Request for improvement about Distortion Data display in Square Waves generation

[lorrain]

In square waves generation, the Distortion Data are not displayed in RTA. Some data are interesting like the frequency of the fundamental and the harmonics levels.
In particular, fundamental frequency which could be different from the entered frequency (a frequencemeter could be also a good idea in REW!).
In external generation, REW does not know what type of signal is present and the distortion data are accessible.
Why what is accessible externally is not internally!!

Eric

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[John Mulcahy]

The harmonics of a square wave are not distortion, they are components of the waveform. When using the internal generator REW only shows harmonic distortion levels when they are meaningful for the signal being generated.

 

[lorrain]

Thank you very much for your answer.
You are right. The information are interesting (fundamental frequency and harmonic levels) but it's inconvenient to put them in "Data distortion".

 

[trobbins]

Lorrain, is there a specific aspect of squarewave testing that you are interested in?

REW RTA will show the fundamental and harmonic frequencies of an external squarewave input when Show Distortion is selected - so there is a 'frequency meter' inherent within RTA '!!'

When using the internal squarewave generator then the exact frequency is shown as the 'Actual" frequency value, even though frequency selection is only available in ~ 1Hz increments (and selection resolution is 0.1Hz), as it looks like the generator aligns with an FFT optimised actual frequency that is not the exact selected frequency value.

 

[lorrain]

Thank you for your comment Trobins.
Nothing is missing in REW and I have no need that REW doesn't cover.
The reason for my comment:
I recently discovered that the frequencies emitted in square signal were not strictly identical to those entered and I tried to check by measuring frequency and in this case, REW does not allow it. REW has a frequency meter as you say but cannot measure the frequency of its square wave . I used another software for that.
It is not a need because as you said, we have the information "Actual frequency".
REW is so easy and pleasant to use that I wish to never need another software!

 

[trobbins]

I recently discovered that the frequencies emitted in square signal were not strictly identical to those entered and I tried to check by measuring frequency and in this case, REW does not allow it. REW has a frequency meter as you say but cannot measure the frequency of its square wave . I used another software for that.

I'm not sure I understand your comments above. Are you saying that you set a specific frequency for a squarewave in REW, and identified the generated squarewave frequency was not the same as your setting? Are you also saying that REW cannot measure the frequency of its squarewave?

 

[lorrain]

trobbins, sorry for my bad english. I understand welll how the square wave generator works (REW documentation is well done). I just wanted to check the frequency emitted for experimental or educational purposes and in this specific case (square wave), REW does not provide fundamental frequency in RTA but it is not a need because REW indicates this frequency (Actual frequency). I then discovered that the distortion parameters (with frequency fundamental in particular) was available for any external signal and I felt a little frustrated which causes my message to John.

 

[lorrain]

REW gives the fundamental frequency in « Show distortion » button which is not easy to find for a new user.
REW has so a very powerful frequency meter function (accuracy, stability, etc.) which is not highlighted.
REW could have a “Show frequency” button which gives the frequency of the fundamental and its level.
Other information could possibly be added such as the frequency/level of the main other spikes with a maximum of N.
Show frequency then become « Show frequencies ».
To avoid overloading the RTA window, “Show frequency” and “Show distortion” information could not be displayed simultanously. .
An exemple of representation with display depth of 4 measures (frequency/level).