Here - at long last - is an opportunity to share some test results and training we did for the fire company that will directly help you out.

First of all, let me start out with some simple background.

Radio communications can happen with:

Base Equipment - a box plugged into a wall, like any other electronic equipment, usually connected to some large outdoor antenna.

Mobile Equipment - a box mounted in a vehicle and wired into the vehicle's electrical system, and connected to a vehicle-mounted antenna

Portable Equipment - also called "Walkie-Talkie" - a battery powered, hand-held radio communications device.

So, that covered, you have an alphabet soup of radio communications possibilities

CB Radio - citizen's band radio, what the truckers use on the highways. Most commonly used with mobile equipment, occasionally portable or base equipment is used.

FRS - Family radio service - usually portable equipment, occasionally mobile, very, very rarely base stations.

GMRS - General Mobile Radio Service - usually portable equipment, occasionally mobile or base stations.

Note that "Ham" or Amateur radio isn't on this list - that's because Ham radio is not about a particular kind of radio or type of signal, rather it is about the fact that the user is authorized to use certain radio frequencies.

OK, so now we have the equipment defined. Why would you use one kind of equipment over another? Because of the way it transmits and receives a signal.

When you tune into a radio station - say 101.5 FM - what you're doing is selecting a FREQUENCY - the rate of change in an electrical signal.

It's too complicated to get into here in detail, but rate of change in the radio signal - it's Frequency of change - or just Frequency - is measured in units called "Hertz". The more Hertz you have, the more rapidly the signal is changing, and so higher frequencies have more "hertz" - millions of them, in fact. When you tune your FM radio to 101.5 FM - that's 101.500 MEGA (million) hertz.

Now, let's pause for a moment and imagine a stormy summer night. You see a lightning flash far away, and then you hear the rumble of thunder miles and miles away. Now, imagine for a moment that the lightning you just saw set off a car alarm where it struck. You're 10 miles away - you hear the low-pitched thunder just fine, but you won't hear the higher pitched squeal of the car alarm.

In many ways, radio signals act the same way - lower frequencies tend to travel (in radio you call it "propagate") well over longer distances. There are some very interesting and specific ways these long-range signals can be blocked (for example overhead wires, metal buildings) but in open air, it's hard to beat lower frequencies for really long distance point-to-point or broadcast transmissions.

So now, I hope you're getting a hint of why someone might suggest one kind of radio system over another.

Let's start with CB radio.

CB Radio uses radio frequencies in the 27 Megahertz band and transmits using Amplitude Modulation (AM) - just like Shortwave radio stations. In fact, a CB Radio is basically a kind of Shortwave Radio Station, in a manner of speaking. If you've ever noticed, AM radio can travel quite far at night. In Pennsylvania, I routinely hear stations in Canada. You won't get the same range as a massive short-wave base station, but you will occasionally get incredible long-range communications with CB.

FRS and GMRS use radio frequencies in the 400 Megahertz Band and rely on "Frequency Modulation" (or FM) just like your car stereo.

FRS radio does not need a license and is limited to very low output power. GMRS does need a license, but enforcement has basically collapsed. FRS has such low power output that it's useless - no matter what they say on the packaging - over 500 yards under most real-world conditions.

Higher powered GMRS radios - even the so-called "11 Mile" ones rarely did better than a 2 mile radius with any reliability. Over water they work quite a bit better, but hardly do they make 11 miles.

We recently tested, side by side, sets of radios as follows:

CB Radio (Mobile)
FRS Radio
GMRS 5 Watt Portables
46.36 Mhz FM Portables (Motorola) (7 Watt)
154 Mhz Business Band FM Radios (5 Watt)
501 Mhz FM Portables (5 Watt APCO-25 Digital & Conventional Modes)

The testing locations are shown on this map:
http://maps.google.com/maps/ms?ie=UTF8&hl=en&om=1&z=13&ll=40.53833,-75.119877&spn=0.085711,0.136471&msid=117285821921356938461.000001122eb39065215c7&msa=0

The results were fairly consistent - only CB radio was able to reliably reach all of the test points from the station.

FRS Didn't make any of the test points, GMRS made it to test point 1 & 3 - but with poor signal quality.

154 Mhz Business band portables did much better than GMRS, reaching test points 1,2,3,4 with ease.

501Mhz radio made points 1,2,3 in digital mode and 1,2,3 & 4 with poor signal quality in conventional FM mode,

It should be noted that the test was coordinated by cell phone and ham radio, and only ham radio in the 144Mhz Band via a repeater in Frenchtown NJ managed to have a reliable, strong signal throughout the test.

We also attempted test point to test point communications, I don't have the results here, but as I recall, CB and 154 Mhz Business band did good, the 46Mhz radios did fair.

So, to get to the point after all of this - if you know your whole crew is going to be on CB radio, by all means, use a portable CB walkie-talkie. We are going to be installing $100 CB radios in our apparatus, because the $7,000 digital radios in the 501 Mhz band don't work as well.