DVB-S Transmitter

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drmpeg
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DVB-S Transmitter

Post by drmpeg » Thu Apr 24, 2014 11:52 pm

I've ported Edmund Tse's implementation of a DVB-S transmitter (https://github.com/EdmundTse/gr-dvb) to GnuRadio 3.7.x and bladeRF. There's some interest in this mode for Digital Amateur Television (DATV) due to it's low PAPR (Peak to Average Power Ratio).

https://github.com/drmpeg/gr-dvbs

A complete gnuradio-companion flowgraph and stand-alone Python script are included. Here's a spectrum analyzer trace of a 10 Msymbols/s (20 Msps) DVB-S signal from bladeRF. At a 7/8 Viterbi code rate, the Transport Stream rate would be approximately 16.1275 Mbps.

For 6 MHz channels, the symbol rate would be around 4.5 Msps (and around 7.25 Mbps Transport Stream rate with 7/8 code rate).

Image

Here's a nice DVB-S (and DVB-S2) bitrate calculator.

http://www.satbroadcasts.com/DVB-S_Bitr ... lator.html

Ron

N2TOH
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Re: DVB-S Transmitter

Post by N2TOH » Wed Aug 13, 2014 6:59 pm

TCP/IP encapsulation, what would it take to wrap internet traffic so it could be send along with a digital video transmission? perhaps as one of the sub channels along with actual video.

drmpeg
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Re: DVB-S Transmitter

Post by drmpeg » Wed Aug 13, 2014 8:21 pm

The only requirement is that you break up TCP/IP (or Ethernet) packets into 188-byte MPEG packets. This is how DOCSIS cable modems work. In the DOCSIS specification, the first four bytes of the MPEG packet format are retained, but the remaining 184 bytes can be used for anything. See Chapter 7 in the DOCSIS 2.0 specification.

http://www.cablelabs.com/wp-content/upl ... 090422.pdf

Ron

N2TOH
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Joined: Tue Aug 12, 2014 10:18 am

Re: DVB-S Transmitter

Post by N2TOH » Sat Aug 16, 2014 1:55 am

So my next question is who has written and tested code to read and decode signals from the catv companies?

f4exb
Posts: 7
Joined: Sat May 16, 2015 7:32 pm

Re: DVB-S Transmitter

Post by f4exb » Mon May 25, 2015 7:37 am

Hello,

the DVB-S transmiter is working like a charm. As an addition to the DVB toolbox I would like a DVB-S receiver. Are there any plans to build some or can it be built out just with the existing GNU radio blocks? I have searched the internet in vain for a DVB-S decoder GRC flowgraph. Has anyone already trying to do this and could help in building one?

Best regards.

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