[ltp] docking with DVI problem

[Joerg Bruehe]

Hi!


Martin Höfling wrote:
> [[...]]
> 
> hmm, I tried a Modeline Generator, it gives me a modeline with 176MHz. How is 
> this calculated?
> 
> I thought a resolution of 1600x1200@60 needs 1600*1200*60=115,2MHz

You forget the time of the gaps which a CRT needs to let the beam return 
to the left (x pixels) for the next row, and to the top (time of y 
lines) for the next picture. Sorry, I forgot the terms and values.
(In German TV, this is where "Videotext" is broadcast.)
So you have to change the formula to

   (1600 + x) * (1200 + y) * 60

Even though a TFT (probably) does not need them, these gaps are still in 
the specs for the signal. With a manually generated modeline, it _might_ 
be possible to reduce them, but this is just my speculation.

> 
> is it possible to go below 60 Hz to reach a valid dot clock?

AFAIK, typical TFTs may require 60 Hz - they have much less "multisync" 
capabilities than CRTs. However, this may depend on the model - check 
your TFT's manual / data.


Regards,
Jörg

-- 
Joerg Bruehe  - persoenliche Aeusserung / speaking only for himself
mailto:joerg.bruehe@web.de