SB ALL @ AMSAT $ANS-219.01 AO-13 Showing More Good Signs HR AMSAT NEWS SERVICE BULLETIN 219.01 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT With more than two week's experience on the new AMSAT OSCAR 13, the number of users on all modes is increasing as is their apparent satisfaction. Veterans and newcomers alike are praising the new satellite even as it remains in the engineering phase prior to its official turnover for general operations. The condition of the satellite continues to be excellent and, except for an apparent glitch in the RUDAK packet system, optimism prevails. Modes B and J have been widely applauded for their performance. Their sensitivity seems to be excellent. Although there seem to be few times when the officially recommended uplink power levels suffice, this clearly is attributable to transponder loading and the realization of a typical power escalation scenario. Higher than the officially recommended uplink power levels are apparently being used by most Mode B and J users. There is thought to be a power escalation cycle that is initiated or accelerated by a few stations who have wholly inadequate receive systems. All users MUST be aware a preamp is essential for all AO-13 modes. Operating without one is a prescription for failure. Operating WITH a good preamp (preferably at the antenna) can convert all the modes (especially L) from a strain to a plain joy. Perhaps the biggest turnaround in user opinion has occurred in the Mode L domain. When first turned on July 24, Mode L was thoroughly panned by U.S. users. Based on what they saw, U.S. users were wondering what European Mode L users where cheering about. It was subsequently learned European Mode L users enjoyed a very strong uplink advantage in the first few days of its operation as a consequence of the squint angle of the satellite; the offset angle between the Mode L uplink antenna and the uplinking station. Analysis now shows a squint angle greater than 10 or 15 degrees to be anathema for good Mode L QSOs. Another confusing element, which strongly abetted the gap between U.S. and European reports on Mode L performance, was the discrepancy between previously published Mode L frequencies and the ACTUAL Mode L frequencies. For reasons not yet clear, the frequencies previously published by AMSAT-DL and re-iterated by AMSAT-NA and in various U.S. publications have proven erroneous. (The Mode B and J frequency discrepancies are inconsequential; Mode L frequency disparity is substantial. The combination of amplitude and frequency discrepancies led many U.S. satellite users to conclude Mode L had actually failed entirely. Few could even find their downlink at all using all the power they had available to them. Fortunately, the big swing in opinion came like a whipsaw last week as Mode L showed off its best to the West. Favorable squint angles have come to the U.S. and Mode L users there have changed their views entirely; have been showing up in droves on the new mode. And, as may be characteristic of U.S. amateurs, they vote with their pocketbooks. When they like something, they support it with equipment purchases. Equipment dealers report an unprecedented run on 24 cm equipment; a sound vote of confidence in Mode L if there ever was one! With the excellent conditions, analysts too have had a good chance to measure the actual Mode L performance. The results show what to expect under ideal conditions and what to expect otherwise. The resulting numbers suggest AO-13 Mode L is now working better than AO-10 Mode L ever was expected to! (Specific data in a separate bulletin). On a slightly less positive note, AMSAT-DL workers report there is a problem with RUDAK, the packet digipeater developed in Munich. When attempting to bootload from the PROM, the RUDAK CPU runs for a while but then hangs up. The 10 byte loader module will not allow a special program to be loaded into RAM. It is now recalled from the thermal vacuum tests that the PROM (a fusable link type) was then found to be temperature sensitive. AMSAT-DL is evaluating ways of warming the RUDAK module. One scheme being considered calls for energizing the module next to RUDAK, the LIU (Liquid Ignition Unit). This will warm up RUDAK considerably and may solve the problem they say. In sum, AO-13 continues to provide excellent performance on all its linear transponders. The RUDAK is being investigated for a possible thermal malfunction and Mode S may be activated next month. New and veteran satellite users alike are singing the satellite's praises and apparently thoroughly enjoying the new bird! Equipment dealers are being swamped with 24 cm equipment orders and there seem few remaining open questions on what Mode L is capable of. /EX SB ALL @ AMSAT $ANS-219.02 Tests Prove AO-13/L Superior HR AMSAT NEWS SERVICE BULLETIN 219.02 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT On-orbit AO-13 Mode L performance tests completed last week strongly suggest it is working well indeed; better even than its predecessor (AO-10 Mode L) was expected to work by a couple of dB. The tests also have shown the range of conditions experienced by Mode L users and how to choose the best times to work the new mode. The key to success on Mode L is now clearly shown to be closely coupled with the positioning of the satellite's Mode L 24 cm uplink receive antenna. As expected, under poor conditions copious uplink power is required. Many tens of kilowatts (EiRP) will be insufficient under the worst conditions. But under good to ideal conditions, very moderate power levels will provide satisfactory results. The key to Mode L success, analysis this week has shown, is that users must pay close attention to the pointing or squint angle of the satellite's 24 cm helix uplink antenna. Under good conditions, an approximate 2 hour sub-window of optimum Mode L time will exist within the general Mode L window for a given QTH. About half the total Mode L time is the prime Mode L sub-window where the squint angles are 10 degrees or less. According to Mode L operator John Gayman, WA3WBU, when squint angles get much over 10 degrees, Mode L uplink power requirements skyrocket. Thus it's important to determine the timing of that prime sub-window when your QTH will fall within that acceptance cone. AMSAT's QUIKTRAK program computes the positioning of the cone based on the satellite's attitude in Bahn coordinates, its current position on orbit and your QTH. The PA (pointing angle or squint angle) parameter is output by QUIKTRAK. Under thoroughly ideal conditions, it now appears a Mode L uplink of 29 dBW (about 800 watts) EiRP will produce about a 10 dB signal to noise ratio in a 2.4 kHz channel when received on a system with an approximate 50 degree Kelvin system noise temperature at or near to apogee. (Figure of Merit = -2 dB/K). A 50 degree K, 435 MHz receive system might consist of a 0.6 dB noise figure preamp behind a 15 dBic RHCP antenna and a standard, modern SSB UHF receiver. (CW signal performance is proportionately better). However, under most practical operating conditions, more uplink power will certainly be required on Mode L. Factors increasing Mode L uplink power requirements include polarization losses (3 dB penalty for running linear polarization instead of Right Hand Circular Polarization); squint angle (penalties mount very fast beyond squint angle of 10 degrees); increased path losses; increased absorption at low elevations angles; heavy transponder loading; local impediments (trees; houses), etc. Based on these preliminary estimates, it now appears 33 dBW (2 kW) EiRP is the lowest PRACTICAL level Mode L SSB users should expect to be regularly successful with. For higher reliability, that is for your ability to work well when combining penalty factors as described previously, another 5 dB or more should be available. Based on these tests then, 38 dBW (6.3 kW) EiRP can be expected to produce good SSB results under most (but definitely NOT all) operating conditions. Obviously, if one wants to work under the most adverse conditions with strong, compound penalty factors, much more power will be needed. The 38 dBW level seems, however, to be a reasonable compromise between performance, reliability, cost and physical structure. For example, 30 watts applied to the feed of a pair of 20 dBi loop yagis will produce about 37.3 dBW 5.4 kW) EiRP including losses; sufficient for good SSB QSOs under most conditions and excellent for CW under most conditions. Comparing AO-13 Mode L and AO-10 Mode L, it now appears the actual measured performance of AO-13 Mode L exceeds the expected performance of AO-10 Mode L by 1 to 2 dB. (Of course AO-10 Mode L never actually achieved its potential performance by a factor of at least 10 dB). By contrast, AO-13 Mode L is coming close to its corrected specs. /EX SB ALL @ AMSAT $ANS-219.03 AO-13 Ops Sked and Freqs Update HR AMSAT NEWS SERVICE BULLETIN 219.03 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT AMSAT OSCAR 13 continues under engineering jurisdiction and has not yet been officially released for full operations. Spacecraft controllers and engineers have been meeting in Marburg, West Germany to evaluate spacecraft systems performance to date and to plan general operations for the near-term and mid-term future. They have agreed on the following revised schedule said to be effective until September 21 but subject to change for continued testing. Revised Operating Schedule: V3.0 6Aug88 +---------------------------------------------------------------+ | Mode | From | Thru | Remarks | Duration | | |(Inclus)| (Inclus)| | MA Minutes| |========|========|=========|==================================== | Off | MA 241 | MA 002 | Solar eclipse window | 18 48.3 | | Mode B | MA 003 | MA 099 | | 97 260.2 | | Mode L | MA 100 | MA 180 | Mode JL optional | 81 217.3 | | Mode B | MA 181 | MA 220 | | 40 107.3 | | Mode B | MA 221 | MA 240 | With omni antennas | 20 53.6 | |--------+--------+---------+----------------------+------------+ | Mode S | | | Commence September(?)