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Difference between revisions of "General Mobile Radio Service"

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**[http://wireless.fcc.gov/services/personal/generalmobile/ GMRS Specifications and U.S. Licensing Info]
 
**[http://wireless.fcc.gov/services/personal/generalmobile/ GMRS Specifications and U.S. Licensing Info]
 
**[http://wireless.fcc.gov/services/index.htm?job=service_bandplan&id=general_mobile GMRS Band Plan]
 
**[http://wireless.fcc.gov/services/index.htm?job=service_bandplan&id=general_mobile GMRS Band Plan]
** [http://edocket.access.gpo.gov/cfr_2008/octqtr/47cfr95.627.htm GMRS frequencies from 47CFR95.627]
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** [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=b92e83e1889f31134420d08785acc5f5&rgn=div8&view=text&node=47:5.0.1.1.5.5.147.8&idno=47 GMRS frequencies from 47CFR95.627]
  
 
*[http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08478e.html#annex6 Industry Canada: FRS & GMRS specifications in Canada]
 
*[http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08478e.html#annex6 Industry Canada: FRS & GMRS specifications in Canada]

Revision as of 20:01, 24 October 2010

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.

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.

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 Notes
"550" 462.550 467.550 Ch. 15
"575" 462.575 467.575 Ch. 16
"600" 462.600 467.600 Ch. 17
"625" 462.625 467.625 Ch. 18
"650" 462.650 467.650 Ch. 19 Use not permitted near the Canadian border.
"675" 462.675 467.675 Ch. 20 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 Use not permitted near the Canadian border.
"725" 462.725 467.725 Ch. 22

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 Notes
"5625" or "FRS 1" 462.5625 Ch. 1
"5875" or "FRS 2" 462.5875 Ch. 2
"6125" or "FRS 3" 462.6125 Ch. 3
"6375" or "FRS 4" 462.6375 Ch. 4
"6625" or "FRS 5" 462.6625 Ch. 5
"6875" or "FRS 6" 462.6875 Ch. 6
"7125" or "FRS 7" 462.7125 Ch. 7

See also FRS/GMRS combined channel chart

Note: PRSG and Popular Wireless Magazines 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.


See also

External links