Need tool to show digital filter response

Hi

I am working on a digital filter, running in a Cortex M0

Currently, I think I will go with a biquad transposed form II

I need a tool to graph the transfer function

Could be just a Mathlab or Mathcad file or a dedicated program

Could also be something linking up to the CMSIS DSP Library, in a perfect world

Anyone got a good recommendation?

Cheers

Klaus

Reply to
Klaus Kragelund
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Not a 100% serious suggestion maybe, but you might do it in LT Spice. Integrators, summers, quantizers. Might wind up with the same transfer function as the digital version.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

Den onsdag den 14. februar 2018 kl. 00.16.18 UTC+1 skrev Klaus Kragelund:

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Reply to
Lasse Langwadt Christensen

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Does this support that?

Tim

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Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
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Reply to
Tim Williams

...

...

GNU Octave has it, too:

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mikko
Reply to
Mikko OH2HVJ

a scritto:

world

Try Scilab.

Bye Jack

Reply to
jack4747

Put in an impulse, FFT, gnuplot.

Jeroen Belleman

Reply to
Jeroen Belleman

I am doing it right now in Pspice, like the gentleman at this reference:

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But, that is the ideal case, so no quantization effects are included. And no easy way to shift between the different digital filter topologies

I was interested in knowing if a tool existed that had all the funny stuff included

Cheers

Klaus

Reply to
Klaus Kragelund

Very nice :-)

Reply to
Klaus Kragelund

The quantizer part is easy:

Version 4 SHEET 1 880 680 WIRE 48 48 0 48 WIRE 112 48 48 48 WIRE 384 48 320 48 WIRE 432 48 384 48 WIRE 0 96 0 48 WIRE 112 112 112 48 WIRE 320 112 320 48 WIRE 432 128 432 48 WIRE 0 224 0 176 WIRE 112 224 112 192 WIRE 320 240 320 192 WIRE 432 240 432 208 FLAG 0 224 0 FLAG 320 240 0 FLAG 112 224 0 FLAG 432 240 0 FLAG 48 48 X FLAG 384 48 OUT SYMBOL bv 320 96 R0 WINDOW 3 36 198 Left 2 SYMATTR Value V=int(5.1*V(X))*0.2 SYMATTR InstName B1 SYMBOL voltage 0 80 R0 WINDOW 3 16 199 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 1k 0 0 0 3) SYMATTR InstName V1 SYMBOL res 96 96 R0 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL res 416 112 R0 SYMATTR InstName R2 SYMATTR Value 1k TEXT 528 160 Left 2 !.tran 0 .005 0 1u TEXT 560 64 Left 2 ;Quantizer TEXT 568 112 Left 2 ;JL 2015

but Spice is probably better suited to model other topologies, like integrator-based IIR filters. A digital simulation of a biquad or state-variable filter can be very elegant and code/time economical, and tends to have sensible coefficients.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

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