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[aprssig] NE Illinois Balloon Tracks

Bill Diaz william.diaz at comcast.net
Fri Jul 24 16:03:04 UTC 2009


Jason,
	See below:

>-----Original Message-----
>From: aprssig-bounces at tapr.org 
>[mailto:aprssig-bounces at tapr.org] On Behalf Of Jason KG4WSV
>Sent: Friday, July 24, 2009 09:51
>To: TAPR APRS Mailing List
>Subject: Re: [aprssig] NE Illinois Balloon Tracks
>

 SNIPPED here and there.

>Lots of opinions, and many apparently from folks who haven't been
>involved in ballooning.  I've been involved in 30+ flights, so I'll
>throw my opinion out.

>Yes, the 30s TX rate is too aggressive for 144.39.  That should be
>done on an alternate frequency.

	Amen.

>Your tracker may be in the default "good citizen" "listen for a clear
>channel before you transmit" mode, and you don't hear it after 1000'
>AGL until it hits the ground again.

>For these and many other reasons, a multi-hop path is VITAL for
>payload recovery.  Our teams have experienced all of these situations.
>

>If digis are correctly configured, multi-hop related QRM should be
>minimized since they will all retransmit at the same time, to avoid
>ping-ponging.

	Unfortunately most WIDE1-1 digis are not correctly configured.  Our
recent experience in NE Illinois illustrated this rather vividly.  Saw many
timestamped packets that were delayed in excess of 30 seconds due to 3
trackers beaconing from altitude at 30 second intervals with abusive paths.
Since  many digis have a dupe time of 30 seconds, these packets were
dutifully digi'd again.  This ping-ponging caused the icons to jump back and
forth on the map.  Was very apparent when copying signals direct.

	Balloons using WIDE1-1 launched within 100 miles or so of large
metropolitan areas may be copied directly by 50-100 stations.  Due to the
hidden station problem many collisions resulted when these stations
attempted to digipeat the balloons packets.  

	Since the Balloons were not "good citizens" in this instance, the
resulting QRM precluded other uses of the channel by "good citizens".  	

>Folks get excited because the balloon's RF footprint is a few hundred
>miles, but remember that APRS is a _local_ network.  There is not a
>lot of difference to the _local_ network in a balloon that can be
>heard by the local digi beaconing once a minute and my truck beaconing
>once a minute if I forget to turn it off when I go in to work (except
>the traffic from my parked truck is pretty boring).

	There is a HUGE direct coverage difference between WIDE1-1 packets
broadcast at 6' AGL and WIDE1-1 packets broadcast at 60,000' AGL.  To
suggest otherwise is......

>People are becoming hams because of ballooning.  Help and advice is
>fine, but please don't be jerks about it.

	Ballooning should be encouraged for this reason, but they need to
realize the APRS channel is a shared resource and not reserved for their
exclusive use during flights.  It doesn't help when they reject any advice
or help from knowledgeable APRS users.  Anyone, balloonist or not who
monopolizes 144.39 for their own purposes is, IMO, either a jerk or someone
who desperately needs elmering.

Bill KC9XG
	
>-Jason
>kg4wsv
>
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