Author: SM0TGU

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Today during the period 0310 to 0320 UTC (orbit 1541) I observed the following.
Prior to issuing the command sequence we tune around the beacon frequency, taking note of the noise spectrum . No variance in amplitude detected, just clean white noise. At 0310, commenced sending a 12 block sequence, 3 * (Reset,Tx-Off,Reset,Tx-On).

At the completion of the sequence, again tuned around the beacon frequency, and noted a noise peak of 4 to 5 db, in the vicinity of expected beacon frequency. The width of this peak was about 5 kHz. Listened to it for about 15 seconds and then sent a Reset, Tx-Off command and the noise peak disappeared, approximately 2 seconds after the Tx-Off block was completed.

Completed my session with a number of Aux-Batt commands, but did not attempt the Tx again. Range was nominally 12000/15000 kilometres during command period. Was using my last calibrated uplink frequency.

This tends to suggest that the IHU and L Band Rx are operational. Bus voltage insufficient to open that damn relay. Considering SA=-72, the remaining cells are holding up well. Hope this makes your day, like it has mine.

Colin Hurst, VK5HI
for the AO-40 Command Team

Klla: AMSAT-DL

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Parkes 64m Radio Telescope Listens for AO-40
With our attempts to restore AO-40 we have received today significant support from Parkes Observatory in Australia. http://www.parkes.atnf.csiro.au/
The Parkes Observatory is operated by the Australia Telescope National Facility (ATNF) which is part of Commonwealth Scientific and Industrial Research Organisation (CSIRO).

From here were received the live pictures of Apollo 11 Moon landing, 1969. See above homepage of Parkes.

The radiotelescope has a diameter of 64 metres and the system noise figure is approx. 25 K.

From about 6:00 UTC, a 4 MHz wide spectrum with center frequency of 1097 MHz was scanned with high level technique in order to find the LO frequency of the AO-40 L1 receiver. A band of approx. +/- 20 kHz around the actual LO frequency was examined intensively. Three hours were needed to prepare the setup for AO-40 and to search.

Unfortunately nothing was heard which could be a signal of AO-40!!

The fact that nothing was heard of the L1 receiver s LO does not lead to the conclusion that AO-40 is completely dead. The receivers of Parkes are not really fitted for frequencies below 1.25 GHz, and naturally one does not know how good the L1 receiver s LO is shielded or how much of the signal would go through the antenna to the outside world. During the next days more research follows.

The L1 command receiver is continuously switched on, and it would have been good news if we had such a confirmation that the 10 V power source for the L1 receivers is still functioning. All receivers and also the IHU are supplied with the 10 V source.

All command stations are continuing to send commands to the satellite in order to switch the batteries.

I would like to say a great thank you on behalf of AMSAT-DL to Brett Dawson, VK2CBD and the team of Parkes observatory, especially to Dr. John Reynolds (Officer in Charge) and John Sarkissian (Operations Scientist).

Peter Guelzow, DB2OS
President AMSAT-DL

AMSAT-DL Oscar 40-sida

Klla: AMSAT-DL