experience with fcdp

Christian Daniel -- maintech GmbH cd at maintech.de
Wed May 25 08:00:33 UTC 2011


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Hi Harald,

I have no Funcube, but from the design of it I would rather assume, that
it is a matter of strong signal immunity. The WBX has a lot of built in
analog filters whereas the Funcube has none. If several other carriers
are in the vicinity (within several MHz of the targeted signal), all
these add to noise in the channel.

You might try a filter between antenna and Funcube or try to use an
antenna that is only sensitive in a small part of the Tetra band. Do not
use one of these DVB-T mini antennas that come with the USB sticks.
These are optimized for covering the whole TV band. This includes Tetra
but also everyting else :/

Just my .02 - and speculation as well...

Best regards,
Christian

On 25.05.2011 08:57, Harald Welte wrote:
> Hi!
> 
> I've borrowed a Funcube Dongle Pro and tried to use it with
> osmocom-tetra.  I've manually tuned it to a tetra carrier using the
> Qt-GUI, and it I can see the carrier very clearly in the spectrum/fft.
> However, I'm getting many more bit errors than with a USRP2+WBX board.
> Also, I have the feeling that the WBX has a much higher sensitivity,
> even with the FCDP input LNA at 30dB maxed out. 
> 
> Can anyone confirm these findings?
> 
> I'll do some more investigation and report back here.
> 
> Regards,
> 	Harald

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