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The waveform of PAL display on DM365

Omin Chou
Genius 3555 points

Dear all,

I use DVSDK_04.02.00.06 as my codebase on DM365EVM. I configure the PAL display through bootargs and switch SW5 to PAL mode.

=================================================================

Bootargs :

setenv bootargs console=ttyS0,115200n8 noinitrd rw ip=dhcp root=/dev/nfs nfsroot=10.1.31.38:/home/dm8168/dm365/filesystem,nolock mem=60M video=davincifb:vid0=OFF:vid1=OFF:osd0=720x576x16,4050K dm365_imp.oper_mode=0 davinci_capture.device_type=1 davinci_enc_mngr.ch0_output=COMPOSITE davinci_enc_mngr.ch0_mode=pal

=================================================================

But I measure the TVOUT waveform and compare with the standard pattern gen that can not get the same waveform. Please refer the below two pictures. Can anyone help me to explain this waveform is normal on PAL display? Thanks in advance.

B.R.

OC




  • 0
    Prodigy 10 points

    I assume you are asking why are the two waveforms different, in particular why the 4 MHz and 5.8 MHz 'bursts  appear degraded ?

    My  guess would be this is a result of filtering and D/A - A/D occuring, where the sampling frequency in too low and produces ALIAS products,  i.e. there isn't really any  4MHz, or 5.8MHz  in the reconstituted PAL output signal.