| | | RUDAK | | | Testing; ops pending | | +--------------------------------------------------+------------| The current attitude is approximately BLON=180, BLAT=0. The updated frequencies, based on in-orbit tests and corrected for Doppler shift, to within 1 kHz, are: Mode B: the sum of uplink and downlink frequencies equals a constant 581.398 MHz. At Mode B mid-band, 145.890, the required uplink is 435.508 MHz. Mode J: the sum of uplink and downlink frequencies equals a constant 580.413 MHz. At Mode J mid-band, 435.965, the required uplink is 144.448 MHz. Mode L: the sum of uplink and downlink frequencies equals a constant 1705.356 MHz. At Mode L mid-band, 435.860, the required uplink is 1269.496 MHz. /EX SB ALL @ AMSAT $ANS-219.04 Surrey/UK Colloquium Summary HR AMSAT NEWS SERVICE BULLETIN 219.04 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT Over 160 persons from 19 countries attended the 3rd AMSAT-UK/UoSAT Space Colloquium held at the University of Surrey last weekend (29-31 July). International speakers presented 20 papers on diverse topics, covering: Geostationary AMSAT Phase 4 spacecraft designs AMSAT Phase 3D spacecraft design UoSAT-C, D and E spacecraft technologies Amateur Radio using High Altitude Balloons AMSAT OSCAR 13 spacecraft orbital commissioning and operations UoSAT-1 & 2 spacecraft orbital operations The Chinese Space Program Digital signal processing techniques for amateur satellite communications Packet Radio Satellites Soviet/Canadian Transpolar SKITREK Future Soviet amateur radio satellites Among the many radio amateurs who attended were Jan King (W3GEY), Karl Meinzer (DJ4ZC) and Leo Labutin (UA3CR). Leo was particularly welcome and read a paper describing the SKITREK project and spoke on future Soviet satellite plans. The Colloquium was preceded by a one-day Satellite Technical Workshop devoted to detailed discussions of advanced amateur satellite techniques and a one-day co-ordination meeting sponsored by the Radio Society of Great Britain focusing on funding, frequency allocation and educational matters. Colloquium Proceedings, comprising 16 of the papers presented, were sold out, However, additional copies will be available shortly from AMSAT-UK. The sponsors send their thanks to all who visited UoS last week and who made the Colloquium such a success! (Bulletin per UO-11 BBS; tks UoS) /EX SB ALL @ AMSAT $ANS-219.05 UO-11 DCE Linking Strides HR AMSAT NEWS SERVICE BULLETIN 219.05 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT The UO-11 DCE (Digital Communications Experiment) packet radio gateway network continues to grow. ZL1AOX, VK5AGR, GB3UP and ZS6SAT are passing messages for large packet radio user networks in New Zealand, Australia, the UK and South Africa. A new station, ZL5BA, is located on Ross Island in the Antarctic. The operator there (SoJo) is working at a Greenpeace scientific base. He will use his DCE station for recreation and to send health & welfare messages home for the others at his base. ZL5BA was activated on 29 July and is providing an interesting insight into the coverage received by polar stations from a polar orbiting satellite. He sees UO-11 on almost every pass although some times of day provide higher elevations than others. Surrey plans to commission a USA gateway soon. The station is N6IIU in the San Francisco area. This station is located in a Red Cross headquarters which already houses an emergency communications station and a packet BBS. Discussions are also under way with an East Coast USA amateur. Meanwhile, a gateway in West Germany is also almost ready to go. DB2OS, one of the AO-13 control operators, will bring DCE access to the well-developed European packet radio network. When the USA and Europe are on line, the DCE will be able to link together all of the major amateur radio packet networks worldwide. (Bulletin per UO-11 BBS; tks UoS) /EX SB ALL @ AMSAT $ANS-219.06 RS-5, RS-7 Dead Report Avows HR AMSAT NEWS SERVICE BULLETIN 219.06 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT Recently, Leonid Labutin of Moscow, a prime mover in the Soviet Radio Sputnik (RS) program, said that on July 15 the first western amateur visited the USSR RS command station RS3A in