Testing Fransys's Accuracy

Introduction

To test Fransys's accuracy I measured the frequency response of RC and LR filters. First the frequency response was measured using an oscilloscope and function generator, then using Fransys. The results match closely.

Here is the circuit used in testing. The opamps serve as buffers to prevent errors due to the interaction of the sound card's impedance with the filter.

Test Circuit

Summary of results

Three filter configurations were used. The average error between the measurement using the oscilloscope and using Fransys was 0.14%. The greatest error in any single measurement was 1.94%, but it is important to note that this occurred at a low frequency (21.4 Hz) and I was using a sound card with fairly poor frequency response, especially at the lower frequencies. The results would likely be much better with a good sound card. The graphs below show that the results match very closely. The data match so well that it is hard to see the red line underneath the green line in the graphs.

Equipment used:

HP 54602B 150MHz digital oscilloscope (set to DC coupling)
HP 33120A function generator
Compaq Presario 5050 integrated sound card (for Fransys testing)

Detailed results

Filter Circuit 1
Circuit 1 Results

Filter Circuit 2
Circuit 2 Results

Filter Circuit 3
Circuit 3 Results

Download complete test data in Quattro Pro 7 format: testdata.zip (59 KB)

Comments and questions are welcome. E-mail address: contact delete-this-before-sending _AT_ vobarian.com (Obviously, delete the extraneous words and replace _AT_ with @. This is to reduce spam.)

Mountains & clouds at top of page (clouds.jpg) taken from photo by Oswald Skene / DHD Multimedia Gallery