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Encyclopedia > General Mobile Radio Service
GMRS capable handheld radio
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. Image File history File linksMetadata Size of this preview: 284 × 598 pixel Image in higher resolution (792 × 1668 pixel, file size: 894 KB, MIME type: image/jpeg) GMRS capable radio. ... Image File history File linksMetadata Size of this preview: 284 × 598 pixel Image in higher resolution (792 × 1668 pixel, file size: 894 KB, MIME type: image/jpeg) GMRS capable radio. ... This article is about the radio frequency. ...


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. The Family Radio Service is an improved walkie talkie system authorized in the United States. ... Recreational, toy and amateur radio walkie talkies A walkie-talkie or two-way radio is a hand-held portable, bi-directional radio transceiver. ...


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.

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 (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 The FCCs official seal. ... The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ... The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ...


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.


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. A simplex communication system is one where all signals flow in one direction. ...

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. The Family Radio Service is an improved walkie talkie system authorized in the United States. ...

Name Frequency (MHz) Motorola convention Icom F21-GM convention Notes
"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.


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 United States, the Office of Management and Budget (OMB) has produced a formal definition of metropolitan areas, which are organized around county boundaries. ... A typical CB base station. ... HF or Hf might be an acronym or abbreviation for: High frequency Radio hafnium, a chemical element the chemical formula for Hydrofluoric acid Historisk-filosofisk fakultet, abbr. ...


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. Two GSM mobile phone base stations disguised as trees in Dublin, Ireland. ...


See also

Ham radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Ham radio station with vintage vacuum tube gear featuring separate transmitter, receiver and power supply Amateur radio, often called Ham radio, is a hobby and public service enjoyed by about 6 million people throughout the world. ... The Family Radio Service is an improved walkie talkie system authorized in the United States. ... The Multi-Use Radio Service (MURS) is a small two-way radio service consisting of five frequencies in the VHF spectrum. ...

External links


  Results from FactBites:
 
General Mobile Radio Service - Wikipedia, the free encyclopedia (617 words)
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 and his or her immediate family members, including a spouse, children, parents, grandparents, aunts, uncles, nephews, nieces, and in-laws (47 CFR 95.179).
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.
Mobile units, base stations and repeaters are not currently permitted on the GMRS channels in Canada.
Two-way radio - Wikipedia, the free encyclopedia (362 words)
Two-way radios are also available in mobile and base configurations.
An example of a two-way radio that both transmits and receives at the same time (or full-duplex) is a mobile phone or cellular telephone, which uses two different radio frequencies to carry the two directions of the conversation simultaneously.
The business band radio service uses the same VHF frequency ranges as MURS, and the same UHF frequency ranges as GMRS and FRS.
  More results at FactBites »


 
 

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