[amsat-bb] Re: AO-73 over UK

Lee Maisel maisel at lobo.net
Thu May 1 23:26:37 PDT 2014


THanks for the explanation!  I wondered!


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 at 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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