Bandwidth limit on Siglent SDS2000X Plus oscilloscope - Page 1
Forum section: electronics / testgear

author: swmcl
author_rank: Contributor
timestamp: July 06, 2023, 05:21:49 am
content: Hi,I recently purchased an SDS2104X Plus oscilloscope. With the deal was an offer to upgrade from 100MHz to 200MHz. I have followed some instructions given by the seller but my screens did not behave like they said in the instructions.How do I check what the B/W limit is in my scope ??Rgds,Steve

author: KeBeNe
author_rank: Regular Contributor
timestamp: July 06, 2023, 06:15:03 am
content: please read this page ->https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-hack/400/

author: tautech
author_rank: Super Contributor
timestamp: July 06, 2023, 06:28:03 am
content: Quote from: swmcl on July 06, 2023, 05:21:49 amThe free BW upgrade if applied correctly will change the model # to SDS2204X Plus.The scope should identify itself as that model which you can confirm in SYS Info.What did the seller provide ?The scope only or the scope and BW upgrade license ?If the upgrade license was supplied it probably needs be redeemed at the Siglent licensing website by inserting the Authorized code, the model series, SN# and selecting the 100-200 BW upgrade license.This will generate the official license that you can download the PDF licensing instructions which has the license in it or download the USB licensing .LIC file that you transfer onto the root folder of a USB stick and point the scope to it for automatic licensing install.Most I have done is IIRC 8 licenses this way and they install in just a second or 2 each < no typing or error risks and so simple.

author: swmcl
author_rank: Contributor
timestamp: July 06, 2023, 09:39:21 am
content: Thanks Tautech,I purchased the scope from AppVision in Sydney. So that is a scope and other bits and pieces (bag and probes) in one purchase. I have no issue with their help so far except that they do take a little bit of time to respond.I went to a website and followed some instructions but the on-screen results on the scope were a little different to what the website stated.It sounds as though we are talking the same thing. I wondered if there was a menu option that showed where the software-limited B/W was sitting.Rgds,Steve

author: Mouse69
author_rank: Contributor
timestamp: July 06, 2023, 09:59:40 am
content: Hi Steve,Page 320 of the user manual: Operate Utility>System Setting>System Status to check the system status.You get a list of HW, serial No etc. including the model number (right at the bottom) which should have changed to: SDS2204X Plus

author: swmcl
author_rank: Contributor
timestamp: July 17, 2023, 10:19:09 pm
content: Thanks Mouse69,My scope does not have this sequence of options: Utility > System Setting > System StatusIt does however have: Utility > System InfoIn System Info it now shows a model of "SDS2204X Plus"So the upgrade from a SDS2104X Plus is complete it seems.Thanks all.

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2023, 10:24:34 pm
content: The "real" bandwith of a 2104X+ is way over the 100Mhz, would be interesting to know what bandwith you have now with the 200Mhz upgrade.

author: tautech
author_rank: Super Contributor
timestamp: July 18, 2023, 01:24:41 am
content: Quote from: Martin72 on July 17, 2023, 10:24:34 pmYes, this is something I need do for 'the record'.Hopefully I can fit it in tomorrow after installing the free BW upgrade option.For the record and as tested before, SDS2104X Plus -3dB BW is ~185 MHz. (checked with 3 different sinewave sources)

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 18, 2023, 03:03:09 am
content: According to my Bodnar pulser for rise time it is 560MHz, according to my testing of the vertical response for -3dB it is in excess of 600MHz, from memory about 670MHz. (after conversion up to 500MHz bandwidth obviously)

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2023, 08:49:00 am
content: Quote from: tautech on July 18, 2023, 01:24:41 amFor the record....SDS2104X Plus with free BW upgrade promotional license applied to become SDS2204X Plus....SSG3000X waveform first checked @ 100 MHz to be precisely 1V p-p.-3dB BW is now 300 MHz+a couple of MHz, an increase of ~115 MHz over SDS2104X Plus

author: pdenisowski
author_rank: Super Contributor
timestamp: July 19, 2023, 09:23:19 am
content: Quote from: swmcl on July 06, 2023, 05:21:49 amAs@tautechposted above, the easiest way to check the bandwidth of your scope is to use a sinusoidal input signal of a known amplitude and increase the frequency until the measured amplitude has decreased by 3 dB. That frequency is the "bandwidth" of your oscilloscope as defined by most scope manufacturers.Bandwidth can also be specified in terms of the rise time of a pulse, but this is a more difficult measurement to make (need a good pulsed signal source) and also requires some knowledge of the frequency response (Gaussian vs. brick wall) of the scope's front end to get an accurate number.I talk about both of these in my video on oscilloscope bandwidth:

