[aprssig] PSAT & igating and Optimum antenna

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Sun Jun 7 21:57:19 CDT 2015


This is why APRSISCE/32 supports a "NoGate ME" option on it's RF ports.  
If one of it's own beacons is heard back, it is NOT sent to the APRS-IS 
if this option is in force so that the only packets that should show up 
on the APRS-IS are those heard by other IGates.

If anyone sends a messages to an IGate running in this mode, it may be 
gated to RF by other IGates, but for satellite gates, this really isn't 
much of an issue.

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


On 6/7/2015 4:46 PM, Lee Bengston via aprssig wrote:
> It's actually part of an algorithm running on the IS servers that 
> helps facilitate transmit Igating.  In the event that your IGate is 
> beaconing only on RF, the way that other IGates in your area "know" 
> that your station is connected to the Internet is via those beacons 
> that look like they are sent directly to the IS.  Without those "fake" 
> beacons, a nearby IGate would gate a message addressed to your station 
> from IS to RF when it really didn't need to.  So in a nutshell, it's 
> part of a "little scheme" to prevent gating packets from IS to RF when 
> it's not necessary.
>
> I think in the case of your test below, the IS server didn't know the 
> difference between a packet generated by your mobile vs. one generated 
> by your IGate due to using the same SSID.
>
> I'm just the messenger on this one.  :-)
>
> Lee - K5DAT
>
>
> On Sun, Jun 7, 2015 at 2:18 PM, Max Harper via aprssig 
> <aprssig at tapr.org <mailto:aprssig at tapr.org>> wrote:
>
>     Then why does the timestamp on findu match the time the beacon was
>     received back and not the time it was actually sent. I have
>     noticed this behavior many times over the years using various
>     Igate software programs. I can also duplicate the problem anytime.
>
>     Back years ago when I first discovered the problem I did a test. I
>     configured my mobile station to the same ssid as my igate and
>     drove to a digi that was about 25 miles away. Using only a few
>     miliwatts of power I sent some beacons that my igate couldn't hear
>     direct, only the digi. The beacons appeared as if my igate had
>     sent them directly to the aprs-is with no sign of the digi.
>
>     I don't know if it is an igate problem or an aprs-is problem but
>     I see it happen all the time. I can understand it being considered
>     a duplicate, but why does the path get changed and made to look
>     like it was sent direct to the aprs-is when it wasn't? And the
>     example beacon WAS sent out RF only.
>
>     Max KG4PID
>
>
>
>
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