[linux-dvb] DVICO Dual Digital 2 - Chris Pascoe's Test branch

Trent Piepho xyzzy at speakeasy.org
Fri Apr 13 09:21:07 CEST 2007

On Fri, 13 Apr 2007, Luke Rosenthal wrote:
> > For SBS @ 536625000 Hz, before 536500000 Hz after 536666667 Hz
> Station is tuning properly on published frequency, so not going to muck
> around with it
> > For Nine @ 191625000 Hz, before 191500000 Hz after 191666667 Hz
> Ok, have some interesting info to report on this one:
> 191625000 gets lock, intermittently, and is unwatchable, signal around 37f7
> 191791667 won't lock, this is an old offset Chris suggested I think
> 191666667 locks, both frontends, gets good signal, will verify pic quality
> tonight.  signal 67ac.  snr c2c2.

191791667 would be for before my patch, when rounding was wrong.  That frequency will
tune one step too high, so it makes sense that it doesn't work.

I doesn't make any sense that 191625000 and 191666667 would have different
effects.  They both tune to the exact same value.

I think you are just seeing that tuning is for some reason unreliable.
It's like flipping one coin and getting heads and another coin and getting
tails and saying the first coins is always heads and second is always

Use a robust testing method.  Tune to 191625000 and measure the average snr
over 30 seconds, then tune to 191666667 and do the same, then 191625000
again and so on until you've done each one at least 10 times.  Then see if
there truly is a difference.

> > For Ten @ 219500000 Hz, before 219500000 Hz after same frequency
> Ok, still can't tune this frequency but I know the card is capable of
> doing it, as it worked prior to compiling last week from HG.  Need some
> other offsets to try.

I don't think it has anything to do with the frequency or offsets.

> Double checked it, yep, correct frequencies.  Have been using the same
> freq for this station all along.  Got any other ideas/offsets to try?
> Would it be possible to patch the driver to somehow log debug info to
> syslog or something?

Set debug to 1 for dvb-pll

modprobe dvb-pll debug=1

or add to /etc/modprobe.conf
options dvb-pll debug=1

or after the module is loaded
echo 1 > /sys/module/dvb_pll/parameters/debug

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