[aprssig] APRS IS question

Keith VE7GDH ve7gdh at rac.ca
Sun Nov 11 09:09:11 EST 2007

Andrew VK4TEC

While there are lots of UI-View users on this list, you can get UI-View 
specific help over on the UI-View list.

> If I set my station up like this, will messaging work ?
> APRS Server filter p/VK

This filter will ask the APRS server to send data to you for all VK 


This could be a bad thing. You are telling your UI-View station to transmit 
all messages to all VK stations out on RF whether they are close to you or 
not. Depending on how much messaging goes on in VK land, you cold completely 
saturate the APRS frequency. On the other hand if there is only one message 
to VK stations every 10 minutes, the impact would be minimal.

> How does UI-VIEW or IS for that matter know, where to message me ?
> Is the IS smart enough to know the reverse path for messaging to me ?
> Or is it a case of just broadcast support in VK areas ?

I was going to going to assume you have the APRS server setup done properly, 
but you know what they say about assumptions. Go to SETUP - APRS SERVER 
SETUP and specify one or more port 14580 servers. If you enter one server, 
only that one will be used. (yes, the "rotate" server can also be used.) If 
you specify two servers, the second will be used only if it can't connect to 
the first server. If you enter three or more servers, they will be chosen 
randomly. Enter your APRS validation number. Enable auto reconnect. Put some 
more thought into the filter you are using. Open the gateway. Gate objects. 
Insert station callsign. IMPORTANT - gate local messages. Decide what to do 
about the path. Is VK the only Australian prefix? Did you want to exclude 
data from visiting hams? If you use reverse digi path, the path used for 
outgoing traffic (APRS-IS to RF) will use the reverse digi path used by 
stations that you have heard on RF. If you don't specify this, it will use 
the path set in your station setup... unless you enter something different 
in IGATE.INI. Transmit IGate status. Max silence... 5 mins is as good a 
setting as any. If you haven't received anything from the APRS-IS in five 
minutes, it will reconnect.

Go to FILE- EDIT IGATE.INI and decide whether to use the default path or 
specify a different one. It all comes down to how far apart the IGates are 
and the number of digi hops between them. Set Max Digis to a reasonable 
setting. In populated areas, you might want to gate traffic to "local 
stations" that you heard direct or perhaps via one digi. If it's half a 
dozen hops between IGates in your neck of the woods, perhaps 3-4 would be a 
better setting. In busy areas, success will be very low if you try to get 
messages through multiple digis, but perhaps the frequency is very quiet in 
your area. Enable Show Inet Entry Point Callsign (although this can also be 
set in APRS Server Setup), Do NOT enable gate all RF to INET. Read the help. 
This should not be enabled for a normal IGate, and nothing in your message 
indicated your IGate was something other than a normal IGate. IGate to RF... 
you had asked about beaconing messages to ALL VK stations to RF. This would 
be a bad thing in most locations. Just beacon LOCAL traffic to RF as set on 
the SETUP tab. Local to you could be "heard direct" or via several hops 
away... depending on how many digis it is from you to adjacent IGates. Don't 
enter anything on the INET to RF unless it is really needed. Leave this 
blank unless there is a specific reason to enter something there.

How does the APRS-IS know what to send TO you? When connected to a filtered 
port, this is done in the filter you entered. Your suggested filter would 
only have it send data for all VK stations no matter where in the world they 
were, excluding other prefixes and hams visiting from other countries and so 
on. How does messaging work? A properly set up IGate will send messages to 
LOCAL stations as determined by the setting in your IGATE.INI file. The 
APRS-IS just sends the data to you that you requested. It's up to YOU to set 
your IGate up properly to send traffic to local stations. Why try and beacon 
to RF a message for a station that's a whole continent away from you on the 
other side of Australia? Using your term of "broadcasting support in VK 
areas"... depending on how many messages are sent to VK stations, you could 
make the APRS frequency anywhere from a bit busier than it needs to be to 
completely saturated and unusable for other APRS users within range of your 
station, as determined by the path you are using, or the reverse digi path, 
or from your station setup, or as specified in IGATE.INI.

I'm sure that I'm telling you lots of things that you already know. I know 
you're a pretty smart guy, but your question really makes me thing you 
haven't thought this through properly yet. UI-View has some pretty good help 
built in. Hit F1 for context sensitive help every step along the way. Except 
for a few things like suggested paths which have changed since the help file 
was written, everything else still applies.

73 es cul - Keith VE7GDH
"I may be lost, but I know exactly where I am!"

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