GMRS - General Mobile Radio Service
The Engineering Web
General Mobile Radio Service
GMRS has been around for many many years. Before about 1989, individuals and organizational entities could obtain licenses to operate this band. This changed around 1989 so that only individual people can obtain licenses. However, all previous licensees were grandfathered in. Thus, GMRS today contains elements of the old school, plus the new.
If you are reading this you probably do not care about the old school and are only interested in what GMRS has to offer for your basic communication needs. In support of this, we will only concern ourselves here with GMRS as you find it hanging on the wall of your local Home Depot or Wal-Mart.
For completeness references to previous GMRS jargon like Interstitial, Lower 550, Upper 600, etc. are included. However, you really only need to pay attention to the "Well Known Channel" the radio manufacturers like Cobra, Uniden, Midland, etc. seem to have agreed on. Namely, FRS only radios have channels 1-14 (and have their channels clearly defined by the FCC regulation 95.627) and GMRS/FRS hybrids have 1-22.
Look at this chart to see what I mean:
|1||Interstitial 5625||462.5625 MHz||Also FRS Channel 1||5.0 Watts|
|2||Interstitial 5875||462.5875 MHz||Also FRS Channel 2||5.0 Watts|
|3||Interstitial 6125||462.6125 MHz||Also FRS Channel 3||5.0 Watts|
|4||Interstitial 6375||462.6375 MHz||Also FRS Channel 4||5.0 Watts|
|5||Interstitial 6625||462.6625 MHz||Also FRS Channel 5||5.0 Watts|
|6||Interstitial 6875||462.6875 MHz||Also FRS Channel 6||5.0 Watts|
|7||Interstitial 7125||462.7125 MHz||Also FRS Channel 7||5.0 Watts|
|15||Lower 550||462.5500 MHz||GMRS Only||50.0 Watts|
|16||Lower 575||462.5750 MHz||GMRS Only||50.0 Watts|
|17||Lower 600||462.6000 MHz||GMRS Only||50.0 Watts|
|18||Lower 625||462.6250 MHz||GMRS Only||50.0 Watts|
|19||Lower 650||462.6500 MHz||GMRS Only||50.0 Watts|
|20||Lower 675||462.6750 MHz||GMRS Only||50.0 Watts|
|21||Lower 700||462.7000 MHz||GMRS Only||50.0 Watts|
|22||Lower 725||462.7250 MHz||GMRS Only||50.0 Watts|
|550||Upper 550||467.5500 MHz||Typically GMRS Repeater Input||50.0 Watts|
|575||Upper 575||467.5750 MHz||Typically GMRS Repeater Input||50.0 Watts|
|600||Upper 600||467.6000 MHz||Typically GMRS Repeater Input||50.0 Watts|
|625||Upper 625||467.6250 MHz||Typically GMRS Repeater Input||50.0 Watts|
|650||Upper 650||467.6500 MHz||Typically GMRS Repeater Input||50.0 Watts|
|675||Upper 675||467.6750 MHz||Typically GMRS Repeater Input||50.0 Watts|
|700||Upper 700||467.7000 MHz||Typically GMRS Repeater Input||50.0 Watts|
|725||Upper 725||467.7250 MHz||Typically GMRS Repeater Input||50.0 Watts|
It all boils down to simply this. If you do not want to pay $80 to the FCC for a GMRS license, either get a FRS radio and use any channel you like or get a GMRS/FRS radio combo hybrid and only use channels 8-14.
If your people can't follow this rule, then don't get them GMRS radios or have them all get their own GMRS license.
Reprinted with permission from Astronomy Net