UTARC News
The Official Journal of the University of Texas Amateur Radio Club
January 1997
The Official Journal of the University of Texas Amateur Radio Club
January 1997
The January meeting of the University of Texas Amateur Radio Club will be held on Thursday, January 16 at 7:30 PM in RLM 5.124 on the UT campus. Talk in on the 147.18 MHz repeater.
The topic of discussion this month will be Spread Spectrum (SS) communications. SS promises to revolutionize packet radio communications for Amateur Radio. UT graduate student Greg Jones (WD5IVD) will discuss some of the main features of SS and why its use in Amateur Radio is needed. Greg currently serves as President of the worldwide TAPR organization which designed the first TNC II units in the 1980's.
Everyone attending January's meeting will receive a copy of QEX, compliments of the ARRL and Texas Packet Radio Society.
Last Meeting
In November, Kenneth Harker (N1PVB, now KM5FA) gave a talk on VHF weak signal work, including discussions about operating procedures, calling frequencies and various modes of propagation.
A discussion was held about what the next major purchase for the club station should be. The majority of votes went for a new 432 MHz multi-mode rig with a TCP/IP station coming in second.
The following people have joined UTARC for the 1996-1997 year:
Name CallsignWelcome aboard! To join UTARC get in touch with one of the club officers listed later.Johnny Chiu KB5SJN
Tony Niesz N1LWI
Pete Nance N5TR
Interested in getting your Amateur Radio license but don't want to study on your own? A license class for individuals who would like to obtain a Novice or Technician ticket will be held at Murchison Middle School starting on March 22. The classes will take place on Saturdays from 8:30AM to noon through May 11. The text for the course will be "Now You're Talking" which is available from Austin Amateur Radio Supply and many area Radio Shack stores. For more information contact Jeff Schmidt (N5MNW) at 255-6753 or at: Jeff_Schmidt@aprdlgtr.sps.mot.com.
Do you already have a license but would like to increase your code speed beyond 20 WPM? The Williamson County ARC is hosting a high speed code class which started on January 9. According to the Williamson County ARC newsletter the classes will be held on Tuesdays from 7:00 to 9:00 PM (though Jan 9 is a Thursday!). For more information contact Bob (AF5Z) at 512-869-4886.
de KM5FA
The January meeting of the University of Texas Amateur Radio Club is going to be one not to be missed. I'm pleased to announce that our guest speaker this month will be Greg Jones (WD5IVD), President of the Tucson Amateur Packet Radio corporation (TAPR) and a fellow UT graduate student. TAPR is the leading Amateur Radio organization dedicated to the promotion and experimentation of digital communications modes. Greg will be addressing the club on the topic of Spread Spectrum communications, with a particular emphasis on the Special Temporary Authority (STA) that the FCC has granted TAPR to experiment with Spread Spectrum emissions on the Amateur Radio bands above 50 MHz. One of the most significant project under the STA will be the creation of a 115 kbps digital network in the Austin area on the 902-928 MHz band, with at least one station acting as an Internet gateway. Greg already has some initial results of the experimentation that he will likely share with us.
UTARC may have a unique opportunity to operate under the STA and participate in the local high-speed networking experiments if we, as a club, decide to do so. At around the same time as our January meeting, Greg will be looking to add stations under the STA and TAPR will be doing a group purchase of spread spectrum radio modems designed for operation in the 902 MHz band. Becoming active with spread spectrum will provide club members with hands-on access to the next generation of Amateur Radio digital communications. We can create experiments and actively participate in a ground-breaking network-building project that will pave the way for future Amateur Radio digital communications.
Figure 1: One of the Spread Spectrum radios to be tested.
After Greg's brief presentation on the theory, technology, and use of Spread Spectrum in the Amateur Radio bands, I intend to put forth a motion that UTARC petition to operate under the STA and join the TAPR group purchase. I encourage every member of the club to come to our meeting and present your ideas and opinions on this commitment. I look forward to seeing y'all at the meeting!
