Interference in PAL TV

Kari

Hello

I have maid two breadboards according to "Propeller Demo Board Schematic".
They both work fine exept when i try to use video output.
I have changed tv mode setting to %0011 for PAL in TV_Terminal and TV_Text spins.
We have 230V/50Hz as AC wall output.

The image has interference as seen in attached images.
One is taken from a portable tv set and the other is from Terratec USB stick.
They both show darker vertical lines in blue bakground.

I wonder if anyone has same problem with PAL TV in 50Hz environment?

Maybe it is in my breadboards, which are carefully done with lots of bypass caps,
but i just want to be sure about the problem before i order any rady made test boards from Parallax.

Mike Green

Make sure tv_ht, tv_vt, tv_hx, and tv_vx are correct for PAL. The comments at the end of tv.spin discuss this.

I don't think that would explain the vertical bars though. There may some problem with ringing from the high speed switching of the video signal. I'm just guessing, but the Terratec USB stick may have a slower response, somewhat smoothing the video signal.

Kari

Hello Mike

I have changed TV_Text parameters to
cols = 50 '40
rows = 16 '13

which were recommended in some other post that i can't find just now.
Anyway, returning them to original did not solve the problem.
There still is 21 steady vertical bars in Terratec USB stick picture. In analog tv-monitor those bars wonder quite fast from right to left, which made me think that line frequency has something to do with this.

Clemens

I have the same effect on my Sony TV hooked to a propstick.
I thought there was something wrong with my resistor values, so I never posted this problem here.

deSilva

I encountered similar problems with all "cheap" monitors, made in Hong Kong, Japan, Korea (or elsewhere ), typically having 320 (or 480) x 234 pixels effective resolution.

It is generally a bad idea to run them in "interlaced" mode (as an unmodified TV_TEXT does)

They work much better in NTSC non-interlaced mode, best when exactly honouring their generic pixel counts...

I had no opportunity to connect my Hydra to a "standard" European PAL-TV set though....