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ZL3AI > APRDIG 12.12.03 10:34l 238 Lines 9288 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Dec 08, 1/3
Path: DB0FHN<DB0FOR<DB0SIF<DB0EA<DB0RES<ON0AR<ZL2TZE<ZL3VML
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Monday, December 08, 2003.
1. Use of ECHO as a path of HF (not)
2. Re: FCS CRC algorithm
3. DB-9 Factoid
4. RE: DB-9 Factoid
5. RE: DB-9 Factoid
6. Re: DB-9 Factoid
7. Re: ? GM-300 Acc Plug to KPC3+ Connections ?
8. RE: DB-9 Factoid
9. RE: DB-9 Factoid
10. New APRSdos MILE-MARK display
11. Re: New APRSdos MILE-MARK display
12. Re: New APRSdos MILE-MARK display
13. APRS and The Appalachian Trail
14. Re: Use of ECHO as a path of HF (not)
15. RE: DB-9 Factoid
16. RE: DB-9 Factoid
17. Re: New APRSdos MILE-MARK display
18. Re: New APRSdos MILE-MARK display
19. Re: New APRSdos MILE-MARK display
20. Re: New APRSdos MILE-MARK display
21. This looks promising
22. Fw: Re: New APRSdos MILE-MARK display
23. Re: Fw: Re: New APRSdos MILE-MARK display
24. Re: This looks promising
25. RE: DB-9 Factoid
26. Re: New APRSdos MILE-MARK display
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Subject: Use of ECHO as a path of HF (not)
From: Bob Bruninga <bruninga@usna.edu>
Date: Mon, 8 Dec 2003 00:05:13 -0500 (EST)
X-Message-Number: 1
On Sat, 6 Dec 2003, Clayton H. Owen wrote:
> I've said this for years..when all else fails go HF with a path of
>ECHO,GATE,WIDE in the mobile
I disagree.
I prefer to think of ECHO as a "911" path to get a packet out. the APRS
HF network is probably the "largest" spacial diversity reeciver on the
planet. Meaning a packet transmitted on HF, probably has 100 or more
TNC's listening to it all over. If there is a band opening ANYWHERE,
then there is probably a station that will receive it. (And usually an
IGate to feed it inthe global system.
BUT using ECHO on EVERY packet cuts the total capacity in HALF, and
actually causes MELT DOWN and SELF-JAMMING of your own signal. If the
band is open and just 10 of the 100 HF statiosn ECHO the packet, then that
is 10 times collisions. A totally inneffective way to communicate.
Remeber when HF is open or even partly open, using ECHO is like the
problem on VHF where more than one digi hears your packet and they all try
to digipeat it. Imagine if 50% of them or 50 of them tried to digiepate
the packet at the same time?
I say,
DONT USE ECHO unles you are having an emergency and must get that packet
out. But for routine operations, it is a waste of precious bandwidth and
runis efficiency.
de WB4APR, Bob
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Subject: Re: FCS CRC algorithm
From: "Scott Miller" <scott@3xf.com>
Date: Sun, 7 Dec 2003 21:33:18 -0800
X-Message-Number: 2
Well, that saves me the table at least. I'm looking for the bitwise
implementation, and I think I found it, or at least the general case if I
can get the polynomial right. It's just a linear feedback shift register.
I've got a couple of beta testers lined up. Got a new prototype built
yesterday and it works, so this week I'll be sending the layout off for
fabrication. Using home-brew boards is a major pain because of the lack of
through-plating and the number of parts that require soldering on the top
side.
Right now I'm mostly working on cleaning up the source code and getting the
altitude encoding working. Next time, I use a chip with room for
floating-point math routines. =]
Scott
N1VG
-----Original Message-----
From: bounce-aprssig-31505@lists.tapr.org
[mailto:bounce-aprssig-31505@lists.tapr.org]On Behalf Of Jeff King
Sent: Sunday, December 07, 2003 7:28 PM
To: TAPR APRS Special Interest Group
Subject: [aprssig] Re: FCS CRC algorithm
Here is something I am using in my 18F452 based 900mhz Xemics FH
transceiver:
Seems to work. What is the status with your beta test?
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Subject: DB-9 Factoid
From: Bob Bruninga <bruninga@usna.edu>
Date: Mon, 8 Dec 2003 09:07:10 -0500 (EST)
X-Message-Number: 3
DB-9 Factoid:
At the Tampa Hamfest this weekend (a large fest in a convention center and
at least 2 acres of tailgators) not a single DB-9 male or female serial
port connector could be found!
