In a message dated 11/01/2008, ian@........... writes:

I note that the ADC board uses the computer supply lines. These can be  quite 
noisy. What noise do you generally see with the input line to  earth?

I just did a very crude noise test: I unplugged the output of  the filter 
(which is the input to the A/D in the PC) and shorted it.  So,  with a 1 metre 
cable attached I got mostly +/- 1 LSB and sometimes +/- 2  LSBs.  I think that's 
pretty good,  considering.



Hi Ian,
 
    This sounds about average to me. It would be a lot  better if you could 
take 16 samples and average them to give maybe +/-1/2 lsb.  Cutting your 
dynamic range by x4 is better avoided.
 
    Regards,
 
    Chris Chapman



   






In a message dated 11/01/2008, ian@........... writes:
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    I note that the ADC board uses the computer supply lines. These can=
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  quite noisy. What noise do you generally see with the input line to=20
  earth?

I just did a very crude noise test: I unplugged the output o=
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  the filter (which is the input to the A/D in the PC) and shorted it. =
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  with a 1 metre cable attached I got mostly +/- 1 LSB and sometimes +/- 2=20
  LSBs.  I think that's pretty good,=20
considering.


Hi Ian,
 
    This sounds about average to me. It would be a=20=
lot=20
better if you could take 16 samples and average them to give maybe +/-1/2 ls=
b.=20
Cutting your dynamic range by x4 is better avoided.
 
    Regards,
 
    Chris Chapman