BATC Forum

I am in the process of debugging an implementation of DVB-S2 for DATV-Express.
It is not working yet but I have figured out most of the spec now so I have high hopes.

Yesterday I bought a DVBSky S960 DVB-S/S2 USB dongle from someone on eBay.
This dongle supports 1 - 45 Ms/s and all the modulation modes QPSK, 8PSK, 16APSK
and 32APSK which a lot of the other dongles don't. I have had it running on
Windows 7 and 32 bit Linux (I can't get it to run on 64bit Linux). I have verified
it runs below 2 Ms/s (I tried 1.666 M), it comes in a nice metal box!
For windows I have been using dvbdream and for Linux Kaffeine.

So if you are looking for a DVB-S2 dongle you might consider it.
http://www.dvbsky.net/Products_S960.html

- Charles G4GUO

Well I am happy to report that I now have DVB-S2 working!
It has taken me about a week to eradicate the bugs.

I currently support QPSK,8PSK,16APSK,32APSK
for Normal frames (64800 bit frames). There are
many other modes for non broadcast use but I don't
have equipment to receive those.

With the 32 APSK you have to keep the transmitter turned
down or the constellation gets messed up.

Now there is the slight problem that a licence is required
to use DVB-S2 ($1) from http://www.s2licensing.com/

Here is a link to my blog with the proof

http://www.g4guo.blogspot.co.uk/

- Charles G4GUO

Congrats ! This is really amazing !

Concerning the licensing, I've heard that some projects avoided (or rather, tried to avoid) the licensing problems distributing only source code and no compiled forms, but that doesn't seem to solve anything anymore : http://www.ffii.org/Frequently%20Asked% ... e_Software

Maybe the FFII or the EFF (http://www.eff.org) could give you better advice about this issue.

73

Matthias
HB9EGM

It would be in S2 licensing's interest for us to release the software as
it has little commercial value (it can only run on a PC) and for every
transmit copy of the software there would be 1 or more licensed rx
copies bought as people upgrade their STBs to DVB-S2. As it would
be illegal to use the software without a wireless telegraphy license
the number of copies in use would be limited to a couple of thousand
at most. Whether they see it that way of course is another matter.

- Charles G4GUO

I recently found these two cards/dongles

http://www.tbsdtv.com/products/tbs6925- ... -card.html
http://www.tbsdtv.com/products/tbs5925- ... r-usb.html

These claim to go down to 200 ks/s and interestingly support some of the non
broadcast modes in DVB-S2 (i.e. other than CCM/Transport stream).

I don't have one of these devices so I have no idea of how well they work.

I have noticed that S2 is about to be extended, from what I can gather
a carrier id facility is being added as is 64APSK as well as more FEC
combinations. They are also adding more filter roll off factors. The other
thing they are working on is very wideband modes, something we wont
be needing!
I suspect it will be sometime before any consumer devices are available
to receive these new features. It will be interesting to see how they add
these features while maintaining backward compatibility as there
is very little room for expansion in the physical header which is used
to signal modulation and FEC settings, so I expect they will have to kludge
the thing.

- Charles G4GUO

Hi Charles, Those look interesting - if a little pricey. Have you seen anything similar
for DVB-T? I have heard there are people experimenting with low bandwith DVB-T
rather than the 6,7 and 8MHz in common use for broadcast.
If you have a look around there are receivers/transmitters sold for surveillance or broadcast use
that are for all intents and purpose DVB-T but taking some liberty with the broadcast spec - for example the
broadcasters favour a version which has a much lewer processing time - at the expense of compression efficency so
interviews with remote camera locations don't have a two or three second delay.
I do wonder if perhaps one of the many usb tv sticks around might lend itself to experimentation
by radio amateurs.

73. Ian.

Hello Ian,

Yes DVB-S dongles tend to be much more expensive than DVB-T ones and DVB-S2
even more so. Not many of the chipsets seem to go below 2 Ms/s especially ones
for DVB-S2. At least with PC dongles you can usually find out what chipset is
being used and from that what they are capable of. Getting the same information
for STBs is very difficult. That is why it would be nice for someone to keep a
registry of what box does what which would help people decide what to buy.

I am not aware of any DVB-T dongles that do narrow bandwidth. I have played
with 6 MHz DVB-T using an Elonics 4000 based DVB-T dongle as that will tune part
of the 1.3 GHz band. It is a shame that all these things are surrounded with NDAs
which makes it much more difficult to hack them. I did ask the chap demoing SR
systems kit with narrow band DVB-T but he wasn't aware of anything other than
the bespoke SR systems gear for reception.

