Ragnar Sundblad wrote:
--On den 1 januari 2003 14:36 +0100 Holger Waechtler
<[EMAIL PROTECTED]> wrote:
To recap:
Most importantly, I had to change the SP5659 tuner PLL charge
pump current from 0 (min, 120uA typ) to 3 (max, 1200uA typ).
That made it work somewhat reliably up to 730MHz, but starts
to fail at 754MHz.
You could also try smaller/wider frequency steps. This changes the
effective frequency offset the onchip AFC circuit has to compensate.
It works much more reliably with a doubled stepsize (now 333333Hz),
both getting-it-to-tune-wise, and also noice-wise, in the
706-778MHz span, so that is what I am currently using. It
seems like 166666Hz steps are needed in the UK, so
I guess it will have to continue to support those too.
The stepsize has nothing to do with the 166kHz offsets used in the UK.
I have now also discovered another phenomenon which I don't
understand:
With some combinations of step size and charge pump current,
the SP8870 can never lock on a channel when the tuner is retuned
from a higher frequency to a lower one. Going the other way
around always works.
The SP5659 says that it locks within a short time, that I am
also waiting out before SP8870 reset, a few loops of i2c poll
reads. I sadly can't really check that is doesn't lie to me,
but it takes longer with larger distances and the time to
lock is consistant with step size and charge current.
What I have do now is tuning the tuner a little bit below the
wanted channel, currently 8MHz, dwell there until the SP5659
says it has locked, tune upwards to the correct freq, and then
reset the SP8870 (as before). This seems to work reliably.
Could that be a problem with the PLL/tuner, or maybe the SP8870
that doesn't like seeing channels gliding in from below at
certain speeds or something? The SP8870 is, as previously,
partitially reset after a retuning.
I still find it very peculiar that my card doesn't work at all
with neither this driver, that at least 2 people use with
TT-DVB-T cards, same rev bought from the same place at about
the same time, without in my case changing the charge current
setting from min to max and changing the step size, nor does
it work with the supplied TT windows software.
Can this really be a reception problem, or is it more likely
that there is something wrong with my tuner and I should
have it replaced, instead of changing the driver to maybe not
work with all other Alps-TDLB7 cards out there?
Maybe, maybe neither the Technotrend boys nor the other people using
this card have any transmissions in these bands they could test.
Are there any other owners of this card out there listening?
What are your experiences, is it hard to get to tune?
I have a very old prototype board with a different PLL on a 3-wire
interface, so I can neither test+verify your results nor do much useful
on my own.
And remember to set all parameters the SP8870 can't find on its own, for
low frequency bands (e.g. band 5) you'll have to use 7MHz bandwidth. IIRC
the SP8870 can't probe this automatically.
I understand the manual as it can? I sadly can't test it anyway,
IIRC the spec was not correct in this point, but I'm not sure.
Could you please prepare + send a patch?
I will as soon as I feel a little sure about what I am doing.
fine.
Holger
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