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ZL3AI > APRDIG 09.12.03 09:38l 232 Lines 9747 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Dec 04, 3/7
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Sent: 031209/0721Z @:ZL3VML.#80.NZL.OC #:14232 [Chch-NZ] FBB7.00i $:2448-ZL3AI
From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: APRS WX Protocol Questions
From: Bob Bruninga <bruninga@usna.edu>
Date: Thu, 4 Dec 2003 14:32:11 -0500 (EST)
X-Message-Number: 15
On Thu, 4 Dec 2003, Ralph Milnes wrote:
>trying to prescribe "standard" measurements that can't be obtained from our
>measurement devices. For example, the $ULT or !! packets from my Peet
>U-2000 WX station don't contain a 2 minute wind speed average in knots or a
>wind direction based on a 2 minute average . They also don't contain "r" (1
>hour) or "p" (24 hours) rainfall periods, the only accepted measurement
>periods by the NWS
That is another reason why we assumed there would always be a PC. APRSdos
properly computes a running wind speed average and also it computes the
running 1 hour rain rate and the 1 day rain rate. THus, what it transmits
on the air was intended to be the right info.
Just slapping a WX station to a TNC and throwing all the data out leads to
this kind of confusion which is why a PC should be involved. APRSdos
further tries to keep a running rain count on even the stand-alone
stations so that it can generate rain per hour rates, but this only works
if the APRSdos has been running for an hour long enough to accumulate the
running rate.
Some other client programs did not go to this trouble and just report what
they see....
(see 12.7.2 a. (3) in the handbook). They do contain "P"
>(since midnight), which is commonly reported on the nightly news, but
>that's not an accepted reporting period by the NWS. ("r" and "p" may be in
>the other two Peet packet types, but those types can't be decoded by APRS
>programs.)
>
>On one hand, it would be nice to give the NWS what they want from APRS.
>
>On the other hand, they may not really care if they have been assuming all
>along that APRS weather wind reports are never reported correctly, i.e. by
>NWS standards.
>
>Furthermore, reporting wind speeds in knots and not mph is not useful for
>the everyday APRS operator, as is seeing "gust" measurements only if peak
>wind speed exceeds 25 knots.
Wind speeds in APRS are supposed to be MPH...
Bob
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Subject: Re: APRS WX Protocol Questions
From: "James Jefferson" <jj@aprsworld.net>
Date: Thu, 4 Dec 2003 13:43:14 -0600 (CST)
X-Message-Number: 16
> APRSdos properly computes a running wind speed average and also it
What does a wind speed average tell anybody? I'm not aware of any
application that would be concerned with wind speed average - in general
because of the power = velocity ^ 2 nature of wind, the average does a
poor job of indicating what is happening over time.
-Jim KB0THN
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Subject: Re: APRS WX Protocol Questions
From: "Earl S. Garber" <n3eg@teleport.com>
Date: Thu, 4 Dec 2003 13:49:37
X-Message-Number: 17
On 12/04/03, "Ralph Milnes <ralphmilnes@patmedia.net>" wrote:
>s = sustained wind speed in mph. The NWS standard is a 2 minute average. It
>also says to report in knots. The APRS Spec says one minute average in mph.
>
>g = gust: The NWS has different definitions for "gusts" and "peak wind
>speed". The APRS spec says "gust" means "peak wind speed in last five
>minutes". The NWS measurement period for peaks is "since your last report".
Further confusion: With a report rate of 10 or 15 minutes, shouldn't the
"gust" period follow that instead of the spec of 5 minutes?
Even further confusion: WinAPRS on my WX station set for .01 inch rain
increments will report every .01 inch, "dynamically" increasing the report
rate. What then?
....N3EG
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Subject: National Parks Digi Coverage (Rev 3)
From: Bob Bruninga <bruninga@usna.edu>
Date: Thu, 4 Dec 2003 14:49:25 -0500 (EST)
X-Message-Number: 18
Just like Cellular, we dont need mobile APRS coverage as much where we
live as where we DRIVE. Yet for us it is easiest to put coverage where we
live... As a community, we also need to consider where are fellow HAMs
are traveling and making sure they are covered. With 32 HAMs a day
visiting the Grand Canyon, we need a digi there... and other places:
TOURIST AREA VISITRS/YR HAMS/DAY APRS REPORTED BY
----------------- ---------- -------- ---- --------------
Acadia Natl Pk 2,469,000 16 ?
Arches NP 786,000 6 no WB4APR
Assateaque Is 1,810,000 12 some WB4APR
Badlands ND 1,105,000 7 ?
Banff, Yoho, Kootenay ? ? YES VE6SZR
Bryce Canyon NP 1,099,000 7 no WB4APR (1999)
Blue Ridge Pkwy 19,153,000 130 yes
Great Smokies 14,486,000 95 yes spotty
Grand Canyon 4,460,000 32 no WB4APR June 99
C&O Canal (MD) 3,115,000 21 yes Hrprs Fy to Whites Fy
Canyonlands NP 401,000 3 ?
