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© 1988-2002 J.Paul Robinson,
Purdue University Cytometry Laboratories
BMS 602 LECTURE 9.PPT
Where is the inaccuracy?
•Consider the 14 bit data (16,384 channels)
•The smallest signal on a 0-10volt scale will be 610 uV
per channel
•Thus a 1 channel change produces a value of 1220 uV
or 100% possible error at the low end – since the bottom 10mV of
this scale is represented by
channels 1-16, the voltage at channel 16 is 9765 mV or at ch# 15 is 9765 uV or an error of about 6%
•This is an unacceptable high error at the low end so we
must try to digitize at a
higher bit rate say for example 16 bits (65, 536)
•Now the same range as above a 1mV signal will appear in
ch# 7 and a 10 mV signal in
Ch# 65 giving an error of 6% at the bottom
end and only 2% at the top end
