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ZL3AI > APRDIG 09.02.04 15:02l 217 Lines 10058 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Feb 06, 5/9
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From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: HF APRS
From: "Stephen H. Smith" <WA8LMF2@aol.com>
Date: Fri, 6 Feb 2004 12:41:02 -0800
X-Message-Number: 34
Adam Pirkle wrote on 2/6/2004, 7:22 AM:
>1. Is HF APRS alive?
YES, BUT.... The only band with any consistent organized HF APRS
operation supported by 24/7 IGATEs in North America is 10 MHz (i.e. the
"30-meter" band). [ The actual RF frequencies of the two tones of HF
packet on this band are 10.149.200 and 10.149.400 MHz. ]
No "quad band" radio is going to cover this band -- you will need a
full-blown standard HF rig, or a "DC-to-light" mobile like an Icom 706 or
Yaesu FT-100 that could work on 2M with useful power in populated areas and
on 30M HF in the boonies. Actually you will need two radios in the van if
you propose to crossband repeat from 2M to HF.
>2. What sort of range could I expect out of a mobile HF APRS rig?
HF propagation is driven by reflection and refraction off the
electrically-charged ionosphere. In turn, the charge level is determined
by the amount of solar radiation hitting it. This make HF behavior
constantly change by frequency, time of day and time of year (i.e.
number of hours of solar exposure).
30 meters is normally open around the clock (excepting major solar
storms or explosions that can knock out all HF) for long-range
operation over varying distances.
In one test where I beaconed on 30M from Los Angeles between 12:00
noon and 6:00 PM using a Yaesu FT-100 and it's companion ATAS-100
autotune roof-mount antenna, I was igated into the APRS Internet system
and findu variously from San Diego, Bakersfield CA, Portland OR, Salt
Lake City, Boise ID, Cheyenne WY, Denver CO and finally after dark, from
about 30 mi west of Chicago. Most of the time, you can count on a
coverage radius of 500-1000 miles at least and closer to 1500 miles
after dark.
Note that HF operation is normally direct to igates or other fixed
stations. You don't use digipeaters as is done on 2M. Bear in mind that
"the local coverage area" on HF is normally a third or half of the
country ( ! )instead of a 10-15 mile radius circle as it would be on 2M.
This means the channel capacity is MUCH MUCH less than on 2M since
every time you transmit (at the painfully slow 300 baud rate, no less)
you are occupying the channel for a third of the county. Once-a-minute
beacons are definitely discouraged on HF!
>3. Would I be able to expect coverage in the Rockies/Canada area?
Certainly
>4. Is it worth the hassle to use HF APRS instead of just 2m for this
>purpose?
Given the remote areas you are proposing to traverse (the great basin
and intermountain west) I would say it is the ONLY option. [ Other than
satellites, at least! ] You will find that once you leave Austin, you
will find only islands of 2M coverage around larger towns with hundreds
and hundreds of miles of absolutely nothing in between except for the
occasional hits from high mountain passes. In Canada, you won't hear a
peep on two meters outside of the Calgary and Vancouver metro areas. In
Alaska, outside of Anchorage and Juneau, you won't hear a thing on 2M
Other considerations:
1) Reliable HF operation requires power. It may look appealing to use a
light-weight low-power all-freq rig like a Yaesu FT-817 "porta-luggie",
but 5 watts just won't do it consistently on HF. You really need a full
power (i.e. 100 W output) mobile into a decent HF whip antenna mounted
over a good ground plane (i.e. the van's roof) to radiate a consistently
strong HF signal. [ Antennas and their ground-planes (or lack there
of) absolutely make or break HF mobile operation. ]
2) HF APRS is conducted with 300 baud / 200 Hz shift tones instead of
the 1200 baud / 1KHz shift tones used on 2M. If you are going to
actually cross-band from a HT on your bike to HF via radios in the van,
you will need a dual-port TNC like a Kantronics KAM that can be attached
to two radios at once, one on 300 baud HF and a separate one on 1200
baud 2M FM. The KAM can be configured to automatically crossband-repeat
from one band to the other.
An alternative, if you have a reasonably high-powered laptop (i.e.
