Is it possible to output MEAS results with a large number of significant digits. For example, I need to calculate the frequency of oscillator oscillation with a frequency of 100 MHz and see this frequency to the nearest hertz.

Such a task occurs in a radio microphone.

I am an experienced LTspice user. Of course I tried to do it in Qspice as well. It didn’t work!

I would like to see a comment from M. Engelhardt about the usefulness of a such high precision.

Even if the representation of the floating point number can be attained in the SW (we’re discussing one part in one hundred million here), it would need to be ascertained the whole chain of calculations if the arrived at number after the algorithms had run and converged bring the result to the display accuracy.

Just my .01999999…

This might not be exactly what you want but try this:

Deselect “Fast (less accurate) Math:” if set.

This mode won’t allow you to select the digits of precision but may yield more precise results.

Len

I was modeling a radio microphone. I modulate it with a varicap. I made a calculation at three points of the low frequency signal. All three frequencies turned out to be the same. Using 80-bit arithmetic did not change the result.

RADIOMICROPHONE3.qsch (16.0 KB)

I cannot see a way to get more digit from .meas

.meas is a post-processing from QPOST.exe, it take the .qraw binary file for processing.

In Qspice, I don’t see any command line option of controlling the total number of significant digit. This possibly need to be a request direct to Mike.

The option has been implemented.

**10/30/2024 The HSPICE measdgt option is now honored.**

I have already successfully used this option in another oscillator circuit. And in my example of a radio microphone, the same period was obtained because the **Meas command did not perceive the TD** parameter correctly. Alas!