Look on the shack walls and you'll see reminders of the club's success in Sweepstakes in the past. During the last 5 years that success was hard to find but all that changed in 1996!
W5EHM was a serious competitor once again during both the CW and Phone portions of Sweepstakes and the Collegiate Championship that takes place at the same time. Although UTARC did not win it all the club is well poised to once again take the CW title for multi-op station in the South Texas section. For phone, W5EHM appears to have placed second in South Texas. Official results will be published in QST in May.
The unofficial results of the Collegiate Championship show W5EHM to have placed 3rd in the phone, 4th in the CW and 3rd in the combined categories. Like the Texas Longhorns, UTARC was tops in the Big 12 conference, sweeping all three categories. This is the best showing yet for UTARC and comes during the most competitive CC to date.
The CW portion of SS was mainly handled by Derek (AA5BT) and Kevin (KG5KI). Kenneth (N1PVB) made some contacts and Robert (KA5WSS) helped with the logging. The club score of 103,500 was the first CW SS score over 100,000 since 1989.
W5EHM 1996 CW Sweepstakes Results
Band QSOs Mults Score 80M 62 40M 173 20M 456 Total 690 75 103,500
The phone portion of SS was handled by the exact same group of operators that worked CW. Where was everyone else? The phone contest achieved the third highest QSO total in club history for SS and managed to work the club's first clean sweep of sections since 1992. The club should be eligible to purchase a "Clean Sweep" mug from the ARRL as a reward.
W5EHM 1996 phone Sweepstakes Results
Band QSOs Mults Score 80M 98 40M 374 20M 437 15M 339 Total 1248 78 194,688
For phone, the operators attempted to set up a two radio station to allow a second radio to look for multipliers while the main radio ran stations. This turned out to be marginally useful both because of interference problems and the fact that the rate on the run radio was often too good to bother stopping it so that the second radio could work someone else. A two radio setup with band pass filters may help the club in other contests where stations may work each other on each band, unlike SS.
George's (K5TR) TS-930 started as the run radio because of the boom microphone and footswitch that was wired up for it. A few hours into the contest the radio locked up and became unusable. Thankfully the club's TS-830 was quickly put into service and the contest continued.
The rest of the club station appeared to work fine and the newly repaired TS-830 performed well. With the exception of VY1JA in the Yukon few stations had a problem hearing W5EHM call them.
So when does the club prepare for the next SS? Right now! If you would like to help the club out next year to do even better now is the time to get more familiar with the club station, help improve it and operate other contests to increase your skills.
de KM5FA
W5EHM participated in the Northern Lights Radio Society VHF/UHF Winter All-Band Sprint as a single operator station. The sprint took place on the evening of December 2nd, from 7PM to 10PM local time. Activity was predictably low for a Monday night, so our score was fairly low. On the other hand, W5EHM was quite likely the only station in Texas participating in the contest. More information can be found on the UTARC VHF web page.
NLRS VHF/UHF Sprint Results
Band QSOs Grids Score 50 MHz 8 3 144 MHz 14 6 Total 22 9 198
de KM5FA
Peter Nance (N5TR) has generously donated a computer to the University of Texas Amateur Radio Club. It is an Intel 80386DX system with ~4MBs of RAM and an 81MB hard disk drive. This machine is replacing an old Intel 8088 system with 640K of RAM and a 21MB hard disk drive. Although the new machine did come with a VGA graphics card, it did not come with a new monitor, so for the moment, the old Hercules 16-color character-based monitor and its interface card have been recycled. The old machine's serial port card has also been recycled into the new machine. The computer is now running MS DOS 6.22, and while a copy of Windows 3.1 did come with the machine, our monitor situation limits us to character-based applications.
