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Subject: Mounted search and rescue

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  • From: Una Smith <una@lanl.gov>
  • To: msar-riders@lists.ibiblio.org
  • Subject: [MSAR] Packet radio
  • Date: Fri Jan 3 10:47:00 2003

I mentioned FidoNet here recently. Sadly, FidoNet seems to
have lost all connections with amateur radio, and now depends
on the telephone networks. But amateur packet radio remains
alive and well, and is ready to serve.

Typical computer data communications via amateur packet radio
are said to run at a baud rate of about 1200 bits per second
(bps)...but I have found mention of higher rates (9600bps is
typical), so I don't know what rate to expect. Even 9600bps
is painfully slow by today's standards, and certainly too slow
for effective transmission of high resolution images such as
photos and topo maps, or for real-time video. But it is more
than adequate for plain text e-mail and file transfer. Note
that packet radio can operate as a store-and-forward system;
generally, it is feasible for users to interact directly with
remote computers in real time, but data can also be delivered
when the hardware is unattended, or would otherwise be idle.

Amateur packet radio has great potential for effective support
of computer applications in the field. In New Mexico, for
instance, there are digital repeaters on mountain peaks that
provide complete coverage state-wide. These are commonly used
to support the use of APRS trackers, which are small portable
boxes containing a battery pack, a low-power radio, and a GPS.
The tracker is programmed to determine its own location and at
a set interval (every few minutes) broadcast that location. A
monitoring station at incident command (or anywhere in receiving
range of the New Mexico APRS digipeter coverage) has a radio
receiver linked to a computer with a geographical information
system (GIS) running. The GIS station automatically updates
the current location of the tracker on a map of the incident
area.

I bet it would not be difficult to hook a palmtop computer to
a portable radio, so the SAR team can submit data directly to
the GIS back at incident command. Data such as the location
and type of clue (tracks, clothing, etc.). Or get data, such
as the current incident map, complete with locations of other
teams.

Anyone interested in packet radio should get an amateur radio
license. That's easy to do! See my next message for details.

Lastly, a happy New Year to you all!

Una Smith
Santa Fe County Sheriff's Posse, in New Mexico


----------------------- some references --------------------------

Usenet newsgroups with relevant interests:
alt.ham-radio.packet
rec.radio.amateur.digital.misc

Resource websites:
http://www.tapr.org/tapr/html/pktf.html
http://www.fidonet.ca/

Technical success stories on the web:
http://www.uspacket.net/l_ecom01.htm
http://www.heise.de/tp/english/inhalt/te/1314/1.html

There are also high performance wireless systems in use now,
based on broad-band microwave technology. See for example
http://hpwren.ucsd.edu/news/021101.html
http://www.computerworld.com/mobiletopics/mobile/story/0,10801,75830,00.html
http://www.computerworld.com/mobiletopics/mobile/story/0,10801,76118,00.html

Jargon:

APRS = Automatic Packet/Position Reporting System; a special
application of amateur packet radio that may serve to support
state-wide SAR logistics at remote incident bases. See these
web sites:
http://www.aprs.net/
http://web.usna.navy.mil/~bruninga/aprs.html
and especially
http://web.usna.navy.mil/~bruninga/APRS-docs/APRS.TXT

digipeter = amateur radio digital repeater; a repeater is a
radio (usually running unsupervised) that receives a signal on
one frequency and almost simultaneously broadcasts that signal
on a second frequency.

packet radio = the signal is digital (that is, an audio
encoding of binary data), the binary data encoding information
(ASCII plain text, images, maps, database records, etc.).





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