[linux-dvb] Re: Problems with a DVB-T

[Holger Waechtler]

Ragnar Sundblad wrote:

I am struggling on with my DVB-T card.

I still have very bad reception. I have tried several tricks
with the antenna signal, for example I made a simple high
pass filter, and have gotten it to improve somewhat, but it is
still far from good or acceptable.

Any hints, tips or tricks are mostly welcome!

I now need some help from you tuner/frontent people out there.

The tuner is an ALPS TDLB7 without internal D/A and has a
pinout which is a mix of this: <http://www3.alps.co.jp/WebObjects/catalog.woa/HTML/BroadcastingComponent/T
errestrialTuner/TDL/TDL_E.HTML>
and this: <http://www.alps.co.kr/pdf/eng/01/eb0601c.pdf>
(it has the pins 16..19 as the Korean TDLB7 but the rest as
the Japanese one, and it is missing pins 20..32).

Question 1:
The module is supposed to get 9V and 32V, it gets 8.75V and
28.85V on those pins. How critical are those voltages?

These tolerances should be specified in the datasheet, not? Usually they are only about a few volts for the PLL charge pump voltage and a few 10th volts for all lower voltages.

Question 2:
The module is made for 470..862MHz. Could my problem be
that there are lower frequency signals in my RF feed that
interferes in the tuner? In other words: that the
first filter doesn't remove lower frequency signals
good enough (I think)?

Question 3:
Does anyone have any other good ideas on what to look for?

maybe you can improve things by playing with PLL and AGC register settings.

Question 4:
What is "AS" signal (pin 9)? I am just curious.

adress select. For some tuner modules you can change PLL and/or Demodulator i2c adress by toggling one adress bit on this line.

Holger



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