Rick314

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  1. I am getting significantly different results with the attached .dwf3work file that was created using WaveForms v3.9.1 and is now being used with v3.10.9. The 3 images below are: Version 3.9.1 results. Open the .dwf3work file in WaveForms 3.10.9. Turn on the Factor window to see Quality and Dissipation. Adjust window size and position. So far things look good and the results from the previous v3.9.1 measurement are shown as expected. Run the Impedance measurement in v3.10.9. There are several differences in the v3.10.9 results. Perhaps these come from a common problem, but what is wrong? The Input window trace changed from attenuation (0 to +27 dB) to something I don't understand with values from +60 to -30 dB. (I had to re-scale to get these values.) In the Impedance window, the Rs results changed dramatically. In the Admittance window, the Gp results changed dramatically. In the Factor window, Quality and Dissipation results changed dramatically. In the Nyquist pane, the results changed dramatically. (Edit added after posting: This is using an Electronics Explorer board, measuring a series 1 kohm resistor and shunt 250 nF ceramic capacitor.) 190324_Impedance.dwf3work
  2. I just upgraded WaveForms 3.9.1 to 3.10.9 (both official supported releases), loaded the attached .dfw3work file, and see that a setting has changed. Fortunately I saved an image from 3.9.1 before the upgrade. Notice that the spectrum analyzer Magnitude setting changed from "dBV, Top 0, Bottom -80" to "dBV<tilda>, Top 0, Bottom 10". It is fine that the units were clarified from V (Volts) to V<tilda> (Volts RMS), but the Bottom value changed too. The workaround is easy once the problem is recognized -- Just re-set the desired value and re-save the workspace file. But this makes all version 3.9.1 .dfw3work files that use this common spectrum analyzer setting fail when opened with 3.10.9. More importantly this brings Digilent's pre-release regression testing of WaveForms into question. What other incompatibilities exist between workspace files created with old WaveForms versions and the recently-released version 3.10.9? 190313_FM_Bessel_Null_workaround.dwf3work
  3. See the images and .dfw3work file. After saving and re-opening this workspace, the SinePower, Power, low limit and current value settings change from their prior values. (Less important is that the AWG window has re-sized, with the waveform wider and the settings narrower.) [Edit after original post: If it matters, this is using an Electronics Explorer board with AWG1 connected to the Scope channel 1 DC input.] 190410_SinePower.dwf3work
  4. Thank you again for your help @attila and I understand the +/- issue now.
  5. Thank you @attila. I mentioned 4 problems and understand "The quick measure and toolbar save/load is corrected for the next version." But I want to discuss the other two more. The windows are resized. You replied "The windows are loaded with WF v3.9.1 from your project like this" and showed a picture. We get different results. When I load the .dwf3work file I uploaded, I get my posted image with the resized windows every time. Let's dig deeper. I am using WaveForms "Version: 3.9.1 64-bit Qt5.6.3 Windows 7" on a Windows 7 PC with all current updates provided by MicroSoft. This is a supported platform for WaveForms. Are you able to replicate the window-resizing defect with that release and platform? 4/7/19 edit to my original 4/5/19 post: The window resizing is related to "Settings, Options, Instruments windows". I have this set to "Docking" both before saving and after re-opening the .dwf3work file. If that setting is changed to Separate or Tabbed before re-opening the .dwf3work file the window sizes appear correctly. (So this provides a workaround to the defect. But saving and re-opening with the Docking setting still looks like a defect that should be replicated and fixed.) Re-opening the .dwf3work file with the "MDI" setting appears very odd and then changes when the resulting pan is moved. The final Time window plots are gone (but all other plots remain). You replied "The time data is not saved in Spectrum, Network and Impedance Analyzers. This plot is only intended to debug the analysis steps, to see the signal margins, distortions..." This seems to say "it is intended to work that way" but I am trying to say it should not work that way. Why? The Time window is just a Scope trace and Scope traces are saved in the workspace file. So customers (like me) expect the same feature in Impedance, Spectrum and Network. In the Impedance tool saving the Time window data is just as useful as saving the other 9 plots displayed. I want it for showing my students a complete set of measurement results after opening the .dwf3work file in the classroom without an EE board and then changing the plot parameters to display/hide and re-scale various windows. So saving the Time window data makes sense for both consistency and functional reasons.
