Moi Matthias
On 13.12.2013 09:02, Matthias Schwarzott wrote:
DVB-T: works with 8MHz BW channels in germany
DVB-C: works with QAM256
I didn't tested with a modulator, but only live signals. DVB-T seems to
work. DVB-C didn't find any channels. Symbol rate is 6875000 and both
QAM128 and QAM256 modulations. I suspect symbol rate... Symbol rate is
like a bandwidth in case of DVB-T (bw could be calculated easily from sr
just adding rolloff factor).
TODO:
- Extract firmware into file
Check from windows driver how it is there. There is many tricks to do
that, but I prefer hexdump.
hexdump -C WinDriver.sys | grep "AA BB CC"
hexdump -s 0x27588 -n 20000 -e '63/1 "%02x "' -e '"\n"' WinDriver.sys
After that implement extractor to get_dvb_firmware script.
- Verify lock is correctly detected
- Strength and Noise reporting
Statistics are not mandatory, you could implement later. Signal strength
is difficult task for demod. That could be done using RF and IF AGC
feedbacks, but it is still very rough estimate. AGC feedbacks are also
very much RF tuner dependent.
- Set correct bandwidth / qam parameters
That was likely reason DVB-C didn't worked :)
- what dvb-c standard is to be announced
Annex A is normal DVB-C, with 8 MHz BW.
There is also Annex B and C, another was 6 MHz BW and the other has a
little bit different rolloff factor. IIRC B is 6MHz and C is like A, but
different rolloff.
- Compiler warnings
yeah, tons of those. Kernel has also tool for checking style etc. issues
scripts/checkpatch.pl. You must use it too.
You have put all logic to single file. It looks like that chips has
integrated two physically rather separately demods, one for DVB-T and
one for DVB-C. If there is not much registers that are programmed just
similarly in both cases, please consider splitting DVB-C and DVB-T to
own files (and maybe one file for general stuff and select weather to
call T or C). Driver is even now quite big, almost 3000 LOC in that
single file.
regards
Antti
--
http://palosaari.fi/
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
