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ADV7180 blockiness

Question asked by power-man on Jun 4, 2015
Latest reply on Jun 5, 2015 by GuenterL

When the end customer input monochrome image signal, there was a blockiness from ADV7180.

The error could be found 1 month later after operation. All 22 sets occurred same issue at same timing.

 

Device     ADV7180BCPZ

Mode     NTSC-J Fixed mode

Input waveform

     No burst signal because of monochrome image

     There are some distortion of a waveform like a V-sag or H-sag. The distortion is between 50mV and 100mV                   

     Sink signal is weaken around 20IRE.

     Sometimes the signal is over 100IRE.

 

Then the customer has some question.

 

Q1 What do you think the root cause about blocking the image?

 

Q2 Are V-sag or low level sink signal or high brightness signal the reason for blockiness?

 

Q3 Is burst signal needed?

 

Q4 What ADV9170 output Cr and Cb with BT.656?

 

I have the circuit schematic. But I couldn't share at here.

 

Regards,

Shumpei

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