DVBS2 code update

Well I finished writing the C++ DVB-S2 transmitter class today.
The final thing to do was to add the Gold code based symbol
scrambler. Next will be the difficult part, testing it!

It is interesting to note that S2 includes a 26 symbol preamble,
64 symbol modulation and code rate indication and the option of
sending pilot sequences in the transmission. This allows automatic
mode identification and enough information for a DFE (Decision
Feedback Equaliser) to be deployed in the receiver. Which makes it
suitable for channels with multipath.

The UHD driver for the Ettus USRPS has been upgraded, the main
improvement has been to further reduce the CPU load. I have not had
time to test it but a couple of releases ago the UHD load dropped
considerably, so much so that it became viable to transmit DVB-S using
my dual core Lenovo laptop.

I still have to get the 64 bit version of my DVB-T code to work. It will be
interesting to see whether I can get that to run on the laptop with the new
UHD.

S2-3600 and Linux

Well that was a waste of time! I can't get it to work with Fedora 13 64bit.

After compiling the drivers and loading them. The green light comes on
to say it is working. Tried to use Kaffeine, it found the device but that was it.
The IR remote works and the dvb-utils indicate the front end is locked to
a satellite and receiving but no video or sound and when Kaffeine is scanning
it detects no signal but it does seem to detect transponders.

Other people have managed to get it to work maybe they
are using 32 bit Linux or something.

Enough time wasted on this I think.

TechnoTrend S2-3600 DVB-S2 USB receiver

Well one of these arrived in the post this morning.
It is a USB based DVB-S2 receiver that uses the ST
chipset, one of the few chipsets that will decode DVB-S2
down to 2M Symbols/sec. Whether the BDA driver for it
supports that I don't know yet.

I have tried the unit under Windows7 with various DVB
receiving programs and it seems to work with them
However software decoding of MPEG4 leaves a lot to be
desired. Each program seemed to struggle in its own unique way.

I will have a go at running it on my Linux system in a couple of
days. I know that the chipset is supported as a PCI device.

On the transmit side of things I have done some more work on
DVB-S2. So far I have done the BB header encoding, CRC8,
required BCH codes, scrambler and the required
LDPC encoders for the different code rates. What I have still
to do is the modem layer for DVB-S2 and eventually for DVB-T2.
It is being done as a C++ class. I may migrate my DVB-S/T code
to a similar structure when I have the time.

For a test antenna I am going to install an Alford slot on one of the
"masts" at least I will be able to get out a signal while I figure out
how best to install the Yagi antennas. The Alford is coming from
Stuart G6NHG . I looked at making my own but I reckoned I would
end up spending more doing it that way.

Finally I notice that Ettus research are going to release a transceiver
board that will operate from 400 MHz to 4.4 GHz. That will give me access
to a couple more ATV bands. I better start saving!

Thats all for now.