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2023, 09:33:48 am
content: Quote from: tautech on July 19, 2023, 08:49:00 amAnd while I have a stock SDS2354X Plus unpacked......Same setup for the source as above but this time pushed to 491 MHz for the -3dB point....Result = purchase a 350 MHz model and receive nearly a 500 MHz one.

author: seronday
author_rank: Regular Contributor
timestamp: July 19, 2023, 11:21:36 am
content: Out of curiosity, what reference frequency did you use for the -3dB bandwidth calculation ?

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2023, 07:23:33 pm
content: Quote from: seronday on July 19, 2023, 11:21:36 amNo calculations are required when you have a 3.2 GHz RF gen.Only a check levels are correct at some base frequency before pushing upward, we used 100 MHz 1V p-p as mentioned here:https://www.eevblog.com/forum/testgear/bandwidth-limit-on-siglent-sds2000x-plus-oscilloscope/msg4968844/#msg4968844Otherwise if using the Bodnar pulser, it provides extremely fast edges @ 10 MHz

author: Martin72
author_rank: Super Contributor
timestamp: July 19, 2023, 07:49:56 pm
content: QuoteBesides the approximate formula (0.35/risetime), you could also try this:https://www.teledynelecroy.com/doc/frequency-response-measurementsThis didn't really work for me when I had a SDS2000X+, but since then 2..3 firmware updates have passed.Maybe it works now.

author: TimFox
author_rank: Super Contributor
timestamp: July 19, 2023, 08:39:53 pm
content: One problem with using 0.35/Triseis knowing in advance what the actual rise time of the pulse source is.Approximately, the two rise times (pulse and scope) add in quadrature.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 19, 2023, 09:51:56 pm
content: The Leo Bodnar pulsar is sold as a 40ps unit, but comes with a cert showing what the supplied unit is actually doing, mine was ~35ps

author: seronday
author_rank: Regular Contributor
timestamp: July 20, 2023, 12:34:13 am
content: Quote from: tautech on July 19, 2023, 07:23:33 pmOK. Thanks Tautech.I did not realize that Siglent had specified the BW performance verification test differently for the SDS2000X Plus.In the service manual for the SDS2000X HD, section 5.4, Siglent specify using 1 Mhz as the frequency for the reference level when working out the bandwidth performance.Regards.

author: tautech
author_rank: Super Contributor
timestamp: July 20, 2023, 01:06:53 am
content: Quote from: seronday on July 20, 2023, 12:34:13 amNot exactly.Tests are donestartingat 1 MHz to beyond DSO rated BW.Eg, for SDS2104X HD all the below frequencies are used and documented for verification checks = does it or not pass a Cal.1M, 1.14M, 1.31M, 1.50M, 1.72M, 1.97M, 2.25M, 2.57M, 2.95M, 3.37M, 3.86M, 4.42M, 5.06M, 5.79M, 6.63M, 7.59M, 8.69M, 9.94M, 11.38M, 13.03M, 14.91M, 17.07M, 19.54M, 22.36M, 25.60M, 29.30M, 33.54M, 38.39M, 43.94M, 50.30M, 57.58M, 65.90M, 75.43M, 86.35M, 100.00M, 113.14M, 129.51M, 148.24M, 169.68M, 200.00MThis will be an automated test using the prescribed Fluke 9500B oscilloscope calibrator.Few of us have such a beast therefore just finding the -3dB BW rolloff is quite sufficient for our needs.Typical method is set source to 1V p-p and start winding up frequency until the scope displays 0.707V p-p from a 1V sinewave input. Just don't forget it need be done using a 50 Ohm system.

author: seronday
author_rank: Regular Contributor
timestamp: July 20, 2023, 01:51:32 am
content: The last paragraph on page 38 of the SDS2000X HD service manual describes the method of calculating the dB change in level at each of the measured frequencies, by using the level at 1 MHZ as the reference.If using a much higher frequency for the reference level, the frequency response may have already started to roll off at that frequency.Regards.

