Wednesday, October 08, 2008

Project 25 and Ham Radio

The next article in September's QST (which I am now officially behind on, insofar as October's arrived last week) to inspire comment is Mike Kionka's (KI0GO) article on Project 25 and its use in amateur radio.

Project 25, also known as P25, APCO25, or just APCO, is a digital voice "standard" widely used in public service radio.  There are no direct sources for Project 25 radios for amateur use, so a ham wishing to use one will have to reprogram a public service or commercial radio; these radios are expensive to purchase new, and (as Mike points out) often of questionable history when purchased used.  Also, because Project 25 uses DVSI's IMBE codec, there's no option to homebrew a radio, nor is there any way to augment a generally available FM HT or mobile with P25 capability.  Some scanners do contain an IMBE chip, which permits them to receive, but obviously not transmit, Project 25 communications.  As far as I know there is no equivalent to the "DV Dongle" for IMBE.

Playing with Project 25 is likely appealing to those hams who are radio techs in their "day job" and have easy access to the appropriate programming tools and have reason to want to interoperate with other Project 25 systems, or, perhaps, use their "day radio" as a ham radio as well so they don't have to carry two radios.  It seems to me that using P25 on ham bands creates a walled garden, tying up valuable bandwidth with communications that most people won't be able to receive successfully unless they can get their hands on one of these expensive radios.  I certainly understand the desire to play with any technology you can get your hands on, but really this isn't all that useful to amateur radio in the long term and so I really don't want to see this sort of thing spread. 

As mentioned above, Project 25 uses the IMBE codec, which means it's based on a closed standard locked up tight behind restrictive patent licensing that deeply limit interoperability and experimentation.  The fact that the standard is closed dramatically impairs innovation, as this discussion on the gnuradio list amply evidences.  In this particular case the fact that IMBE is a closed, secret standard effectively prevents someone from developing a new technology that would both advance radio communication technology and benefit emergency communications, both specific aims of the amateur radio service (although I don't think the individual in question is actually a ham).  It's unfortunate that the public service people have made the mistake of adopting a closed standard (gee, I wonder how that happened?), but that's no reason why the amateur radio service should repeat that mistake. 

Because the use of closed standards like Project 25 is antithetical to the goals of the amateur radio service, I would strongly oppose the coordination of any Project 25 (or D*STAR, for that matter) repeaters simply because the voice protocol used is nonopen.  Frankly, I think the use of a nonopen codec violates at least the spirit, if not the letter, of FCC regulations.  We're not allowed to transmit data using an unspecified encoding except under very specific conditions; the only reason Project 25 and D*STAR are legal on the amateur bands is the FCC regulation in question doesn't apply to voice modes, and the FCC's outdated mentality about voice and data preserves a distinction between the two that died years ago with convergence.  This problem is seen in all aspects of the FCC's regulatory milieux, not just in the regulation of amateur radio.  Neither the FCC nor Congress have come to grips with the simple fact that voice is data.

At the most, coordinators should set aside a small section of uncoordinated bandwidth for digital repeaters to use, similar to the way many set aside a frequency pair or two for uncoordinated temporary repeaters, and tell them to sort out their difficulties on their own.  We need to encourage the development of open digital voice standards, not make excuses for perpetuating existing closed ones just because they already exist.