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| MSO5000 Bode Plot Capability: Is it Good Enough? [Many tips about a 1st scope] |
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| nctnico:
--- Quote from: balnazzar on October 01, 2022, 10:33:22 pm --- --- Quote from: nctnico on October 01, 2022, 06:00:15 pm ---Have you considered getting a specific device for doing bode plots? What kind of frequency range are you after? Any amplitude & dynamic range requirements? The analog discovery is mentioned often as a tool for doing bode plots. From a comparison between various oscilloscopes made by one of the forum members, it seems Siglent's bode plot is rather slow so may not be ideal for doing a lot of bode plots in a short time. --- End quote --- Thanks for the heads up about Siglent's sluggishness at bodeplotting, I wasn't aware of that. Mh. TBH, I considered the AD2. It matches my requirements (barely, but it's workable). It has other perks, like differential probing (as long as you don't use the BNCs), and with the BNCs it can get to 30 MHz, which is kind of OK. Plus, it has other handy features. Not to mention the good software, a thing that finds both Siglent and Rigol gravely wanting. My problem with the AD2 is that I need a scope with at least 3 channels. So, considering some 400 eur for the AD2, I should also buy a 4-ch basic scope (5-600 bucks max). Any advice about this would be welcome, but I think it boils down to the usual couple.. The aforementioned Siglent, or the old (not good old, just old) 1054Z. You seem to be an experienced contributor.. Tell me one thing: would it be possible to connect both the AD2 and a Keysight 1052A to a computer so that one can use the whole contraption as a 4 ch scope? --- End quote --- No. But depending on your location, a GW Instek GDS1054B could be a good alternative to buy a decent 4 channel oscilloscope (options can be enabled for free using a key generator available on this forum). For example: https://eleshop.eu/gw-instek-gds-1054b.html |
| Warpspeed:
What you require, really depends on the application and test envioronment. What are you planning to Bode plot ? Things such as frequency range, noise floor and dynamic range are pretty obvious, and many measuring instruments these days have some excellent features. If you are studying just analog type circuits, amplifiers, filters, servo systems etc... that is all pretty straightforward. These days switching power supplies are a significant area of interest, and Bode plots are just about a must have, if you wish to maintain your sanity. Switching supplies are are very Bode plotter unfriendly by being significant producers of wideband noise by the power components. Trying to resolve a sine wave of a couple of millivolts submerged in hundreds of millivolts of spikes and ripple is something very simple equipment is just not capable of doing. Its all very well the software being able to plot a nice smooth gain curve over 100db dynamic range, but unless millivolt or microvolt level signals can be resolved beneath huge levels of noise, the pretty plot on the screen is just not going to happen. Many if not all low end Bode plot systems just use direct analog to digital conversion and some clever number crunching. That works fine for demo purposes by the plotter salesman, but not when trying to make real world measurements on switching power supplies or in really noisy applications. The only way to do it is with a couple of very narrow band swept filters, similar in concept to a spectrum analyser. That can be done either with hardware or very sophisticated software to reject everything but the exact test frequency being run through the equipment under test. All very clever, but it does not come cheap unfortunately. So a simple low end Bode plotter may be all you need, or it may not work for you at all, depending on the test environment. |
| mawyatt:
--- Quote from: nctnico on October 01, 2022, 09:56:45 pm ---I get that you are happy with the tool available to you, but have you tried other tools as a comparison? I have a DSO with bode plot as well but I always use my network analyser for doing bode plots. The network analyser is just more convenient to use. --- End quote --- We have a VNA, but often prefer the Bode Function because of the higher impedances and/or voltages and lower frequencies involved. Haven't used any of the other brands Bode functions tho, so can't speak for them. Sure a dedicated High Input Z Lower Frequency Network Analyzer is a better instrument, but that's another instrument and expense, for us the SDS2000X+ has filled that need nicely!! If you actually use the Bode function in the SDS2000X+ and spend some time with it you will appreciate the performance they've achieved. Like the comment just above about the Frequency Selective measurement capability, don't think they use the Synchronous Sampling, but whatever technique they employed does work well rejecting signals not of interest!! Best, |
| Fungus:
--- Quote from: balnazzar on October 01, 2022, 10:53:00 pm ---One solution would be buying the AD2 for the Bode plots along with the good software that comes with it (and logic & network analyzers) AND the siglent for having a decent 4chs scope with buttons, knobs and a screen... --- End quote --- Obvious first question: What frequencies and sensitivities do you need for your bode plots? What are you measuring? --- Quote from: mawyatt on October 01, 2022, 08:26:01 pm ---Having considerable 1st hand experience with the Bode function in the Siglent 2000X+ --- End quote --- When did the 2000X series come into it? That's way over budget. |
| 2N3055:
--- Quote from: Fungus on October 02, 2022, 01:11:02 am --- --- Quote from: balnazzar on October 01, 2022, 10:53:00 pm ---One solution would be buying the AD2 for the Bode plots along with the good software that comes with it (and logic & network analyzers) AND the siglent for having a decent 4chs scope with buttons, knobs and a screen... --- End quote --- Obvious first question: What frequencies and sensitivities do you need for your bode plots? What are you measuring? --- Quote from: mawyatt on October 01, 2022, 08:26:01 pm ---Having considerable 1st hand experience with the Bode function in the Siglent 2000X+ --- End quote --- When did the 2000X series come into it? That's way over budget. --- End quote --- I believe Mike simply speaks of his experience with the product he owns. Truth is BodePlot II on SDS2000X + is same algorithms as the one on SDS1000X-E. So Mike's good experience with it is very relevant for both scopes, one within the budget and one that is not. |
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