Moscow. Danny Kohn, SM0NBJ, of AMSAT-SM, visited UA3CR during his recent stay in Moscow. Danny interviewed the chief operator there, Leo Maxakov, RA3AT, made tape recordings and took pictures. According to Nico Janssen, PA0DLO, upon Danny's return to Stockholm, he promised to make an extensive report on his visit to RS3A. One of the interesting things he has already told the European AMSAT Net (on July 23) was, that according to the operators at RS3A, the old RS satellites, RS-5 and RS-7, are definitely out of operation now. RS3A has gradually lost control over these last two active RS satellites of the RS-3 to RS-8 series. They are convinced that the batteries in RS-5 and RS-7 are dead so no new activities can be expected from these satellitese. RS-3 through RS-8 were launched together on December 17, 1981. /EX SB ALL @ AMSAT $ANS-219.07 Absurd FCC 220 Move Shocks AR HR AMSAT NEWS SERVICE BULLETIN 219.07 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT Amateur Radio was badly shaken last week when on August 4, the FCC adopted a report and order in general docket 87-14, the proposal to reallocate the 220-222 MHz band to the land mobile service. According to the ARRL, in balancing the impact on existing users, emergency communications, and future amateur growth against land mobile requirements, the Commissioners concluded that the reallocation was in the public interest despite overwhelming opposition. Wishing to reassure amateurs of its strong support for the service, the FCC emphasized that the remaining 3 MHz of the band, 222-225 MHz, would be available to amateurs on an exclusive basis, thus removing the cloud that has hung over the status of the band for many years. The effective date of the reallocation will be announced later. ARRL continues to oppose the reallocation, and will pursue all available means to reverse the commission action. AMSAT emphasized other bands of even greater import are similarly vulnerable and urged support of its landmark Phase 4 Geosynchronous Satellite Program to deflect further frequency grabs especially at 1.3 GHz and up. /EX SB ALL @ AMSAT $ANS-219.08 Short Bursts HR AMSAT NEWS SERVICE BULLETIN 219.08 FROM WA2LQQ WARWICK, NY August 06, 1988 TO ALL RADIO AMATEURS BT The annual meeting of the Central States VHF Society took place in Lincoln Nebraska the weekend of July 22-24. According to Bill Tynan, W3XO, quite a number of AMSAT Members were on hand. They included AMSAT Regional Coordinator Keith Pugh, W5IU, who accepted a donation from CSVHFS on behalf of AMSAT. Keith got the "customary" $400 check plus a $200 "Well Done" bonus for the success with AO-13. AMSAT expresses its thanks to the CSVHFS for these kindnesses. The current AMSAT fund raising drive initiated by a letter to all domestic AMSAT members is quickly becoming the most successful in AMSAT history only 3 weeks after it was kicked off. Those who donated $20 or more to the fund will be receiving their free, handsome all-OSCARs frequency guide in the mail soon. The frequency guides, including the latest AO-13 frequency updates, are now in production and will be mailed to all qualified donors before the end of August. There is still time for those who haven't already done so to mail in their donations in the envelope supplied and receive their frequency guide free before supplies are exhausted. AO-13 "First Day Club" logs, certificates and QSL cards are being processed and should be mailed to all qualifiers by mid-September. Here is the current AO-10 operating schedule: August 1 - August 15: Mode B MA 30 to MA 240 August 16 - Further notice: Out of Service AO-10 is showing some signs of the anticipated seasonal power-down. FMing has been heard and the beacon has appeared to be under low-power duress. Please do not use AO-10 if you observe these symptoms which are expected to become more common in the next few days. The satellite will be unavailable for use beginning August 16 because of predicted insufficient solar illumination and reduced battery charge. JARL says it will soon begin work on another flight model of JAS-1 with an eye towards launching a second OSCAR after a long hiatus since the launch of JAS-1 (FO-12). Efforts with JAS-1B will focus on improving the satellite's tight power budget and antenna directivity in order to obtain a flatter pattern for better performance. Here is the FO-12 operating schedule. Mode From (UTC) ---------------- JA Aug 06 0845 D 07 0751 JA 11 0617 D 12 0724 JA 13 0630 D 14 0536 JD 18 0603 DI 19 0712 JD 20 0415 DI 21 0523 JD 25 0348 DI 26 0457 JD 27 0606 D 28 0511 JA 30 0120 D Aug 31 0228 JD = Digital mode JA = Analog mode D = All systems off DI = Systems off except CPU and memory The transponders will be off at other times. The actual operating