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1994-11-13
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Date: Thu, 13 Oct 94 04:30:02 PDT
From: Advanced Amateur Radio Networking Group <tcp-group@ucsd.edu>
Errors-To: TCP-Group-Errors@UCSD.Edu
Reply-To: TCP-Group@UCSD.Edu
Precedence: List
Subject: TCP-Group Digest V94 #228
To: tcp-group-digest
TCP-Group Digest Thu, 13 Oct 94 Volume 94 : Issue 228
Today's Topics:
Antenna Switching Time [fwd]
compileing wnos-94xx
Send Replies or notes for publication to: <TCP-Group@UCSD.Edu>.
Subscription requests to <TCP-Group-REQUEST@UCSD.Edu>.
Problems you can't solve otherwise to brian@ucsd.edu.
Archives of past issues of the TCP-Group Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives".
We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party. Your mileage may vary. So there.
----------------------------------------------------------------------
Date: 13 Oct 94 00:41:00 PST
From: "UCLA::CORBIN" <CORBIN%UCLA.decnet@physics.ucla.edu>
Subject: Antenna Switching Time [fwd]
Hi Folks, the following is a forward for Mike, wd6ehr
=====================================================================
Date: Mon, 10 Oct 94 14:14:05 PST
From: "Mike Curtis" <wd6ehr@wd6ehr.ampr.org>
Message-ID: <7613.wd6ehr@wd6ehr.ampr.org>
To: wy6s@wa6epd.ampr.org
Reply-to: mike@wd6ehr.ampr.org
Subject: Please post to TCPGROUP
Comments: Laissez les bons temps rouler
KD5I writes:
(addressing excessive keyup delay @ 9600 and 19k2)
> I experimented with the tx delay and found that this radio takes about 0.4
> seconds to go from receive to transmit!
>
> At 1200 baud .4 seconds is not a real problem
>
> karl k5di
It might not SEEM like a problem, based only on lost data time, but it is a
tremendous problem when you consider you have nearly a half second of de facto
hidden terminal syndrome when your rig plugs its ears before ready to tell the
channel that it's using it.
If you're point to point with just a single station, or channel capacity is
below the Aloha effect 11% usage, this is not a big deal. But if you're on a
busy channel, retries will be the rule rather than the exception.
Even at 300 baud half duplex, it is important to get your transmitter putting
out RF as soon as possible.
Of course, if you're running full duplex, this is a non issue.
On duplex repeaters, where "there are no hidden terminals", certain users
invariably retry heavily. Without exception, these have self-induced "hidden
terminal syndrome" from slow rigs and/or running multiple ports on the same
band. I've not only seen this, but have received several reports from others.
A good test is to set retry low, i.e. 2 oe 3, and test over a good RF path
that's not real busy. If you consistently retry out, it's likely that
something is wrong with your station. It could be deviation/splatter (I've
monitored some "plug and play" 1200 baud that's close to 100 kHz wide @ -40
dB) or other transmitter related problems, receiver front end overload,
"intermod" or generic thereof, a slow T/R or R/T turnaround, etc.
Many HT's are notorious for receiver overload, especially the "scanner"
variety that receives from DC to light. What kind of front end selectivity do
you think they build into these? Also, these are designed for rubber ducks at
5', not megagain antennas at 50'. Many of these also have slow keyup and/or
recovery times.
Regarding 9600 baud, what I have found is that long TXDelays also increase bit
error rate, all other factors being equal. Why, I don't really know, nor am I
interested in fixing something I view as inherently undesireable.
MORAL OF THE STORY: As long as your radio takes too long to key up or recover,
it's not going to work all that well for packet.
This is often easy to fix. Many times, it is caused by circuits normally
turned off when inactive. Some rigs can be speeded up by running the low
level transmitter sections constantly, and turning on the receiver full time.
Not much fun to listen to, but who listens to BRAAAPing (or hissing) that
would care one way or the other about hearing themselves :-)
Also, does anyone know if the HSMODEM (high speed modem) newsgroup is still in
existence?
--
73, Mike
------------------------------
Date: Thu, 13 Oct 94 08:31:27 EWT
From: BARRY TITMARSH <BTITMARS%ESOC.BITNET@vm.gmd.de>
Subject: compileing wnos-94xx
>From: iw1cfl@ik1qld-10.ampr.org
>Hello Barry,
>I have tried unsuccesfully to compile the last wnos version.
>I use BC 3.1.
One basic mistake already The code is only Designed to compile
with Borland C++ Version 2.00
Due to too many problems with borland lib's and bugs with them
and the return of the memory leak if you dont use version 2.00
we dont compile wnos in any other compiler.
maybe later we convert it to use the GCC GNU C++ compiler
I know of one users who is porting the code here at work to use
the SUN OS 4.1.3 rev C and hope to run wnos on unix.
>Thanks in advance.
>Mike
sorry cant help.!
Barry
------------------------------
End of TCP-Group Digest V94 #228
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