Re: 2 way radio suggestions
I don't want interference, of course. Maybe it's FRS frequencies then that the suppliers are referring to? (GMRS is license-free in Canada, maybe that's why they are suggesting that)
What are your thoughts on the DTR radios vs. other digital radios?
I'm not familiar with the Canadian regulations on radios, so what follows is from a US perspective...
There are 7 frequencies that overlap between GMRS and FRS. FRS is limited to 1/2W, while GMRS has a higher power limit. FRS cannot use detachable antennas. Both of these requirements preclude the use of business-band radios as license-free FRS radios (although MURS is a decent option for license free). GMRS currently requires a license, although that *may* change in the future. GMRS licenses are neither difficult nor expensive to obtain. GMRS units are limited to analog voice, so no digital systems qualify under a GMRS license.
The Motorola DTR series is attractive because it uses FHSS in the 900Mhz ISM band. So no license is required, and sustained interference is highly unlikely. Most other digital systems are using digital encoding to cram voice transmissions into less and less bandwidth so that more channles of voice can be crammed into the same spectrum (sound familiar?). They also typically are using business-babd frequencies, and so a license is required. Note that the business band-licenses are either for a fixed area, in which case frequency coordination typically occurs, or are one one of the itinerant frequencies, of which there are only a handful. So RF interference is a distinct possibility, although the digital modulation scheme will typically prevent the interfereing audio from being decoded by the radio.
I spec'd and used a DTR system a few years back for a technical team traveling the country, and we were quite happy with the radios. Range was adequate (seemed similar to 5W UHF radios), no interference was noted, battery life was exceptional (we managed to fully drain the batteries once, and that was on a 16 hour shift with heavy use), and durability seemed fine. Are they as durable as the more expensive public safety radios? No, but they are certainly better than the cheap FRS toys. On the scale of "consumer, commercial, industrial" these are squarely in the "commercial" realm. I haven't used any other digital systems, so can't comment directly as to a comparison.