schedule may change due to unexpected situations such as variations in available power. Mode JA Beacon: 435.795 MHz. Mode JD Beacon: 435.910 MHz. /EX SB ALL @ AMSAT $ANS-215.01 AO-13/L Perspectives Improve HR AMSAT NEWS SERVICE BULLETIN 215.01 FROM WA2LQQ WARWICK, NY August 2, 1988 TO ALL RADIO AMATEURS BT AMSAT OSCAR 13's linear transponders, Mode B, J and L have been putting in regular service for more than a week now and, while Modes B and J have been drawing rave reviews, Mode L reports from U.S. users were not quite as rosy. Since August 1, however, U.S. Mode L users have gotten to see the satellite from a different perspective in both a literal and figurative sense. The result is a renewed optimism in Mode L functionality. During its first week of operation beginning July 24, would-be Mode L users in the U.S. were discouraged by poor results and confused by optimistic reports originating in Europe. Many couldn't even find their downlinks. This has been determined to be the result of two factors: 1. The Mode L translation frequencies previously published have been invalidated (probably by a change in an electrical parameter in the transponder) so many were listening on the wrong frequency and 2. Perspectives on the satellite from the U.S. were poor. Last week European Mode L users were looking "right down the barrel" of the satellite's Mode L receive antenna and had good results. In contrast, U.S. Mode L users were pounding against the side of the satellite outside the narrow Mode L uplink beam. Now that U.S. users are well-situated in the beam, reports from U.S. Mode L users are much more positive. According to AMSAT officials, recent tests on Mode L indicate its performance is actually quite good; even better than AO-10 was expected to be had it worked properly. AO-13 is exceeding the expected performance of AO-10 Mode L by a dB or 2 they said. Whereas uplink recommendations for AO-10 Mode L were in the 3 kW EIRP range, it now appears a good, if not booming, SSB QSO can be had under good conditions with 2 to 3 kW (33 - 34.8 dBW) EIRP or with 1.5 to 2 kW (31.8 - 33 dBW) EIRP under ideal conditions. These values can be reduced by another 3 dB if right hand circular polarization (RHCP) is used on the uplink instead of linear polarization. Under transponder loading, however, the required uplink power will obviously go up. In sum, under totally ideal conditions (boresighted, RHCP and alone on the transponder), about 800 W (29 dBW) EIRP will be adequate for a reasonably good SSB QSO. Under less than ideal conditions, you'll need more power. It would be a good idea to have another 6 to 8 dB in reserve. Thirty watts to a pair of 20 dB loop yagis will yield about 37.3 dBW (5.4 kW) EIRP including splitter losses. So AO-13 is in fact doing quite well! And last week's optimistic reports by G3RUH and other Europeans have been largely corroborated by subsequent reports from U.S. users. The key to the renewed optimism is the realization that there is an additional constraint on Mode L use beyond that of the Mode B and J transponders. That additional constraint is the satellite's 24 cm uplink antenna beamwidth. Its fairly narrow beamwidth (-3 dB value is 49 degrees), combined with the beamwidth of the 70 cm downlink antenna means one needs to be fairly close to "boresight" to do well on Mode L. But now that that fact is recognized, Mode L users can take it into account in planning their use of this powerful mode and be successful. Mode L is not just a higher frequency Mode B, AMSAT officials point out. When planning Mode B operations, one simply checks to see if the satellite is above the horizon and if the Mode B transponder is scheduled to be on. With Mode L, they point out, there is an additional consideration: Where is the narrow 24 cm footprint relative to you? The angle between the boresight and your QTH is often called the squint angle. In AMSAT's QUIKTRAK program it's called PA or pointing angle. Using QUIKTRAK, one can readily determine when the PA is sufficiently low so as to facilitate Mode L QSOs. Best results occur when PA is less than about 10 degrees. When using QUIKTRAK, be sure to set STABTYPE to 0 to get the pointing angle function to work properly. Current Bahn coordinates are about BLON=180, BLAT=0. Now that both the Mode L frequency translation matter and the squint angle issues have been resolved, Mode L use in the U.S. is expected to skyrocket. Equipment suppliers already report unprecedented activity in 70 and 23 cm equipment and attribute this largely to a huge ground swell of interest in AO-13. AMSAT says it's preparing numerous special event activities on Mode L including the return of the popular ZRO Test and Technical Achievement Awards Program. Stay tuned. /EX