Bode Plot Measurements with a Scope

I came across this article from Rohde & Schwarz and am curious if people are using this approach (or something similar) to verify their design.

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Its been a long time since I was doing this sort of work and am impressed with this capability. Couple of questions:

  1. Are people using this approach to verify their designs? (possible alternatives?)
  2. Is this capability particular to Rohde & Schwarz scope?

Thanks John

Reply to
three_jeeps
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Scopes from Pico Technology and Keysight can do this (that I know for sure.) I think some LeCroy and Tek scopes can as well. With Keysight it was quite an expensive software option, comes as a free third party software with Pico. I have a and R&S scope but find the Pico is a great deal easier to use, the small screen on the R&S and scope like controls make it hard to use. The Pico Tech stuff is all PC based.

MK

Reply to
Michael Kellett

This was mostly the territory of frequency domain instruments, vectornetwork analyzers and such. Those still get much superior performance. Once you have a scope with an integrated AWG and a fair bit of processing power, it's possible to get the same information from time-domain data.

Jeroen Belleman

Reply to
Jeroen Belleman

I generally just use a function generator and a scope. That's easy to set up.

Has anyone used the R&S scopes? Comments?

Reply to
John Larkin

You don't need a fancy scope to do that--just bang on the input and output with a nice square squarewave and watch it ring. Usually you don't want more than a few percent overshoot, and no more than two visible peaks, one positive, one negative. You may also care about tilt on the pulse tops, which indicates low-frequency problems.

If you really want the closed-loop transfer function, the tool of choice at low frequency is a dynamic signal analyzer such as an HP 35665A, and at high frequency a vector network analyzer.

But for most wideband things, what you care about is stability and decent transient response, and that's all there in the step response curve.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

I've done this with a keysight 'scope. But there was no menu options to fine adjust the scan range... ~1,3,10 frequency steps I find a sig gen and AC voltmeter is better.

George H.

Reply to
George Herold

I have recently bought an R&S RTA4004 which was on offer with all known

replacement to be launched soon !) It's competitive with the Keysight 3000 and 4000 series.

1GHz bandwidth, 4 channels, 10 bit, 5G/s sampling rate (2 channels), 16 channel digital. Like all scopes in this format the screen is too small to really support the features it offers. It can be connected to a computer via Ethernet and there is a good web app which gives you a virtual scope on the PC, but no increase in screen resolution. The Keysight 4k series have bigger screens which would be nice. I bought it to backup a LeCroy 610zi that I bought new about 6.5 years ago. It's gone intermittent on the power supply and they won't supply

The ergonomics of the LeCroy are way ahead of the R & S or Keysight (when it starts :-(

I slightly prefer using the R&S rather than the Keysight MSOX 3024T that I have.

I'm currently testing a Pico Technology 6424E but I've only had it a day, so too soon for formal comment - but I do like the 42" 4k resolution screen and the Windows GUI. (It's a USB scope !).

In the end your choice is going to need to take into account what you'll use it for.

MK

Reply to
Michael Kellett

Our default scope is the Rigol 350 MHz 4-channel, which we've always managed to get upgraded to 500 MHz for free. We use it in test racks and have Python libraries to talk to it. My favorite button is DEFAULT, which means "get me the hell out of here and be an oscilloscope again."

We have one 7 GHz 4-channel LeCroy. The performance is fabulous and the menus and nomenclature are bizarre to the point of unusable. Their support people don't seem to understand it either. Cost about $50K.

My favorite scope is my ancient Tek 11802 sampler. It will die one of these days and I will mourn its passing.

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It just makes so much sense.

--
John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 
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Reply to
jlarkin

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