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To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Thursday, June 17, 2004.
1. potting a GPS module in resin - RF attenuation
2. Re: potting a GPS module in resin - RF attenuation
3. Re: potting a GPS module in resin - RF attenuation
4. Re: APRS-IS vs RF backbones
5. Re: potting a GPS module in resin - RF attenuation
6. Re: potting a GPS module in resin - RF attenuation
7. FW: High Altitude HF Propagation Test
8. Re: GPS in resin - microwave test
9. Re: APRS in the field. Big step forward...
10. Re: potting a GPS module in resin - RF attenuation
11. Reject list for WinAPRS?
12. Any new symbols?
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Subject: potting a GPS module in resin - RF attenuation
From: Dale Mosby <dale@archcape.com>
Date: Wed, 16 Jun 2004 22:22:20 -0700
X-Message-Number: 1
I want to get my GPS off the dash and outside the vehicle. I have a couple
of the Radio Shack Digi-Traveller units that I picked up on close out. I
wanted something like the Garmin GPS-35 but have had a hard time locating
them and the one place I saw selling them had them priced higher than a GPS
with display. I guess it is a case of building in volume bringing the price
down.
So now I am thinking about just casting one of the Radio Shack units in
resin and mounting that on the outside of the car. I am wondering about the
attenuation of a layer of resin. The units already have a plastic shell,
but I suspect my layer of resin would be quite a bit thicker than the
supplied plastic case.
Does anyone on the list have any expertise in the area of RF transmission
of resin? I would be using the stuff you find at the local hardware store -
not in a NASA lab.
Thanks & 73,
Dale Mosby, K7FW
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Subject: Re: potting a GPS module in resin - RF attenuation
From: Jeff King <jeff@aerodata.net>
Date: Thu, 17 Jun 2004 01:49:50 -0400
X-Message-Number: 2
No idea, but a way to test it.
Place a sample of the resin (not the GPS!) in a microwave oven with a small
cup of water. Turn the oven on for 30 seconds to a minute.
Then check the plastic. If it is hot (or has melted) then it has significant
RF attenuation. If cool to the touch, no problem is likely.
No, this is not April fools.... it really works...
----------------------------------------------------------------------
Subject: Re: potting a GPS module in resin - RF attenuation
From: "Mike Yetsko" <myetsko@insydesw.com>
Date: Thu, 17 Jun 2004 05:58:23 -0400
X-Message-Number: 3
>I want to get my GPS off the dash and outside the vehicle. I have a
>couple of the Radio Shack Digi-Traveller units that I picked up on close
>out. I wanted something like the Garmin GPS-35 but have had a hard time
>locating them and the one place I saw selling them had them priced higher
>than a GPS with display. I guess it is a case of building in volume
>bringing the price down.
If it's just to get it off the dash, and you have a vehicle with a 'rear
deck', consider mounting it UNDER the rear deck.
Or, like in my Intrepid, the dash just lifts up and out. Now there's LOTS
of places to slip in something like the digitraveler that it will be out of
sight and secure when the dash is replaced. (And if you don't have the
expensive Infinity sound system, you can even mount a speaker there for
your HAM radio)
Mike
----------------------------------------------------------------------
Subject: Re: APRS-IS vs RF backbones
From: "Brian Riley (maillist)" <n1bq_list@wulfden.org>
Date: Wed, 16 Jun 2004 20:32:12 -0400
X-Message-Number: 4
I have Direcway two-way service with the self-hosted (no PC front end
needed) DW6000 modem/xcvr/router, their NOC is in the Las Vegas area.
Cheers ... 73 de brian, n1bq
On 6/16/04 5:03 PM, "n5oom@arrl.net" <n5oom@arrl.net> wrote:
>On 16 Jun 2004 at 12:23, Bob Snyder wrote:
>
>>On Tue, Jun 15, 2004 at 06:06:47PM -0400, Danny wrote:
>>Lets face it,
>>the internet is everywhere. In the event of a disaster, you cant be
>>more than a couple hops to an IGATE. Replacing what we already have
>>with APRS-IS with our own MUCH SLOWER and LESS RELIABLE backbone
>>system doesnt make sense.
