ch. 5 shared with the FRS, simplex only
"675" 462.6750467.6750 Ch. 20 Nationwide emergency and road information calling. Nationally recognized coded squelch for 675 emergency repeater operation is 141.3 Hz.
"6875" or "FRS 6" 462.6875 467.6875 Ch. 6 shared with FRS, simplex only
"700" 462.7000467.7000 Ch. 21 Use not permitted near the Canadian border.
"7125" or "FRS 7" 462.7125 467.7125 Ch. 7 shared with FRS, simplex only
"725" 462.7250467.7250 Ch. 22


See also FRS/GMRS combined channel chart

Note: PRSG and the now-defunct 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.

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.

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.

The Future: It is the opinion of many, and FCC insinuations have arrived at the conclusion that GMRS will eventually no longer require a license. Repeaters will be disallowed and the repeater input frequencies will be added to the general use frequencies making 29 channels available.

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.

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 licensed and unlicensed 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 446 MHz known as PMR446.


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