Ah!

THanks for the explanation! I wondered!

Lee W5LMM

On 5/1/2014 11:41 PM, Paul Stoetzer wrote:

Well, FUNcube's primary mission is education. When it's in educational mode, during the day, it provides a strong 300 mW telemetry signal easily received by simple antenna and receiver equipment. Amateur mode is turned on at night (when schools aren't expected to be in session), the telemetry is only 30 mW and the rest of the power is allocated to the transponder. In an 11am/11pm sun synchronous orbit, this generally works well. However, for a couple of months around the summer solstice, the satellite is in sunlight much more often, so this solution doesn't always work. It's more of a problem in the northern hemisphere since there is a far larger population at higher northern latitudes than higher southern latitudes.

Since schools are also not expected to be in session on the weekends, the controllers have been turning on amateur mode continuously during weekends, allowing use of the transponder during the day and night. Transponder mode is actually easier on the satellite's power system as the average power output is somewhat lower and varies depending on use of the transponder. This has presented another challenge as FUNcube has been running much cooler than expected and they have had to keep an eye on running the satellite in transponder mode to make sure the battery temperature doesn't fall below -5 degrees Celsius while operating in full-time transponder mode.

The best solution, of course, would be a computerized schedule loaded into the spacecraft's systems. However, FUNcube uses an extremely simple design and it's onboard control system does not have this capability.

73,

Paul, N8HM

On Fri, May 2, 2014 at 12:04 AM, Lee Maisel maisel@lobo.net wrote:

...

WTF? It shuts off when it sees sunlight?? That seems absolutely opposite of normal behavior of a solar powered bird.

W5LMM

On 4/30/2014 6:05 PM, Paul Stoetzer wrote:

...

Hi Peter,

The AO-73 transponder shuts off as soon as it sees sunlight. That is why your signal suddenly disappeared.

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