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Old Jul 31, 2003, 04:24 PM
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Joined Nov 2001
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It may very well be that the memory card problem calls Aiptek receives -or more specifically, the applications engineer I spoke with - comes from PNY card users. I did think about whether this problem would exist with any other memory card manufacturer but I did not think of it before I ended my call so I'll save the question for the next time I contact Aiptek.

Wow John, you brought forth some really interesting news there. I would never have thought about differences between memory cards and how they could affect image quality.

Memory circuits - much like any other electronic component - have variances in their electrical properties from die to die and lot to lot so even obtaining one data point may not be enough ascertain whether one memory card is optimum over another.

It does suggest that perhaps the primary differences between all of the inexpensive Digi-Cams and their image quality are also affected by system memory and not just the imager itself.

[This part is kinda long-winded]
Keep in mind that we are talking of a device that stores logic bit values and not an analog voltage that spans some range. As long as a bit's 'Logic High' or 'Logic Low' falls within specific parameters it is considered to be in that state. So the difference in image quality has to be caused by the imaging processor itself.

The conversion from an 'analog' value (from the CCD or CMOS array) is converted to a digital representation and if the reference for that conversion varies then so does the converted bitstreams values.

The only way the reference voltage could vary is by the main power supply rail. Now keep in mind the variance in electrical properties of one device vs. another and you may have Flash RAM chips that 'sink' more or less current than another comparable device. This in itself could be causing the supply rail to vary thus directly affecting the processors ability to convert analog data into a digital bitstream (worst case scenario here).

I could be entirely wrong here but based on my past experience in data acquisition that would be my first guess.

Anyone else out there with different SD cards care to add to Johns observation?

Roger

Edit: changed 'video processor' to 'imaging processor'.
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Last edited by Wild Moose; Aug 01, 2003 at 01:12 PM.
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