Products > Test Equipment
Siglent SDS1x04X-E BodePlot II (SFRA) features and testings
rf-loop:
--- Quote from: KungFuJosh on July 05, 2019, 01:25:01 am ---
--- Quote from: Performa01 on July 04, 2019, 08:58:14 pm ---
--- Quote from: rf-loop on July 04, 2019, 06:13:51 pm ---In some special cases perhaps also this kind of principle is possible? (as my nickname tell I'm more RF.... ;) )
(of course it need well known ref Mic etc... and very carefully istalled so it do not mess Microphone under test and it get as perfectly same as Mic under test get.)
--- End quote ---
Thanks for pointing this out. It is of course viable, but now requires an calibrated measuring microphone, which makes the setup even more expensive. Just like reference sound pressure sources, measuring microphones do not have a perfectly flat response, but are calibrated, i.e. their response is precisely known and the corresponding correction can be applied to the measurement results.
EDIT: I think your point is that the sound pressure source needs not be calibrated, but it still needs to be high quality to come close to a point shaped source without partial oscillation of the membrane to give a uniform sound field.
--- End quote ---
Very interesting. It appears that you're suggesting that the test should use a live capsule on the microphone. I often test the mic prior to installing a capsule. So the mic would have a ~72pF dummy load instead of the capsule, and then I insert a signal directly to the mic circuit.
Shouldn't this be significantly simpler to test the circuit that way?
Thanks,
Josh
--- End quote ---
First your question about my images editing.
Because these are technical pictures, example instrument display copy (never use jpg, jpg is for photographs) and need simple things - like txt, some highlights or color balance etc and of course it have quite nice advanced batch conversion/adjust tools. Fast and easy but still can do many things and it is not mammoth like some photographers Photoshop or GIMP etc.
I have used over 20 years Irfan Skiljan's nice Irfanview. For this kind of simple technical images purposes it have today lot of tools. It is today, and have been long long time, lot of more than just viewer what is was over 20 years ago when IrfanView was launched.. So this name is bit fun today, but name have history. In beginning it wast just more like simple viewer, at this time world was bit different.
It is not suitable for real The Photographs editing. Camera Photographs are other things.
(today with Irfan you still can do really meany things.. (Irfan + plugins package))
But then return to the actual subject.
So you are testing microphone without microphone.
I think this do not belong to this thread at all. It belongs under topic something like "how to measure microphone frequency response"
If you are testing microphone amplifier circuit freq. response alone - then you need tell you are testing this kind of electronic circuit (explanation). Microphone is receiving acoustic waves in air. (because you talk this kind of microphone. Of course, the medium in which mechanical vibrations are transmitted can be something other than air.) Normally when we talk microphone (music, speak etc sounds) frequency response we talk this frequency response how it move acoustic waves in air to electric signal. Other question is after then how these electronic circuits handle this microphone "capsule" signal. These circuists are not "microphone". and if you talk alone these amplifier / buffer circuits response you do not talk microphone frequency response. So these kind of things very easy mess whole discussion and soon, as also here now, we are like out from BodePlot II things.
Microphone real freq response measurement is imho really different case. It need sound. For other than crap result it is quite complex case and need - hard knowledge how to do it and also instruments for do it. There also BodePlot II can use.
If you want only test this microphone amplifier without microphone itself (capsule) you can of course do it also using BodePlot II. But now it looks your problem is not at all BodePlot II things. You need perhaps help how to do this test setup between your circuit and SFRA system. Please open new topic for it and give deep detailed information about your this DUT. Schematics and specifications what ever are available. Perhaps then someone(s) can try help how to do it. Includind also perhaps some tips how to then finally do BP II settings. But first you need some help for do hardware test setup for this. First you need good setup. BPII settings are then in final case.
For your self learn how to use BPII itself:
I recommend you do some very very simple circuit, just example RC filter.
Then run BPII with it and exercise and try understand all settings what they are and how they affect what you get on display. Also including understanding level scales. Adjusting display when BPII is running
Sidenote:(Siglent need improve this vertical autoscale so that user can select it or use last user adjusted vertical and remember it if stop and adjust example horizontal or other parameters. Now it is frustrating to adjust these scales every time again after start sweep because it always goes to autoscale and least I have not find how to deny vertical autoscale for level and phase draw.)
I highly recommend to firtst exercise with known circuits if it is not clear how to use SFRA (BodePlot II). For base level exercise/learn how to use BPII , imho, it is best to use known circuit what result we already roughly know and simplest circuit is example 1st or 2nd order RC low pass (or something like it, band pass, high pass etc). If you want simplest possible DUT and frequency can be "what ever" because it is only for learning. You can use setup (if you are sure you can set SDG for tracking mode with equal outputs so that CH2 is tracking CH1 with 0 phase, 0 level and 0 freq difference.)
