[amsat-bb] Re: AO-73 Question (mode efficiency?)

Stefan Wagener wageners at gmail.com
Fri Dec 27 11:28:00 PST 2013

>From Graham earlier in November on the BB:


Hi All,

Yes in telemetry (also known as  educational) mode we have around 300mW and
this is a much higher average RF output than when in amateur (also known as
transponder) mode.

Total current drain is therefore greater when in educational mode. This is
convenient because we had planned that educational mode would be more
useful when the spacecraft is in local daylight - ie schools would be more
likely to be open. This is the primary mission of course. Also amateurs
often have to work during the day so would appreciate the availability of
the transponder during the local evening passes.

We were not, before launch, 100% certain that we would have a good enough
power budget to run the transponder during every eclipse period but, at the
moment, this seems to be ok - we still have quite a positive power budget.

Its a bit late here and we are quite tired after three very hectic days but
I hope the above explanation makes some sort of sense:)

best 73


On Fri, Dec 27, 2013 at 12:01 PM, Robert Bruninga <bruninga at usna.edu> wrote:

> > The satellite is only in transponder mode when it is in eclipse..
> > In full sunlight it is in beacon mode only.
> Just curious about the overall design goals of this operating mode?
> Putting solar energy into and then taking it out of batteries suffers
> about a 30% loss in efficiency.  All else being equal it is usually better
> to use solar power directly if possible.
> Maybe the value of this mode is for hams to use the satellite in the
> evenings during play time instead of during the day when schools and
> students could benefit.
> Just curious.
> Thanks
> Bob, WB4aPR
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