# Frequency (speed) of linear scale

17 Sep 2021 07:27 #220863 by Jonas
I see that there are two types of linear scales. The glass and the magnetic.
Looking at the magnetic ones they specify a speed for example of 2 meters per second. And then there is also a max frequency that is 300 kHz.
I would think that the 300 kHz would limit a 5 um scale. For example if the balls screws are 5 mm per rotation and the scale is 5 um per step. Then there will be 5 mm / 5 um = 1000 steps per revolution of the stepper. I guess that is good since I see that rotation encoders that fit on the stepper axel can be 1000 steps per revolution as well.
But if there is 1000 steps per revolution and a max frequency of 300 kHz that would mean that stepper could only spin at max 300 rpm so that the linear scale could keep up.
The 2 meter seems like a mechanical limit then?

17 Sep 2021 13:21 - 17 Sep 2021 13:26 #220888 by Aciera
Those 300kHz is probably the maximum output frequency of one channel. Full resolution requires the receiver to combine both channels to a full quadrature signal

So really the 2m/s is the maximum axis speed your sensor can keep up with and the max. frequency is relevant for the receiving electronics.
That is how I would read that.
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Last edit: 17 Sep 2021 13:26 by Aciera.