jak@mtunh.UUCP (Jim Kutsch) (06/03/85)
Gateway: The ARRL Packet-Radio Newsletter
Volume 1, Issue 20
May 21, 1985
Published by:
ARRL
225 Main Street
Newington, CT 06111
203-666-1541
Editor:
Jeffrey W. Ward, K8KA
CALIFORNIA PACKETEERS PARTICIPATE IN "QUAKE '85"
A simulated earthquake occurred on April 16 in southern
California. The simulated quake was 8.2 on the Richter Scale.
A quake of this size would cause a great deal of destruction and
would most likely result in the immediate loss of most
communications over a large area for several hours. As is the
case for most large-scale exercises of this type, amateur radio
played a part. This year, for the first time, packet radio made
major contributions.
The goal was an ambitious one: to move traffic from the State
Office of Emergency Services (OES) communications trailer in Los
Alamitos to the OES office in Sacramento, 400 miles to the north,
using VHF. This required the use of seven digipeaters. We
learned several things during the exercise: First, it is
possible to move a large amount of traffic that distance through
that many digipeaters, and second, it wasn't possible to do it in
the way we had originally intended.
We also had several unplanned events preceding and during the
exercise which added to the simulated emergencies. First,
California is blessed with a geography that provides 4000 to 8000
foot mountains and over-water paths. The length of most of the
paths used in the network (called WESTNET) is 90 miles, with one
path of 120 miles and another close to 200 miles. The longer
paths require over-water ducts, which are in place for much of
the year. Two days before the exercise, a weather pattern went
through that destroyed the ducts, which didn't return for several
days.
Also, three digipeaters failed the day before the exercise. This
was the largest network failure experienced before or since. The
systems were repaired in hours, and portable systems were
readied. During the exercise, one system was driven to a
mountain top to supply backup for the lost duct, and another
system was "car mobile" at the OES site, ready to be driven or
helicoptered should the need arise.
In addition to the amateur-owned equipment in place, the OES had
previously purchased several TNCs; one was installed in their
communications van in Los Alamitos and another in their office in
Sacramento. A third was at an intermediate digipeater site in
northern California. To make a long story short, soon after the
exercise began, we established communications with Sacramento.
Unfortunately, it was lost soon after, because of a flaky path at
the far northern end. We didn't find this out until much later,
of course. We interspersed an hour of attempted reconnects up
north with passing traffic around the southern California area -
San Diego, Santa Barbara, Glendale and others. This activity was
very successful. After it became apparent that we couldn't stay
connected to Sacramento, the goal became to get the traffic as
close to there as possible. We sent several CQ messages to San
Francisco, which was outside of the simulated affected area, and
attracted the attention of a ham with file store capabilities.
We transferred two hours of accumulated traffic in short order to
San Francisco, through four digipeater hops. The San Francisco
station then transferred the traffic to the Sacramento station
though two hops, again with little difficulty. Later in the
afternoon as the paths improved, we were able to transfer traffic
directly to Sacramento.
We learned these lessons during the test: First, two teams are
needed at the packet position in the communications trailer. One
team establishes and maintains the link, the other enters the
traffic on a separate computer system. When a link is available,
the data can be moved quickly by moving a disk from the data-
entry computer to the computer with the TNC attached. During the
"quake," even though two computers were available, message
traffic piled up in the "IN" basket while we were trying to
establish a path. Once contact was made with the San Francisco
station, it took half an hour to clear the backlog. It would
have taken less than five minutes had the data already been
entered on disk.
We also learned that it would have been better if we had planned
on an intermediate file relay station part way up the link in the
first place. The cumulative effects of dropped packets increases
with number of digipeaters until the probability of a packet
making it all the way to the end and the ACK getting all the way
back becomes small. In our case, four hops was 90% reliable (one
packet not ACKed in 10), but seven hops was less that 10%
reliable. Had we sent all traffic with to the intermediate
station in San Francisco, we could have passed the traffic as it
came in, instead of building up a large backlog.
Finally, we learned that it was possible to pass traffic a long
distance through a large number of digipeaters, provided that we
did it the right way. It was possible to maintain a clear
channel; people with non-simulated-emergency traffic stood by or
went elsewhere. We also learned that as with other types of
emergency exercise, success depends on planning and on the hard
work of many amateurs.
At the risk of leaving someone out, here is a list of the packet
participants in "Quake 85" -- keyboarders, mountain-toppers, HQ
and other office station setup, north and south: KA6SOX, W1UUQ,
WA6CFM, WD6FPY, WB6DAO, W6IXU, N6BGW, N6CXB, NK6K, AJ6T, WB6UCK,
N6ZH, NG6P, K6QIF, KB6JM, WB6HHV, W6AMT. There were 6 packet
stations directly involved with traffic handling and 10
digipeaters involved in the network.
