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ZL3AI > APRDIG 08.05.04 20:48l 99 Lines 3762 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Apr 18, 4/4
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: APRS greater precision
From: Jeff King <jeff@aerodata.net>
Date: Sun, 18 Apr 2004 20:44:42 -0400
X-Message-Number: 20
On Sun, 18 Apr 2004 19:53:44 -0400, Tim Cwik wrote:
>On 2004.04.18 19:31, Jeff King wrote:
>>
>>On Sun, 18 Apr 2004 17:47:36 -0400, Robert Bruninga wrote:
>It would appear Bob suggested backwards compatible. This does not
>mean that the older systems must display the format, it means that
>using the greater precision must not break the older systems. By
>including the greater precision information as a comment, the older
>systems can ignore it.
The older systems can also ignore binary precision formats.
>>Computers eventually moved beyond C/PM and TTY terminals and maybe
>>it is time for APRS to do the same? Printable ascii is all well and
>>good, but we are a long long way from the standalone TNC and
>>terminal program, or at least one would hope. My 2 cents.
>but one of the best ways to debug interfaces in software and
>hardware is to be able to look at the data. Printable ascii makes
>this a lot easier.
I've got numerous serial display programs that can happly display full
binary data. Why lessen the efficenty of the system for the benefit of
those that don't want to do a 5 minute search on google for some freeware??
Bottom line, in 1999 when the APRS WG was formed we were told that once the
spec was adopted (in 2000) we could make additions to the format. Now, 4
years latter folks are still clinging to 1970's technology. Backwards
compatibility be damned! Full speed ahead!!
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Subject: Re: APRS greater precision
From: "Eric H. Christensen" <kf4otn@earthlink.net>
Date: Sun, 18 Apr 2004 21:06:16 -0400
X-Message-Number: 21
I agree!!! If my GPS can find me more accurately then why can't my friends
on APRS? I think the format shouldn't show more precise or LESS precise
than what my GPS receiver can handle. If my GPS says it has me within 10
feet, then by golly don't show me somewhere else! I know that my software
might be a limitation, but that will only get better if the protocol is
better! If the protocol isn't better then why should the software?
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Subject: Re: APRS greater precision
From: Gerry Creager N5JXS <gerry.creager@tamu.edu>
Date: Sun, 18 Apr 2004 20:48:05 -0500
X-Message-Number: 22
But how do you know if your GPS is lying to you? Too many trust the
hardware without understanding the error budget behind it. Worse, some
manufacturers add software that tells you how "accurate" your autonomous
position fix is, without a true scientific basis for that number.
If you assume you can routinely get better than about 6m horizontal
accuracy with a civil GPS, you're likely not well grounded in spatial
statistics.
That said, there should, in my opinion, be a better mechanism for
transmitting and user control of precision than what we have today.
Geodetically yours,
Gerry n5jxs
--
Gerry Creager -- gerry.creager@tamu.edu
Network Engineering -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843
----------------------------------------------------------------------
Subject: Re: APRS greater precision
From: "Eric H. Christensen" <kf4otn@earthlink.net>
Date: Sun, 18 Apr 2004 21:59:12 -0400
X-Message-Number: 23
Gerry,
I understand what you are saying. And that was just an example... But if
my GPS is showing me in one location, I expect to be seen at that location
on APRS as well, and I know it isn't happening.
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END OF DIGEST
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