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Re: Feeding P3T with PSKDEM/TLMDEC: done !!!

Just tried it and it works just fine.Used the free ware HexEdit32


----- Original Message -----
From: <robson@medidata.com.br>
To: <amsat-bb@AMSAT.Org>
Sent: Saturday, November 25, 2000 6:38 AM
Subject: [amsat-bb] Feeding P3T with PSKDEM/TLMDEC: done !!!


For those wishing to look the telemetry on the nice windows the Stacey has
provided to us
with the P3T but has only sound card here is how I have finally

1 - Record the telemetry with cooledit. During the recording keep open the
spectral analysis window
and try to keep constant the central frequency around 1200 e 1800 Hz using
your up/down mic keys.
This is the working range of the PSKDEM as per its doc:
>A la réception, il convient d'utiliser la BLU et de caler le récepteur de
manière à ce que le signal ne
>soit pas tronqué, c'est à dire pour placer la fréquence centrale entre 1200
et 1800 Hz.

2 - Name this file p3d.wav and run PSKDEM. This will give you a P3D.TLM
file. Run TLMDEC and observe
the output. If it happens to contain a "A" block you are lucky. Use on
binary file editor and extract the "A" blocks,
but stripping the two bytes by the end of the "A" blocks that contains the
CRC. P3T need files with size
multiple of 512 bytes. Unfortunately PSKDEM has a limit on the size of the
WAV file that it supports:
>Le logiciel d'évaluation est limité volontairement pour ne lire que 360000
octets, ce qui correspond à
>environ trois trames. Le reste du WAV est ignoré.

3 - Rename this file to whatever_you_want.raw and place it on the P3T
Telemetry directory.

4 - Use the option replay of the P3T menu and click on the windows you want
to see. If you are not sure you
know how to use the replay option try it first with the raw files supplied
by Mark on:


These files need to be filtered first because to use the Graph option of
the reply function the file must contain
only "A" blocks. Although the filter option has a ignore CRCC option it
needs files of size multiple of 512 bytes !!.

5 - To decode the other "A" blocks that happens to be on your WAV captured
file you will need to repeat the
procedure again with the next chunk of the captured file. You can use
copy/paste of cooledit or write a program.
I think that all the procedure could be automated.

6 - After having a lot of "A" block files you can append them altogether
and feed P3T with this single file.

73 de Robson - PY1DGV

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