<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#ffffff">
Hi Scott,<br>
<br>
Regarding your weather station. I'd consider exchanging the unit. The
temperature sensors are usually pretty good. Although you didn't
mention the brand or price, more pricey usually means better sensors.
If you have two units side by side, they should read within 1- 2
degrees of each other. From my prior research on consumer weather
stations, I think any humidity sensor under $ 300 will only give about
+ / - 5% accuracy. Anything under $ 30, you can probably forget that
sensor. It may be way off.<br>
<br>
Regarding the "atomic clock" signal, make sure you've initialized the
unit to search for the atomic clock signal. Then, leave it very
still. Even if it's receiving, it may take several minutes to
synchronize. Make sure there are no large metal appliances or building
parts blocking it toward the West. The signal comes from Colorado.
Usually, in the daytime, you cannot receive the signal due to
ionospheric interference. However, I have 2 wall clocks, a weather
station, and a wrist watch that all read this signal. They usually
synchronize at between 2 and 5 AM. There are very few days when they
miss. Most units have an indicator that tells if it synchronized or
not.<br>
<br>
If you cannot get yours to work, I'd exchange it or take it back, if
you can.<br>
<br>
Sincerely,<br>
<br>
Ron<br>
<br>
On 2/26/2013 7:45 PM, Scott Plante wrote:
<blockquote
cite="mid:1420515638.3207.1361925901491.JavaMail.root@insightsys.com"
type="cite">
<style type="text/css">p { margin: 0; }</style>
<div
style="font-family: arial,helvetica,sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Derek,
<div> I'm pretty sure Ron realized that--that's why he mentioned
getting it from online sources for his locality. The problem was they
all reported different values.</div>
<div><br>
</div>
<div>Separately,</div>
<div><br>
</div>
<div> A family member gave me a fancy weather station / atomic clock
(well, it supposedly reads the atomic clock radio signal) with an
outdoor remote unit this Christmas. It tells the indoor/outdoor
temperature, pressure, and other stuff. Testing it out, I place the
remote unit right next to the indoor unit and they consistently
reported values 10 points off! It also never read the clock signal. Oh
well, so much for technology.<br>
<br>
Scott</div>
<div><br>
<hr id="zwchr">
<div
style="color: rgb(0, 0, 0); font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><b>From:
</b>"Derek Atkins" <a class="moz-txt-link-rfc2396E" href="mailto:warlord@MIT.EDU"><warlord@MIT.EDU></a><br>
<b>To: </b>"Atlanta Linux Enthusiasts" <a class="moz-txt-link-rfc2396E" href="mailto:ale@ale.org"><ale@ale.org></a><br>
<b>Sent: </b>Tuesday, February 26, 2013 11:17:53 AM<br>
<b>Subject: </b>Re: [ale] WAY [OT] but geeky - how do I calibrate
GPS barometric altimeter<br>
<br>
Ron,<br>
<br>
...</div>
<div
style="color: rgb(0, 0, 0); font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><br>
The issue is that the barometric pressure is constantly changing.<br>
Pilots use barometric altimeters, and the rule is that they need to<br>
reset them every 100 miles or every hour. An airport will report the<br>
current altimeter setting every hour, but some automated systems will<br>
report it every minute, and yes, it can change rapidly if you have<br>
strong storm systems.<br>
<br>
Basically, this is a long-winded way of saying that you need to be<br>
constantly resetting altimeters. When they are set properly they are<br>
very accurate. However they need to be reset frequently to remain<br>
accurate.<br>
<br>
One tip: the barometric pressure doesn't usually change significantly<br>
over short distances. Most of the local airports will have the same<br>
setting, so you could theoretically just dial the weather at, say,<br>
Kennesaw (770-425-3406), to get a local altimeter setting that should be<br>
"close enough" for you. Worst case you'll be maybe +/-50 feet off, but<br>
is that really too much error for your use-case?<br>
<br>
-derek<br>
<br>
-- <br>
Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory<br>
Member, MIT Student Information Processing Board (SIPB)<br>
URL: <a class="moz-txt-link-freetext" href="http://web.mit.edu/warlord/">http://web.mit.edu/warlord/</a> PP-ASEL-IA N1NWH<br>
<a class="moz-txt-link-abbreviated" href="mailto:warlord@MIT.EDU">warlord@MIT.EDU</a> PGP key available<br>
_______________________________________________<br>
Ale mailing list<br>
<a class="moz-txt-link-abbreviated" href="mailto:Ale@ale.org">Ale@ale.org</a><br>
<a class="moz-txt-link-freetext" href="http://mail.ale.org/mailman/listinfo/ale">http://mail.ale.org/mailman/listinfo/ale</a><br>
See JOBS, ANNOUNCE and SCHOOLS lists at<br>
<a class="moz-txt-link-freetext" href="http://mail.ale.org/mailman/listinfo">http://mail.ale.org/mailman/listinfo</a><br>
</div>
<br>
</div>
</div>
<pre wrap="">
<fieldset class="mimeAttachmentHeader"></fieldset>
_______________________________________________
Ale mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Ale@ale.org">Ale@ale.org</a>
<a class="moz-txt-link-freetext" href="http://mail.ale.org/mailman/listinfo/ale">http://mail.ale.org/mailman/listinfo/ale</a>
See JOBS, ANNOUNCE and SCHOOLS lists at
<a class="moz-txt-link-freetext" href="http://mail.ale.org/mailman/listinfo">http://mail.ale.org/mailman/listinfo</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
(PS - If you email me and don't get a quick response, you might want to
call on the phone. I get about 300 emails per day from alternate energy
mailing lists and such. I don't always see new email messages very quickly.)
Ron Frazier
770-205-9422 (O) Leave a message.
linuxdude AT techstarship.com
</pre>
</body>
</html>