Automatic Voice Relay System

One of the reasons why I have not been an enthusiast of the D-Star system is that it creates a separate class of activity incompatible with existing voice modes just for the dubious benefit (from an amateur point of view) of using digital voice instead of analogue. Using EchoLink, IRLP and APRS we already have a global network that allows one ham to contact another anywhere in the world using ham radio, one that does not require anyone to purchase expensive new equipment from Icom or anyone else. What we have not done is put it together in a way that makes it work seamlessly as a coherent network.

Automatic Voice Relay System (AVRS) is an idea by Bob Bruninga, WB4APR, the inventor of APRS, first published in 2000, to create a system that allows users of EchoLink, IRLP and even D-Star to inter-communicate. APRS provides the location and identification information for the analogue FM EchoLink and IRLP users, something that is already built in to the D-Star system. As is often the case, those who have the great ideas don’t always have the skills needed to bring them to fruition, so AVRS remained little more than an idea for ten years.

Now, apparently, a developer has been found who is able and willing to write the software that will enable AVRS version 2 to come into being. You can read more about AVRS here. For seamless one-button operation you will need one of the new generation of APRS-capable radios (Kenwood TM-D710, TH-D72 or Yaesu FTM-350) that are able to QSY to a frequency contained in an APRS packet. Some will argue that if you are going to buy one of those, why not buy a D-Star radio instead? But AVRS capability, being based on APRS, can easily and inexpensively be added to any analogue FM radio. AVRS will not leave analogue FM users out in the cold because their local repeater converted to D-Star, as has happened in some parts of Britain.

One of the interesting aspects of AVRS version 2 is the development of A-Star repeaters. These are analogue FM repeaters with a D-Star gateway that use the D-Star network to link them together. Callsign and location (if known) information is transmitted as a 0.3sec APRS packet burst at the end of each over. A-Star users will appear to D-Star users just like other D-Star users and can easily intercommunicate. A-Star users can initiate a contact with another A-Star or D-Star user just by sending an APRS message starting with A*. A-Star users don’t even need to be monitoring a repeater in order to be contactable: they will receive the message as an ordinary APRS message and can QSY to the repeater (with one button press if using one of the radios mentioned above) using the information contained in it.

AVRS looks like a great idea with the potential to bring digital and analogue voice users together. It might even erode some of the analogue vs D-Star conflict.

Julian Moss, G4ILO, is a regular contributor to AmateurRadio.com and writes from Cumbria, England. Contact him at [email protected].

3 Responses to “Automatic Voice Relay System”

  • Demetre Valaris - SV1UY:

    Amen Julian,

    Unfortunally the vast majority of Radio Amateurs are only interested in Voice Communications without putting any effort to it in order to do something more advanced, such as global networking as Bob suggests with AVRS. All they want is to do is to buy a VHF radio and start talking on the local repeater, and some on HF SSB hunting down DX. They want to buy the radio, connect it to the mains, or battery, connect a microphone to it and start yapping away! To this majority, anything that deviates from CQ DX is heretic!

    Even the APRS fans use APRS to show the rest of the world where they live. They do not even bother to send an APRS message never mind AVRS, or APRN etc. Poor Bob Bruninga has been saying all the time that APRS is not only about position beaconing, but noone seems to listen to him!
    This is the reason why young kids have turned their back to us and prefer the internet instead. It is not Internet that has killed Amateur Radio, it is the lack of enthusiasm from Radio Amateurs who fight against everything new and everything that takes them away from their convenience. If they have to do more than connecting a microphone to a radio they do not like it anymore, never mind about setting up or even supporting or even just using APRS properly.

    Tell me, how many Amateurs carry with them their VX-8 or TH-D7 on a daily basis? Very few I’m afraid!

    73 de Demetre SV1UY

  • John Gorkos AB0OO:

    I’m the “developer” that has been found to move the AVRS project forward, and I’m making good progress.
    All of the source code for the AVRS project is licensed until GPL3, and the whole mess can be found at
    http://sourceforge.net/projects/avrs/
    I welcome other developers to work with me to move the project forward.
    Your blog post is an excellent summary of the idea of using APRS as a signaling channel for voice communications. While I agree that SV1UY makes some points that may be valid for any segment of any ham-radio population, but the experimental spirit is not dead. Change is very slow to come about in amateur radio. We’re nearing the 20 year anniversary of APRS, and we’re just now getting to the critical mass point of deployed equipment to make AVRS really work.
    One of the biggest challenges I face is rekindling the spark of the APRS “early-adopters.” There are hundreds of hams who jumped on the APRS bandwagon early, deploying digipeaters, building nodes, and developing the protocol, but have since “petered-out” and moved on to other modes and other means, leaving aging, incorrectly configured infrastructure in their wake. By demonstrating a fusion of several of the “new” modes (APRS, Echolink/WIRES/IRLP), we put a nice shiny coat of “newness” on something that a sizable segment of the ham-population already has the equipment to take part in.
    Anyway, I appreciate the write-up and look forward to scratching Bob’s 10-year itch for AVRS. All of my updates are made on the TAPR APRSSig, so check it out there.

    de John Gorkos
    AB0OO

  • Andrew M1DNS:

    Hi John
    Well done for taking up the challenge, I do not wish to pour water onto your coals but…..

    I have to agree with the post above by Demetre. Here in Cornwall i run an APRS Digi & Igate, I run a D-Star Repeater, I also have a hand in a D-star gateway, two ana. repeaters 2M & 70Cms and a ATV 1.3 Ghz Repeater.. and today there has been a grand total of 3 QSO’s through all these systems….. when implementing the d-star connections only 3 people were interested in the idea, we are now up to a total of 5. when the aprs system was raised, many of our club members thought it was a great idea ( as a would-be thief could see, from the internet when you weren’t at home ??) We added weather and time info to the ana. repeaters, and echolink to try and bring more users, ( but the weather / time announcements were deemed an irritation and now we have many international voices on our boxes, who go un-answered ) This is the general consensus over an entire county. But we continued with the idea, as we hoped to prove them wrong…….. we are still waiting for the uptake.

    Also, I was under the idea that you would be using echolink / irlp to link this system, if as Julian has reported elsewhere you intend to link through the d-star network, you will have the purists in the reflectors bemoaning the audio quality ( i have experience of this, as i have x- connected the systems and have just about lived too tell about it). As it stands many of the reflector owners will not permit analogue audio onto their systems.

    And finally all dstar rigs have this ability. They are also comparable in price to the Kenwood TM-D710 or Yaesu FTM-350. The rigs operate Digital APRS and also have a messaging option. So why “cobble” something together, when you can purchase a radio with the above availability built in?

    Andrew M1DNS.

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