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ZL3AI > APRDIG 03.10.03 09:38l 203 Lines 9158 Bytes #999 (0) @ WW
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Cheap GPS receivers / RS232 / Digitraveller
From: "J. Lance Cotton" <joe@lightningflash.net>
Date: Mon, 29 Sep 2003 23:56:49 -0500
X-Message-Number: 3
WA8LMF2@aol.com wrote:
>Just picked up a blowout clearance-priced $29.95 Digitraveller GPS today at
>xx and it works. What a deal!
I cleaned out one local xx's whole stock of 2 of these. Quite the deal.
> You DO have to have a positive voltage on the incoming (RXD) line however to
>make it turn on. In other words, you have to connect both the TXD and RXD
>lines of the DB9 (i.e. full two-way serial hookup), even though you don't need
>to send any initialization commands to the device. This simple 3-wire serial
>hookup will work with most commercial software as-is. See below for null
>modem simulated handshaking info, if needed.
First thing I did when I got mine home was crack it open. You can see where,
on the RJ-12 (telephone-like) connector, the red wire goes to the circuit
board. This is the wire that needs any voltage other than 0V in order to
bring the digitraveler out of suspend mode (off). I took a 7805 5 VDC
regulator and noticed that the ground and output pins will easily solder on
the backside of the power port on the GPS. Took the "input" lead of the 7805
and stretched it out to the side. Got a little piece of wire and connected
the solder point for the red wire to the voltage input of the 7805. The
digitraveler can then be stuck back into it's case with none the wiser.
(just don't hook it to a real serial port, as the stuff coming in on the red
wire will likely be -10v or so and might not react well with the 7805.
Now, I can supply 13.8 VDC on the red wire and it will both hold the GPS in
the "on" mode with the +13.8v AND supply the GPS with 5v of regulated power
through the nomal power port. Note that that GPS doesn't have its own
voltage regulator, and the specs say it needs 6v. 5v from the 7805 appears
to work just fine.
Moving to the TinyTrak3, I soldered up JP7, which allows the input power for
the TT3 to flow on to Pin 4 of the "GPS" port. Soldered the red wire to that
pin, black wire to ground, and brown wire to "serial in" on the TT3. Now
just by the normal TT3 hookup, you also power the GPS and get it's serial
data back to the TT3. With only 3 wires!
I used a 1 amp version of the 7805 since that's what I had laying around,
but since the GPS draws 75mA max, you could replace it with the lower
current, smaller package version with no ill effects.
73 de KJ5O
--
J. Lance Cotton, KJ5O
joe@lightningflash.net
Three Step Plan: 1. Take over the world. 2. Get a lot of cookies. 3. Eat the
cookies.
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Subject: Nice points Tim & some questions for the gang
From: "Jeff Thomas - KD4EVB" <kd4evb@hotmail.com>
Date: Tue, 30 Sep 2003 00:54:58 -0400
X-Message-Number: 4
Tim,
After being one of 'em that started this hornet's nest up, I've been setting
back dealing with direct emails, working with some sysops in taking a closer
look at their network, and soaking up the discussion here on the list. Not
to exclude a few others, but I found your email points very nice. It's glad
to see some "real world rf data" being used along with some analysis of it
(we can argue till the cows come home on who's analysis is correct) versus a
lot of opinions with either no data or "textbook math" being applied to it,
out in the real world things are not so neat and textbook like.
Thanks for taking the time to post "supporting" real world traffic to
support your suggestions, thoughts, and opinions. This is the type of
discussion (right or wrong) that will help us solve the issue eventually.
The last few years on this list has seen this core issue (channel
overloading) stirred up time and time again, but little if any progress is
made as it becomes a battle of opinions versus opinions, suggestions and so
on rarely backed up with even basic real world collected data. Thus, we're
still pretty much where we were on this topic 2 years ago, except the
problem is getting worse and worse on us.
Okay, something else that caught my eye in your posting was something I'd
been waiting to see. Somebody discussing NOID in UIFLOOD's parm's. Often I
find when someone is complaining about WIDEn-n not working right, I can't
count the number of times they had ID set instead of NOID and that was the
issue, an issue quickly/easily fixed.
