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. 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.