I'm working on a low light still camera project using low cost Sony ICX429AL interlaced CCD sensors.
Project architecture is : a PIC 16F877A (@20Mhz) for timing signals generation, double correlated sampling, 16 bits ADC, data download to a PC via USB.
In software I generate an acquisition sequence as follows :
- Sensor reset ( via a single PhiSUB pulse )
- Delay ( exposure )
- Odd field start sequence ( from ICX429 datasheet )
- Odd field download ( a loop of vert.shift and horiz.reg. read )
- Even field start sequence
- Even field download ( a loop of vert.shift and horiz.reg. read )
Camera works fine, but I have an important difference in ADU levels for odd and even fields. That generate a very annoying pattern of horizontal stripes ( sometimes called "Venetian blind" )
Even though a small amount of "venetian blind" seems to be normal for interlaced sensors, the amount i have is not normal. Gap between even and odd fields could be as high as 5000 ADU (in a 0-32767 scale).
I checked hardware and software sequences many times, and everything seems correct. So, I guess, I'm missing something very basic that I may give as granted, but that must be wrong.
Anyone with more experience could please give an advice ?
Don't be afraid to ask, if you need more details ( I'd like to get rid of this....!!! )
Regards,
Marco Paolilli Italy