[amsat-bb] Re: DO-64

Wouter Jan Ubbels wjubbels at gmail.com
Tue Sep 16 02:18:11 PDT 2008


Hi Sebastian,

besides the fact that polarization of your uplink signal may make a
huge difference since the satellite is slowly tumbling, the
transponder has a frequency offset. 435.556MHz actually corresponds to
145.900MHz on the downlink (instead of 435.550). Some people have
reported even higher offsets which are likely to be caused by
temperature dependency of the local oscillators on board the
satellite, so it may help to tune around a bit in order to find your
own downlink, which makes operating the transponder a challenge hi:).
Good luck working DO-64!

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

Wouter Jan Ubbels PE4WJ



> I listened to a pass earlier this morning ago over Miami Florida.
> Good strong CW beacon heard throughout the entire pass, down until
> about 1 degree, but still nothing heard on my uplink.
>
> 73 de W4AS
> Sebastian
>
> On Sep 13, 2008, at 12:03 PM, Luc Leblanc wrote:
>
>> On 13 Sep 2008 at 8:15, WILLIAMS MICHAEL wrote:
>>
>>
>>> As usual, the downlink signal gets weak on the second half of the
>>> pass.
>>>
>>> Mike Williams K9QHO
>>
>> Got the same results here i got explanations regarding this signal
>> drop for polarisation change but as the satellite attitude is
>> uncontrolled i tend to believe it's more an effect of the antennas
>> pointing towards the earth station and pointing away than a
>> polarisation
>> issue. This change in the signal level start exactly pass the TCA
>> point and signal degrade up to a point he's drop below the noise?
>>
>> I try to figure out the satellite shape spinning and thumbing in
>> space in regard of the polarisation and it will be very odd that the
>> polarisation change happen just at TCA?
>>
>> Any ideas here?
>>
>
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