I was preparing to give a talk on APRS and one of the things I like to do
is hook up the HT in my pocket to some small speaker zip cord and toss the
wire out into the audience with a handfull of DB-9's and tell eveyone to
use the two clip leads on the DB-9 to connect their favorite flavor of
APRS on their laptop to the "ZIP-LAN" and lets all see what we see.
Usually this accompliahes two things:
1) It shows how trivial it is to wire up every PC in a room to something
as simple as an HT (Think TH-D7) so that every operator has his OWN
display of the LIVE tactical APRS picture...
2) It shows also how different operators of different APRS clients find it
quite difficult to communicate with each other by voice about what they
are seeing..
But in 2 hours of seaching, I couldnt, and then many others COULD NOT FIND
A SINGLE DB-9, not at the vendors, not in the flea markets and not in the
junk piles! Even the piles of dead mice are all now PS2.
FINALLY I found TWO complete MOULDED DB-9 serial port cables IN plastic
bags at the bottom of a junk pile. (NOT!). We hooked them up and nothing
worked. We cut them in half and found that neither pin 2 nor pin 3 (TXD
and RXD) went anywhere. The pins simply were not connected to anything...
Being moulded, we couldnt even solder new wires...!
WARNING! It may look like a serial cable, but they were actually for
connecting a UPS system to the serial port. The ONLY wire used in the
cable are the DTR and one other handshaknig wire so that the UPS can
signal the PC that it has lost power... The cables are useless. Even the
4 pins on one end that are used dont go to the same pins on the other
end... but it looks like a perfectly good DB-9F to DB-9M serial cable..
COMMENT: Now what else does this tell you about the ubiquitous Serial
Port in HAM radio? When I announced my frustration at my talk, others in
the room also said they also could not find a DB-9 serial port connector
anywhere at the fest...
de WB4APR, Bob
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Subject: RE: DB-9 Factoid
From: "Herb Gerhardt" <hgerhardt@CHARTER.NET>
Date: Mon, 8 Dec 2003 08:46:38 -0800
X-Message-Number: 4
It has been a trend for the last two years in computers to do away with the
serial port and replace it with the USB port. My present laptop does still
have a serial port but I had to do some looking 2 years ago to find one with
a serial port. Today, it is next to impossible to find a computer with a
serial port as a standard port. The usage for the serial devices in the
real world is going away.
We in ham radio still use the serial port almost exclusively. It is time to
upgrade our ham radio software programs to also utilize the USB port in
addition to the serial port. Since hams are basically cheap individuals, we
do need to preserve the serial port in the ham programs so we can utilize
all of old, old computers but we also need the programs to be able to
operate with USB ports.
By the way, the 3.5" Floppy Drive has also gone to the way side. Time
marches on, we must mark on with it.
Herb, KB7UVC
NW APRS Group, West Sound Coordinator
Our WEB Site: www.nwaprs.org
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Subject: RE: DB-9 Factoid
From: "Scott Miller" <scott@opentrac.org>
Date: Mon, 8 Dec 2003 09:10:52 -0800
X-Message-Number: 5
I wouldn't be surprised to find in a couple of years that any computers
still available with serial ports are actually using internal USB to serial
converters. The traditional serial port support in PCs has always been
limiting, and really should have died off years ago.
On the other hand, wireless LANs are commonplace now, and APRS software
should take advantage of that. Forget piping serial data from a TNC. This
is a packet-oriented data network and we need to treat it as such. Within a
single machine, the AX.25 stack does a good job of sharing network
resources, but it needs to be easier to extend that to a whole LAN. I know
there are AX.25 encapsulation mechanisms, but none of them are particularly
easy to use.
OpenTrac takes a different approach. TCP and UDP port 3389 are registered
with IANA for OpenTrac traffic, and the idea is that you can plug in to a
LAN and start broadcasting OpenTrac over UDP and treat the subnet as you
would an RF channel, or connect to a known server with TCP like an APRS-IS
feed. That's still in development, though, so it'll be awhile before
there's anything significant to demo.
Scott
N1VG
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Subject: Re: DB-9 Factoid
From: Bill Vodall - WA7NWP <wa7nwp@jnos.org>
Date: Mon, 8 Dec 2003 09:15:18 -0800 (PST)
X-Message-Number: 6
Todays ubiquitous Serial Port is WiFi. The client for application
demos is a web browser. I bet a high percentage of folks in
attendence with laptops had 802.11b ready to go -- if it wasn't already
going. Many conventions these days furnish wireless Internet access for
the attendees.
73,
Bill - WA7NWP
PS. Wasn't it really a "DE-9" you were looking for. :-)
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