  6. Thank you @attila but I am not trying to get better results or workarounds to problems. I am trying to submit what appear to be WaveForms software defects. I have tried to re-word them more directly. Feel free to correct me if something I am saying here seems wrong. A user interface defect: When the negative sign is removed from a measured value for any reason, the plot label of the value should be "|Parameter|" (magnitude of Parameter), not just "Parameter". So in my example, the Impedance window button label should be "|Xs|", not "Xs". This same principle applies to all situations where negative values are plotted as positive. A plot error: At 20 Hz, the value of Rs is +2.5 kohm, but the Nyquist plot reports it as -2.5 kohm. The Nyquist plot is incorrect. A plot error: The Inductance plot shows large negative values such as "-200 Henries". Resistance, Inductance and Capacitance values should always be positive. If this isn't the case then it should be explained in the Impedance tool documentation what negative values for these model components means.
  7. See the images for what WaveForms 3.9.1 looks like before "Workspace, Save" and after "Workspace, Open". I included the .dwf3work file to hopefully help replicate the problems. I am guessing fixing these will fix similar problems in other Graphical User Interface (GUI) setups. The windows are resized. The Impedance, Capacitance and Admittance windows have their "Quick Measure: Free" cursors turned on. The right "trace toolbar" is expanded. The final Time window plots are gone (but all other plots remain). 190324_Impedance.dwf3work
  8. I am trying to understand all the plots shown in the Waveforms Impedance measurement below. It was made on an Electronics Explorer board, AWG1 to a 1 kohm resistor to a 245 nF capacitor to GND. Scope1 is on the AWG1 output and Scope2 is on the R-C connection. I am measuring a 245 nF capacitor by sweeping from 20 Hz to 20 kHz. (The capacitor is actually four 0.1 uF ceramic caps in parallel that total a measured 245 nF.) Notice on the Impedance plot at 20 Hz that Rs = 2.5 kohm and Xs = |Z| = 30 kohm (the two plots are on top of each other). Notice on the Nyquist plot at 20 Hz that (Rs, Xs) is indicated as (-2.5k, -30k). I think that since Xs is capacitive reactance it makes sense it has a negative sign. But then shouldn't the Impedance plot say "|Xs|" (magnitude of Xs) as the plot label instead of "Xs" to indicate that the plot is always positive? Shouldn't the Nyquist plot indicate Rs as +2.5 kohm (in quadrant 4) instead of -2.5 kohm (in quadrant 3)? Why does the Inductance plot indicate negative hundreds of Henrys?
  9. Is this a defect with Electronics Explorer and WaveForms 3.9.1 or am I misunderstanding something? The image shows my Supplies setup. All 3 Power measurements are manually scaled 0W to 10W. The 2 Vmtr measurements are manually scaled -10V to 10V. Save the workspace (also attached). Then Re-Open it (without saving again when asked if you want to). The Power measurements are re-scaled to -10W to 10W instead of keeping their desired settings. 190323_Supplies.dwf3work
  10. Thank you for your help @attila but I do not think I am being understood correctly. I see that your left image has changed from the bottom image in my original post. I understand that grayed-out settings don't apply currently. That isn't the problem. I don't think replacing grayed-out "1 V" with grayed-out "1 V(+squiggle)" is needed. My confusion was that I thought your left and right images describe the exact same situation: dB relative to 1 Volt RMS. I mentioned Hewlett-Packard, Agilent Technologies, and Tektronix spectrum analyzers. I don't think any of them display dB relative to 1 Volt Peak in any circumstance. That is where my confusion came from. But I now understand that the WaveForms user interface uses "1 V" to mean 1 Volt Peak and "1 V(+squiggle)" to mean 1 Volt RMS. Correct me if this is wrong. But if this is the case, your left-image "Units: dBV" should change to "Units: dBV(+squiggle)" because they mean dB relative to 1 Volt RMS. This should be applied consistently everywhere "V" appears as a unit. Also, in the list of Magnitude Units, choosing "dB" only allows setting numeric Reference values in Volts Peak. It makes equal sense to allow a numeric Reference value in Volts RMS and that can't be done. (I was the firmware project leader on the HP 8920A RF Test Set with multiple RF/audio generation/analysis instruments in it, similar to the Electronics Explorer board. It had to address similar user interface issues with Volts Peak, Peak-to-Peak, Average, RMS, dB, %, dBV, dBuV, W, dBW, dBm, dBc, etc.)