author: pdenisowski
author_rank: Super Contributor
timestamp: July 20, 2023, 10:08:34 am
content: Quote from: TimFox on July 19, 2023, 08:39:53 pmAnother problem is that the "0.35" factor only applies when the scope has a Gaussian frequency roll-off. A scope with a more flat or brick wall type frequency response would require the use of a higher number factor (usually 0.4 - 0.45).Since almost all analog scopes have a Gaussian frequency response, 0.35 is commonly cited as the factor to be used when calculating bandwidth from rise time, but care should be taken if the shape of the scope's frequency response is not known. Also, it's important to know whether "rise time" is being defined as the 10-90 or 20-80 interval.In my experience, the easier and more accurate approach is to use the "amplitude of a sinusoid" method to determine the bandwidth of a scope. The bandwidth <-> rise time relationship is best used when you already know the rise time of a pulsed signal and need to calculate the minimum required scope bandwidth to accurately measure that pulse.

author: Performa01
author_rank: Super Contributor
timestamp: July 20, 2023, 04:22:46 pm
content: Quote from: pdenisowski on July 20, 2023, 10:08:34 amYou should avoid the term "brick wall" here, as no serious scope frontend will have a frequency response that is even remotely brick wall."Measuring" the bandwidth of a scope with a pulse is rather popular - maybe because the results sound so much better (and more impressive), if the Gaussian factor 0.35 is used for scopes with a more flat frequency response.Another problem with the fast rise-time pulse (e.g. 40 ps) is that it might ask too much from the average modern DSO with less than 10 GHz bandwidth, where the Nyquist frequency exceeds the bandwidth only by a factor of 1.25 in full channel mode, as is very common today. This results in aliasing artifacts which in turn invalidate the rise time measurements. So care must be taken that the half (or even quarter, in cheap instruments) channel sample rate is utilized to avoid this pitfall.At the end of the day, the good old levelled signal generator is still the preferred method to get a true and really informative picture. With modern DSOs and their advanced features we can even let the scope plot its own frequency response, see the example for the SDS2504X Plus below. And of course 1 MHz is the most commonly used reference frequency - in some cases like the example below (that goes up to 1 GHz) it can be desirable to have it a bit higher, so I chose 10 MHz back then. But thanks to the frequency plot we can clearly see that there are no significant differences below ~150 MHz, so this choice is legit. It might be different with an artificial bandwidth limit, which is implemented by a first order filter, so amplitude drop starts earlier.

author: Martin72
author_rank: Super Contributor
timestamp: July 20, 2023, 04:57:34 pm
content: Quote from: Martin72 on July 19, 2023, 07:49:56 pmOnce again I'm too stupid to do it and can't get it to work on my HD, it looks just like it did on the X+.But since 2N3055 showed it with an HD(didn´t find the thread so far), I assume it's my stupidity.

author: BillyO
author_rank: Super Contributor
timestamp: July 20, 2023, 07:03:04 pm
content: Quote from: Performa01 on July 20, 2023, 04:22:46 pmNot quite true. Obviously 0.35/Risetime is going to be LESS than 0.4/Risetime.BTW, the SDS2000X-P scopes are definitely in the "flat" response category (at least when un-corked), so you should be using 0.4 which will give you more accurate (and more impressive) results than 0.35.

author: Performa01
author_rank: Super Contributor
timestamp: July 21, 2023, 10:29:43 am
content: Quote from: BillyO on July 20, 2023, 07:03:04 pmThank you for pointing that faux pas out. You can tell that I've never worked with that formula, always used accurate frequency response measurements instead. There were several reasons that got my thinking wrong - ridiculous bandwidth claims being one of them.Quote from: BillyO on July 20, 2023, 07:03:04 pmWell, let's see how the formula accords to the data sheet for the various models:Model tr  BW real  k [-]SDS2104X+ 3,50 100 0,350SDS2204X+ 1,70 200 0,340SDS2354X+ 1,00 350 0,350SDS2504X+ 0,80 500 0,400SDS5034X 1,00 350 0,350SDS5054X 0,70 500 0,350SDS5104X 0,40 1000 0,400SDS6054A 0,55 500 0,275SDS6104A 0,35 1000 0,350SDS6204A 0,23 2000 0,460According to the datasheet for the SDS2000X+, the factor 0.35 would be accurate up to 350 MHz, i.e. for all artificially bandwith limited models/modes. According to this, factor 0.4 would be correct for the 500 MHz option. Now we all know that the bandwidth is significantly higher than specified for the SDS2000X+, so we can expect faster rise times too.It is basically the same for the SDS5000X. The artificial bandwidth limit (which is just a first order lowpass) leads to a Gaussian frequency response, hence factor 0.35 in the data sheet. for the 1 GHz model, the natural roll-off of the input buffer and PGA lead to a more flat response, hence factor 0.4.It looks very different for a higher bandwidth scope like the SDS6000A. The 0.35 factor fits for the 1 GHz model, but nothing else matches.

