Open source justMLS impedance analyzer

 
 
 
justMLS usage tutorial
justMLS is a function in LSPCAD. Binary Maximum Length Sequence (MLS) is also called Pseudo-Random Binary Sequence (PRBS). The sound card outputs a piece of random noise and samples it, and calculates the impedance of each frequency through the Fourier algorithm. Actually The test takes a short time and is effective.
 
First open the sound settings, disable all sound effects and gains of the speakers and microphones, turn the volume to about 80%,
 
connect the board to the computer with a pair of recording cables, start justMLS
 
and first move the switch to the calibration position (you can connect at this time Test load), at this time both sampling channels are connected to the same point, the software can calibrate the difference between the two channels,
click Test Level, and then adjust the computer volume output to ensure that the level bar in the upper left corner does not appear red before
 
clicking Measure, then click Z to enter the impedance measurement page as shown below, then click Settings to start impedance measurement calibration
and adjust the appropriate buffer size and MLS length (I have a computer where the buffer setting is too large and it will be abnormal, just appropriate. The length of the MLS should be as long as possible. The longer it is, the more accurate it is. It only takes two seconds at most). Click the sound card button under the test level to start calibration. Make sure that the frequency domain curve below is as straight as possible.
 
 
Then you can start measuring. Switch Switch to the measurement mode, re-enter the Z tab under the measurement tab, fill in the resistance value of the sampling resistor you are using, and click start. It is recommended to test a high-precision resistor first to calibrate the resistance value of the sampling resistor you fill in.