Numerous applications have been loaded on the new machine, including a new packet terminal program and a bona fide copy of the TR logging program, contributed by George Fremin (K5TR), who was instrumental in securing the donated machine for the club. In the process of setting up the new computer, the old dot matrix printer in the shack was also brought back to life and is now fully functional.
Extensive documentation of the new terminal program used for packet can be found in a green binder on the bookshelves next to the other equipment manuals. The new packet software has been configured to automatically switch to the VHF port of the TNC and set the callsign to W5EHM on startup.
The club's new computer system can be made even more useful with a future acquisitions of a VGA monitor, a high-speed serial port card, and a PS/2 mouse. Nevertheless, this new machine is a tremendous improvement over our previous computer. Thanks Pete!
The Texas Packet Radio Society (TPRS) is a state-wide organization that promotes the use of packet radio. It is also the main supporting organization behind Texnet, one of the largest Amateur packet networks in the world running from Brownsville to Missouri.
TPRS held its fall 1996 meeting on the UT campus in the Education building on Saturday, December 7. UTARC members Kenneth (KM5FA), George (K5TR) and Robert (KA5WSS) were among the 35 people attending.
The meeting covered topics ranging from Spread Spectrum, APRS and the current and future status of the Texnet network. The meeting was organized by UT graduate student and past TPRS President Greg Jones (WD5IVD).
One of the highlights of the meeting was an on-the-air demonstration of the 902 MHz Spread Spectrum equipment that TAPR will use in their SS experiments. The 115 kbps radios should allow a great deal more computer-based communication to be done with Amateur Radio than is realistic given the 1.2 kbps setups now widely in use.
Since Greg will be graduating soon and will no longer be able to reserve space at UT for future TPRS meetings. The UTARC officers have decided to host the fall meeting in future years. The participants gave the club an ovation when this was announced at the meeting.
Figure 2: 1993 W5EHM Spring Cleaning
de KM5FA
After an unsuccessful meteor scatter schedule attempt on Friday night, as I was leaving the club station, I noticed a large illuminated cloud of smoke off to the west-north-west. When I got to the source, it turned out to be a 6-alarm apartment fire near the intersection of 27th and Guadalupe that was consuming almost an entire city block. I remembered I had my dualbander HT with me, so I took it out to see if maybe there was an ARES presence at this large fire scene I could help out with.
While I'd not been active in the Travis County ARES group before, I remembered that their net meets on the 146.94 MHz repeater. Checking that repeater and the few other ones I could remember off the top of my head, as well as some of the standard simplex frequencies, I couldn't find anything that sounded like ARES activity. It was also quite clear by the time I had gone through this that there were more professional emergency response personnel on the scene than I think I've ever seen in one place before, and that Amateur Radio support was almost certainly unnecessary in this particular situation.
But it occurred to me that I really had no way of systematically checking all the Austin area repeaters or FM simplex frequencies, because I don't use but a few of them frequently enough to remember them all off the top of my head. If I had been in another part of the city, I might have had trouble finding the geographically closest repeater system that an ARES net might have been on. I checked the memories in my HT just to see what was there and discovered that the few memories I had programmed in were left over from the years I lived in the Upper Valley region of New Hampshire and Vermont! How could I remedy this for the next time? I remembered that Robert Barron (KA5WSS), our club newsletter editor, had compiled a list of Austin area repeaters on the club web pages.
Checking out http://www.utexas.edu/students/utarc/freqs/rptrs.html I found all the information I needed to program the memories of my dualbander. Now I can simply do a memory scan and quickly determine which repeaters or simplex frequencies in my range are being used. I may never talk on some of the repeaters I have programmed into my radio, but I feel good knowing that in an emergency, I'll know what local repeater resources are available.
And while I may not be able to make every net check-in, I do intend to try and become more involved with the Travis County ARES nets. The nets meet on Sunday night at 6:30 PM on the 146.94 MHz repeater, at 7:30 PM on 145.73 MHz 1200 bps packet unconnected mode, and at 8:30 PM on the 146.78 MHz repeater. There is a face-to-face ARES meeting at the Luby's cafeteria on North Loop on Tuesday, January 28, 1997.
