jak@mtunh.UUCP (Jim Kutsch) (08/06/85)
Published by:
ARRL
225 Main Street
Newington, CT 06111
203-666-1541
Editor:
Jeffrey W. Ward, K8KA
FIGHTING FIRES WITH PACKET RADIO
This report on packet-radio communications during the Lexington
and Santa Cruz Mountain (California) Wildfire was filed by Ken
Chong, WB6MLC, and edited by Hank Magnuski, KA6M.
"During the afternoon of Sunday, July 7, reports were being
received by the local Amateur Radio Emergency Service (ARES)
District Emergency Coordinator (DEC) that a new fire had been
discovered in central Santa Clara County near the Lexington
Reservoir, about 60 miles south of San Francisco.
"Since the 4th of July the local ARES 'Strike Team' had been
assembled and put on alert. This particular amateur radio team,
unlike previous ones, was equipped with a complete packet radio
station. Late that Sunday, the team was called out to set up
operations at the Alma Fire Station to handle communications
concerning resources, tactical messages, fire updates and
evacuation notices.
"Throughout the day and further into the week, Fire Status
Updates were sent out over packet when the voice nets were tied
up. Once, when the phone lines were busy, packet radio got
through to KA6YRK at another fire camp in San Luis Obispo, in
Southern California. Many operators who had never operated
packet before were literally baptized by fire!
"On Tuesday, July 9, with the fire leaping rapidly from hill to
hill, the main base camps and staging areas were moved to Vasona
Park in Los Gatos. The towns of Los Gatos and Saratoga were
severely threatened and many held their breath, hoping that
evacuation orders would not be issued. At 'Vasona Com,' where
the future amateur operations were to originate, a well-equipped
van from the Palo Alto Red Cross was set up with packet equipment
and an IBM PC programmed for use as a terminal. Two other radios
for the voice nets were also in the van. Again, packet radio
continued to function when the voice nets were busy.
"One glaring problem, receiver desense, reared its ugly head
during the operations. The local mountaintop digipeater was also
malfunctioning, and two meter full-duplex repeaters were pressed
into service. The retry rate increased so much because of the
intermod products and desense that the packet technical crew
transferred all digital traffic to full-duplex voice repeaters on
440 MHz. Finally, with the packet net secured on 440 MHz, all
relays of fire updates to the different base camps continued
without interference from the nearby two-meter radios.
"Thanks to the hard work and contributions of many, the packet
operation at the main fire camp solved one more disturbing
problem. The large pool of fresh operators had little or no
experience with TNCs. Most had barely heard of TAPR! The IBM PC
was cleverly programmed to use its function keys to connect,
disconnect and send various 'canned' messages. By Thursday,
July 11, the whole operation was almost foolproof. At last an
untrained operator could sit down and keep the net going.
"Packet radio did an outstanding job in proving to the fire
officials its usefulness in an emergency and at the fire camps.
The initial strike team of Frank Kibbish, WB6MRQ; Kit Blanke,
WA6PWW and Bob Tarone, WA6ZBX and the packet setup crew of David
Palmer, N6KL and WB6MLC were pleased with what evolved during the
course of the emergency. When the smoke clears, a more detailed
report will be filed.
VIA DRNET
ANOTHER FIRE REPORT
Paul Hansen, KA6UPD, sent in a newspaper article detailing some
of his activities as a packet-radio operator assisting California
firefighters. The article appeared on the front page of the July
14 edition of the Thousand Oaks, California, News Chronicle, and
it carried a photo of Paul and Jerry Boone, emergency coordinator
for Ventura County ARES. The article gives some description of
packet radio and the of work done by ARES members in the
California disasters. Several paragraphs are devoted to the
reasons that Amateur Radio operators get involved in public
service. Paul is quoted, saying, "We have an obligation to give
public service to pay back for the right to use the frequency
space we have." Ray Volkmar, leader of the Conejo Valley
Disaster Action Team, says that public service stems from "a love
of our hobby and a love of being able to do something for someone
else."
VIA KA6UPD.
FIELD DAY REPORTS
It looks like a lot of stations took advantage of the 100-point
packet-radio bonus this Field Day. The following reports detail
some successes and some lessons learned.
In The Chawed Rag, newsletter of the Richardson (Texas) Wireless
Klub, George Baker, W5YR, reports that "unfortunately, the packet
station performance left much to be desired...Only one QSO could
be managed. But that produced another 100 points. On 145.01
MHz, where the packet action took place, the racket has to be
heard to be believed. At times it sounded like one long 'brrrap'
as one packet followed another the instant the frequency was
clear. It was a good demonstration of how packet allows a lot of
stations to work on the same channel concurrently without QRM.
"I 'printed' stations from all over Dallas and Tarrant
counties...Many stations were extending their range by using the
'digipeater' capability of the AX.25 packet protocol.
"Field Day has shown that packet can add another dimension to
traditional contest modes, as well as proving that you can take
reasonably delicate home computer equipment and set it up in the
field under adverse conditions and make it play...Packet radio is
really out there, and it is beginning to 'intrude' into areas of
ham radio that formerly were the exclusive domain of CW or
phone."
