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DVB-S Transmitter

Posted: Thu Apr 24, 2014 11:52 pm
by drmpeg
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

Re: DVB-S Transmitter

Posted: Wed Aug 13, 2014 6:59 pm
by N2TOH
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.

Re: DVB-S Transmitter

Posted: Wed Aug 13, 2014 8:21 pm
by drmpeg
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

Re: DVB-S Transmitter

Posted: Sat Aug 16, 2014 1:55 am
by N2TOH
So my next question is who has written and tested code to read and decode signals from the catv companies?

Re: DVB-S Transmitter

Posted: Mon May 25, 2015 7:37 am
by f4exb
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.