OK, I see,

Well, it would be out of my reach.

Thanks for the info Graham!!!

73,

Raydel

----- Mensaje original ----- De: Graham Shirville g.shirville@btinternet.com Para: Raydel Abreu Espinet cm2esp@frcuba.co.cu, amsat-bb@amsat.org Enviado: Tue, 21 May 2013 14:34:41 -0400 (CDT) Asunto: Re: [amsat-bb] Question about HamTV

Hi Raydel,

I stand to be corrected but a these dongles are specified for DVB-T so I dont think they would work for signals using DVB-S modulation.

The signals from the ISS will be at 1.3Msps or 2.0Msps - I believe that only the Technotrend T1600 and T3200 cards have, so far, been identified as being suitable for these very low symbol rates http://www.technotrend.eu/2920/TT-budget__S2-1600.html

It is anticipated that more detailed info for potential ground stations will be made available quite soon.

thanks

Graham G3VZV

I thought the whole idea with these SDR "Dongles" is that you could decode practically anything in software. Unless the required bandwidth is too high, and perhaps not in real time, but they can be decoded. For example, people do SSB and FM with them, neither of which are anywhere close to DVB-T modulation.

Couldn't something like that be done with HamTV?

Greg KO6TH

Miguel Barreiro wrote:

Raydel,

Apart from the frequency and signal level differences, DVB-T is a 6-8MHz wide signal with COFDM modulation, using 2k to 8k subcarriers, while DVB-S is a single carrier, 6..36MHz wide signal, usually QPSK or 8PSK. You cannot use a downconverter and a DVB-T receiver to tune into a DVB-S channel.

However, the digital bitstream carried by both is the same - so if you have software analyzers and audio/video players for DVB-T they will work for DVB-S too.

Miguel EA1ICZ

2013/5/21 Raydel Abreu Espinetcm2esp@frcuba.co.cu

...

Hello,

About the future HamTV experiment, is it possible to use a cheap RTL DVB-T dongles used or RTLSDR to receive such signals with proper LNA and downconverter. If the downconversion fits the signal on a proper channel does it device is capable of decode the transmitted format???

Thanks,

Raydel

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