SB NEWS @ AMSAT $SPC0616 * SpaceNews 16-Jun-97 * BID: $SPC0616 ========= SpaceNews ========= MONDAY JUNE 16, 1997 SpaceNews originates at KD2BD in Wall Township, New Jersey, USA. It is published every week and is made available for non-commercial use. * P3D ENGINEERING SOFTWARE NEWS * ================================= Regular users of FO-20 may have been puzzled by a strange buzzing sound on its mode JA transponder over the last couple of weeks. This was due to command stations testing the new P3D Range Determination software and hardware. P3D's orbit will change significantly after motor firings, and NORAD will lose track of us. So would we! The P3 ranging system enables our world wide network of Command Stations to measure distance to the satellite from different locations and at different times and so compute the new orbit's Keplerian elements. This information is used by us, the AMSAT community, and of course given back to NORAD so that they can re-acquire our satellite by radar. This methodology was used to remarkable effect in picking up OSCAR-13 after both its motor firings. Back in 1988, the P3C engineering software was still based on the Atari-800XL computer. This was a legacy from the very successful designs originating as far back as 1979 and the ill-fated P3A satellite (1981). However, the prospect of working on P3D yet again using a dual audio cassettes for storage and 8-bit 2 MHz processors has never been very attractive, and a re-engineering of many of the tools has been undertaken by James Miller G3RUH over the last couple of years. The P3 Range Determination package marks the successful completion of a substantial development programme that includes the following principal packages: - Tracking - Telemetry Display - Command Uploader - IPS-X1802 - Ranging - OrbitFit Tracking of course needs no introduction. Telemetry Display is essentially as already available for AO-13, but with P3D specific changes. This will be publicly released for several platforms when P3D is finally "nailed down". Command Upload software is used for commanding the spacecraft both during lab-testing and in space. These first three packages were used for AO-13. P3D, like its predecessors, has a flight computer based on a radiation hardened CDP-1802 microprocessor. It runs an operating system called IPS. But generation of the flight operating system and on-board control software is done on a ground-based host computer. The IPS-X1802 package is, as its name suggests, a cross compiler. Source files for P3D are written using the IPS language. They are compiled by the IPS-X1802 development system (itself written in IPS) which outputs a target binary in 1802 machine code. In the days of P3A/B/C, this compilation used to take half an hour on the Atari-800XL. Imagine how tedious a simple edit used to be. Flight software compilation, from source files to uploadable binary, now takes half a second. The IPS-X1802 cross-compiler is a major part of the P3D development programme. Without it, the flight software which controls the spacecraft, and is much different than that of P3A/B/C, would be impossible to produce efficiently in the short timescales left to us. The Ranging software, mentioned earlier, measures range to the satellite with a basic accuracy of about 150m (1 microsecond). Comparison of ranges measured via FO-20, with ranges displayed by regular tracking programs, shows agreement within 5 km, often better. During tests, signal strengths have been kept to the absolute minimum needed for "lock", and are weaker than AO-13's general beacon used to be. The uplink power to FO-20 is typically under 1 watt to a KLM14C antenna, rather less than a typical SSB user's. The ranging software can track down to a level where the signal is virtually inaudible. Sample GIF (5 kbytes) taken during an FO-20 pass is at: http://www.jrmiller.demon.co.uk/IPS/range.gif The final program OrbitFit takes range measurements from the network of command stations, and computes an orbit that best fits the data. It was written 10 years ago by Stefan Eckart DL2MDL, and has been adapted for our current needs by G3RUH. Tests processing FO-20 ranging data have been completely successful. Software is written in BASIC and ARM assembler for the Acorn Risc Computer. Current machines use the DEC SA-110 processor at typically 200 MHz/700 mW/$50, representing the highest MIPs/mW and MIPs/$$ (taken together) in the business and currently the embedded systems processor of choice. It makes a cool personal computer too. Acorn Risc Computer: http://www.acorn.co.uk/acorn/products/strongarm/ DEC SA-110 information: http://www.europe.digital.com/info/semiconductor/sa110.htm Software is not as photogenic or as sexy as hardware, and thus gets little or no exposure. Yet it is hoped that this short precis provides a better understanding of how the backroom boys have been keeping busy. There are many such heroes