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[aprssig] BRRRAAAPS and listening

Lloyd Mitchell lloyd at mitchell-web.net
Fri Oct 21 17:27:31 UTC 2011


Steve, Yes that is the same..I heard her speak years also and I will
never forget her.

KO4Lloyd

Gye Nyame 



-------- Original Message --------
Subject: Re: [aprssig] BRRRAAAPS and listening
From: Steve Dimse <steve at dimse.com>
Date: Fri, October 21, 2011 11:31 am
To: TAPR APRS Mailing List <aprssig at tapr.org>


I think you are talking about Admiral Grace Hopper, a pioneer in
computing (she coined the term debugging and co-invented COBOL among
many other accomplishments). She was an excellent public speaker and
famously used a wire about a foot long to illustrate how far an electron
travels in a nanosecond. I had the pleasure of meeting her and hearing
her speak at the 1984 Symposium on Computer Applications in Medical Care
where I won the student paper competition (which was why I was sitting
next to her in the front row). The nanosecond she gave me that day is
one of my prized possessions.

Steve K4HG

On Oct 21, 2011, at 10:33 AM, Lloyd Mitchell wrote:

> Bob, You make me laugh....this reminds me of the admiral that wanted a
> piece of wire one nanosecond long...
> 
> KO4Lloyd
> Gye Nyame 
> 
> 
> 
> -------- Original Message --------
> Subject: [aprssig] BRRRAAAPS and listening
> From: "Bob Bruninga" <bruninga at usna.edu>
> Date: Fri, October 21, 2011 10:27 am
> To: "'TAPR APRS Mailing List'" <aprssig at tapr.org>
> Cc: APRS at yahoogroups.com
> 
> 
> Sometimes I get the feeling that few people listen to the APRS channel
> now
> and then to hear what is going on. There is a lot to be learned just by
> listening.
> 
> For example.. If you hear
> 
> BRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRAAAAAAAAAAAAAAAAAP
> 
> You are hearing a 50% wasted channel, because all the BRRRRRR's at the
> beginning are just TXD delay. The AAAAAP on the end is the actual APRS
> data. The data in an APRS Mic-E packet lasts typically 1/2 second. If
> the
> TXD is 500 ms, then channel capacity in THAT ENTIRE AREA is suffering a
> 50%
> loss in channel capacity.
> 
> Typically, we can operate with TXD's of about 150 ms. PLEASE everyone,
> listen in your area and fix any digipeater that is blathering all this
> wasted bandwidth!
> 
> This also applies to your own station. Kenwoods used to come with a
> default
> of 500ms which was unbelievably long. Please check your settings and
> permanently re-configure to 200 or 150 ms.
> 
> A packet should sound more like:
> 
> BRRRRAAAAAAAAAAAAAAAAP
> 
> But the most important setting is the DIGIPEATERS! Because they impact
> EVERY SINGLE PACKET in the area. Fixing them with minimum TXD can have a
> nearly doubling of channel capacity. Fixing one LID's mobile setting is
> only going to change the area load by 1%...
> 
> FIX THE DIGIS. And also make sure they are providing the local area
> repeater frequency object in the local area as well while you have the
> SYSOPS attention...
> 
> Bob, WB4APR
> 
> 
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> 
> 
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> 


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