Friday, December 14, 2012

Digital voice QSO

The Digital yahoogroup been buzzing for the last few weeks with the new FreeDV and Codec2  
mode


I wanted to try it, but kept putting it off...  This morning Peter VK2TPM emailed me... Hey do you know about this...  Yes, said I... just too lazy to get it and try.   Well he made me to do it... and thanks Peter... it was fun.

http://freedv.org/tiki-index.php

To download and set up the program was not complicated... I kept Peter waiting with my problems... I have "complicated" switching system between my Signalink and my SCS PTC-II modems.  Never remember how i left it last time....

What can I say?  It works well.  Most QSOs happen on 14.236 but that frequency was busy at the time so Peter and I tested on 14.230 (the SSTV frequency, but nobody was there).

Peter's signal at the beginning.  Running about 50 watts.

The screen close: you can see the stream of digital carriers

Here I'm trying to "squeeze" the signal through about 1.1 kHz filter without any negative effect.  When I narrowed the filter to about 1.0 or less kHz the dropouts were quite apparent.

Here you can see the detailed view of the signal in the P3.

The interface of the modem.

This signal is by VK4CAG Graeme.  We had not perfect but pretty good link at that distance.



 

Apology for the video quality... taken with hand held little camera without preparation. 

Please have a look at Peter's blog about our test: http://blog.marxy.org/ 

The same afternoon I "hooked" Horst VK2HL into downloading the program and setting it up.  The test between  him and me was successful .

Apart from Graeme VK4CAG the distances were small, but we used rather low power.

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