P25 for Ham Usage?

After having some limited exposure to governmental radio comms in the course of my work, I'm very impressed by the P25 Mode / Protocols that have been implemented over the last few years.... and I wonder if they (or some portions of them) could be applied to Ham Radio. They certainly offer a lot of advantages over our current VHF and UHF analog systems, and could help bring us along technically to a higher standard. Some of the Open Interfaces look especially useful.

Since I've not had any training or read any of the detailed technical data on P25, I have no idea how easy or difficult it might be.... but since many of our radios are software defined, it seems reasonable to me that such an implementation would be a matter of writing the proper software incorporating the modes/ protocols that are applicable. Obviously, as hams we could not use the encryption portions, but there are a number of P25 modes that are not encrypted and could be beneficial to use, especially for use in a disaster situation.

However, this is outside of my area of expertise and I have a few questions related to it:
1. P25 does not appear to be proprietary, but is it otherwise restricted by law for non-governmental use?
2. IS there a hardware component to the implementation that could not be replicated using software only?
3. Has anyone done this.... and I've just not found their web-site yet?
4. Has the protocol been published in a publicly available location so we can examine them for applicability to ham radio?
5. If P25 is not directly usable, would it be possible to create a similar protocol for our own uses, using P25 architecture as a starting point?

Dave
kk4nsf

ps: in case you are not familar with P25, here is the Wikipedia page: https://en.wikipedia.org/wiki/Project_25#P25_open_interfaces

 

If you Google for "P25 amateur radio" you'll find all kinds of discussion on the subject.

 

P25 radios and repeaters have been used by amateurs for many years, the standard is mostly public, the vocoder (IMBE and AMBE depending on Phase I or II) is not. If you want to see a truly open source, digital ham radio project, check out https://teletra.pl/M17/blog/summary

 

P25 talk groups and pi-star mmdvm access
http://www.pistar.uk/p25_reflectors.php

 

Sure. It would be just as easy to implement as DMR, Fusion and DStar. It's just another time division frame definition squeezing the AMBE codec through it that's only interoperable with other radios that apply the same level of P25 standard.

My question is: When is someone going to implement a radio that, through firmware, implements DMR, Fusion, DStar *and* any other digital VHF/UHF digital standard that can be updated with a firmware update and automatically selects the correct protocol upon detection when scanning the frequencies?

 

While that sounds great on paper, in reality, there are licensing issues with the vocoder used in all the modes you mentioned, as well as system registration issues for many - you need to have registered on a system (with an ID or callsign) to be able to access. You can't just "scan, detect, and use".

 

Don't hold your breath for that to happen. Would love to see it and I believe that is the biggest drawback to the digital modes for most. Having to buy different radio's for different modes. They all need to get on the same page!!

 

Or better yet, AR could move to using open-source DV codecs, and the radios could (better) support integration with outboard DV modems that can be field-upgraded by anybody as the open-source DV codecs change and improve. This is what HF digimodes do -- people use outboard software to communicate using whatever digimode software they download from the internet, or invent themselves.

Following the commercial DMR world is a lose-lose proposition for AR.

 

Have a look at https://teletra.pl/M17/blog/summary It uses Codec2 by David Rowe.

 

KV6O DING!
K0EED DING!
KK5JY maybe... that would only require everybody who has bought a DMR radio or a Fusion radio or a DStar radio to scrap 'em.

I refuse to participate in the continued fracturing of hams by buying any radio that ONLY does DMR, or ONLY does Fusion, or ONLY does DStar, or ONLY does P25, or ONLY does...

Peace out.

 

Oh yes, I have done a lot of work with Codec2 -- as have several others. It's promising, and at least it's development in the right direction for the AR service.

 

I tend to agree with you on this one. That is why I'm wondering IF a software based solution could be implemented.... so anybody with a digitally capable radio and a computer could use it.

 

The IMBE vocoder used in P25 is completely out of patent and there is an open source version. (Source: It was introduced in 1993, and more than 20 years has passed, and is listed as legacy on the DVSI website)

 

That's why I prefer a radio that ONLY does analog FM.

 

Occasionally, one of the repeaters that supports Fusion pops up while scanning the bands when I'm in the truck. It usually results in listening to a conversation that is unintelligible or can't be heard over the ambient noise in the cab. The audio levels run up and down and the way the system rebuilds the audio output makes it pretty much worthless to me, while I'm mobile. When parked, the audio is harsh sounding to me. I doubt that I'll ever spend any time using it or DMR or any of the other digitized audio systems for now.