From NK6K.
IBM PC PACKET ADAPTER
Jack Botner, VE3LNY, whose article "A Packet Radio Adapter for
the IBM PC" appeared in the January 1985 issue of QEX, has
received many inquiries concerning software for his 8273 HDLC
adapter. He reports that an implementation of the VADCG protocol
is available from the Hamilton Area Packet Network (HAPN). The
protocol software is written in assembler, and the support
programs are written in C. To receive the software, send $15, a
diskette and a disk mailer to:
Jack Botner, VE3LNY
35 Wynford Hights Circle #1708
Don Mills, Ontario
CANADA M3C 1L1
Software supporting the AX.25 protocol is not yet available for
Jack's adapter. HAPN would like to hear from anyone interested
in developing AX.25 software for the interface.
From VE3LNY.
COLLECTION OF PACKET PAPERS
If you have been reading any of the books recommended in Gateway,
you have probably noticed that a few "classic" papers on packet
switching are referred to over and over. Tutorial Principles of
Communication and Networking Protocols, edited by Simon S. Lam is
a comprehensive collection that includes many of these essential
papers on digital communications. The papers cover link
protocols, multiple access methods, local-area networks, resource
allocation in networks, network and internet services, and
protocol verification. The collection is published by The
Institute of Electrical and Electronics Engineers (IEEE), and it
is ISBN 0-8186-0582-0.
Via KA9Q.
PACSAT FUNDING
As reported in Gateway 15, the Radio Amateur Satellite
Corporation (AMSAT) and The Volunteers in Technical Assistance
(VITA), have completed engineering specifications for PACSAT, a
proposed store-and-forward, packet-radio satellite. In the two
months since the design and strategy meeting, no sources of the
necessary funding have been identified. Recently, VITA was
granted several thousand dollars to retain a professional fund
raiser for the PACSAT project. While this should help, it is
still important that amateurs assist by identifying potential
sources of major contributions. Also, as in past amateur-
satellite projects, individual and club donations to the PACSAT
fund will be necessary. If you can help, contact:
VITA
1815 N. Lynn
Arlington, VA 22209
Attn: Gary Garriott, PACSAT Project Manager
Ed.
JAS-1 PACKET INTERFACE
The April issue of the Japanese magazine CQ Ham Radio has an
article by JA1ANG, based on material from Miki Nakayama,
JR1SWB, describing the user interface to the packet mailbox that
will fly on the JAS-1 satellite. It shows a sample message from
W3IWI to JR1SWB as it would be received at JR1SWB and then a
reply. The dialog shown in the magazine is reconstructed below:
(Legend in left-hand column:
$: JAS-1 ==> User
%: User ==> JAS-1
&: TNC <==> User)
& cmd:CONNECT JAS-1
& *** CONNECTED to JAS-1
$ Hello JR1SWB de JAS-1
$ Your last access was on 85/01/11 at 1922 UTC
$ NO. DATE FROM TO SUBJECT LINES
$ 15 01/28 W3IWI JR1SWB AX.25 SOFTWARE 3
$ Command ?
% READ 15
$ Posted: Mon 85/01/28 From: W3IWI
$ To: JR1SWB
$ Subj: AX.25 SOFTWARE
$ I have the disks ready to mail to you and the
$ packet is all sealed. $ Tom
$ COMMAND ?
% WRITE W3IWI
$ Subject:
% Re: AX.25 SOFT.
$ Text:
% Tom, I'm looking forward to receiving the
% packet.
% 73's Miki
% .
$ Message from JR1SWB to W3IWI saved as #18
$ COMMAND?
% BYE
& *** DISCONNECTED
This protocol is a combination of features of the W0RLI MailBox
(JR1SWB has a Xerox 820 and is running the MailBox) and of
TeleMail (the message in the example was sent via TeleMail).
JAS-1 is scheduled for launch in 1986. Uplinks will be on 2
meters (145.85, .87, .89, .91 MHz) with a single downlink on 70
cm (435.91 MHz) using 1200 bauds, phase-shift keyed (PSK).
From W3IWI.
SIGHTLESS HAM ON PACKET RADIO
April 25, 1985 marked an important event for the Rochester
packet-radio fraternity. 1985 has seen rapid growth of packet in
the Rochester area, but the highlight has to be the appearance on
packet of Walt Keleher, KA2ASL. What's so unusual? Walt is
blind.
Operating on voice or CW without sight presents some challenge,
but think about operating on packet radio without your sight.
Sending is not a big problem, since Walt can touch type, but
receiving is another story. Walt has an Apple IIe computer, an
Echo voice synthesizer and a specially developed terminal
program. This terminal program unites the computer/terminal and
the text-to-speech functions of the synthesizer or "talker."