Awards
UTARC received its Worked All States (WAS) certificate.
Contests
The January issue of QST reports that in the Sept. VHF QSO Party W5EHM achieved first place in South Texas and third place in the midwest region in the limited multi-op category!
Derek (AA5BT) served as control operator for Lindsay for a recent kid's Sprint contest (SquINT). Lindsay made 31 QSO's in 90 minutes of operating time working other kids varying in ages from 3 to 82.
The ARRL January VHF Sweepstakes takes place the weekend following January's club meeting (Jan 18-19). Please help the club break previous club records for VHF contesting! Contact Kenneth (KM5FA) if you would like to help operate. No previous experience in VHF contesting is required.
Work Done
In December the club installed a new 386 computer (see story elsewhere in this issue).
In an effort to protect equipment from being stolen the club has begun to install security cabling to the major items in the shack.
Work To Be Done
If you would like to help with some of these items, contact one of the club officers.
Have you checked out the UTARC web page lately? There a couple of new features including:
W5EHM isn't the only user of the radio spectrum on campus. Student run radio and television broadcast stations are also in operation.
http://www.utexas.edu/students/kvrx/
http://www.utexas.edu/depts/output/www/tstv.html
Kenneth Harker (N1PVB) upgraded his license to the Advanced class on Saturday, November 16, 1996. After the test he promptly visited the club station to put his new privileges to work at W5EHM during the phone Sweepstakes contest. A few days later he discovered that his new callsign is now KM5FA. Congratulations!
UTARC alumnus James Brooks (ex-KB1CM and now 9V1YC) is one of the crew on the much anticipated DXpedition to Heard Island this month.
(While not Amateur Radio per se and some would argue not "real" SS, the technology in use here can be of use on the Ham bands. Perhaps we can learn a thing or two! -editor)
de KQ6DK
Metricom has been in the wireless modem business for a few years now. Their product, the Ricochet modem, uses a spread-spectrum, micro-cellular data network (MCDN).
The Ricochet modem is casually attached to a laptop computer with a few strips of Velcro hook and loop fasteners. The modem is roughly the size of an HT, and sports a rubber duck antenna. Packed into this very mobile package is a one watt radio, that transceives using Gaussian FSK technology. These mobile modems transmit to cellular receivers located on street lights and telephone poles. Oddly enough, these are called "pole-top radios". It's roughly the size of two loaves of bread, side by side, with an antenna that looks like a car mount cellular phone antenna dangling underneath. These are usually slung under the arm of a street light and take power from the socket for the photo relay that starts the street light. All in all, it's a fairly clever and unobtrusive design.
The Ricochet modem is licensed under FCC part 15.247 which sets some of the design criteria for the technology. While no license is required for operation in the 902 to 928 MHz part of the spectrum it does not allow for a lot of transmitted power. Only one watt is allowed into a +6dBi antenna. This section of the FCC rules requires the Ricochet to use spread spectrum technology, effectively requiring the modem and the pole-top radio to change frequencies with some regularity. In fact, each modem can only use a channel for a maximum of 400ms. Fortunately, there are 162 channels to choose from, each with 160 KHz of bandwidth.
The frequency hopping characteristics are rather interesting. On any power-on, each modem will "wake up" on a random channel somewhere in the spread spectrum sequence. It will then transmit synchronization requests (syncs) while moving among the channels until it is acknowledged by a pole-top radio. These syncs are sent within 25 milliseconds on each channel before moving on to the next channel. The sync request from the Ricochet contains key information about the user's modem and includes it's MAC address (effectively it's serial or manufacturing number) and key timing information. With this information, a pole-top radio and modem can synchronize on one of 55 channel hopping sequences.