author: rf-loop
author_rank: Super Contributor
timestamp: July 21, 2023, 12:57:19 pm
content: Quote from: Performa01 on July 20, 2023, 04:22:46 pmBut still "brick wall" is commonly used (for Flat-response meaning in oscilloscopes) when professionals talk because they know context.It have widely used in old HP-Journals, and HP-Agilent-Keysight appnote etc papers. All we know (I hope) what it mean when we talk oscilloscopes and brick-wall type freq response and still we do not mean (in any cases) ideal Brick-wall filter aka rectangle filter because it do not exist in practice... just as all we know that there is not perfect square waves or true DC but still we talk using these...of course.Or is it only allowed for engineers from A-group manufacturers. At least they quite often use that term.----Common sidenote... HP-Journal, Oct 1993 is still good to read. The basics don't expire (mostly).

author: pdenisowski
author_rank: Super Contributor
timestamp: July 21, 2023, 02:16:08 pm
content: Quote from: rf-loop on July 21, 2023, 12:57:19 pmKeysight: "Responses that havebrick-wall filtersare desired as they produce less noise"https://www.keysight.com/us/en/assets/7018-04317/application-notes/5991-4088.pdfLeCroy: "the tailoredbrick-wallfrequency response"https://cdn.teledynelecroy.com/files/whitepapers/enhanced-sample-rate-whitepaper.pdfR&S: " The user can choose between Gaussian orbrick wall filtercharacteristics to optimize the oscilloscope step response"https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/pdm/cl_brochures_and_datasheets/product_brochure/3608_6919_12/RTO6_bro_en_3608-6919-12_v0502.pdfTektronix: "Most real-time oscilloscopes today have a rather sharp roll-off (e.g. "brick wall")"https://www.tek.com/en/datasheet/dpo7oe-series-optical-probesQuote from: rf-loop on July 21, 2023, 12:57:19 pmWell, I've worked atbothHP/AgilentandR&S, so that might explain it

author: BillyO
author_rank: Super Contributor
timestamp: July 21, 2023, 02:56:57 pm
content: Quote from: Performa01 on July 21, 2023, 10:29:43 amThat formula is based on the physics of the system. Provided you can mathematically characterize the system's response you can work out a version of that formula for it. It should be quite accurate. Gaussian response is well characterized and the resulting 0.35/risetime is accurate. For moderately flat response systems (the top end of most mid-range PGA/VGA) the response is also well characterized and 0.4/risetime is also accurate.Using a sine wave generator has it's perils. Unless you have calibrated it and are confident in it's performance it can also give very skewed results. Ideally you would measure it's output and normalize it before taking each data point of the DUT to ensure it is flat at the frequency being tested. The rise time is a single measurement and is accurate as long as the character of the response of the DUT is known.Quote from: Performa01 on July 21, 2023, 10:29:43 amLike the over 600MHz for a un-corked SDS2000X-P? As an example mine has a rise time of 660ps, not the 800ps claimed by Siglent. Using the formula (0.4/risetime) we get a BW of 606MHz. Using a sinewave sweep @ I got 650MHz . That 606 MHz does not look like a ridiculous claim to me. The difference is probably got to do with my not being able to determine if the sine wave generator was flat.Quote from: Performa01 on July 21, 2023, 10:29:43 amI imagine the 500MHz license on the 6000 series has much better performance than advertised. As for the 2GHz version, it is most likely using more advanced PGA/VGA with more agressive flattening. Tektronix claim .45 for their "maximally flat" response so 0.46 seems very much in line with that.

