Select proper filter

[UniSA]

I need to measure 3Pahse AC Sine signals, the acquired signal contains quite a few noises from the inverter and the testing environment. I don't know which low pass filter is best suitable for this application. Thanks in advance.

[Jesse_O]

Hello,

There are several different ways you could filter your signal.  To start do you want to perform Digital or Hardware filtering?  Although digital filter can be performed in software and works well in many cases, if you have a lot of noise that is aliased into your signal when you sample the signal this cannot be removed with digital filtering.  If you need to make sure aliasing of the noise does not occur, you will need a hardware filter.  Perhaps an SCC-68 and a SCC-LP would work for you.  If you would prefer to perform software filtering there are two main classes of filter FIR and IIR.

There are advantages to FIR filters such as a constant phase delay for all frequencies (linear phase response).  IIR filters do not have this advantage, however they require less taps to achieve the same level of attenuation.  There is a table here that goes over some of the steps you can take to pick a digital filter.  I hope this helps get you started.

Regards,

Jesse O.
Applications Engineering
National Instruments