[aprssig] AVRS Online

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Fri Jan 14 19:19:41 EST 2011

Just tried it from APRSIS32 as KJ4ERJ-AP.

"?" didn't get an answer.  APRSISCE/32 sends all queries (anything that 
starts with a ?) as a non-ack-requested packet.  Hopefully you'll answer 

Sending "KJ4ERJ" from KJ4ERJ-AP sent the following:

KJ4ERJ-AP received "CALL KJ4ERJ-1 on 444.700MHz T77.00 IRLP node 4853"

KJ4ERJ-1 received "VOICE CALL from KJ4ERJ-AP, PSE QSY 444.700MHz T77.00"

The problem is that KJ4ERJ-1 is an unattended W1 Digi/Igate.   I'm 
usually active on KJ4ERJ-12 or KJ4ERJ-AP.

Also, I have no 70cm capability.  It seems that there needs to be a way 
to register acceptable bands for a callsign (which you'd have to 
remember) as well as a (set of) preferred SSIDs for AVRS notification.  
I'm sure I'm not alone in having multiple unattended -SSID stations as 
well as more than one that I might be staffing at any point in time.

So, I send "G6UIM" from KJ4ERJ-AP and AVRS sent:

KJ4ERJ-AP received "CALL G6UIM-12 on 444.700MHz T77.00 IRLP node 4853"

G6UIM-12 received "VOICE CALL from KJ4ERJ-AP, PSE QSY 145.650MHz T94.8"

Interestingly, I was in an APRS messaging QSO from KJ4ERJ-AP to G6UIM 
(no -SSDI) at the time.  I have no idea if he has 2m capability, but the 
same comment from above applies.

So, in summary, initial questions:

a) Does a ? have to request an ack to be answered?

b) I believe you're going to need a way to register and recall 
"preferred" -SSID(s - more than one)) for a callsign.  Or you'll need to 
blast the message out to all "recently" heard -SSIDs for the call.

c) You really can't tell what band an APRS message was received over.  
And even more interesting, many users use one band for APRS and a 
different band for voice.  You either need to send the closest on each 
band as options to be chosen or again, support some sort of registration 
system that allows one (or more) bands to be assigned to a callsign.

d) The "Total path length" doesn't seem like it matters.  I'd really 
like to know my end's distance and maybe an advisory of the other side.  
But the total doesn't affect what's usable, only the power, band, and 
range of one end or the other.

e) T77.00?  How about formatting the tone as specified in the FreqSpec 
documents?  I know it eliminates the decimals, but it's a format that's 
been established, is QSY-able on some radios, and we can train ourselves 
on what to expect.  Unfortunately, EchoLink (I don't know about IRLP) 
doesn't differentiate wide versus narrow band FM so the difference 
between a T and a t (case difference) on the tone spec won't matter (yet).

f) I didn't try it, but what happens if I send in a CALLSIGN-SSID?  Does 
that skip over the auto-SSID selection and only do the station I 
specify?  If so, how would you get the auto-SSID selection to kick in if 
I'm running a non-SSID (-0) station that is also unattended?

If you're ready to get hammered with hits, I'll add an AVRS menu option 
to the station pop-up menu in APRSISCE/32's next release.  It will send 
the base callsign of the selected station (or the entire callsign-ssid) 
to AVRS.  If they select AVRS on "Me" (their own station), it will send 
a ? query for themselves.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

John Gorkos wrote:
> The AVRS responder described at http://aprs.org/avrs.html is online and 
> running, and all code is current in the SourceForge project.  I'll be adding 
> usage information this weekend on the SourceForge page, but the bottom line is 
> pretty easy:
> Message "?" to "AVRS" to get a message with the closest EchoLink OR IRLP node 
> sent back to you, as well as two objects sent to the APRS-IS stream 
> representing the two closest nodes.
> Message CALLSIGN to "AVRS" to initiate a voice-over-Internet link to a distant 
> station.  AVRS will find the best path (EchoLink or IRLP) and send two 
> messages:  one to your target, asking them to QSY to the appropriate frequency 
> and stand by for a QSO with you, and the second message to you telling you to 
> QSY to your closest node and the node number of the distant node you need to 
> bring up.  
> Please give it a try, and email me with any issues or problems.  Right now, 
> the node selection algo uses a "shortest total path" to determine the best 
> node, and doesn't differentiate between nodes based on frequency (i.e. if you 
> ask on the 2m APRS frequency, you may get a 440 node in response).  Total path 
> length is based on distance from you to the closest node plus the distance 
> from your target to his closest node.  
> Target callsign does not need an SSID.  For targets with multiple SSIDs, right 
> now I'm just grabbing the station with the most recent transmission.   I'm 
> working on an algorithm to make the selection based on SSID, stations that are 
> moving, stations that have a history of RF messages, stations that indicate 
> message-capable based on = or @ in their positions, etc.
> I'm also working on the item-in-message format.  Should have that at the end 
> of the weekend, depending on my football-watching schedule and how exiting the 
> games are.
> Again, the source code for all parsers and AVRS logic is at 
> http://sourceforge.net/projects/avrs/
> Since I've never really used EchoLink or IRLP, and don't have any friends 
> anywhere else in the world, I'm a little stymied to actually test this.  
> Please help me.
> de AB0OO
> John Gorkos
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