Author: SM0TGU

Frst info frn Henry/SM5BVF:

OSCAR-7 :s telemetri hrs bra p 145,975 ca fr den som r intresserad.
Kepler enl. fljande:

AO-07
1 07530U 74089B 02167.52996888 -.00000029 00000-0 10000-3 0 935
2 07530 101.7955 212.2077 0012102 193.4285 166.6467 12.53558681262239

Satellite: AO-07
Catalog number: 07530
Epoch time: 2167.52996888
Element set: 93
Inclination: 101.7955 deg
RA of node: 212.2077 deg
Eccentricity: 0.0012102
Arg of perigee: 193.4285 deg
Mean anomaly: 166.6467 deg
Mean motion: 12.53558681 rev/day
Decay rate: -2.9E-07 rev/day^2
Epoch rev: 26223

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Sedan frn Ingemar/SM0AIG:

En ganska fantastisk historia

AO-7 sndes upp 1974 och fungerade bra fram till 1981 d den avsomnade pga kortslutning i ett eller flera batterielement. Nu har tydligen batterierna torkat ut s att kortslutningen slppt och den har pltsligt brjat snda s snart den r solbelyst.

Det var Pat, G3IOR som p midsommarafton av en ren slump upptckte telemetrisignalerna p 2 meter – frst utan att ha en aning varifrn signalerna kom. Nu har man ocks upptckt att ven transpondern fungerar.

Flera stationer i USA har redan krt QSO via den teruppstndne Lazarus alias AO-7. Mode B: upp ca 432.120-180 och ned 145.920-980 inverterande. Hittills verkar ingen ha vgat sig ut p passbandet i Europa. Uppfrekvensen r kanske ngot tveksam fr knsliga naturer.

Telemetrin p 145.975 +/- doppler snds enligt fljande schema:

1aa 1bb 1cc 1dd
2aa 2bb 2cc 2dd
3aa 3bb 3cc 3dd
4aa 4bb 4cc 4dd
5aa 5bb 5cc 5dd
6aa 6bb 6cc 6dd
Hi Hi

Den som r lagd t knep och knp kan dekoda med hjlp av bifogad bmp. Nedan r ngra exempel frn passagen 15:30z idag:

> 100 145 176 156
> 297 245 200 254
> 370 34x 328 354
> 453 455 450 451
> 542 501 553 529
> 60x 601 601 651
>
> 100 166 179 156
> 297 263 201 254
> 376 368 331 354
> 448 455 449 451
> 541 501 552 529
> 60x 601 601 651

Halvskaplig mottagning p en gp. AO-7 snder s snart den lmnar jordskuggan och vxlar mellan snabb och lngsam cw vid olika pass. Ingen har hittills lyckats hra beacon p 10 meter och 70 cm. Den hade p sin tid ven en transponder i mode A: 145.850-950 upp och 29.400-500 ned.

73 de SM0AIG
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Lnk till telemetrinyckeln:
http://members.aol.com/rogerkola/chart.bmp

Klicka hr fr att se nyckeln direkt (185 kBt):
http://amsat-sm.mailsystem.net/bilder/misc/ao-7_chart.gif
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Info frn AMSAT-NA

Klla: SM5BVF och SM0AIG

En ngot makals historia kan vi lsa om i senaste bulletinen frn ANS. Dr psts att den gamla satelliten Oscar 7 har gett ifrn sig livstecken i form av CW-telemetri. En titt i historiebckerna sger oss att Oscar 7 skts upp den 15 november 1974 och slutade fungera i mitten av 1981. Den innehller en mode-B transponder.

Ls sjlv nedan. Sant eller inte?
—

STOP PRESS – Announcement….

First heard by Pat Gowan G3IOR, Oscar 7 seems to have made a comeback! Pat copied and downloaded CW telemetry. This information was confirmed by several AMSAT members as coming from OSCAR-7. This satellite was launched on November 15 1974, giving it a life of 27 and one half years. The receive frequency was 145.9738.
Jan King W3GEY commented:-

G3IOR s telemetry frame is interesting. Apparently he did hear the AO-7 Mode B beacon tonight.

I got out my December 1974 and looked up the telemetry equations for the Morse Code Telemetry Encoder and what I found is in the attached spreadsheet.

I m blown away. Most of this stuff makes pretty good sense. In particular, the temperatures make sense and I would have guessed that they would be the most sold IF the reference voltage held (which it did). Interpreting some of this for those who may not understand or don t remember, the telemetry says the spacecraft was in Mode B; all the other beacons and Mode A were off. It is possible that the thing had just turned on because the old 24 hour timer just reset it to Mode B. The damn thing may think it is still on an every other day cycle. The power output of the transponder is 1.16 watts which may mean it is transmitting white noise plus beacon power. That seems about right, but a little low as I recall. The instrumentation switching regulator is in the middle of it s normal range and seems to be working fine. The internal temperatures are around 15 deg. C; the external temperatures are around 5 C and the transponder PA temp, which should be the warmest – IS – it s 35.1 deg. C. The array current value is bust. I think maybe it always was. Need to look for some old telemetry to confirm that. The array current calibrations looks off. The array currents are in the normal range but all four show current. This can t be. Only two at a time should show current. Without a battery on line, this is entirely possible. The big find is that the battery voltage telemetry shows a voltage of 13.9 volts. Normal is 13.6 to 15.1 volts. So that would suggest the battery was normal BUT, the 1/2 battery voltage is measuring only 5.8 volts. That can t be. This imbalance probably means that the 5.8 volts is the correct value for the lower half of the battery (which is a low value for that half, if the cells were normal – they are probably not) and there is a break somewhere in the upper 1/2 of the battery string. My guess is the indicated voltage is really what the BCR is putting out with only the spacecraft load as a real load and the battery string has an effective break (or a pretty high resistance) somewhere in the upper half.

So, this old war horse of a spacecraft seems to have come back from the dead if only for a few moments. And it is telling us, that even in a 1460 km high orbit a cheap spacecraft built by a bunch of hams, without very many high rel parts and without designing for a radiation dose like this, can last for 27+ years in space as far as a majority of it s electronics is concerned. Even the damn precision reference voltage regulator is still in calibration!

Like many of us, stunned by the announcement of the return of an old friend, Past President and BOD Chairman Bill Tynan added Wow! Shades of Harry Potter and Steven King. It makes one believe in ghosts.

[ANS thanks President Robin Haighton for this item]

Klla: ANS 174

Om du har vgarna frbi England i sommar kan du beska AMSAT-UKs rsmte – Colloquium. Det gr av stapeln 26 – 28 juli i Surrey University, Guildford, Surrey. AMSAT-SM kommer att vara representerat.

Lr mer p:
http://www.uk.amsat.org/colloquium.htm
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Klla: AMSAT-UK