DiveLeader
Earning My Ears
- Joined
- Jan 14, 2003
There seems to be some confusion here over the two way radios, so I thought I'd better clarify.
In America you have FRS and GMRS. For the purposes of my explanation I'll concentrate on FRS.
FRS has 14 channels. These are on set frequencies in the region of 462MHz and 467MHz (actually 462.5625MHz to 462.7125MHz and 467.5625MHz to 467.7125MHz). I must be clear on this there are ONLY 14 frequencies available. There are NOT 532 total channels as an earlier post said.
"Subchannels" that are referred to is actually marketing speak for CTCSS tones. To call them subchannels is actually deliberatly misleading - although apparently common practice.
CTCSS - Continuous Tone Coded Squelch System. This is like a mains hum on the modulation, a constant musical note... almost as if someone is standing by you humming as you talk. The receiver can be set to only open its squelch if this tone is received. Using CTCSS a channel can be shared by many different groups each with their own tone, and each group would not be affected by the others. Transmit with a different tone and another set's receiver will stay quiet unless you change its tone setting to match.
Just to be absolutely clear - you are STILL using the same frequency. Even if you use a "subchannel" a radio without that capability, or with it turned of will receive everyone on that frequency. If someone transmits at the same time as you, you will still interfere with them.
While I'm on the topic - a couple of other points.
Europe has a similar system to FRS, called PMR446. Only 8 channels are available, and each of these is on a different frequency to FRS. If you buy a 2 way radio in Europe, it is not legal in the US. The frequencies are within the Amateur band, so you will be found out (presuming Orlando has radio hams).
Another poster asked about range. Well here's some estimates for PMR446 (borrowed from another web site). I would think FRS is likely to be similar :-
Really trying (!) : miles
High altitude, line of sight 125 or more
Freak conditions past the horizon 100 or more?
Normal use, ground level :
Outside, clear flat terrain 1.5 - 3
Suburban neighborhoods 1 - 1.5
Urban areas & car to car 0.5 - 1
Inside buildings 0.5 or 5 floors
Between buildings 0.12- 0.5 (1/8 - 1/2)
Woodlands, level, moderate vegetation 1 - 1.5
Woodlands, hilly, thick vegetation 0.25- 1
In America you have FRS and GMRS. For the purposes of my explanation I'll concentrate on FRS.
FRS has 14 channels. These are on set frequencies in the region of 462MHz and 467MHz (actually 462.5625MHz to 462.7125MHz and 467.5625MHz to 467.7125MHz). I must be clear on this there are ONLY 14 frequencies available. There are NOT 532 total channels as an earlier post said.
"Subchannels" that are referred to is actually marketing speak for CTCSS tones. To call them subchannels is actually deliberatly misleading - although apparently common practice.
CTCSS - Continuous Tone Coded Squelch System. This is like a mains hum on the modulation, a constant musical note... almost as if someone is standing by you humming as you talk. The receiver can be set to only open its squelch if this tone is received. Using CTCSS a channel can be shared by many different groups each with their own tone, and each group would not be affected by the others. Transmit with a different tone and another set's receiver will stay quiet unless you change its tone setting to match.
Just to be absolutely clear - you are STILL using the same frequency. Even if you use a "subchannel" a radio without that capability, or with it turned of will receive everyone on that frequency. If someone transmits at the same time as you, you will still interfere with them.
While I'm on the topic - a couple of other points.
Europe has a similar system to FRS, called PMR446. Only 8 channels are available, and each of these is on a different frequency to FRS. If you buy a 2 way radio in Europe, it is not legal in the US. The frequencies are within the Amateur band, so you will be found out (presuming Orlando has radio hams).
Another poster asked about range. Well here's some estimates for PMR446 (borrowed from another web site). I would think FRS is likely to be similar :-
Really trying (!) : miles
High altitude, line of sight 125 or more
Freak conditions past the horizon 100 or more?
Normal use, ground level :
Outside, clear flat terrain 1.5 - 3
Suburban neighborhoods 1 - 1.5
Urban areas & car to car 0.5 - 1
Inside buildings 0.5 or 5 floors
Between buildings 0.12- 0.5 (1/8 - 1/2)
Woodlands, level, moderate vegetation 1 - 1.5
Woodlands, hilly, thick vegetation 0.25- 1