On the move again!

After a slight break from DATV, so I could revise for a maths exam
I am back. I started doing the maths for fun but things got a bit hectic
as the exam approached. Next year it is pure maths but whether I
will have the time to do that yet I don't know.

This week I bought a copy of "Advanced FPGA Design" by Steve Kilts.
I will post a mini review after I have read it. The book tries to show
you how to do FPGA designs rather than how to actually code (in Verilog).

I started doing some work on the FEC codes for DVB-S2 mainly building
the polynomial tables required for the BCH code (some have coefficients
to the order of 192). It is increasingly looks like the best way to implement
DVB-S2 and later DVB-T2 is in an FPGA.

I am also starting to get interested in the idea of using the DVB protocols for
transmitting blindingly fast computer data as well as for video. Probably
I will have to use DVB-S/T for the down channel and conventional packet
radio for the up channel in a similar way to how ADSL works.
Another idea would be a modified version of the PACSAT protocols. Just
using the slow return path to send fill requests for missing blocks.

I have an article appearing in the next issue of the TAPR PSR magazine
which will be available for download on the 1st of November. For those that
follow this blog there won't be anything new to read but I thought I should
try to spread the light of DATV to the unconverted.

DVB-S2

I have started to look at the DVB-S2 specification again.
After a bit of research, the new error correcting schemes
and format don't look too difficult to do. The draft spec
I have could do with some clarification but I think I have
figured most of it out now.

The main concern I have is that the majority of the receiver
chipsets available seem to have a minimum symbol rate of
10 M Symbols per sec. The only one that seems to be able to
operate at a lower rate is the 6899 set from ST.

10 M Symbols per sec looks like it will heavily load the Linux
box. So I am a bit concerned as to whether it will be possible.
I need to be able to operate at that rate so that I can verify
my implementation is correct using an off the shelf STB.

I understand that the idea is being mooted of transmitting
1 M Symbol per sec DVB-S2 from the ISS. This should not cause
a problem for my Linux / USRP2 system. However at those low
symbol rates it is probable that I will have to implement a
decoder as well. Most of the presentations I have seen on DATV
from the ISS are for DVB-S but I also hear rumours.