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April 15, 2004

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OSCAR-11 Report 14 April 2004

OSCAR-11 celebrated its 20th birthday on 01 March. After 20 years in orbit, it is still transmitting useful data. To commemorate this event, AMSAT-UK issued a special QSL for reports of reception, during March. 320 reports from 37 different countries were received, 122 for reception on 01 March. 57 reports were for mode-S reception.

For full details of the reports received, visit the AMSAT-UK website at http://www.uk.amsat.org/

Many thanks Jim G3WGM, Secretary of AMSAT-UK, who organised this event, Martin G3YJO and his UoSAT team for their support, and all those who sent reception reports.

During the period 08 March to 14 April 2004 the 145.826 MHz beacon has been heard transmitting continuous ASCII telemetry from 09 to 19 March, and from 30 March to 09 April. Ground control turned the beacon ON during 09 March, to minimise the OFF time during March. It now operates under control of the watchdog timer, approximately 10 days ON followed by 10 days OFF. If the current 20 day cycle continues, the beacon should switch OFF on around 19 March. During this period good signals have been received.

The internal temperatures have decreased by about 2C. They are now 12.0C, 9.6C and 15.6C for battery, telemetry electronics and command decoder, respectively. Solar eclipse predictions indicate that temperatures are now expected to decrease, from the peak reached in March, towards a trough in June/July and then increasing until the end of September, when the satellite will encounter continuous sunlight for the remainder of the year. Higher temperatures and greater temperature changes are expected this year, compared to 2003.

The battery voltage observed during daylight passes has decreased, during the second ON period. Observations have varied between 13.2 and 13.7 volts, with an average value of 13.5 volts for 09 March to 19 March. From 29 March to 09 April the voltage varied from 13.3 to 13.6 with an average value of 13.4 volts.

Spin periods of 390 to 626 seconds have been measured from the magnetometer telemetry. The rotational speed has decreased steadily during the reporting period, but recovered at the end. The direction of rotation is normal.

Users of OSCAR-11 should note that the date in the telemetry is now advanced by FOUR days. The time is advanced by 19.6 minutes, and this error is increasing by about one minute per year.

OSCAR-11 now operates in a default mode, controlled by the watch-dog timer.

The satellite transmits continuous ASCII telemetry for about 10 days on 145.826 MHz, followed by about 10 days of silence. This regular sequence might be interrupted by ground control, at any time.

 The mode-S beacon is ON continuously, even when the VHF beacon is OFF, nominally transmitting an unmodulated carrier on 2401.5 MHz. There is however a VERY low level of AFSK modulation, (now a constant audio tone), which has been detected on strong signals. Telemetry indicates that the beacon has partially failed, and is delivering half power. This beacon is a useful test source for those testing mode-S converters, as an alternative to OSCAR-40. However the signals are very weak, and there is a lot of Doppler. Users should also note that the polarisation of OSCAR-11 is LHC. Even if you can't hear OSCAR-11, your equipment may still be OK for OSCAR-40. Any reports of reception on 2401.5 MHz would be most welcome. Please e-mail g3cwv@amsat.org.

The 435.025 MHz beacon is normally OFF. It can only be heard on the very rare occasions when the satellite is being commanded by ground control, i.e., within range of Guildford, UK. When the 435 MHz beacon is transmitting, the 145 MHz beacon is normally OFF. The data transmitted is mainly binary.

Listeners to OSCAR-11 may be interested in visiting my web site.

The web site contains details about using a soundcard for data capture, and also details about using hardware demodulators. There is software for capturing data, and decoding ASCII telemetry. There is an archive of raw data for analysis, which is continually being expanded, as new data is captured. Originally this was for WOD, but it is now being expanded to include ASCII telemetry. At the present time the telemetry covers 1996 to April 2003. I will add other years as time permits. In parallel there is a news archive which provides an overview of the state of the satellite, at the times when the telemetry was captured.

If anyone out there can provide any data, particularly for the 1984 to 1993 years, this would be most appreciated. Please e-mail me with details. However please DO NOT SEND ANY FILES, before further discussion.

Also included are some audio files, examples of each type of data transmitted by OSCAR-11, each one plays for about ten seconds. There are also examples of mode-S reception. All the audio files are zipped, so that they can be played off-line. These should help listeners identify the various types of data, and give an indication of the signal quality required for successful decoding.

