LabVIEW
Implementation of 8th order filter on FPGA
Hi all,
I am trying to implement 8th order Butterworth filter on FPGA (cRIO-9048; LV2021). There is Butterworth filter vi available on FPGA, but it can only go up to 4th order.
Implementation on FPGA:
Butterworth Coefficient express vi generates coefficient array to send to FPGA. FPGA then use these coefficients to feed to Butterworth filer.vi
Implementation on RT:
Butterworth Filter.vi on RT uses Butterworth Coefficient.vi to get IIR filter Forward and Reverse fileted coefficients along with IIR order. Then feed these coefficients to IIT Filleter.
Implementing 8th order on FPGA:
I tested both RT and FPGA filtering for 4th order and results are exactly same. Now I am trying to implement 8th order on FPGA by cascading 2 4th order filters, but results are not the same.
FPGA implementation:
Observations:
1. RT 8th order Filtering results:
2. FPGA 8th order Filtering results:
Does anyone know relationship of IIR Filter coefficients calculated on RT with Coefficients used by FPGA filter vi? is there any way to calculate FPGA scaled coefficients from RT's IIR filter coefficient?
I would really appreciate help, if anyone worked on this before or have any suggestion how can i implement 8th order filter on FGPA.