400-500 MHz or higher) with a sound card with stereo LINE input (not
just mic) is to use the AGW Packet Engine software. This program (one
version is FREEware, the other a $50 shareware package) creates a packet
TNC entirely in software using the soundcard as a digital signal
processsor. In turn, AGW can communicate with any of the Windows APRS
programs (UI-View, APRSplus, WinAPRS, APRSpoint, etc)
With a stereo line input on the soundcard, AGW can actually
simulate a DUAL-PORT TNC like a KAM, with one channel running at 300
baud HF and the other side at 1200 baud VHF. You would then need TWO
sound card interfaces to couple the computer to two radios.
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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Subject: Re: Mapping plans
From: James Jefferson <jj@aprsworld.net>
Date: Fri, 6 Feb 2004 15:00:28 -0600
X-Message-Number: 35
>>This sounds alot like APRSWORLD, so why not just help James out with
>>APRSWORLD? That is the beauty of open source, if you don't like something
>>or it doesn't do something you want it to, you add it yourself. He
>>already has the sourceforge project set up and it would be a good start.
>
>First, as I understand it, APRSworld is a parser and web interface, just as
>findU.com is. What we are really talking about here is the maps he is using
>on his web site. These are generated from shapefiles using code from UMN
>called MapServer. Perhaps Jim can clarify the exact mechanics more...
I think what Jeff is getting at is that there is no reason for a whole new
mapping system to be created. There should be very little custom software
needed besides some converters to translate aprs type maps into shapefiles.
The mapserver software automatically chooses the right data to create a map
from based on a number of criteria.
maps.aprsworld.net is based around Mapserver (http://mapserver.gis.umn.edu)
as Steve suggsted. However going from the mapserver software to what you
see generated by maps.aprsworld.net is a non-trivial step. There are about
20 gigabytes of GIS data that has been collected and is kept up to date - a
manual process. Then there is a "map" file which is the input to mapserver
that defines the criteria above. For example when zoom in at a certain
scale some things show up and somethings don't. Then on top of that is my
little web interface. Mapserver is designed to be run as a CGI, however it
cumbersome in this form. I wrote a wrapper that invokes shp2img, a
standalone program that is part of mapserver, to render a map otherwise it
gets it from cache.
I don't know if the mapserver stuff in in CVS or not. If it is not and
people want the code it's easy enough for me to tar it up and send it to
you. I can't reasonably do the same for the data because some of it is
licensed under terms that prohibit redistribution. Likewise on the true
type fonts that it needs - however there are plenty of freeish true type
fonts to be found on the internet.
So, the way I see it ... Steve's vision of using other APRS maps for
coverage of the rest of the world would take about 2 person-days of time
for somebody to write converters to shapefile .... or about 3 person-years
to write a new mapping system. But I'm biased in this because I already
have a few solid man-months of my time invested in a mapping system (that's
on top of many years of time required to write mapserver).
de KB0THN
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Subject: Re: Mapping plans
From: James Jefferson <jj@aprsworld.net>
Date: Fri, 6 Feb 2004 15:09:49 -0600
X-Message-Number: 36
>However, the APRSworld maps are US only. The coverage outside the US is
>limited to coarse coastline and international borders. He depends on
>shapefiles, the only comprehensive solution to making his mapping server
>work for the world is to buy shapefiles for all countries that have APRS
>users. However, none are free, and APRS cannot even afford to buy the files
>for Canada.
Actually there is a complete set of 1:1 million scale highway maps for the
world. It's called the Digital Chart of the World. It's obviously not street
level, however. I can put the raw e00 files online if some people wanted to
do convert them to shapefiles and perhaps merge some of them together.
data point:
Street level data for most of Europe could be purchased for $90,000 from ESRI.
Go to www.esri.com and look at their online store.
-Jim
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Subject: Re: Mapping plans
From: Jeff King <jeff@aerodata.net>
Date: Fri, 06 Feb 2004 15:14:35 -0600 (CST)
X-Message-Number: 37
Quoting James Jefferson <jj@aprsworld.net>:
>>>This sounds alot like APRSWORLD, so why not just help James out
>>>with APRSWORLD?
>>called MapServer. Perhaps Jim can clarify the exact mechanics
>more...
>I think what Jeff is getting at is that there is no reason for a whole
>new mapping system to be created.
Exactly.
I knew that APRSWORLD, as it sits, would not do what Steve needed. Yet it
would do part of what he needed, so instead of an entirely new application,
just extend upon what APRSWORLD is already doing.
This is really the root of opensource and how much of successful open
source applications are developed. That is, "someone has an itch", in
Steve's case he need's worldwide mapping, and then they find an existing
opensource application to extend.
The end result being the sum of the two efforts is greater then if they
where done seperately.
-Jeff
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