Has LED noise been fixed?

Has LED noise been fixed?, a forum discussion on Cleverscope Mixed Signal USB Oscilloscopes. Join us for more discussions on Has LED noise been fixed? on our Other Issues forum.

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18 Mar 2008


I'm getting interested in purchasing a Cleverscope, as I have longed for a high resolution yet reasonably fast scope for a decent price.

One thing that bugs me a little is the noise blob that appears when measuring low levels, as depicted on pg. 14 of the document ""CS328A Performance"" which can be found here:


Has this noise been fixed or can it be made to go away by perhaps disconnecting the LED or something?

Thanks for input.

28 Mar 2008

I'm curious about this also.
Getting real close to purchase now, and hope that issue is fixed.

Digital transitions that transfer to the sensitive analog section is a bear to cure in mixed-mode equipment.
Good luck on a solution.
rhcarter rhcarter

28 Mar 2008
Posts: 114

That document was written last year and we have made further efforts to reduce the effect by adding more filtering and slowing the current rise to the LED.

We would certainly not want it to put anyone off purchasing as it is a very small level signal now; less than 50uV and only visible if averaging is on.

It happens only with the trigger LED switching, the digital circuitry is far enough away to have no effect on the analogue inputs. Yes, you could take out the LED and it would disappear totally.

If it still really bothers you after you have purchased and tried the scope, let us know and we will add a switch in the acquisition settings to allow you to disable the trigger LED!

I look forward to seeing those orders.

Roger Carter

28 Mar 2008

Thanks for the reply Roger.
That's fair enough. 50uv is probably not going to cause too much trouble, but its reassuring to know if there is a problem with it you are willing to work with me on it.
Excellent customer service.

6 Apr 2009

I didn't know that taking out the LED would make it disappear totally. Good thing I am browsing threads first before deciding to solve problems by myself. I have to agree, the customer service is indeed satisfactory! :)

27 Aug 2009
Posts: 481

Hello all,
we have made a change to the software so that if the acquisition window is less than 100 ms, the LED now gets turned on after the acquisition finishes. This means the noise is gone. I hope that helps.

Also for those wanting better amplitude resolution, we have added a moving averaging filter option on the Settings/Acquisition Settings dialog. You can choose a moving average time constant of 40ns - 1.28us. Enable which channels will use the filter. Select a 20 Mhz pre-filter if you want it. Then on the Control Panel, select Filter ON or OFF as required, and the setup you made will be applied. With a 1.28us time constant the noise standard deviation drops to 50uV, and you get 14 bit ENOB. The tradeoff is that bandwidth is now 1MHz, but for many people that will be pretty useful all the same.
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