  11. @attila said 'The dBV "standard" is relative to 1Vrms, 1.41Vpeak, 2.83Vpk2pk.' I agree the spectrum analyzers I know (Hewlett-Packard, Agilent Technologies, Tektronix) do this, so "dBV" meaning dB relative to 1 Vrms makes sense. But making "dBV" and "dB" "Reference: 1 V" have different meanings in your user interface seems wrong. The abbreviation "dBV" means "dB relative to 1 Volt" and "dB" "Reference: 1 V" looks like exactly the same thing. Are you aware of any mainstream spectrum analyzers that interpret "dB" "Reference: 1 V" as meaning dB relative to 1 Vpk instead of dB relative to 1 Vrms?
  12. It appears that the Electronics Explorer Spectrum Analyzer amplitude display shows "dB relative to 1V" as relative to 1 Volt peak, but "dBV" as relative to 1 Volt RMS. Shouldn't they both be relative to 1 Volt peak? See the two images. A 1 Vpk sine wave is being displayed on the spectrum analyzer. In one case, the top of the spectrum analyzer corresponds to "dB relative to 1V" and as expected the signal comes to the top of the image. So this is dB relative to 1 Vpk. In the other image the top of the spectrum analyzer corresponds to "0 dBV" and the indicated signal drops by 3 dB. So this is dB relative to 1 Vrms. (I found this by expecting a "1V" AWG level setting to correspond to "0 dBV" on the spectrum analyzer, and finding the unexpected -3 dB shift.)
  13. So let me clarify for other readers -- Everything in reply to my original 2/4/19 issue regarding the Electronics Explorer spectrum analyzer is unrelated to the root problem. It is instead a defect with the Electronics Explorer arbitrary waveform generator (AWG) that is generating the FM modulation signal. I tried what @attila suggested and the workaround works as shown below. Compare the following image to the image in my original post. Now the FM Bessel null (delta_f/f_mod = 2.405) correctly happens at an Electronics Explorer FM Index setting of 19.25%, derived by solving delta_f/f_mod = x*f_carrier/f_mod = x*12340/987.6 = 2.405, for x = 19.25%.
  14. @attila: I am still interested in getting my February 25 questions answered if you are able to help. In that post I also described what appears to be a misunderstanding on your part regarding the spectrum of an FM modulated signal. I think correcting that understanding will lead to other corrections in what you contributed to this topic.
  15. Thank you @attila, especially for the National Instruments "Understanding FFTs and Windowing" paper. It was very helpful. I still have the following related questions and issues. Given an AWG FM signal of 12.34 kHz carrier frequency, 987.6 Hz modulation frequency, and 19.25% "Index" (+/- 2.375 kHz deviation, or a Modulation Index of 2.375/987.6 = 2.405), how can I configure the Spectrum Analyzer to most accurately indicate the first Bessel null, where the carrier level is at a minimum? I know it won't be exactly the null, but what settings come closest? You show spectrum analyzer images and mention their corresponding FFT capture periods. Where in the Waveforms user interface or online Reference manual is it described what FFT capture period, windowing function, etc. result from given spectrum analyzer center frequency and span settings? In your February 12 post, you say "If you look at the frequency measurement which is performed progressively you see ~9kHz/~11kHz, but the FFT shows wrongly much wider spectrum." I believe this is an error in your interpretation and that the spectrum image is correct. It shows a 10 kHz carrier, 1 kHz modulation rate, and 10% (1 kHz) FM deviation. This is a modulation index of delta_f/f_mod = 1/1 = 1. Bessel functions say that the level of the FM carrier and side-bands 1 through 5 in this situation should be -2, -7, -19, -34, -54, -74 dBc (dB relative to the un-modulated carrier) respectively. Within the resolution of the image, this is just what it is being displayed.