Video Decoder( ADV7282A) outputting noise instead of Blue screen

Hi ,

The ADV7282A does not provide an equivalent gain adjustment option to that available in the ADV7842.

For gain adjustment on the ADV7282A, please refer to the Gain operation/ Filter section in the ADV728x Hardware Reference Manual (UG-637), which describes the luma and chroma gain control registers and their operation.

Reference:
https://www.analog.com/media/en/technical-documentation/user-guides/adv7280_7281_7282_7283_ug-637.pdf

Thanks,

Ebin

Hi ADI Engineer Team , 

//For gain adjustment on the ADV7282A, please refer to the Gain operation/ Filter section in the ADV728x Hardware //Reference Manual (UG-637), which describes the luma and chroma gain control registers and their operation.

I think this your suggestion and response would not improve our our problem , please find the illustration below 

We think the problem is not from Gain operation/ Filter section , we assume problem should be from sync extraction and something else  .   

Let me explain our encountered  problem again 

We are using the ADV7282A to decode an analog CVBS video stream from an FPV drone wireless receiver. The digital video is outputted via an 8-bit parallel ITU-R BT.656 interface to our backend SoC.

In our application, when the drone flies far away, the CVBS signal experiences severe static noise (snow noise) and low SNR. We noticed that a standard monitor can still show the noisy image with OSD data, but the ADV7282A frequently unstable EAV/SAV outputs to backend SoC (as shown in our attached illustrations below , left side is our benchmark , right side is using ADV7282A monitor ). This frequent switching severely disrupts the BT.656 EAV/SAV timing sequence, causing synchronization issues on our backend SoC.

Our goal: We want the ADV7282A can keep stable BT.656 EAV/SAV as much as possbile . We prefer the decoder to output pure snow/noise rather than blanking out the video stream ,keeping the BT.656 sync codes continuous.

#1  Left side : Benchmark monitor, Right side: Using ADV7282A monitor

 ADV7282A monitor is kept to display noisy image ----> Okay 

#2  ADV7282A outputs unstable to our backend SoC and then leads to black screen   --> NG 

Current key setting as below :
//DEF_VAL_AUTO_EN set to 0
//VID_SEL[3:0] set to NTSC

This problem has been troubling us for a while,we hope ADI team can give us specific recommendations as soon as you can so that we can try to see if any improvement . 

Hi ADI Engineer Team , 

//For gain adjustment on the ADV7282A, please refer to the Gain operation/ Filter section in the ADV728x Hardware //Reference Manual (UG-637), which describes the luma and chroma gain control registers and their operation.

I think this your suggestion and response would not improve our our problem , please find the illustration below 

We think the problem is not from Gain operation/ Filter section , we assume problem should be from sync extraction and something else  .   

Let me explain our encountered  problem again 

We are using the ADV7282A to decode an analog CVBS video stream from an FPV drone wireless receiver. The digital video is outputted via an 8-bit parallel ITU-R BT.656 interface to our backend SoC.

In our application, when the drone flies far away, the CVBS signal experiences severe static noise (snow noise) and low SNR. We noticed that a standard monitor can still show the noisy image with OSD data, but the ADV7282A frequently unstable EAV/SAV outputs to backend SoC (as shown in our attached illustrations below , left side is our benchmark , right side is using ADV7282A monitor ). This frequent switching severely disrupts the BT.656 EAV/SAV timing sequence, causing synchronization issues on our backend SoC.

Our goal: We want the ADV7282A can keep stable BT.656 EAV/SAV as much as possbile . We prefer the decoder to output pure snow/noise rather than blanking out the video stream ,keeping the BT.656 sync codes continuous.

#1  Left side : Benchmark monitor, Right side: Using ADV7282A monitor

 ADV7282A monitor is kept to display noisy image ----> Okay 

#2  ADV7282A outputs unstable to our backend SoC and then leads to black screen   --> NG 

Current key setting as below :
//DEF_VAL_AUTO_EN set to 0
//VID_SEL[3:0] set to NTSC

This problem has been troubling us for a while,we hope ADI team can give us specific recommendations as soon as you can so that we can try to see if any improvement .