Cape Cod Seashore 4,581,000 30 ?
Chatahoochee Rvr 2,659,000 18 yes
Cape Hatteras 2,647,000 18 no
Death Valley 1,179,000 8 ?
Devils Tower 383,000 2 no N2IPH & KC5JIF
Everglades 1,000,000 7 yes N4TCW
Gettysburg 1,542,000 10 yes
Glacier NP 1,728,000 12 ?
Grand Tetons 2,590,000 17 no WA8LMF
Glen Canyon 2,568,000 17 no WB4APR (99)
Hawaii Volcanoes 1,514,000 10 ?
Indiana Dunes 1,820,000 12 ?
Lake Meade 8,755,000 60 yes N7ZEV
Mamouth Cave 1,749,000 12 ?
Mesa Verde 452,000 4 yes at top
Mount Rainer 1,344,000 9 ?
Mt Rushmore 1,868,000 12 no N2IPH & KC5JIF
Natchez Trace Pky 5,737,000 38 some?
Ozarks 1,568,000 10 ?
Rocky Mountain 3,185,000 21 no camps nor hdqtrs
Shenandoah NP 1,419,000 9 probably
San Antonnio(Alamo)1,394,000 9 yes K5ZZT
Sequoia 838,000 6 ?
Virgin Islands 704,000 6 no WB4APR (1995)
Yellostone 3,100,000 20 no N2IPH & KC5JIF
Yosemite 3,400,000 22 ?
Zion Natl Pk 2,432,000 16 no WB4APR
The criteria here are those areas that are remote from the existing
terrestrial APRS infrastructure and which probably do not have enough
permanent locals to support a digi... "Coverage" means that you can
communicate from the parking lot of the biggest Campground or
Headquarters (Hiking to the TOP of the mountain doesn't count).
If you can supply any info above, please send to me and I will update this
list... Including of course, adding other areas.
If you can HELP place a digi there, PLEASE DO!
de WB4APR, Bob
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Subject: Re: NMEA at >100,000 feet
From: Gonzales Andy <agonzales@arc.nasa.gov>
Date: Thu, 4 Dec 2003 11:49:25 -0800
X-Message-Number: 19
>Does anyone have a sample of actual NMEA output from a GPS at an altitude of
>greater than 100,000 feet? Gotta get the altitude parser working for the
>OpenTracker tonight. I can fake a file with what I think it should look
>like, but I'd rather see the real thing just to be sure. Not that I would
>expect it to look any different save for an extra digit, but I'd rather find
>out now.
Scott,
The temperature problem is very much a design issue but we found when we
put together our electronics package for our Mars airplane prototype
(100,000 ft+ altitude) that we were more concerned with things getting too
hot. most of our electronics were inside of a carbon fiber fuselage with a
black interior and a white exterior.
Between 35,000 ft and 60,000 ft. the air temp gets very cold down to -70 F,
BUT the solar insolation gets up to 1,000 w / m^2. Above 60,000 ft the air
temp actually gets warmer. Since the air is getting thin, convective
cooling goes away. The CABIN air temp at the critical flight stage was
actually above 0 F. the overall profile was a "double dip" curve with one
low point at the critical flight stage (when we released the airplane from
the balloon). The second low point was about half way back down and did
get well below 0 F. The self heating of the autopilot was our greatest
concern and we tested it in bell jar at room temp up to about +120 F case
temp.
We found that trying to push hardware & batteries to temps down to -40 F
was not relevant since the actual temps never got there. Of course we had
the advantage of an excellent thermal analyst that predicted our temps
before hand - and got them very close - but the point is with just a
little care, your electronics won't get down to anything like -70 F but
with too much care might get up over + 120 F.
The only equipment item we had to modify were our servo actuators. We
changed the grease so it wouldn't freeze and tested them at vacuum to
verify no motor arcing.
>Has anyone had any experiences with reed relays at low temperatures? I'm
>thinking of using one to trigger a camera's shutter, and it's rated to -20
>C, but the required activation voltage rises as it gets colder and I'm
>worried about it not being triggered by a TTL output. Also, I was looking
>at the specs for the 78L05 voltage regulator, and the TO-92 package is only
>rated to 0 C. With the amount of power it's dissipating I can't imagine it
>getting too cold, but I'm new to this sort of thing. I think I might pick
>another, lower drop-out regulator anyway.
>
>Thanks.
>
>Scott
>N1VG
--
Andy Gonzales
KG6RWO
NASA / Ames Research Center
Moffett Field, CA 94035-1000
Bldg. N-244, Rm. 240
MS 244-19
agonzales@arc.nasa.gov
650-604-0309
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