David Cheek, WA5MWD, of the Texas Packet Radio Society, operated
at the K5QHD Field Day site in Garland, Texas.
"More than twenty three packet stations in the North Texas
Section participated in the Field Day. About half were operating
in the field, on emergency power. At K5QHD in Garland, we made 20
contacts, while two stations in Ft. Worth, made 23 each. At
least two other stations went over 15 contacts, including W5CR in
Athens. The best DX on two meters was the Salado contact on
packet. Huston packet stations made lots of contacts with the
help of the WD5GAZ digipeater.
"We learned a few lessons: First, make sure all of your packet
equipment is ready to operate in the field. Try to have 25 watts
or more and an antenna at least 30 feet high. Second, finding a
route to a station can be difficult, as is learning the call of
the distant station you want to connect to. This can be handled
by some limited beaconing, with each station continuously
monitoring to gather new information about who is operating were.
This can all also be mapped out in advance. Third, excessive
beacons can seriously slow down traffic on the frequency and
should never be any more frequent than once every ten minutes.
Beacons must include useful information, such as, 'reach me
through KC5LW-1, WB5QNG and WA5MWD'. Fourth, the frequency must
be kept as clear of other traffic as possible. This is no
different from any other emergency operation. Finally, in a real
emergency operation, two people are needed for each packet
station. One will operate the transmitter while the other types
traffic into a message computer. Only a station handling very
little traffic -- less than ten ARRL radiograms per hour -- can
be operated by one person."
There are two Field Day reports in the June/July issue of the
NEPRA PacketEar, newsletter of the New England Packet Radio
Association. John Langner, WB2OSZ, operated with the Billerica
(Massachusetts) Amateur Radio Society. They only made a few
contacts, but did use packet radio to receive the official Field
Day bulletin and send a message to the Section Manager. The
packet operators explained packet to those who had never seen it
and may have inducted a few new packeteers.
Robert Gettys, N1BRM, was the sole packet operator at the
Framingham (Massachusetts) Amateur Radio Association Field Day.
Robert found that the lack of a second operator familiar with
packet kept the station from being operated for the full contest
period. He "found that you can't teach someone who doesn't
understand the concepts of computers in general how to run a
packet station and 'search' for possible contacts...or even
enough [to conduct] a simple contact." Robert made 21 contacts,
and he was able to send and receive Field Day messages from the
K1BC PBBS.
Robert concludes that we need to find a recognized procedure for
soliciting contacts (calling CQ), and he also notes that beacons
and PBBSs contributed to severe channel congestion. His article
ends with a few questions that the packet-radio and contesting
communities should begin to think about:
o Should packet be used in contests at all?
o If so, in which contest(s)?
o What rules should be specified concerning digipeaters,
beacons and frequencies?
o Should contacts with PBBS or stations under automatic control
count?
Robert feels that because Field Day is as much a test of
emergency communication as it is a contest, packet radio is
probably appropriate for Field Day. He is less sure about other
contests.
If you would like to put forth answers to any of Robert's
questions, send a letter to Gateway and to the members of the
ARRL Contest Advisory Committee.
CHAWED RAG, DRNET, PACKETEAR.
EASTNET NOTES
Gary Hoffmann, AK3P, in Hummelstown, Pennsylvania, has his W0RLI
MailBox system running on 145.05 MHz as well as on 145.01 MHz.
This allows users of the 145.05 MHz digipeater in York to access
his system. Gary is using two radios in parallel to implement
his dual-frequency node. He hopes to install a true multiport
digipeater in the future. Gary is also planning to add an HF
port to his MailBox, with antennas beamed toward Europe.
Tom Clark, W3IWI, is also operating a MailBox with both 145.05-
MHz and 145.01-MHz inputs. Tom, however, is using the W0RLI
GateWay software to connect the two frequencies. To reduce the
congestion that is beginning to bother everyone on 145.01 MHz,
all local users in Baltimore and Washington D.C. have been
encouraged to use the 145.05-MHz port. This helps keep 145.01
MHz open for EASTNET traffic entering and leaving the Washington
area. The 145.05-MHz input is served by the W3GXT-5 (Baltimore)
and W3VD-5 (Laurel/Columbia) digipeaters. The novel thing about
this installation is that the radios for the two ports are
combined using an RF-hybrid combiner to drive a single power
amplifier and antenna.
Tom sends these other notes: W0RLI MailBox systems are beginning
to be used as personal mailboxes. Three new digipeaters on
145.05 MHz are W3TMZ in Mt. Airy, Maryland, K3VPZ near Baltimore
and N8FJB in Harper's Ferry, West Virginia. Also, Bob Bruninga,
WB4APR, has his Commodore VHF-to-30-meter gateway software
converted to support commands and mail forwarding like a W0RLI
system. So, the Baltimore/Washington network has the following
major stations on 145.05 MHz: N8FJB, W3TMZ, K3VPZ and WB4APR-5.
W3IWI has a GateWay between 145.05 and 145.01 MHz, and KS3Q scans
145.01, 145.05 and 145.09 MHz. All of these stations are linked
by automatic mail forwarding.
