DC Amplitude

[engcad]

Hi 

I use labview and mydaq board to read force from load cell and signal conditioner. to stabilize the reading I use a moving average filter, it works well but the problem that the signal amplitude level jump in about 2-3 mv as shown in the attached picture 

is there a filter or idea that let me stabilize the level

thanks

[crossrulz]

Thers's not much you can do about those sudden jumps.  A moving average is a good way to take care of this issue.  Something you might want to try is to use less samples in your moving average.

[johnsold]

Are you certain that this is not a real measurement of something which is happening in your mechanical system? The signal seems quite stable within each segment.  Try replacing the load cell with a fixed resistor bridge to see if the jumps occur.  That will isolate load cell/mechanical system effects from DAQ system effects.

A better approach than a moving average (or in addition to it) might be to identify the jumps and process the data on either side of the jump separately.  When you start the moving average, initialize it with the first value in the segment rather than zero.  There is still a transient effect but it would likely be so small as to be nearly unnoticeable.  Consider that the first element in the image you posted is ~1/4 mV above the mean for the first segment.  If the moving average had been initialized to that value, no output from it would have been outside the peak to peak noise over the first 0.09 X-axis units.  The jumps are bigger than the peak to peak noise so they should be fairly easy to detect.

Lynn