The URL is http://www.users.zetnet.co.uk/clivew/

[ANS thanks Clive, G3CWV, g3cwv@amsat.org for the above information]

Big FCC Proposal

Well folks if the FCC has it way, things are going to get a little more crowded in the two meter satellite band. This is just one of many proposals the FCC has put forth today. Surf on over to http://www.arrl.org and read all about it.

Editors input...

The actual article from the FCC can be found at http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-04-79A1.doc

Of interest to AMSAT may be:

"18. On November 4, 1999, Kenwood Communications Corp. (Kenwood), a manufacturer of amateur radio equipment, requested a declaratory ruling confirming that its "Sky Command System" (Sky Command) complies with the amateur service rules. Alternatively, Kenwood requested the Commission to grant blanket rule waivers so that amateur service licensees could utilize Sky Command. In 2000, the Public Safety and Private Wireless Division denied Kenwood's request, concluding that Section 97.201(b) of the Commission's Rules does not authorize auxiliary stations to transmit on the 2 m band, and that Kenwood did not meet the standards for a waiver request.

19. Subsequently, on May 1, 2001, Kenwood requested that we amend Section 97.201(b) of our Rules to allow auxiliary stations to transmit on the 2 m band above 144.5 MHz, except 145.8-146.0 MHz, in addition to the frequency segments previously authorized. Kenwood states that this proposed rule change would increase the flexibility of amateur radio licensees without adversely affecting other services or amateur radio stations that use the 2 m band, and would promote the development and use of new technology, including Sky Command."

(Ed.)

[ANS thanks Keith, N4ZQ for the above information]

AMSAT Project Opportunity?

Tracking the position of tiny amateur satellites (cubesats) down to a few seconds in their orbit can be easily done using the technique we propose on our RAFT cubesat.

Using a simple direct-conversion receiver at 216.98 MHz (the frequency of the 80 megawatt ERP Naval Space Radar), an audio-ping will be heard whenever the satellite flies through the very narrow 0.2 degree fan beam over Texas. The ping lasts on the order of a second, but it nails your position quite accurately. You command it on for a few seconds in your satellites downlink whenever you want to find your satellite over the southern USA.

We think we can build these things about the size of a book of paper matches. Just a 216.98 MHz local oscillator and an NE602 mixer should do it?

Does anyone want to help us develop this device for our RAFT satellite to fly next year? This will also possibly help other amateur projects as well. A good volunteer project.

See the project http://www.ew.usna.edu/~bruninga/raft.html

Remember, the NSSS Radar fence is 80 Mwatts, so this thing does not need to be sensitive... nor have its own antenna even. Thus it will fit nicely on just about any amateur satellite if you are worried about losing it.

[ANS thanks Bob, WB4APR for the above information]

Call for Papers -- 2004 Digital Communications Conference

The 2004 TAPR/ARRL Digital Communications Conference will be held September 10-12 at the Airport Holiday Inn in Des Moines, Iowa. You'll find more conference information on the Web at http://www.tapr.org/dcc/.

We are now accepting papers for the conference proceedings. You do NOT have to be present at the conference to have your paper included in the proceedings.

Please send your submission by August 10 to:

Maty Weinberg
ARRL
225 Main St
Newington, CT 06111

[ANS thanks Steve Ford, WB8IMY for the above information]

AMSAT-UK Colloquium 2004

The dates of the AMSAT-UK Colloquium for 2004 are Friday 30 July to Sunday 1 August. The venue is as previous years at the University of Surrey, Guildford, UK

More details: http://www.uk.amsat.org/Colloquium/default.php

[ANS thanks AMSAT-UK for the above information]

Weekly Satellite Report

Link to the weekly report on satellite ...

All Satellites
ISS. RS-12. RS-13. RS-15. AO-7. AO-10. UO-11. UO-14. AO-16. LO-19. FO-20. UO-22. KO-23. KO-25. IO-26. AO-27. FO-29. GO-32. SO-33. PO-34. UO-36. AO-40. SO-41. SO-42. NO-44. NO-45. MO-46. AO-49. SO-50


Please send any amateur satellite news or reports to the ANS Editors at ans-editor@amsat.org

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This week's AMSAT News Service bulletins were edited by AMSAT News Service Editor Dave Johnson, G4DPZ, g4dpz@amsat.org

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