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| Rohde & Schwarz CMU200 |
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| RBBVNL9:
--- Quote ---CMU200 as a spectrum analyzer would be the best video to do :-+ --- End quote --- --- Quote ---don't forget the use of freeres as a tracking generator. --- End quote --- Upon request, I now made a YouTube video on using the Rohde & Schwarz CMU200 as a Spectrum Analyzer. Actually, I made two: one as a stand-alone device and one when the CMU is used together with other software (FreRes and VMA). In the video's I basically ask the question: "Is the CMU200 worth turning to, even if it is some 20 years old?". To do so, I put it side to side to the FPC1500, the current entry-level spectrum analyzer of R&S. As you will see in the videos, there are indeed reasons why you might want to turn to a CMU ;-) I also wonder whether people earlier in this threat called the 'missing' preamplifier' is really an issue or not. In the software video, I explore how Rohde & Schwarz FreRes (v5.30) and VMA Spectrum Analyzer for Rohde & Schwarz CRTU (By VMA'S SATELLITE BLOG) can significantly add to the functionalities of the CMU. Teaser: I also find some serious problems with FreRes, and started to enjoy VNA (even if it cannot exactly do what FreRes was designed for). Enjoy, and thanks for the positive feedback I already received on the video series of the CMU! https://youtu.be/I_sxesKyAXE https://youtu.be/-OL2PRv5Vhs |
| _Wim_:
--- Quote from: RBBVNL9 on May 28, 2023, 09:14:39 am --- --- Quote ---CMU200 as a spectrum analyzer would be the best video to do :-+ --- End quote --- --- Quote ---don't forget the use of freeres as a tracking generator. --- End quote --- Upon request, I now made a YouTube video on using the Rohde & Schwarz CMU200 as a Spectrum Analyzer. Actually, I made two: one as a stand-alone device and one when the CMU is used together with other software (FreRes and VMA). In the video's I basically ask the question: "Is the CMU200 worth turning to, even if it is some 20 years old?". To do so, I put it side to side to the FPC1500, the current entry-level spectrum analyzer of R&S. As you will see in the videos, there are indeed reasons why you might want to turn to a CMU ;-) I also wonder whether people earlier in this threat called the 'missing' preamplifier' is really an issue or not. In the software video, I explore how Rohde & Schwarz FreRes (v5.30) and VMA Spectrum Analyzer for Rohde & Schwarz CRTU (By VMA'S SATELLITE BLOG) can significantly add to the functionalities of the CMU. Teaser: I also find some serious problems with FreRes, and started to enjoy VNA (even if it cannot exactly do what FreRes was designed for). Enjoy, and thanks for the positive feedback I already received on the video series of the CMU! https://youtu.be/I_sxesKyAXE https://youtu.be/-OL2PRv5Vhs --- End quote --- Nice video's! Some comments (also posted on youtube): For the issue with points and comma's, this could be easily fixed by Viktor if he adds the following lines when his main form is loaded: CultureInfo newCulture = CultureInfo.CreateSpecificCulture("en-US"); Thread.CurrentThread.CurrentUICulture = newCulture; Thread.CurrentThread.CurrentCulture = newCulture; This forces the dotNet culture to a specific culture, and not take the culture from the OS it is running on (which is the default). As for the Freres normalization, you should use the "repeat" button instead of "start" after a normalization. This does work correctly as far as I remember. Repeat can be used multiple times and adds additional corrected sweeps. As for the dips in the spectrum using the VMA software, this is probably because the generator needs some settling time when switches between frequencies. If Viktor would add a configurable time the signal remains on at the same frequency, this function would work in one sweep, but the synchronous implementation of Fre-Res still seems the better approach. |
| _Wim_:
--- Quote from: _Wim_ on May 28, 2023, 12:24:08 pm ---As for the Freres normalization, you should use the "repeat" button instead of "start" after a normalization. This does work correctly as far as I remember. Repeat can be used multiple times and adds additional corrected sweeps. --- End quote --- This document has a section about using fre-res with normalization (from page 72 onwards): https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_application/application_notes/1ma201_1/1MA201_9e_spectrum_analyzers_meas.pdf |
| _Wim_:
--- Quote from: _Wim_ on May 28, 2023, 12:51:56 pm --- --- Quote from: _Wim_ on May 28, 2023, 12:24:08 pm ---As for the Freres normalization, you should use the "repeat" button instead of "start" after a normalization. This does work correctly as far as I remember. Repeat can be used multiple times and adds additional corrected sweeps. --- End quote --- This document has a section about using fre-res with normalization (from page 72 onwards): https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_application/application_notes/1ma201_1/1MA201_9e_spectrum_analyzers_meas.pdf --- End quote --- Just had a quick check in the lab, with Fre-Res 5.3.0 normalize does indeed work. In summary: 1) use the play button to measure your reference plot 2) normalize the receiver 3) use repeat to add additional normalized traces of the DUT (with the minus button traces can be deleted) 4) press "stop" to end. When the play button is now used, all traces as well as the normalization are deleted. |
| RBBVNL9:
Dear all, thanks for the various replies. Indeed, I can now confirm lake others have said that FreRes normalisation does work when one uses "repeat" rather than "start". Great to know (but if this is the way the user is supposed to work, it would have been better of R&S to prevent a crash if the user did something different). The normalisation crash was not my only issue with FreRes, however. Below is a list of particularities, issues and crashes I jotted down when trying it in the last days... * Predictable crash when using “start” right after “normalize” (but using “repeat” instead of “start” solves that issue) * Using ‘Level sweep’ (great for detecting linearity issues!), the program sometimes performs the measurement as expected; at other times, it does not execute the expected sweeps. * Occasional crashes when: switching from ABS to REL activating the LOG in the sweep settings (not in the display settings) Using level sweep * Setting a ‘Dwell time’ different from 0 does not seem to result in the expected pause * “Power Measurement Error” appearing at random moments. Repeating the exact same measurement later usually results in no errors. (It might be the CMU itself, but this is hard to tell) * The actual sweep time (left bottom) is only shown correctly after a sweep is already over. It would be great to have this as a predicting value (so, when you increase the steps by a factor of two, and select a different frequency range, the indicator could show how long that would take). * When using “repeat”, earlier measurements should stay on the screen. Sometimes, I do eight measurements and they all stay. Sometimes, at the fifth measurement, the previous ones are deleted. * Sometimes (not always), the program starts by showing “Level/dBm) on the left axis of the graph and “Rel. Level / dB” on the right side of the graph (see my video) . But after a couple of operations, the right side disappears. When both readings are there, that is nice, but when the “relative” switch is used, the right-hand side value (being relative) is no longer correct. * Sometimes (not always) the program starts by not showing a legend on the left side of the graph at all (!) * “Delete the last trace” (while using repeat mode) sometimes works, sometimes not. * After a crash, the program starts with the same parameters the next time you start. You may need to change those parameters to prevent an crash again when doing a sweep. I might have gotten some points wrong, of course, Please correct me if I did, or add if you know more ;-) |
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