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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/FVBUNUSUXEWMN7X35RLNTOEPKUY42SUE/", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/", "message_id": "[email protected]", "message_id_hash": "FVBUNUSUXEWMN7X35RLNTOEPKUY42SUE", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/FVBUNUSUXEWMN7X35RLNTOEPKUY42SUE/", "sender": { "address": "amsat-bb (a) g3cwv.co.uk", "mailman_id": null, "emails": null }, "sender_name": "Clive Wallis", "subject": "[amsat-bb] OSCAR-11 Report", "date": "2010-01-14T12:27:19Z", "parent": null, "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": " OSCAR-11 REPORT 14 January 2010\n\nThis report covers the period from 30 November 2009 to 14 January 2010.\nDuring this time the satellite was heard briefly on 10 & 11 December and\nthen from 31 December until 10 January. Good signals were received, and\ndecoded. Sometimes signals have been very strong, although frequent changes\nin polarisation have been observed. The satellite was not heard\nduring solar eclipses, which now occur during the afternoon and evening\npasses over the UK.\n\nThe last two 'off' periods have lasted 14 and 19 days respectively,\nsuggesting that the watchdog timer has been reset. However, the last\ntransmission period lasted for the full ten days, so it is possible that\ntransmissions may resume after ten days of silence, ie. around 20 January.\nHowever, please note that the satellite's behaviour is now very\nunpredictable, and until a pattern of operation is established, it is\nimpossible to predict what will happen next, with any certainty.\n\nThe telemetry is unchanged from the 2008 downloads. The on-board clock\nis now 252 days slow. When last received in 2008 it was 83 days slow.\nThe increasing error suggests that the clock may be stopping, when the\nsatellite is in eclipse. During the last transmission period the date\nfailed to increment on one occasion, from 29 to 30 May.\n\n\n -------------\n\n RECEPTION REPORTS REQUESTED!\n\nPlease send reception reports to [email protected] (replace xxxxx by\ng3cwv) or post to amsat-bb. If you have a file, please discuss it with me,\nbefore sending it!\n\nYou may also like to add your reception report to the live satellite status\npage, on the website set up by David KD5QGR and Bob WB4APR. The URL is\nhttp://oscar.dcarr.org/index.php\n\nThe satellite transmits on 145.826 MHz., set receiver to NBFM. OSCAR-11\nhas a characteristic sound, rather like raspy slow morse code, sending\n\"di di dah dah dah dah dah dah dah\" sent over five seconds. If you are\nreceiving a very weak signal, switch the receiver to CW or SSB. You\nshould hear several sidebands around the carrier frequency, should be\nable to hear the characteristic 'morse code like' sound usually on at least\ntwo of the sidebands.\n\nPlease note that you need a clean noise free signal to decode the\nsignals. There is an audio clip on my website\nwww.g3cwv.co,uk which may be useful for identification\nand as test signal for decoding.\n\n -------------\n\nReception reports have been received from Peter ZL3TC, Mike DK3WN, Jon\n2M0IBO and Detlef DJ3AK. Many thanks for those.\n\nThe Beacon frequencies are -\n\nVHF 145.826 MHz. AFSK FM ASCII Telemetry\n\nUHF 435.025 MHz. OFF\n\nS-band 2401.5 MHz. OFF\n\nThe satellite is now subject to eclipses during every orbit. Long term\npredictions indicate that eclipses will occur until 2019, when there will\nbe some eclipse free periods until 2023. However these very long term\npredictions should be regarded with caution, as large tracking errors can\naccumulate over long periods of time.\n\nWhen analogue telemetry was last received in March 2005, it showed that\none of the solar arrays had failed, and there was a large unexplained\ncurrent drain on the main 14 volt bus. After 25 years in orbit the battery\nhas undergone over 100,000 partial charge/discharge cycles, and\nobservations suggest that it cannot power the satellite during eclipses\nlasting more than about ten minutes, or sometimes even during periods of\npoor solar attitude.\n\nStudy of the satellite's behaviour prior to 2008 suggested that its\nbattery would not sustain operation during solar eclipses, and the watchdog\ntimer would switch the satellite OFF after less than an orbit. Eclipses\nare now occur during every orbit and will continue for many years. In\npractice this meant that OSCAR-11 would only be heard occasionally by\nstations monitoring the frequency while listening for other satellites.\n\nThe satellite unexpectedly started sustained transmissions during\nNovember 2009, suggesting that there may have been a failure causing\nreduced drain on the power supplies or a change in the watchdog timer\ncharacteristics.\n\nThe current status of the satellite, is that all the analogue telemetry\nchannels, 0 to 59 are zero, ie they have failed. The status channels 60 to\n67 are still working. The real time clock is showing a large accumulated\nerror, although over short periods timekeeping is accurate to a few seconds\nper month. The day of the month has a bit stuck at 'one' so the day of the\nmonth may show an error of +40 days for some dates. The time display has\nswitched into 12 hour mode. Unfortunately, there is no AM/PM indicator,\nsince the time display format was designed for 24 hour mode.\n\nThe spacecraft computer and active attitude control system have switched\nOFF, ie. the satellite' attitude is controlled only by the passive gravity\nboom gradient, and the satellite is free to spin at any speed.\n\nThe watchdog timer now operates on a 20 day cycle. The ON/OFF times have\ntended to be very consistent. The average of many observations show this to\nbe 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor\nsolar attitude may result may result in a low 14 volt line supply, which\nmay cause the beacon to switch OFF prematurely, and reset the watchdog\ntimer cycle. When this occurs, the beacon is OFF for 20.7 days.\n\nListeners to OSCAR-11 may be interested in visiting my website. If you need\nto know what OSCAR-11 should sound like, there is a short audio clip for\nyou to hear. The last telemetry received from the satellite is available\nfor download. The website contains an archive of news & telemetry data. It\nalso contains details about using a soundcard or hardware demodulators for\ndata capture. There is software for capturing data, and decoding ASCII\ntelemetry. The URL is www.g3cwv.co.uk Please note that my old website\nwww.users.zetnet.co.uk/clivew is no longer being updated, athough it may\nstill be available.\n\nIf you place this bulletin on a terrestrial packet network, please\nuse the bulletin identifier $BID:U2RPT146.CWV, to prevent duplication.\n\n73 Clive G3CWV [email protected] (please replace xxxxx by g3cwv)\n\u001a\n", "attachments": [] }