Connect CH1 to scope CH1 (as DUTin) (coaxial, 50ohm termination)
Connect probe 1. BNC end to SDG CH2 Output BNC.
Connect probe 2. to scope channel (example CH2) as DUTout.
Connect probes GND wires together. Connect probe tips together. Set both probes for 1x.
These probes are now your DUT. This DUT is low pass filter, corner somewhere well under 10MHz
If you now want look lot of lower freq things.
Just keep this setup but take example 100ohm resistor and 100nF capacitor. Connect capacitor other end to probes GND joint. Open probes tips joint. Connect capacitor other end to probe 2. tip. Connect also resistor other end to this joint. Then connect resistor other end to probe 1. tip.
Start exercise using BPII default settings and set sweep logarithmic and start from example 1kHz to 10MHz.
Of course you can do some other filter or cascaded filters.
Here can find nice tools for calculate these and also get calculated responses. So you can see how close practice and theory goes when you look your BodePlot II results. (of course calculus are made using ideal components what do not exist at all in real world, never. Even DC voltage exist only in theory books but not in real world. Never.)
But I hope we can see this "microphone what is not microphone" testing things goes to under some other new topic or other appropriate thread.
KungFuJosh:
I'll try those simple tests and eventually start a new thread if I decide to keep the SDG. This seems to be more hassle than it may be worth.
BTW- That was somebody else that asked about your graphics. My day job is web and graphic design. I'm well versed in the adobe suite, and I have irfanview too. ;)
Thanks,
Josh
rf-loop:
--- Quote from: KungFuJosh on July 05, 2019, 11:32:33 am ---I'll try those simple tests and eventually start a new thread if I decide to keep the SDG. This seems to be more hassle than it may be worth.
BTW- That was somebody else that asked about your graphics. My day job is web and graphic design. I'm well versed in the adobe suite, and I have irfanview too. ;)
Thanks,
Josh
--- End quote ---
Sorry, it was @Electro Fan who ask this. ;)
Btw, I do not understand what "hassle" there is. SFRA works just as SFRA works. Even if you buy big brand SFRA machine there is very important to think and understand what things machine do not for you. User must arrange a suitable test connection setup between DUT and Analyzer. User is responsible about test signals are right and DUT and test instrument see suitable and good quality signals. Some times it need also thinking, knowledge and experience. First before all, need fully understand how test instrument works and what are all things there. I want easy, immediately all for me just as in movies and stories. It do not work like this.
I have been in situations where need first design test setup. In some cases it need lot of work. Finally after long long work and design etc... then power up test instrument and push three - five buttons and turn some knobs and after some minutes there is nice result on screen. If someone look when start instrument and how easy all goes to final nice graph on display... then he may think why company pay to you this salary. Just because he did not know what was 99.99% of this work what final and result he simply see, one dirty graph on the screen..
It is because every time you measure something (connect something, probe, wire or what ever) to DUT you change DUT. More or less. Yes in many simple low freq audiuo things this must not care so much except perhaps if go to some state of art things. Some times it is major problem and sometimes it may need deep knowledge and hard design etc to know how to arrange probing and how to know how much it affect DUT and how much it bend result what we hope is as accurate truth as possible. Never overlook how much need do work for good reliable test setup, its is perhaps most important (and some times frustrating) thing when do some testing.
Turning instrument knobs is most easy peace of this cake. And even in this, doing instrument settings, many even experienced peoples are messing because they do not know how instrument is designed to work. So, also knowledge need include - always: "know your tools and instruments". And this is what need exercise and study and it IS hard work and it need do or if not then just better stay with toys and playing some simple things. There is no free lounges. Home works need do or if not then some day all feels "difficult" and messy. Look some videos around internet and you know what I mean...but it is not appropriate to talk about it here.
tautech:
This ^^^ and so much all this !
Practice with simple pass filters and get to understand BPII. It does take time but this investment in time and X-E plus AWG is much less than other equipment that has similar capability.
mrprecision:
I have tested the Bode Plot Function of my scope (SDS1104X-E) and have been very enthusiastic about it so far. I connected the scope to the generator (DG2042X) via Ethernet, this worked without any problems right away. However, there seems to be a problem with the Bode Plot function.
In the simple example I tested a passive filter of the 1st order with 100Hz at -3dB. The sweep for the Bode Plot function was chosen from 10Hz to 1kHz with 10 points per decade. "Channel Gain Auto" was selected under the channel settings.
Then the Bode Plot measurement was started. The first run is as expected. However, the first point in the Bode Plot is incorrectly determined in all further runs. In my view, this is a mistake. However, if you select "Channel Gain Hold" under the channel settings, this incorrect measurement does not occur. It also appears to occur only at low start frequencies.
Video
http://www.schaeck.eu/download/eev/siglent_bode_2_error.mp4
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