in the P3D program, but special recognition is given to P3 command stations Peter Guelzow DB2OS, Graham Ratcliff VK5AGR, Stacey Mills W4SM and Ian Ashley ZL1AOX for enthusiastically thrashing every development as it has staggered off the production line. Notes by James Miller G3RUH 1997 Jun 10 [Tue] 0653 UTC * SAFEX IS BACK ON * ==================== The following notice was posted to the packet radio BBS on the Mir space station by Mike Foale, KB5UAC, and was downloaded by Miles Mann: Stat : PR Posted : 06/07/97 13:10 To : ALL From : R0MIR @ BBS : BID : Subject: SAFEX is ON Turning SAFEX II on today. Repeater mode tx 437.950, rx 435.750 ctcss 141.3. SAFEX is turned off during all joint ops missions with soyuz, shuttle because of interference. Mike kb5uac BJ Arts, WT0N, reports the Mir 70 cm repeater is up and running, and several stations were worked during the 0030 UTC pass on June 8th. Strong downlink signals were reported while Mir was over north America. BJ's uplink was 435.750 MHz FM, while he received downlinks on 437.950 MHz. A CTCSS tone of 141.3 Hz is required for access. * SCOPE NEWS * ============== A brief description of the SCOPE project is now available in Japanese and English. The SCOPE Home Page is located at: http://www.jamsat.or.jp/scope/ SCOPE is an experiment flying on the Phase 3D satellite that will provide images of celestial objects through the use of a CCD imaging camera. [Info via Tak Okamoto and the JAMSAT SCOPE Project Team] * STS-94 ORBITAL DATA * ======================= STS-94 Nominal orbital data is now available on the AMSAT Web Page. The time-independent State Vector and the Keplerian elements corresponding to the scheduled launch time of 01-JUL-97 / 18:37 UTC are available at: http://www.amsat.org/amsat/sarex/orbit.html The full set of nominal state vectors and mission profile schedule is also available on the AMSAT Web page at: http://www.amsat.org/amsat/sarex/vectors.html As in the past, updates will be made to the AMSAT Web page using actual orbital data during the mission. E-Mail updates are no longer made to the SAREX mailing list during the mission. These updates were discontinued when NASA Spacelink began sponsoring a mailing list called *STSTLE* for this specific purpose. Subscriptions to STSTLE are available on request. To subscribe send a E-Mail message to the following address: listproc@spacelink.msfc.nasa.gov The text of the mail message should be as follows: subscribe STSTLE FirstName LastName Where "FirstName" and "LastName" provide the list manager with your name. Those considering subscribing to STSTLE should be cautioned that the list typically provides three to four updates per day on the Shuttle (and also for any satellites deployed by the Shuttle). The frequency of updates ensures current data for several NASA agencies that subscribe to this mailing list. If this many updates are undesirable, you should get your Keplerian elements from a different source. I created one additional source for Shuttle orbital data. In some high-interest SAREX missions, I received E-Mail messages from individuals having difficulty accessing the AMSAT Shuttle Orbital Data Web page. These individuals did not want to subscribe to STSTLE because of the frequency of updates. Therefore, I provide a backup source of a current STSTLE update message on my personal Web page. This page may be accessed at: http://www.mindspring.com/~n2wwd Because of the workload in providing updates to both the AMSAT Web page and the STSTLE mailing list, my personal Web page is sometimes only updated with the STSTLE message at ~13:00 UTC and ~20:00 UTC during the missions. Thus, the AMSAT page is the primary data source on the World Wide Web. Ken Ernandes, N2WWD n2wwd@amsat.org * KF0JT SILENT KEY * ==================== It is with sadness that the death of Dennis Caton, KF0JT, author of UP/DOWN is reported. Dennis lost a three year battle with cancer June 4 at his home near Colorado Springs. He was a native of England and is survived by his wife and two grown children. Dennis was a long time supporter of AMSAT and satellite projects. For a time he was AMSAT's coordinator for activities at the Air Force Academy. When he hit upon the idea for the UP/DOWN program he was delighted to have found a way to contribute to AMSAT and satellite operations. A service was held at Our Lady of The Pines in Black Forest, Colorado on June 11. Messages may be sent to Jim White, WD0E (wd0e@amsat.org) for forwarding to the family. Jim White wd0e@amsat.org * FEEDBACK/INPUT WELCOMED * =========================== Comments and input for SpaceNews should be directed to the editor (John, KD2BD) via any of the paths listed below: WWW : http://www.njin.net/~magliaco/ PACKET : KD2BD @ KS4HR.NJ.USA.NA INTERNET : kd2bd@amsat.org, magliaco@email.njin.net SATELLITE : AMSAT-OSCAR-16, LUSAT-OSCAR-19 <<=- SpaceNews: The first amateur newsletter read in space! -=>> /EX