I have been doing some 1 Ms/s DVB-S2 tests today using MPEG4 only across the shack
on 70 cms. Next I need to find someone else that can receive the stuff. For receive
I am using DVBDream running on an Atom PC with the DVBSky S960, it works
well on both MPEG2 and MPEG4 (certainly a lot better than Kaffeine does on my Linux box).

- Charles

Hello Charles,
Now that some Ham radio will send DATV with DVB-S2 mode I plan to upgrade future version of Tutioune to DVB-S2.
For Tutioune, I am also now working to implement the TT S2-1600 that allow blindscan and I have tested to be good down to 270 kS.
TT S2-1600 use STV0903+STV6110 chips
I have studied STB tuners cards last year and if I can remember, I have noted that ( in sept 2011):
TBS 6925 v1.x and v2.x use STV0900AAc or STV0900AAB ( = 2 x STV903 = double DVB-S/S2 demodulator)
TBS 5925 use STV0903
TBS 5980 = QBox-CI use STV0903 BAC
I don't know if last revisions of these cards have new version of chips.

Techno Trend TT s2-1600 use same chips and have same results, so I decided to add this card in Tutioune card-list.
the first difficulty : the complete documentation for these chips is under NDA.
Studying Linux implementation of this card will help.
I have now finished to test how to "speak" with them.
I can set the frequency and SR. It remains now to rewrite the different procedures and add them in Tutioune.
and last step : adding DVB-S2 possibilities.
I will test also if Blindscan can be a good tool to allow us not to have to give the SR. If it can be found quickly, we could receive anyone giving only the frequency.
for the moment I must give frequency and SR - (the SR search implementation of STB0899 exist but take ltlle time). fec and Pids and codec are found automatically, but if in future we could let our receiver on a frequency and receive any SR, any Pids, any fec and codec it will give us more easy use.

Jean Pierre F6DZP

Hi Jean Pierre,

That is good news, I look forward to the new software.
It is useful to know what cards do what. When looking at the
data sheet for the TT-S2-1600
http://www.tt-downloads.de/Update/engl/ ... 600_en.pdf
It seems that it only goes down to 2Ms/s but if I understand your post
it will in fact go lower than that. I notice that it can only handle QPSK and 8PSK
I suspect that may be adequate for Amateur use. However I quite like the APSK16
mode especially at 1 Ms/s but I have only tested that across the shack.
I am looking forward to actually working someone on DVB-S2 some day.

- Charles G4GUO

TechnoTrend specifications are not very accurate...

I really don't know real STV0903 specifications as long as I have not tried, but:
on a general specification page, I read :
"DVB-S2 profile implemented:
QPSK Yes
8PSK Yes
16APSK No
32APSK No
CCM Yes
VCM No
ACM No
normal Frame mode : 64800bits Yes
short Frame mode 16200 bits No"

but about some register setup, we can find several 16APSK and 32APSK modes and short Frame mode! :
If I read the Linux implementation of these card I can see that 16APSK and 32APSK are implemented in long frame mode and in short frame mode.

About SR values, for the STV0903, only maximum values are written. I have not seen anything about lowest SR admitted.
It is only about STV6110 that we can read "support 1 to 45 MS"
But I have tested it with TransEdit/DVBviewer + TT bda driver, it works very well at SR 270 kS
For the moment I have not tried with Tutioune as I have not finished the implementation of this ships.
They write "1MS" just to say that specification will give you sure that value, but in reality we can reach lower values.
I think we can obtain also better result than transEdit by programming ourself the chips ( lowering the masterclock...)
and looking at Linux sources we can see that they stop lowest SR admitted at 400 kS.
Windows Bda driver has no lowest SR limit.
Windows Saa7146a driver + STV0903_Tutioune_driver has no lowest SR limit.

so for the moment my tests give me:
old chip STB0899 ( inside TT s2-3200 card ) : lowest SR OK = 390kS
new STV0903 (inside TT S2-1600 card) : lowest SR OK = 270 kS

I have tried several times DATV DVB-S transmission of the HD moving test card (H264- 1920x1080p) at SR 460 kS and works well with Tutioune and TT S2-3200
( i have made demonstration of this transmission/ reception at the BATC convention)
i have uploaded this file here : http://www.batc.org.uk/forum/download/file.php?id=125



Jean Pierre F6DZP