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ITTSB Blog Specific => ITTSB - Small projects by Kiriakos & User reviews => Topic started by: Kiriakos GR on July 05, 2016, 08:29:55 PM

Title: Nerdish Oscilloscope benchmark, Autoset key and it lowest usable limits
Post by: Kiriakos GR on July 05, 2016, 08:29:55 PM
I do belong in the group of people giving attention to user’s manual especially of measuring equipment's.
Most of times I do shown 100% faith to any written specification, and I do that because  by following this path you are staying in the safe side most of times.

GW Instek products documentation this is quite good.
So far I am impressed of work made regarding supplied documentation also from Keysight and HIOKI.

Now, what triggered my very own trigger so me to further investigate it, this is a limitation note printed at GDS-2000A Oscilloscope user manual at page 66.
This note mentioning limits regarding amplitude and frequency of input signal, anything below these limits will force Autoset this to fail at setting-up the oscilloscope automatically.

GW Instek Original note:
Autoset does not work in the following situations.
1)  Input signal frequency is less than 20Hz
2)  Input signal amplitude is less than 30mV

Now at GDS200 & GDS300 user’s manual there is also such a mentioned limitation.
Exact text:  The Autoset function cannot catch signals under 30mV or 20Hz. (Page number 174)


Now at my workbench I did also actual testing, so me to verify these specifications’ too.
Especially after receiving a note and video footage from a friend at Rohde & Schwarz Oscilloscopes R&D division, which was a demonstration of latest RTH portable scopes and their capabilities regarding Autoset.

Instead typing numbers of my results, I am posting bellow screenshot samples which both proving that GW Instek limitation notes, they are rather generic than actual specifications.

GDS-2102A this it did confirmed in my eyes for another one time that is an instrument of high precision even when you challenge it with nerdish games as there is no real applications down to 3Hz.
Regarding lowest amplitude and Autoset this found to be at the level of microvolt’s which this is remarkable.

Portable GDS-320 Oscilloscope this shown less sensitive than GDS-2102A but even so, minimum required amplitude and input signal frequency this was much lower than specified.

 
Conclusion No1:  If your oscilloscope does not have necessary sensitivity this will fail measuring power supply ripple.   

Conclusion No2: Smallest SMPS this producing today ripple above 30mV RMS, this is partial good news for Low-end Oscilloscope owners but do not forget that a sensitive Oscilloscope this will do measure at the same conditions with higher accuracy too.
 
Conclusion No3: GW Instek this has better Oscilloscopes than their specifications’.
I hope my findings to motivate them to correct their documentation regarding GDS-300 and GDS-2000A series.