C
colin
- Jan 1, 1970
- 0
Im measuring the time difference between two signals from two opto encoders
basicaly on the same shaft, at the moment ive got down to a peak at 15ps.
averaged over a few days, but I assume this is still mostly noise.
I need to get down to a noise floor of 0.1ps. although im only running at
1krpm I hope to run at 10krpm,
but need to do some balancing and some more noise insulating.
if only I could run at 100krpm but my mech engineering abilites are a bit
limited.
this should give 1/10 the error for the same mechanical error,
although the vibration might not help much,
but the increased number of samples helps reduce the noise by averaging.
I also need to look at different bearings again.
remagnetizing the motor rotor with a sinewave instead of squarewave pattern
helped a fair bit.
and using an accelerometer to get it level to within 500ug helped too.
although it tends to wander off being level througout the day,
maybe I need to set it up in an optics lab or something but that is unlikly,
a better table would help that wasnt on wooden floorboards,
but not sure what I can do about that.
Colin =^.^=
basicaly on the same shaft, at the moment ive got down to a peak at 15ps.
averaged over a few days, but I assume this is still mostly noise.
I need to get down to a noise floor of 0.1ps. although im only running at
1krpm I hope to run at 10krpm,
but need to do some balancing and some more noise insulating.
if only I could run at 100krpm but my mech engineering abilites are a bit
limited.
this should give 1/10 the error for the same mechanical error,
although the vibration might not help much,
but the increased number of samples helps reduce the noise by averaging.
I also need to look at different bearings again.
remagnetizing the motor rotor with a sinewave instead of squarewave pattern
helped a fair bit.
and using an accelerometer to get it level to within 500ug helped too.
although it tends to wander off being level througout the day,
maybe I need to set it up in an optics lab or something but that is unlikly,
a better table would help that wasnt on wooden floorboards,
but not sure what I can do about that.
Colin =^.^=