>>
>>[Whatever Mail client you use doesn't seem to wrap lines properly]
>>
>>The Internet is everywhere. But most providers I know of tend to
>>aggregate up a region's traffic to a single Point of Presence, and
>>connect that back using larger pipes to the provider's backbone, to a
>>regional interconnect point, or both. Often the POP is co-located with a
>>regional interconnect, since that saves on transit costs. The POPs and
>>the interconnects are generally hardened with protected transport,
>>UPS/generators, etc, but hardening against rising flood waters or bomb
>>damage is challenging.
>
>Directway! Now, I don't know where Directway's headend is...
----------------------------------------------------------------------
Subject: Re: potting a GPS module in resin - RF attenuation
From: Gerry Creager N5JXS <gerry.creager@tamu.edu>
Date: Thu, 17 Jun 2004 10:05:35 -0500
X-Message-Number: 5
Rather than resin, consider one of the good quality electronic component
conformal coatings. DO NOT use off-the-shelf silicone sealant.
Concerns will focus on adequate convective cooling of the GPS receiver
components.
Gerry
----------------------------------------------------------------------
Subject: Re: potting a GPS module in resin - RF attenuation
From: Gerry Creager N5JXS <gerry.creager@tamu.edu>
Date: Thu, 17 Jun 2004 10:07:16 -0500
X-Message-Number: 6
Excellent suggestion from Jeff.
Jeff King wrote:
>No idea, but a way to test it.
>
>Place a sample of the resin (not the GPS!) in a microwave oven with a small
>cup of water. Turn the oven on for 30 seconds to a minute.
>
>Then check the plastic. If it is hot (or has melted) then it has significant
>RF attenuation. If cool to the touch, no problem is likely.
>
>No, this is not April fools.... it really works...
----------------------------------------------------------------------
Subject: FW: High Altitude HF Propagation Test
From: "Eric H. Christensen" <kf4otn@earthlink.net>
Date: Thu, 17 Jun 2004 11:44:53 -0400
X-Message-Number: 7
Thought this might be of interest to the APRS community.
73s,
Eric KF4OTN
kf4otn@amsat.org
-----Original Message-----
From: Richard.McClung@dielectric.spx.com
[mailto:Richard.McClung@dielectric.spx.com]
Sent: Thursday, June 17, 2004 11:31
To: NVIS@yahoogroups.com
Subject: [NVIS] High Altitude HF Propagation Test
Forwarded FYI..... RICH
A high altitude weather balloon flight ANSR-19 will be launched June 19,
Saturday morning, 14:30 UTC, from Maricopa, Arizona. It is carrying several
radio payloads, and will ascend to around 100,000 ft before the payloads
will be cut down for a parachute recovery. The flight will last around 2
hours.
The QRP interest is a 1 watt HF PSK31 beacon that will be transmitting the
balloon GPS coordinates every two minutes on 14.070 450. The frequency is
locked to GPS, so it should be correct within 1 Hz.
The hf propagation programs predict good propagation to the United States
west of a line from Pensacola, Florida to Cleveland, Ohio and up into
Canada, west to northern British Columbia. We would like signal
reports,and maybe audio recordings of a transmission, if you can! There is
a cross-band FM repeater with Input: 145.560 MHz/162.2 Hz PL tone with
Output:445.525 MHz that is linked to IRLP reflector 9255, where you can
talk with us at the ground site.
