[amsat-bb] Uplink Frequency Computation

[Paul Yeager <w4ski@xxxxxxxx>]

Thanks to all who responded so quickly to my query regarding the 
proportionality of Doppler shift to frequency.

I could use a little further help!

I am developing an Excel spreadsheet to compute Mode U/S uplink frequency 
from displayed 2 M IF frequency, taking into account the following factors:
Downconverter LO and LO error
Downlink Doppler Shift
Uplink Doppler Shift
Transponder Offset

Once I get this working, I plan to transfer the algorithm to a lightweight 
computer program, and make same available to the AO-40 community.

Yes, I know, there is a spreadsheet available for download from the 
AMSAT-DL AO-40 page.  No offense to the author (probably my fault), but I 
cannot get it to work, and it seems unneccesarily complex (at least for my 
needs).  Also, I like the idea of having a tool that does not require using 
Excel to get the job done.

Now... here is the help I need.....  If some kind hams out there who 
operate mode U/S could help me with a little data, it would be helpful in 
testing the algorithm before I test it in actual use.  I am asking for this 
because I cannot work A0-40 from home, I must haul all the gear somewhere 
with a better view to the south than I have from my location, here on the 
north side of a mountain.

Here is the data I would like to have, if some of you would like to 
help.  For a given point in time:
Your indicated RX frequency, either as displayed on your IF rig, or your 
actual 2401 Mhz frequency.
Your indicated TX frequency.
Doppler shift, as reported by your tracking program, either for 435 or 2401 
MHz.
Your nominal LO Frequency and LO error, or your exact LO frequency if known.

Here is what I offer in return:
A marble statue in your honor, on my front lawn (just kidding)
Participation in the work product, i.e., a copy of the spreadsheet for your 
own use, once it is verified to work; and a copy of the eventual program, 
once created.

Why am I doing this?  No offense meant personally, but I find "swishing 
dits" to be a suboptimal means of getting TX and RX synchronized.

Tnx & 73

Paul W4SKI




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