On Sun, Oct 15, 2006 at 10:08:32AM -0400, graywolf wrote: > The sensor output is an analog voltage. The ADC converts that to a > digital number. What is being said here is that they do not feel the max > output voltage from the sensor is high enough to require a 22 bit ADC. > As I said in another post I feel that is way over simplified.
No - it's nothing to do with max output voltage. To measure the voltage output from the sensor to a *precision* (not maximum value) of 22 bits mean's you are claiming to be able to measure a voltage change a couple of orders of magnitude smaller than would be produced by one electron more or less in the sensor well. At these levels the voltage isn't "analog" in the sense that you understand the word, with a nice smooth continuous curve going from empty to full - it goes up in steps. In fact the illustrative graphs that were posted earlier are a good illustration of what I mean (albeit perhaps not quite the way the original writer intended them to be used :-). The nice smooth continuous curve is an illustration of what you could measure with a 22-bit processing system; the red dots show the levels you would actually measure in the real world. Fitting that nice smooth 22-bit curve to the sampled data points is inventing data that doesn't really exist. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