Whatever appears on the screen of the computer is "read" by the
talker, in nearly perfect speech. If pronunciation errors are
made, Walt can back up to get a repeat or to have the unit spell
out the unknown word or phrase.
On the evening of April 25, Dave Denz, N2DWL, and Mark Winrock,
both members of the Rochester packet group, went to Walt's home
and set up his TNC and radio. After a short period of
instruction and coaching, the big moment arrived. The equipment
worked perfectly. Walt worked WB2NBU, K2YNW and W2DUC in rapid
succession. While Walt was taking his time learning about packet
operation, the rest of the gang was taking turns sending to him.
Walt reports that we are perfect copy, but all seem to have a
Swedish accent (a common trait of text-to-voice processors).
It was exciting evening, introducing Walt to packet radio and
helping willpower overcome a great barrier.
From W2DUC.
CONTACTS IN THE SOUTH
At a recent packet-radio forum at the Baton Rouge, Louisiana
hamfest, several amateurs from Louisiana and Mississippi
expressed the need for better communications among the scattered
centers of packet radio in the southern U.S. If you are
interested in helping connect the western reaches of "SOUTHNET,"
write:
Ken Shutt, K5GUU
12433 Archery Dr.
Baton Rouge, LA 70815
or
Alan Clark, WD5IKD
2325 Milam Street
Pearl, MS 39208.
In areas where packet stations are few and far between, it is
important that those who are on the air or interested in getting
started can get in touch with others who've been bitten by the
packet bug.
Via WD5IKD, K5GUU.
INTERMOUNTAIN REPORT
Dave Pedersen, N7BHC, of the Utah Packet Radio Association
(UPRA), recently gave a packet-radio introduction and
demonstration to more than thirty people in Boise, Idaho. There
are several packet stations under construction in Boise. Dave,
located in Salt Lake City, Utah, reports that he has been able
to make a 300-mile direct connection with Jeff Bishop, W7ID, in
Boise. Unfortunately, the path is not quite solid on 2-meter FM.
Dave and Jeff regularly hold 2-meter SSB skeds, and they hope to
try some SSB packet (real FSK instead of AFSK on FM) soon. A
digipeater link between Salt Lake City and Boise should be
completed this summer.
From N7BHC.
HF PACKET
If your VHF packet network is getting a bit crowded or you just
want to try out another facet of packet radio, connect your TNC
to your HF rig and give HF packet a try. HF packet stations
transmit at 300 bauds, using a 200-Hz shift. While some stations
are using Bell 103 modems modified to transmit and receive on one
set of tones (simplex), any 200-Hz shift modem can be used. If
your transmit tones are the same as your receive tones, just tune
in another station and you're on your way. Packet-radio employs
NRZI encoding, so which sideband you use is not important. Most
of the HF packet activity is on 30 and 20 meters, with 10.147 MHz
and 14.102 MHz the popular frequencies. The following stations
are running the W0RLI GateWay software on HF packet: KI0Q, Ames,
Iowa; N4CI, Conyers, Georgia; KF4JF, Hahira, Georgia; K7PYK,
Scottsdale, Arizona; WA4SZK, Florence, South Carolina; W0RLI,
Westport, Massachusetts; KD6SQ, Cucamonga, California; KA1PN-1,
Nashua, New Hampshire. Hank Oredson, W0RLI, reports that a new
GateWay station comes on the air each week. So, slow down your
TNC and narrow your modem to try HF packet.
Via W0RLI.
TAPR "OLD BUSINESS DAYS"
From Monday, May 20, through Friday, May 31, 9:00 AM until 5:30
PM PST, TAPR will double its office staff and disconnect the
telephone recorder. During this time they will have a human
answering the phone, and they will be returning the backlog of
calls that has built up.
What exactly is "Old Business Days"? It's a marathon session
during which TAPR hopes to clear out the last loose ends of the
TNC-1 product line. Call if you have any outstanding business
with TAPR regarding any of the following items:
TNC-1 Kits
TNC-1 cabinet kits.
Beta Upgrade kits.
Outstanding spare parts orders.
Also take this opportunity to order spare or replacement parts
for TNC-1.
If you are calling about a backlog order, please have the date of
the transaction available and information on the method of
payment. If you call after hours, you will get the answering
machine; Please leave a number where you can be reached during
the day.
Please do not call about any of the following items:
Orders for TNC-2
New TNC-1 kit or cabinet orders
9600-bit/s modems
TNC software or hardware questions
Both TNC-2 and the 9600-bit/s modem boards are in beta test now.
TAPR will begin taking orders when they are available.
The TAPR phone number is (602) 746-1166.
From NK6K.
REPRODUCTION OF GATEWAY MATERIAL
Material may be exerpted from Gateway without prior permission,
provided that the original contributor is credited and Gateway is
identified as the source.