author: mawyatt
author_rank: Super Contributor
timestamp: July 21, 2023, 04:07:19 pm
content: Amplitude Brickwall Filters are not realizable but the analog IIR high order Chebyshev, Inverse Chebyshev and Elliptical filters produce a good approximation at the expense of highly non-linear phase response, FIR digital filters do even better. One issue for scope use of one of these analog filters would be the highly non-linear Group Delay (derivative of phase with frequency) associated with these type filters, whereas the less Brickwall like Bessel and Gaussian have a much better Group Delay which is very important for scope use and why they are usually employed. Of course the Digital FIR filters can disconnected the phase/delay and amplitude responses, which is a huge benefit in some applications.Seems the swept frequency is the overall best way to accurately characterize a DSO. Since one doesn't know the exact relationship between the frequency response and step/impulse response, one uses the usual fudge factors, i.e. 0.35, 0.4 and so on, if that's important! The issue with the swept frequency response; Does the signal generator remain "flat" across the entire band in question? This is easily resolved with a quality SA, where the amplitude variation can be accurately measured across the band of interest. The tracking generator in our SA is pretty good and we've used such to "characterize" our uncorked SDS2000X+, which demonstrated over 600MHz BWThis is not to say the DSO inherent rise time and channel characteristics aren't important, it is and one must always consider the displayed waveform rise time/pulse waveform characteristics as being distorted by the DSO, how much so depends on the waveform and DSO. One must consider that the scope and waveform measurement at hand are non-coherent (generally a good assumption), so the display is the result of the root-sum-squared (RSS) response if the DSO is moderately well behaved. So for a 10% DSO displayed contribution/degradation the DSO rise time needs to be better than ~3.2 times the waveform under consideration, similar concept applies for waveform bandwidth measurements.Best,

author: pdenisowski
author_rank: Super Contributor
timestamp: July 21, 2023, 07:23:00 pm
content: Quote from: BillyO on July 21, 2023, 02:56:57 pmAgree completely that you would want to be sure your signal generator amplitude is either "flat" or has a known frequency response (output level as a function of output frequency).Most "professional" sig gens should have very good spectral flatness over typical scope bandwidths (100s of MHz up to low tens of GHz), especially as many monitor their own output level and can internally adjust output level as needed to maintain good "flatness" over their specified operating range.

author: Martin72
author_rank: Super Contributor
timestamp: July 21, 2023, 07:57:39 pm
content: Quote from: Martin72 on July 20, 2023, 04:57:34 pmYepp itwas...https://www.eevblog.com/forum/testgear/math-problems-on-sds2k-(trying-to-display-bandwith)/msg4972270/#msg4972270Now I´m curious if this will also function on the SDS2000X+ after several firmwareupdates.Will check it when I´m back to work or someone could check it before.

author: tautech
author_rank: Super Contributor
timestamp: July 21, 2023, 08:21:06 pm
content: Quote from: Martin72 on July 21, 2023, 07:57:39 pmTry on P2 in the SDS2000X Plus thread:https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg2787168/#msg2787168

author: Performa01
author_rank: Super Contributor
timestamp: July 22, 2023, 08:28:09 am
content: Quote from: BillyO on July 21, 2023, 02:56:57 pmNobody said the formula isn't exact, yet as long as the frequency response is unknown (i.e. as long as it is not properly plotted with a levelled signal generator), the factor in that formula is unknown as well. This is where the cat bites their own tail.Quote from: BillyO on July 21, 2023, 02:56:57 pmCome on. I was talking about signal generators, not toys from ali express. Especially higher end ones have excellent flatness, all the more so when only the range up to about 500 MHz is really important, as for the usual entry level DSOs discussed here.I even demonstrated the accuracy and amplitude flatness for both the Siglent SDG6052X AWG and my Anritsu MG3633A signal generator here. I think this should be flat enough for characterizing a scope bandwidth:https://www.eevblog.com/forum/testgear/siglent-sdg6000-series-awg_s/msg2621457/#msg2621457Quote from: BillyO on July 21, 2023, 02:56:57 pmI think I have alredy stated that the actual bandwidth exceeds the specifications, especially in the entry level DSOs.As I've posted many times before, my own measurements resulted in ~570 MHz - and I have not taken the cable loss into account, which was about 1 dB @ 500 MHz. There was no need to, in my book, because this gives some safety margin for "guaranteed results", so to speak. If we add that one dB and look at -4 dB, we are at about 605 MHz.650 MHz on the other hand sounds not very realistic, yet not ridiculous either.Quote from: BillyO on July 21, 2023, 02:56:57 pmThe hardware is the same for all SDS6000A devices.I've tried to explain numerous times, why artificial bandwidth limits have high tolerances. So you can bet that pretty much all SDS6204A will have an actual bandwidth of about 2.2 GHz, but there might be quite some variation for the artificially bandwidth limited 1 GHz and 500 MHz models. The only safe bet is that the bandwidth of those will exceed the specification - but the amount could vary a lot.

