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.