Send reports to KD7LMO at mgray@kd7lmo.netDetails on the HF
payload at http://www.kd7lmo.net/psk31.html
Details on the balloon flights at http://www.kd7lmo.net/ansr.html
Kent Torell
AB7OA 480-675-2003
Fax 480-441-8400
Pager 877-590-6841
General Dynamics C4 Systems
Space and National Systems Division
8201 E. McDowell Road H2171
Scottsdale, AZ 85252
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----------------------------------------------------------------------
Subject: Re: GPS in resin - microwave test
From: Dale Mosby <dale@archcape.com>
Date: Thu, 17 Jun 2004 09:00:13 -0700
X-Message-Number: 8
I had a block of the resin from a previous project so tried the idea Jeff
posted - placing the resin in the microwave.
I put this in the microwave for 30 seconds on high power. It was just
barely warm to the touch, not hot at all. So I would guess that a thin
layer of this resin would not have a great deal of attenuation. Thanks to
Jeff for the suggestion.
73, Dale
----------------------------------------------------------------------
Subject: Re: APRS in the field. Big step forward...
From: Keith Allen <kallen2@bellsouth.net>
Date: Thu, 17 Jun 2004 11:13:10 -0500
X-Message-Number: 9
Sorry for delay in replying to this, but I just read it this date (17th).
The other night, I decided to hook mobile stations in my area (Northern
Alabama n/of I-20). Out of 11 mobiles, including 3 semi drivers, 7 of them
were in fact D-700's and D-7A's. Not quite 90 percent but definitely not
10 percent either. 73. Keith.
----------------------------------------------------------------------
Subject: Re: potting a GPS module in resin - RF attenuation
From: "Keith - VE7GDH" <ve7gdh@rac.ca>
Date: Thu, 17 Jun 2004 10:16:50 -0700
X-Message-Number: 10
Dale K7FW asked June 16, 2004 10:22 PM
>So now I am thinking about just casting one of the Radio Shack units
>in resin and mounting that on the outside of the car. I am wondering
>about the attenuation of a layer of resin. The units already have a plastic
>shell, but I suspect my layer of resin would be quite a bit thicker than
>the supplied plastic case.
>
>Does anyone on the list have any expertise in the area of RF
>transmission of resin? I would be using the stuff you find at the
>local hardware store - not in a NASA lab.
Short of replacing your GPS with something like the low priced Garmin GPS18...
Grab a copy of Visual GPS from www.visualgps.net/VisualGPS/default.htm
Fire it up and connect your GPS and watch the signal strength when you
cover the GPS with your hand / newspaper / magazine / resin or whatever.
I am sure that some attenuation will be acceptable, but at least you
should be able to find out ahead of time how much you will be dealing
with. Let us know what you end up potting it in.
73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am."
----------------------------------------------------------------------
Subject: Reject list for WinAPRS?
From: "Ralph J Schutz" <rschutz@infionline.net>
Date: Thu, 17 Jun 2004 22:21:33 -0400
X-Message-Number: 11
Can anyone tell me if a reject list can be created for WinAPRS, what the
format would be and which folder in the WinAPRS Directory to place it?
Ralph J Schutz N6GVG
----------------------------------------------------------------------
Subject: Any new symbols?
From: Fritz Anderson <fritza@manoverboard.org>
Date: Thu, 17 Jun 2004 22:19:45 -0500
X-Message-Number: 12
I've been working on an APRS packet reader for Mac OS X, and have
gotten it to the point where it will absorb the global feed from a
javAPRS server without breathing very hard.
I've been supplying graphics for object symbols more or less in order
of how often they turn up -- I see a lot of my "unassigned" graphic for
a symbol code, I make a graphic, and I add it.
I'm now down to the point where most of the unknown graphics I see are
for unassigned or reserved symbol codes, specifically
\" \} /J /L /c /F
.. As of the 1.0.1 version of the protocol reference, \" is reserved,
and the others are unassigned. But the document's nearly four years
old, and perhaps meanings have been attached to them. Can anyone point
me in the right direction? I'd be grateful for any help.
-- F
WT9T, Chicago, Illinois
---
END OF DIGEST
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