author: Performa01
author_rank: Super Contributor
timestamp: July 22, 2023, 09:59:04 am
content: Quote from: mawyatt on July 21, 2023, 04:07:19 pmThat's the key. We cannot do anything but Gaussian (or Bessel, at most) at the analog side, otherwise the step response gets awful and pulse fidelity is lost. Yet you can do it digitally – a FIR filter can actually approximate a brick wall and still have constant group delay. High End scopes combine analog and digital filters to optimize their frequency and phase response. But this requires a sufficiently high sample rate to bandwidth ratio – the usual factor of 2.5 in modern top models (within their class) will not allow an effective digital filtering, if only because of the ineffective AA-filtering in the analog frontend.

author: gf
author_rank: Super Contributor
timestamp: August 10, 2023, 08:40:15 am
content: Quote from: Performa01 on July 20, 2023, 04:22:46 pmApparently just a FFT plot. This, of course, requires a stimulus with a flat spectrum in the frequency region of interest. May I ask what stimulus you used for this test? Sinc pulse? Chirp pulse? If you used a chirp pulse, how did you tweak it to avoid Fresnel ripples?

author: Performa01
author_rank: Super Contributor
timestamp: August 11, 2023, 01:50:15 pm
content: I use a levelled signal generator (usually Anritsu MG3633A or an AWG like SDG6000X and SDG7000A), slowly sweeping over the desired bandwidth. FFT in peak hold collects the measurements over a few minutes.This method has proved to be just as accurate and still way faster than manual data acquisition.The big advantage is that we can tweak it a lot.We can use very slow sweeps in order to get a nice looking graph right away. We can use a faster sweep so we get a first result pretty quickly, and the let it sweep some more times to fill the gaps in the plot.What resolution in the frequency domain (RBW) do we need? I've chosen about 920 kHz, (8192 FFT-points @ 2 Gsa/s), but we can alter that if required. More FFT points will slow it down, so we need longer sweep times and/or more sweeps to get a nice contigous plot.

author: gf
author_rank: Super Contributor
timestamp: August 11, 2023, 03:35:02 pm
content: Quote from: Performa01 on August 11, 2023, 01:50:15 pmThank you, that makes a lot of things clearer.[ I was errenously assuming that the stimulus was some kind of wide-band pulse fitting into a single FFT window of only 4.096µs, and that would have been quite challenging, with good SNR. ]

author: Martin72
author_rank: Super Contributor
timestamp: December 06, 2023, 09:28:27 pm
content: Quote from: Performa01 on August 11, 2023, 01:50:15 pmI had bought an SML01 (1.1Ghz) to recreate this for my 2504X HD.But I have never done this before, how could a suitable sweep setting for this purpose be parameterized?500Mhz bandwidth has the scope according to the model name, do you start at 300Mhz and stop at say 800Mhz?And how could "slow" turn out?

author: Performa01
author_rank: Super Contributor
timestamp: December 07, 2023, 10:25:48 am
content: Quote from: Martin72 on December 06, 2023, 09:28:27 pmFor a frequency response plot from 1 MHz to 1 GHz I use the following setup:Signal generatorSweep mode: linearSweep time: 300 sSweep frequency setting: 1 MHz to 1 GHzSweep direction: upCarrier amplitude: 0 dBmDSOAcquisitionTimebase: 500 ns/divTrigger: edge, 0V, auto - or mainsInput: 50 ohms, 100 mV/divFFTMax points: 8 kptsWindow: FlattopFFT mode: Max-HoldVertical: 2 dB/div, Ref = +2 dBm, Unit dBm, Ext. Load = 50 ohmHorizontal: 0 - 1 GHzThe trace might not be perfect after the first pass, but you can just wait and let consecutive passes accumulate to get an optically nice result.See attached example.SDS2504X HD_FR_Full_0dBm_splitOf course you can choose a different frequency range, but this doesn't make much sense, because we always want to see the level at low frequencies as a reference. Usually, we take 1 MHz as reference and with the settings given above, this is just possible, because the RBW is still below 1 MHz. For faster scans we need to use wider RBW (= less FFT points) and then we also need to switch to 10 MHz as the reference frequency.

author: Martin72
author_rank: Super Contributor
timestamp: December 07, 2023, 11:10:20 am
content: Thank you very much