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Re: Uplink Frequency Computation



Hi Paul,
You can get free source code that calculates all of this
in real time as well as radio drivers for most of your
favorite radios to make it completely automatic via
InstantTune. It is free at www.amsat.org under
"InstantTrack accessories."

I agree, swishing dits is not very civil.

Tony AA2TX
---
At 03:54 PM 8/13/02 -0400, Paul Yeager wrote:

>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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>
>
>
>
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