Filter coefficients in SignalExpress

[JeffryesBP]

Hi,

I have data acquired using SignalExpress which has been low-pass filtered using the built-in FIR filters and then downsampled.

I need to compensate for the low-pass filters in the downsampled data - but cannot find anywhere how to either find the coefficients, or the design procedure that was used (the only inputs are cut-off frequency and number of coefficients) that would enable me to replicate it.

Can anyone help me with finding the coefficients ? 

(In this case I have a 43 element FIR filter, with cut-off of 0.05 of Nyquist).

Ben Jeffryes

[AmyNK]

Hi Ben,

It seems that the info isn’t readily available, and you can’t dig around much in SignalExpress because it’s designed to be an easy to use, non programming environment, so it’s hard to find this in depth information sometimes.

What you can do is export your SignalExpress project to LabVIEW and dig around in LabVIEW for the coefficients. Do you have acces to LabVIEW?

Here are the steps to find the information I think you’re looking for:

1. In SignalExpress, click Tools >> Generate Code >> LabVIEW Diagram, open this

2. Open the Filter express VI

3. Open the Digital FIR Filter subVI

4. Open the Design FIR Filter subVI

The indicator labelled Forward Coefficients I would imagine would give you this information.

It seems quite tricky to find this out, what do you need the information for? If you don’t have access to LabVIEW, you can download a free evaluation trial from ni.com/download-labview.

I hope this helps, sorry there’s not a simple answer to this!

Amy