[amsat-bb] Re: DO-64/Delfi-c3 telemetry

[Wouter Jan Ubbels]

Hi David,

yes, we have received your telemetry, thanks a lot for that!
the 145.870 and 145.930MHz are separate transmitters (which are only
combined just before the antennas), they are connected to the same
databus from the On Board Computer.
The drop out issue is not an issue with one of the transmitters
itself, but is related to the databus mentioned above, and it occurs
when large volumes of data are transferred. (And it is not dependent
on which transmitter is on).
Delfi-C3 is currently in basic mode, in which the datavolume no the
bus is relatively low since no payload data is gathered from the
payloads, in fact, the payloads are switched off, causing the dropout
issue not to occur (and it also does not occur in transponder mode).
This is why the downlink is still on when the satellite is over your
qth down under hi:)

73 on behalf of the Delfi-C3 / DO-64 team,

Wouter Jan Ubbels PE4WJ


On Fri, Oct 17, 2008 at 12:57 AM, David Giles <vk5dg at aapt.net.au> wrote:
> Hello All,
>
> Just decoded my second set of telemetry from DO-64.  So far I have heard
> the 145.870 beacon every pass.  Unlike during the first 3 months when it
> was heard 1 pass in 10.
>
> A question for the designers - are the two beacons separate transmitters
> or just separate feeds to the one transmitter?  The 145.870 is far more
> reliable.
>
> 73 de David VK5DG
>
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