[aprssig] Airborne Digis

[Gregory A. Carter]

Hi Keith,

I hadn't thought of using: WIDE1-1,WIDE2-1,SAR1-1,WIDE2-1

The only down side to that I can think of would be this scenario:

Tracker TXs: Packet A
Airborne Digi Sees SAR1-1, retransmits using up WIDE1-1*,WIDE2-1*,SAR1-1*
leaving WIDE2-1: Packet B
Mountain Digi Sees original (packet A), digis on first WIDE2-1
Mountain Digi Sees last unused WIDE2-1 from Airborne digi (packet B) and
Digis a second time.

I am assuming that dup checking on the mountain digi should catch that last
one right?

Greg

On Mon, Sep 14, 2009 at 12:55 PM, Keith VE7GDH <ve7gdh at rac.ca> wrote:

> Greg NV6G wrote...
>
>  My thoughts were perhaps to set WIDE1-1,WIDE2-1,SAR1-1 and turning on
>> preempting on our airborne digi setting it to only digi on SAR1-1.  My
>> question here is, if the airborne digi preempts, hitting on SAR1-1
>> what happens on the RF network with the WIDE1-1,WIDE2-1, will they be
>> skipped or will they be processed?
>>
>
> I just gave it a try. In a T2-301 (5W radio with OT2m built into it) I
> enabled SARn-N with pre-emptive digipeating turned on for that alias. On
> a T2-135, I entered a path of TEST1-1,TEST-2-1,SAR3-3 and forced it to
> beacon. Watching the return coming back from the T2-301, all of the digi
> path ahead of the SARn-N were marked as used...
>
> <Digi Echo>
> VE7GDH-2>APOT21,TEST1-1*,TEST2-1*,VE7GMI-3*,SAR3-2
> :!4848.96N\12327.30WkT2-135 P1
>
> A suggestion... if you used a path something like...
>
> WIDE1-1,WIDE2-1,SARn-N,WIDE2-1
>
> and the airborne digi with pre-emptive digipeating (e.g. from Argent
> Data a Tracker 2... i.e. OT2m, T2-135 or T2-301) responded to the SARn-N,
> it would leave the remainder of the path intact. If the SARn-N was SAR1-1,
> then any regular WIDEn-N digis that heard it would respond. If the SARn-N
> was e.g. SAR2-2, the remainder of the SARn-N would have to be acted upon
> before any WIDEn-N digis would respond to remaining path. Of course, if you
> had an airborne SARn-N digi and several mountain-top SARn-N digis, you
> probably wouldn't need any additional path. If any of your teams happened to
> make it to a WIDEn-N digi or fill-in digi, the SARn-N would still be
> available if the airborne digi heard it.
>
> The advantage of being on your own frequency is no "QRM" from regular
> APRS users and the advantage of being on 144.390 (in North America) is
> that they could take advantage of the regular APRS infrastructure.
>
> I followed up my test with a beacon using a path of
> WIDE1-1,WIDE2-1,SAR3-3 and watched it coming back from my own SSI digi
> and from the T2-301 which had pre-emptive digipeating turned on for
> SARn-N...
>
> <Digi Echo>
> VE7GDH-2>APOT21,SSI*,WIDE1*,WIDE2-1,SAR3-3
> !4848.96N\12327.30WkT2-135 P1
>
> <Digi Echo>
> VE7GDH-2>APOT21,WIDE1-1*,WIDE2-1*,VE7GMI-3*,SAR3-2
> :!4848.96N\12327.30WkT2-135 P1
>
> Another time made a bit more noise...
>
> <Digi Echo>
> VE7GDH-2>APOT21,SSI*,WIDE1*,WIDE2-1,SAR3-3
> !4848.96N\12327.30WkT2-135 P1
>
> <Digi Echo>
> VE7GDH-2>APOT21,VE7DID-1*,WIDE2-1,SAR3-3
> !4848.96N\12327.30WkT2-135 P1
>
> <Digi Echo>
> VE7GDH-2>APOT21,VE7DID-1*,SSI*,WIDE2*,SAR3-3
> :!4848.96N\12327.30WkT2-135 P1
>
> <Digi Echo>
> VE7GDH-2>APOT21,VE7DID-1*,SSI*,WIDE2*,VE7GMI-3*,SAR3-2
> !4848.96N\12327.30WkT2-135 P1
>
> <Digi Echo>
> VE7GDH-2>APOT21,WIDE1-1*,WIDE2-1,SAR3-3
> :!4848.96N\12327.30WkT2-135 P1
>
> <Digi Echo>
> VE7GDH-2>APOT21,WIDE1-1*,VE7RNA-10*,WIDE2*,SAR3-3
> :!4848.96N\12327.30WkT2-135 P1
>
> Perhaps WIDE2-1,SARn-N would have been better from my QTH. My test was
> right beside my own SSI digi and of course within earshot of other
> WIDEn-N digis in at least a couple of directions.
>
> The "Tracker 2" series which is capable of pre-emptive digipeating is
> available from Argent Data at www.argentdata.com.
>
> 73 es cul - Keith VE7GDH
> --
> "I may be lost, but I know exactly where I am!"
>
>
>
>
>
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