Once a Ricochet modem and pole-top radio have acquired each other the spread spectrum frequency hopping can begin. The hopping centers around 25ms time periods called "slots." One burst of data between the modems may span up to 16 slots or 400ms, but must move on to a new channel before 400ms have elapsed. If a burst of data, or packet, exceeds one slot then the channel that both radios would have hopped to next is skipped. In fact, one channel is skipped for each additional slot required to transmit a packet.
As you might imagine, this could require feats of timing magic between the two modems across this asynchronous network, but the Metricom engineers figured this out too! By default both modems are in receive mode and it is only when data is exchanged that synchronization is enabled. Some synchronization information is contained within each packet. Based on this data, a "drift rate" can be calculated. Occasionally a "maintenance packet" is introduced to correct the drift.
The spread spectrum technology allows many Ricochet modems to communicate within a fairly small area. Micro-cellular frequency reuse combined with asynchronous frequency hopping provides for very large capacity and low duty cycle transmissions from each micro-cellular site.
Until now, we've discussed only how the two modems, the Ricochet and the pole-top radio, communicate with one another. So, you may ask, how does your data get to where you want it to go? When each pole-top radio is installed it is configured with the latitude and longitude coordinates for that unit. Thus, the pole-top unit "knows" where it is. It also knows the location of the closest Wired Access Point or "WAP."
The WAP is a special node within a cluster of pole-top units that is wired to a telephone line based network interface. Each WAP serves many pole-top radios within a cluster of about 5.5 square miles. Each pole-top radio maintains the statistical best routes to other pole-top radios to pass traffic to the WAP. This permits traffic to route in the best direction towards the WAP for quickest response.
Metricom is currently well entrenched throughout the Bay area, and they have high hopes to expand into other markets. The markets will be connected as they come up allowing someone in the Bay area to communicate with someone in another market, but that is down the road a few years. Seattle is the next planned market to enter. There are a few universities that have also installed Metricom technology. Take a look at their web page for details [http://www.metricom.com].
Metricom charges $29.95 per month for their services. This includes unlimited usage (unlike cellular telephones there are no air time charges); unlimited Internet access and electronic mail. It works equally well on your PC or Macintosh. The modem is $299 if purchased, or $10 per month to rent. There is also a $45 one time registration fee. All of this is backed by a 30 day money back guarantee.
When asked if there a hand-off between cells like a cellular telephone, David replied not really, it was only tested to 6 mph, although anecdotal reports suggest that BART passengers can keep a Ricochet connection just fine.
Bob Nagy (AA5PB) reports that there is a part-time opening for a technician at the student run KVR channel 9 station. Work involves simple repairs, soldering and would use up about 20 hours per week. For more information contact Bob at 471-4286.
Zeke Harvey (W5NFC) reports that the December 19 issue of the Austin American Statesman contains the obituary of Lloyd Edmonds (WA5CVL). Lloyd served as UTARC faculty advisor from 1967 to 1982 and also served as the station trustee before Zeke.
President: Tom Orzechowski SQ9DDZVice President: Kenneth Harker KM5FA 467-8724 kharker@cs.utexas.edu
Secretary/Treasurer: Kourt de Haas KB5PRZ 445-4759 kourt@mail.utexas.edu
Newsletter Editor: Robert Barron KA5WSS 837-4051 barron@liant.com
UTARC Web Page URL: http://www.utexas.edu/students/utarc/
Mail Reflector: utarc-l@mcfeeley.cc.utexas.edu
UTARC News is published by the UT Amateur Radio Club, a registered student organization. UTARC News is not an official publication of The University of Texas at Austin and does not represent the views of The University or its officers. This newsletter was not printed with state-appropriated funds.
Newsletter Contributors: KM5FA, W5NFC, AA5PB, KQ6DK
Join or renew your membership to the ARRL through the club. It costs you nothing more but UTARC gets a portion of the membership fee!
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The University of Texas ARC
Box 170, Texas Union
Austin, TX 78713