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ZL3AI > APRDIG 12.05.04 10:25l 138 Lines 5515 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Apr 23, 10/10
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Help with a Trace
<LYR36507-196219-2004.04.23-14.40.00--mikejp#videotron.ca@lists.tapr.org>
From: "Eric H. Christensen" <kf4otn@earthlink.net>
Date: Fri, 23 Apr 2004 22:01:31 -0400
X-Message-Number: 58
Depending on your area, you may not need that RELAY in your path for your
vehicle. Yes, that second WIDE is exactly as your say.
-----Original Message-----
From: bounce-aprssig-36602@lists.tapr.org
[mailto:bounce-aprssig-36602@lists.tapr.org] On Behalf Of Michael J.
Pawlowsky
Sent: Friday, April 23, 2004 15:24
To: TAPR APRS Special Interest Group
Subject: [aprssig] Re: Help with a Trace
<LYR36507-196219-2004.04.23-14.40.00--mikejp#videotron.ca@lists.tapr.org>
I've contacted the club that owns VE2RTS-3 and am simply waiting for their
permission to use VE2RTS-3,WIDE as the path for the wx station. I want to
remain polite and ask permission before I send out a packet every 5 minutes
to them.
As for myself in my car, I've been using RELAY, WIDE, WIDE. (simply because
it was part of an example that I saw on the net when I first started using
APRS). It mentioned appropriate paths for different areas and that was the
one closest to me.
I understand the first relay and the first wide. But I'm not so clear on
what the second wide does. Does the second WIDE mean that the first WIDE
will transmit it again to be picked up by another WIDE? So as long as my
first WIDE is gating it, there's no reason to pass it to the next wide if
all I really want is to get onto the net.
But just so I'm clear about this one... If for instance I wanted you in
Albany to receive my position for whatever reason over the air I would use
something like RELAY, WIDE,WIDE,WIDE (if it needed to go through 3 WIDES to
reach Albany)
Would it be better then to simply have RELAY,WIDE.
I basically drive anywhere between Quebec City, Toronto and NYC. I'm also
pretty lazy about changing the path everytime I go somewhere different and
would like to keep one setting if possible.
>If you can reliably hit the VE2RTS-3 digi a nice path for you might be
>VE2RTS-3, WIDE or maybe just VE2RTS-3, assuming your goal is to have
>your wx data archived at findu or aprsworld.
----------------------------------------------------------------------
Subject: Davis Barometer Errors
From: isobar@bcpl.net
Date: Fri, 23 Apr 2004 22:56:19 -0400
X-Message-Number: 59
The Davis weather system which I use for APRS transmitting has a
calibration feature for some of its sensors. It works fine, as my barometer
display tracks well with a reference quality barometer and nearby BWI
airport reports.
I discovered, though, by looking at the findu weather reports in my
vicinity (see, for instance:
http://www.findu.com/cgi-bin/wxnear.cgi?call=n3ozb ) that my pressure
readings look about 2-3 millibars low. My local display both on the
console & PC screen using Davis' control software was accurate. The same
discrepancy happened whether I transmitted via RF to the APRS network or
directly to findu via Davis software thru the internet.
All set to blame findu, I luckily called Davis first. Their tech checked
and found that when the Davis serial port is queried for pressure it
returns the raw, uncalibrated value; the calibration must be separately
queried. Both Davis's own software, and at least APRS DOS, broadcast the
raw, unca;ibrated data . Thus, findu is just reporting what it heard. The
tech said there is no solution.
I don't suppose it bothers anyone except me, but I don't like to send out
bad data. The Davis absolute accuracy spec is NIST certified +/- 1.7 mb,
but my unit is old and its uncalibrated error is over 2mb. That's a lot
considering you usually analyze surface weather maps at 4mb intervals;
those are the isobars you see on a weather map.
Has anyone else had this problem? Please check your barometer reading
against your findu report. I don't know if this problem applies to other
brands.
Bob Kirk
N3OZB
----------------------------------------------------------------------
Subject: Fw: BalloonSat 9 to launch April 24th around 10:30 am CDT from
Huntsville AL
From: "Tim Cunningham" <tim_cunningham@mindspring.com>
Date: Fri, 23 Apr 2004 22:13:55 -0500
X-Message-Number: 60
BalloonSat IX will launch Saturday morning at approx 10:30am CDST.
73's
Tim - N8DEU
----------------------------------------------------------------------
Subject: Re: Davis Barometer Errors
From: bob evinger <wd9eka@evinger.com>
Date: Fri, 23 Apr 2004 22:44:24 -0500
X-Message-Number: 61
The calibration difference is documented in their API reference. I run a
Davis Weather Monitor II, I ran into the variance pretty much from day
one. My field elevation is about 580 feet so it is a fairly respectable
calibration difference, dont remember the exact amount but it is enough
that it would not e acceptable to me.
I run Linux boxes and wrote my own code to poll the Davis equipment,
store the values in my own database and forward it to findu and
wunderground. When I initialize the program at start up one of the first
things I do is interrogate it for its calibration values. The monitor II
also has a calibration value for outside humidity (I think) been a while
since I needed to be in the code.
It really surprises me that their pclink software doesnt take that into
account.
I realize this probably doesnt help you, just letting you know what I
did to incorporate a davis with my igate.
bob
---
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