[wxsig] Hobby Boards Barometer

[John Yost]

I am using a T238+ with the TAPR X1W-1 barometer kit.

I see the same behavior, the local display in inches
of mercury seems to be ok but loses the resolution
when sent to aprs.

my .02

john
K3YJP

--- Ken Brown <Ken.A.Brown at noaa.gov> wrote:

> 
> The problem with the pressure reading only reporting
> whole millibar
> readings is not in the barometer but in the T238
> code that converts
> the reading received from the barometer to the
> millibar reading
> transmitted.  At my station, n5kuk, I have two T238s
> each with a
> Bray barometer. One is on APRS and one is a test
> unit on the bench.
> Both exhibit the same problem. The problem is seen
> on the APRS output
> but not on the displayed value in inches of mercury.
>  I use the APRS
> T238 as a standalone with it's own tnc and radio. 
> On another APRS
> station with WinAPRS the nice weather graph clearly
> shows the stair
> step of the pressure reading. My units are T238 and
> not T238+.  On
> the bench unit the reading were noted on the rad
> RS-232 output that
> would go to a tnc in APRS service.  Both T238 units
> running the latest
> firmware.
> 
> Ken, n5kuk
> 
> Dave Barton wrote:
> > More information on this issue.  This web site, 
> >
>
http://www.wxqa.com/callsminmax/index_callsminmax.html,
> has logs of 
> > T238+ weather stations.  I've only checked a
> handful of T238+ stations, 
> > but I have found a couple of stations which seem
> to to have the same 
> > issue as mine, N5KUK and K3YJP-4.
> > 
> > There is another station, KA1GEU*, *that has a
> normal range of first 
> > decimal places.  However, his station is reporting
> via the Internet, not 
> > radio.
> > 
> > I'll try to find more examples after work today. 
> Now I wonder if it's 
> > the modem board?
> > 
> > Dave
> > AI4GF
> > 
> > 
> > Gerry Creager wrote:
> >>
> >> I'll have to get some sleep, then check but I
> think the APRS spec, and 
> >> therefore FindU, resolve to 1 mB.
> >>
> >> More's the pity.
> >>
> >> gerry
> >>
> >> Dave Barton wrote:
> >>>
> >>> I am puzzled by something.  I recently bought
> and hooked up a Hobby 
> >>> Boards barometer (B1-R1-K) and it seems to be
> working OK.  One thing 
> >>> I am seeing is that the barometric pressures
> reported by FINDU almost 
> >>> always have a .0 for a decimal millibar value. 
> In other words, 
> >>> 1016.0, 1017.0, 1018.0.  I have occasionally
> seen xxxx.1 or xxxx.2, 
> >>> but never xxxx.3 through xxxx.9.  My FINDU plots
> (AI4GF-4) have a 
> >>> very jumpy barometer chart.  The barometer is
> supposed to have a 
> >>> resolution of 0.007 in.Hg.
> >>>
> >>> I looked at the raw packets and the anomaly is
> reflected in the raw 
> >>> packet.   I have the latest firmware, 1.15.8R.
> >>>
> >>> I saw a suggested mod of a resistor in parallel
> with R1 but have not 
> >>> done that because I don't quite understand the
> mod.  Could this 
> >>> problem somehow be related to not having done
> the mod?
> >>>
> >>> 73, Dave
> >>> AI4GF
> >>> Tallahassee, FL
> >>>
> >>>
> >>> _______________________________________________
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> >>> wxsig at lists.tapr.org
> >>>
>
https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >>
> > 
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> >
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