Recent content by John Mulcahy

You can do an impedance measurement then fit a component model to get an equivalent circuit. The graph will directly read dissipation factor values at the cursor frequency.

There are two things to consider. Firstly, the reference for IMD distortion figures. That varies depending on the test signal, for DIN and SMPTE IMD it is the level of f2, which is 12 dB lower than f1 and slightly lower again than the total stimulus rms level. The "fundamental" in the...

No, the noise floor measurements are very similar for me using the dBr axis and measuring using the current V5.40 build, using either generator or input as reference.

By "remove" I mean deselect.

That's not something REW controls. If you are using a WASAPI Exclusive Java entry there may be some other application that has taken exclusive access.

If you remove a measurement using the selectors on the left the number of entries in the legend changes. That may change the size of the graph, if it does the graph will be redrawn.

What about the configurable equaliser?

With the axis on dBu the figure could be used directly since your test signal is 0 dBu, but note that the SNR definition excludes harmonic distortion so the result would be worse than an SNR figure unless all the harmonics were below the noise floor. You can apply A weighting via the mic cal...

I wouldn't use a method that subtracted anything from the observed energy. REW is a little more conservative than it could be, I agree, and so can include more noise than it might. I'll look at that, but analog systems are often much less well behaved with broader distortion peaks and there...

REW's SNR figure is unweighted, and the N component excludes harmonic distortion. There is an A-weighted N+D figure that is the level of noise + all distortion but that is an absolute figure in the current graph Y axis units, not relative to the signal.

That's on the to-do list to look at for a future version.

If you are attempting to identify the noise floor then I'm afraid that becomes very problematic, since noise floors are rarely flat for real systems and can often include non-harmonic distortion contributions. It is similarly not appropriate to exclude harmonics that appear to lie within or...

That's great, well done. Not sure what you want from me, though.

If the system has a common clock for output and input and the tone is on a bin centre, as seems to be the case here, you could use a rectangular window to reduce the contribution of the noise floor for low level harmonics. In other cases the energy within the spreading span of the window should...

There was an update in V5.40 beta 101 to fix an issue with detecting the 8c on IPV4-only networks.