[linux-dvb] Re: My DVB-c patch (Re: The drivers and HTV)

[Dennis Noordsij <dennis.noordsij@wiral.com>]

Hi,

After some months of not much time, I've now been playing with the new 
firmware / drivers and VDR. As you know Jaakko we have the same cards and the 
same cable network :-)

> - Disables zigzag for everything except DVB-s.  This is from Metzler
>   driver.  Maybe someone with DVB-t needs it?  In that case change the
>   "!= FE_QPSK" to "== FE_QAM".

Disabled zigzag. For QAM_64, if I hit the exact frequency, it locks 
immediately. Picture is perfect, etc. But I have 2 cards, and if I let the 
frequency bending step in (i.e. offset the frequency by one stepsize, 
62.5kHz) locking for that card becomes more unreliable, it does better if it 
doesn't bend the frequency at all. So it's very touchy, if I step 62.5kHz 
away from the "right" frequency the results get much worse.


> - The IF of 35937500 might be better to be 36000000.  This might be

While using your IF.


> - Has anyone ever tested this auto inversion thing?  DVB-c is far too slow
>   to tune and lock for this auto inversion code to work.  Therefore you
>   need to manually set it.

I had inversion turned off with the reg0 |= 0x20 code in ves1820.c
(Your HTV channels.conf specifies inversion off for all channels, hope that 
was right :)


> - QAM registers have been tweaked to non-specification values.  I do not
>   know if someone has counterexamples, but this works for a lot of people.

Tried both your "100" for Reg1 but also "106", noticed not much difference.

For QAM_128 channels (or maybe it's the signal rate of 5900, or maybe the 
frequency, 283MHz and up compared to 162MHz for the working channels) I can't 
seem to get reliable lock-ons at all. Scanning down from advertised_frequency 
+ 10*stepsize to advertised_frequency - 10*stepsize, it does better closer to 
the advertised_frequency but never hits the sweet spot.

If and when it does lock, the block errors jump from 0 to 15 every few seconds 
or so, causing a very noticable glitch in the video.

But what should I play with to improve the results? ves1820 register values, 
PWM value, setup values ? Can it be caused by the tuner rather than the ves? 
etc.

Apart from my frontend troubles (never mind me :) the new driver/firmware 
seems otherwise perfect, OSD is perfect, a fantastic job by everyone !! 

Cheers,
Dennis



-- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe linux-dvb" as subject.