VIA EASTNET.
NEWS FROM SOFTNET
The Swedish SOFTNET User Group (SUG), in Linkoping, Sweden, has
had its third workshop. SOFTNET is an experimental packet-radio
system that uses distributed processing to provide network
services. The SOFTNET nodes run at 100 Kbits/s and are remotely
programmed in a FORTH-like computer language. [For more
background on SOFTNET, see Gateway Number 5.] The following
report on the SOFTNET workshop is from the newsletter SOFTNET
News.
The event was attended by about 50 SUG members and other
participants from Sweden and Denmark. The first session started
with introductory talks on the SOFTNET concept. These talks were
followed by a hardware session which was dominated by Ingvars,
SM5LRF, who presented the latest news on the Softnet radio
transceiver [100-kbit/s modem]. While the transceiver has been
available for about six months, minor modifications to improve
the performance are continuously being made. During the lunch
break, there were demonstrations of SOFTNET nodes and connections
to several main-frame computers.
The first session after lunch was devoted to SOFTNET programming.
Fritte, SM5PSL, talked about activities of the SOFTNET
Specification Group and presented some of the group's proposals.
Peter, SM5PQZ gave a talk on the implementation of an algorithm
for distribution of system software through intelligent network
flooding.
An interesting talk on some of the commercially available packet
radio systems was given by a member of the Swedish
Telecommunications Administration. SOFTNET-like systems are of
great interest to the Administration because they can solve data
communication problems for fixed and temporary networks in
difficult terrain.
The next session was on packet radio in satellite systems.
Sigge, SM5KUX, presented some of the plans on SWASAT, a Swedish
Amateur Radio Satellite which is to carry advanced, high-speed
packet-radio experiments. An interesting paper on the design of
a doppler-shift adaptive modem for the IC-251/451 was also
presented.
The workshop concluded with a panel discussion chaired by Carl-
Lennary, SM5ELD. Among the biggest issues of the discussion was
the negative view of digital communications and packet radio
taken by the HF Working Group of the IARU. The participants
urged the spreading of more information to bring on a more
positive attitude towards packet radio and experimental
activities in general.
VIA SOFTNET NEWS, SM5PSL.
QSL TO HELP DRNET
One of the constant sources of Gateway news is DRNET, a
computerized conference that is part of the New Jersey Institute
of Technology's, Electronic Information Exchange System (NJIT
EIES). NJIT is interested in knowing how many people are served
by DRNET. As Gateway readers, you all receive regular DRNET
information. Please send a post card to
CCCC @ NJIT
Tom Moulton, W2VY
323 King Blvd
Newark, NJ 07102.
Tom is the NJIT "sponsor" of DRNET, and he would like to be able
to show that the 30 DRNET accounts are actually serving several
thousand information-starved packeteers. He is also interested
in how far messages from DRNET get distributed. On your card to
Tom, tell him your name, call, location and packet setup, how you
got the message, how often you receive messages that originate on
DRNET, the name of your local packet group and the number of
members in your group. The few minutes that you take to do this
will help keep a vital source of information active.
VIA DRNET.
COHERENT DEMODULATION?
Fred Weidenhammer, W4SDL/2 writes that he is looking into the
application of the techniques involved in coherent CW (CCW) to HF
packet demodulation. If you are interested in this, contact Fred
and experiment. His address is
322 Blacksmith Road
Levittown, NY 11756.
FROM W4SDL.
600-Hz SHIFT FOR HF PACKET?
While all of the stations using packet radio on HF are using 200-
Hz shift at 300 bauds, there has been a lot of discussion of
eventually using wider shifts. To start some public dialog and
experimentation on this matter, we present here a letter sent to
Gateway by Dr. Alan Chandler, K6RFK, of Advanced Electronic
Applications.
"The 200-Hz shift that is becoming the defacto standard for 300-
baud HF packet has a substantial deficiency when on an
ionospheric path. Due to differential path length, both
frequencies may be present simultaneously at the receiver and
will generate a beat frequency. If the beat frequency is greater
than the highest desired harmonic of the data, it may be filtered
out and will not be a problem. If it is lower, the beat will be
treated as data by the TU and will generate errors. In the case
of 300-baud data, the fundamental is 150 Hz, and the minimum 3rd
harmonic should be passed. This gives a minimum shift of 450 Hz,
and to allow economical filters, the minimum shift should be 600
Hz. The TAPR and TAPR equivalent modems will receive 600 HZ
shift without modification and they can easily be adjusted to
transmit 600-Hz shift tones (1400 and 2000 Hz)."
FROM AEA.
MINICOMPUTER ON PACKET
St. Louis Amateur Packet Radio (SLAPR) has acquired a DEC PDP-8
minicomputer. They would like to put the machine to some
practical use on the local packet network. Because there are
already several mailboxes on the St. Louis ares, the club is
interested in using the PDP-8 to store and distribute large files
like Gateway. If you have any expertise that you might donate to
this SLAPR project, contact
Pete Eaton, WB9FLW
35 Norspur, Route 4
Edwardsville, IL 62025.
VIA DRNET.
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