[linux-dvb] MT2060 IF1 calculation

Patrick Boettcher patrick.boettcher at desy.de
Wed Dec 6 10:48:45 CET 2006


Hi Hartmut,

On Tue, 5 Dec 2006, Hartmut Hackmann wrote:
> I assume the MT2060 is similar to the MT2050. In this case, the IF center
> frequency is defined by the SAW filter on the board. The TDA10046 driver
> currently supports 2 "direct" IF frequencies: 36.125MHz and 36.1667MHz.
> IF you have a down converter like the tda9889, you can use either 5.1667MHz
> or 4.0, 4.5, 5.0MHz depending on the bandwidth.
> These can be chosen in the tda1004x_config structure. It is possible to add
> other frequencies, but yneed to extend some tables. The equations are in the
> datasheet.

The MT2060 is, afaik the MT2050, not similar at all. MT2050 is an in-can 
tuner whereas the MT2060 is a silicon tuner. The IF1 offset Chun Chung Lo 
is asking for is the offset for the first IF. This offset is to have a 
better alignment when the signal is at down-converted to the second IF 
(around 36 MHz).

You can find a calibration function in the reference driver from 
Microtune. You should have it, when you are working on a hw-ref-design.

A simple why to do is to try all offsets (after having the demod locked) 
and afterwards take the one where the demod gave you the highest C/N.

Patrick.



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