[aprssig] Identifying TX Igates

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Mon Sep 19 11:03:31 CDT 2011

On 9/19/2011 11:39 AM, Bob Bruninga wrote:
> An easy way to check an IGate is to find a mobile Kenwood, Yeasu or other
> two-way APRS messaging device on http://map.findu.com/callsign and then from
> the internet send him a message.  If he gets it, then the nearby IGate is
> 2-way.

An even better way is to run an APRS-IS client on your local machine 
with a validated APRS-IS connection and send a message to the mobile 
from there.  Many clients will indicate that an ack has been received 
(or a reject if the target mobile's inbox is full) back from the target 
device.  That way you're still confident that there's at least one IGate 
within earshot of the mobile that gated your message to RF and some 
(potentially other) IGate gated the ack back to -IS.  And the mobile 
operator didn't have to key in a message to confirm your test, although 
that's always nice to hear as well.

Just because the mobile received the message doesn't mean that it came 
through the "nearby" IGate, but that it came through some -IS to RF 
transmitting IGate with an outbound path sufficient to reach the mobile 
to which the message was addressed AND that the transmitting IGate has 
heard a packet recently enough from said mobile with a short enough used 
path to be considered local.

Remember, you can't fire up a mobile and expect to receive messages 
immediately.  Even a properly configured, transmit-capable -IS to RF 
messaging gate requires having heard packets over RF within a short 
enough time frame (typically 30 minutes) with a short enough used path 
to be considered local.

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

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