On Tue, Oct 24, 2023 at 07:36 PM, Tom DJ6TB wrote:
When receiving, you have to adjust in one direction; when transmitting, it's the other way round.
HI All
100% correct!
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I would also add that compared to the position of the minimum distance (= height at EL 90 degrees), you will have the frequency of the SATELLITE which for the IO-117, would seem slightly lower than the 435,310 announced.
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- Start SAT approaching:
Doopler RX DW > ~435.310 to go lower
Doopler TX UP < ~435.310 to go up
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SAT 90 degrees:
Doopler RX DW = 0 TX = 345.310 (~435.308.6)
Doopler TX UP = 0 RX = 345.310 (~435.308.6)
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-SAT moves away from me:
Doopler TX DW < ~435.310 to go lower
Doopler RX UP > ~435.310 to go up
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Don't misunderstand the list above, in the sense that if for example the doopler is 5kHz, with the satellite, when approaching we will have FREQ+5kHz in RX and when descending
And
FREQ-5kHz in TX and up
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i.e. doopler (UPLINK+ / DOWLINK-) are backwards, and NOT QRG EQUAL RX and TX in doopler, as I also thought at the beginning!
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I too have dedicated myself to the GreenCube with my FT847 which I have been using on satellites since its arrival on sale with many thousands of QSOs via SAT: at moment FIRST WORLD PLACE SPACE SAT SLOT IN CLUBLOG ;-) ;-)
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On the GC in the 3 orbits made I completed a ~30 'QSO' (the first time to understand clearly I received everything but I only digipeated 2 time with my call/digipeater and 1 QSOs when I was in minimum distance maximum elevation, i.e. ~RX=TX.
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Then I tried to understand the necessary doopler which is very important on GC.
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Then I built a mini soft home made to manage the doopler which I combined with my AZ/EL tracker to understand where to tune exactly.
I saw that it must be very precise..
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In fact, in the 2 following orbits "calculated" with the my soft, I made about 30 successful contacts and many, many digipearers...
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In UHf my FT847 is also a little shifted between RX and TX already and is not precise by a few hundred Hz and I had to correct that in the UP/DW too.
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FT847 CAT apparently does not have the management of VFO B in split, I was unable to use a DOOPLER in TX with SPLIT on VFO B.
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I couldn't find any information on the CAT manual to select and send the CAT VFO B of the FT847.
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Is there just no possibility or trick to manage both the RX and the VFO B TX together?
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Since full duplex is not needed, I'm thinking of a solution by working only on MAIN VFO A, moving between RX and TX if it doesn't require too much speed due to the latency of this continuous change... I'm trying right now!!
If anyone wants to join this option and evidence make themselves heard...
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ps: even openAI wasn't clear about the doopler and gave me the two possibilities without knowing what it was, it invented... absurd AI :-) ;-)
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73
Frank
Frank