Oscar-40 Ham Satellite Transmitting Again

Bruce Perens K6BP writes: "The Phase 3-D Amateur satellite, called "Oscar 40" now that it is in orbit, is back on the air. A ground station sent a reset command and a command to turn on a microwave transmitter, which worked on the first attempt. The transmitter is sending an unmodulated carrier until telemetry software is reloaded, but it's clear from the doppler shift of the signal and the loss-of-signal time as the transmitter crosses the horizon that the signal is coming from the satellite's orbit. The ground controller will now reload the flight computer software and bootstrap the main flight computer. It will take a while to reload both computers and to investigate problems with the satellite, as this is complicated by the attitude and orbit of the satellite - right now it's not actively stabilized and is only pointing the antennas toward the Earth during part of its orbit, and of course it's only above the horizon from any ground controller's perspective during part of each orbit." Read on for a bit more on this promising news."

"A board of inquiry will convene to investigate the loss-of-signal incident and to change procedures to avoid another such incident with this or a future Amateur satellite. General information about the satellite can be found at www.amsat.org. The following announcement is from www.amsat-dl.org:

The Santa Claus brought AO40 back On Air! At 2000-12-25 21:45 command station Ian, ZL1AOX sent a RESET command through L-band and an initialization block to switch the S2 S-Band transmitter On. Just after the first attempt the S2 beacon came on 2401.305 MHz, Signal was about S5 to 6 which was comparable to when S2 was heard last during testing The S2 beacon produced a steady signal and from the doppler wobbling it is also clear that it is in fact coming from AO-40. Ian ZL1AOX reported that he was able to copy and observe (with Spectrogram) the S2 beacon. His LOS time was 2000-12-26 03:45:15. Predicted LOS from NORAD set #12 keps gave 5 secs later. Approx distance was 61,470 Kms. Today, 2000-12-26 at about 16:05 UTC, ZL1AOX will acquire AO-40 shortly after perigee with a reasonably good squint angle. He will than start reloading the IPS software. Until than the beacon will not carry any telemetry, just a carrier. Once the bootloader for IPS is up, you will see "X" blocks in the telemetry until IPS is completely loaded... (Thanks to DB2OS for this information)."

Comments

WHY - bacuse it is a good hack.

[cpuffer_hammer]

The HAM (Amateur radio) community. Has a long history of building its own satellites. They are put in orbit by NASA on rockets that are being tested. Many of these satellites have been lost to launch problems.
There is a lot of similarity between the Hacker and the HAM communities in fact some of the first networking code in LINUX is the amateur packet radio code.

Re: From amsat.org

[Bruce Perens]

InstantTrak is a ground application distributed by AMSAT as a fund-raiser, for people who want to track the satellite (using windows, I think) so that they can communicate with it. But there are a lot of free applications to do this, too. Debian distributes at least one, and has a good collection of free ham radio apps.

Thanks

Bruce

Because, that's why :)

[Randy Rathbun]

There are a ton of reasons, but the main one is education. First, anyone with a ham license can use these satellites. They are actually very easy to use and it does not require large antenna arrays consisting of 20 foot dishes or millions of dollars of equipment to use them. I have talked through the birds using only a small off the shelf handie talkie and a mobile antenna - total cost for all the equipment was about $500.

These are not just "things slopped together". A whole hell of a lot of engineering goes into them, and there really is not much of a difference between the hamsats and the ones put up by megacorp. They have Earth locators on them. Some sats, like WO-18 had video cameras. Other sats like DO-17 had voice encoders (which did not work for some reason) but would orbit and send down telemetry. Even though you could not use DO-17 for communcation, it was probably the most awesome of the hamsats at the time. I was able to listen to it go overhead without even having an antenna on the receiver, and was able to decode the telemetry packets when I put a rubber duckie antenna on the thing.

Check out the amsat.org web site some more. There are links to things like the University of Surrey satellites and the aformentioned WO-18 made by Weber University.

73 DE NV0U