--------
Now for Tim and the rest of the list..................
How about some digi sysops that are up to a challenge some weekend:
With multiple monitoring points setup across the area, collect data on what
happens when:
1. You run a pure WIDEn-n path of WIDE5-5
versus
2. You run a path of WIDE,WIDE,WIDE,WIDE,WIDE
3. Be nice if digi hardware/software and configuration were fairly
consistent across the digi's involved! Yeah, I know....dream on ;-)
4. Make the results and data available for any/all to look over.
Okay, now the disclaimer, this is just for test purposes! I'm not endorsing
the above paths for day to day uses, just for the test :-)
-------
Now some questions that have come here in the last few days or I've already
read all kinds of conflicting opinions on, maybe the protocol purists can
answer these for us all:
Is 5 WIDE's in a path a valid path? I seem to recall hearing that you could
only do a 3 WIDE's in a path that way, but I tend to think I've seen a lot
worse in action, grin.
I haven't confirmed it (didn't want to get shot, shot again, and drug thru
the streets by certain folks if they saw me try such a path) but isn't
WID7-7 the max you can do under WIDEn-n or does that depend upon how. Or
was that another one of the protocol standards that sort of never got
implimented in the final product?
How long do the IGATE's remember hearing a station as "local" to them? This
info would be invaluable for determining how far "back" you degrade the tx
rates before the IGATE's loose track of you as being local to them.
Say I message station B over on the west coast with a path of whatever I
choose, how does that come back thru the IGATE? Does the reply back to me
come out of the IGATE using the path set by the local IGATE? My original
path? The remote station's path that was used to get the reply to the IGATE
on his end? Does having the first digi's callsign inserted in the path help
get the packets back thru the igates? Example: would WIDE3-3 or
digi,WIDE2-2 be better in terms of the IGATE getting things back to where
they need to go (digi = specific callsign of the first digipeater). Of
course some of this is not that applicable to the mobiles, but I'm basically
asking this assuming fixed stations on a perfect rf network.
Hopefully not adding to the hornets nest anymore, but from the number of
questions and conflicting "guesses" I'm getting on some of these topics, I
figure they are perfect list discussion material. Maybe many of us can
learn something here.
73 de Jeff, KD4EVB
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Subject: Re: Cheap GPS receivers / RS232 / Digitraveller
From: WA8LMF2@aol.com
Date: Tue, 30 Sep 2003 03:33:23 EDT
X-Message-Number: 5
In a message dated 9/29/2003 10:48:18 PM Pacific Daylight Time,
froby@earthlink.net writes:
>So tell me how to wire mine up for the D7?
>
> I can do it, but tell me how to wire the stereo plug.
For a direct miniplug-to-RJ11 cable for the Digitraveller <--> Kenwood
D7/D700:
Pinout for this cable is:
o RJ11 Pin 2 -- 2.5mm Miniplug RING
o RJ11 Pin 3 -- 2.5mm Miniplug TIP
o RJ11 Pin 4 Not Used
o RJ11 Pin 5 -- 2.5mm Miniplug SLEEVE
If you don't want the aggravation of trying to crimp the miniplug cable
conductors directly to a modular plug (it IS a painstaking process), an
alternative way to make the connection would be to get a standard
surface-mount phone jack. Connect the miniplug cable ends to the screw
terminals inside the jack. Then connect the jack to the Digitraveller with
a short (6" modular-to-modular phone cord -- the kind used between a
wall-mount phone and the wall jack). Be sure the cable is wired straight
thru -- same colors at the same positions in the plugs at both ends of the
cable.
> I am assuming I will still need to power the thing seperately.
It will run either on three internal alkaline AAA cells which it eats in
10-15 hours, or from an external source of 5 to 6 VDC fed into a tiny
coaxial power jack about half the size of the ones on common TNCs.
Amazingly, my Digitraveller came with 3 RS AAA "Alkaline Enercells" already
installed. Don't know if this is normal or mine was a floor model that
they forgot to remove the batteries from.....
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.com
Ham Radio/Mobile SSTV page: http://members.aol.com/wa8lmf/ham
APRS Stuff
http://members.aol.com/wa8lmf/aprs
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