Filtering Digital data

[Mosio79]

 Hi,

Im using myRIO Encoder vI to read an incremental encoder data. I need to feed this data as an input to another device, but the problem is that the data is very noisy and it needs filtering. I tried some signal processing vi. s but usually got the error that I can't connect the output of Encoder VI to those filter VIs.

Does anybody have any suggestion on how to filter my encoder data? Thank you

[Bob_Schor]

To paraphrase (badly), "It all depends on what the meaning of 'noise' is."

An encoder gives you a digital code, which should be (nominally) 0 or +5 volts at any instant in time.  It should remain constant at that level until the encoder moves one "click", then all of the bits should change at the same time, resulting in another bit pattern.  

Nothing is ever ideal!  You could have voltages that fluctuate, so even if the encoder didn't move, the voltage might have "noise" on it that resulted in "flipping a bit".  It could be that when the bits change, they don't all change in synchrony, so you might read bit 4 "flipping" before bit 8, so instead of changing from 84 (hex, -4) to 00 (0), you might see the sequence 84, 04, 00 (-4, +4, 0).  Or you could have a combination of woes.

I'm not an engineer, so I don't know what the Standard Engineering Practices for dealing with this might involve, but I'm certain that "digital noise" is a well-studied phenomenon.  Have you tried the Web or colleagues who have an EE background?

Bob Schor

[Mosio79]

Thank you for your response, actually my question is how to apply a filter to a digital signal on labview. I tried some of the Vi but they didnt make any difference.

[paigec]

Hi Mosio79, how do you want your digital signals to be filtered, and which signal processing VIs have you already used? Additionally, depending on the version of LabVIEW you are using, you may have toolkits with more robust VIs available to work with.