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 <[email protected]> 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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