Wednesday, 16 June 2010


I spent some time today looking at LDPC
"Low Density Parity Check" codes. These are
the codes used in DVB-S2 and DVB-T2. I
think I understand the concept of them now.
To work well the messages have to be very
long, in DVB-S2 they are 64800 bits long.
Their performance is similar to Turbo codes
(which I played with over the new year) but
they have some advantages and in certain
instances can exceed the performance of
Turbo codes, also they are not littered with

I took the FPGA development board I bought
a while ago out of its box and looked at it.
I have written a couple of FPGA programs
but nothing major.

Apart from that I have been installing various
versions of Gnuradio to try and get to the
bottom of the missing 6dB.

Oh yes, I put another shelf in my 19 inch rack
to house the 2nd STB. I am after some DVB
stickers to go on the outside of the rack to make
it look like a real DTV sender. Maybe I will
make up a label using my labelling machine
that says "DTV Sender A"

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