Re: [amsat-bb] P3D Report

[Udo Schneider <uschndr@xxxxxxxxxxxxxxxxxx>]

Hello Jean-Louis,

you wrote:

> Here below is was I plan to do tomorrow to try to identify any AO-40
> carriers:
>
> - record any potential weak AO-40 carrier during a long period of time
> - carefully draw a curve of any frequency shifts (using a spectral analysis
> software)
> - compute theoretical AO-40 doppler shifts and draw the corresponding curve
> - compare the curves
> That the only easy way I have found to eliminate any local or distant
> spurious sigs.

That's what I am always doing. But to draw curves is a hard
work, I wrote a small program to calculate the frequency shift.
It works on the basis of TRAKSTAR by D.Ransom and produces
a list like below (22 Dec, QTH Berlin):

----------------------------------------------------------
Input file: obs26609.016      Output file: temp.utc
Frequency:  145.90 MHz
----------------------------------------------------------
  Date      Time      AZ     EL    range     v    delta f
            [UTC]    [deg]  [deg]   [km]   [km/s] [Hz/min]
==========================================================
2000Dec22  03:30:00   97.9   0.1  55418.0   1.08
2000Dec22  03:40:00   99.2   1.1  56049.5   1.02      2.9
2000Dec22  03:50:00  100.6   2.2  56645.6   0.96      2.8
2000Dec22  04:00:00  102.0   3.4  57207.1   0.91      2.8
2000Dec22  04:10:00  103.4   4.5  57734.8   0.85      2.7
.
.
.
2000Dec22  15:00:00  230.8  22.1  33327.6  -2.62      6.1
2000Dec22  15:10:00  231.5  21.5  31714.3  -2.76      6.6
2000Dec22  15:20:00  232.0  20.8  30016.7  -2.90      7.1
2000Dec22  15:30:00  232.2  20.2  28227.8  -3.06      7.8
2000Dec22  15:40:00  232.2  19.6  26337.8  -3.24      8.5
2000Dec22  15:50:00  231.7  19.1  24337.1  -3.43      9.4
2000Dec22  16:00:00  230.7  18.6  22214.3  -3.65     10.5
2000Dec22  16:10:00  229.0  18.1  19955.1  -3.89     11.6
2000Dec22  16:20:00  226.3  17.5  17546.7  -4.14     12.6
2000Dec22  16:30:00  221.8  16.7  14979.9  -4.41     12.9
2000Dec22  16:40:00  214.5  15.3  12266.8  -4.62     10.0
2000Dec22  16:50:00  201.8  11.9   9501.5  -4.50     -5.6
2000Dec22  17:00:00  178.4   2.1   7127.6  -3.00    -72.9

With this list it's easy to identify the signal. The shift
is mostly in the order of a few Hz/min (exept positions
near perigee, of course).

73, good hunting

Udo, DL7OL ***



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