PicoScope PS5000a and traditional oscilloscope

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Mirko_CLTD
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PicoScope PS5000a and traditional oscilloscope

Post by Mirko_CLTD » Mon May 21, 2018 5:14 am

Hi guys,

I have PicoScope 5244B and integrating the unit using LabView.

What I am missing are some of functions that most of DSO have:
- noise filter (not 20MHz bandwidth limiter)
- zero offset
- ground input (coupling to ground)

Above three features can't be found in PS5000A.dll hence I can't control them with LabView.

On the other hand, noise filter and zero offset functions are present in PicoScope 6 software (6.12.9.2917) and they are working perfectly. I tried LabView's low pass filter express VI setting cut-off frequency as per Nyquist criterion but cannot match what you have on PicoScope 6 program.

I already have gone through LabView forum on your web site but found none advise.

Could you please share the code regarding above or add the features to PS5000a.dll or help me regarding the above required features.

Thank you very much for your help.

Kind Regards,

Mirko

Hitesh
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Location: St. Neots, Cambridgeshire

Re: PicoScope PS5000a and traditional oscilloscope

Post by Hitesh » Mon May 21, 2018 2:35 pm

Hi Mirko,

The low pass filter and zero offset features available via the channel options in PicoScope 6 are implemented in the application rather than via the API functions.

The PicoScope User's Guide provides some information about the low pass filter - open the User's Guide via the Help menu and search for lowpass filtering in the Index. You should find information about using a moving average or FIR filter depending on the ration of the selected cut-off frequency to the sampling rate.

For the zero-offset, please refer to this post.

With regards to coupling, the PicoScope is grounded via the USB connection to the PC (unless it is a laptop without the power supply connected) and you can set AC/DC coupling via the channel settings in LabVIEW. Are you referring to something else?

Regards,
Hitesh

Technical Support Engineer

Mirko_CLTD
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Re: PicoScope PS5000a and traditional oscilloscope

Post by Mirko_CLTD » Tue May 22, 2018 1:46 am

Hi Hitesh,

I understand these three functions are not in API. It would be beneficial from user point of view (usability) if you guys wrap them in separate DLL. That way PicoScope would be better match for real oscilloscope. You may argue further signal processing is not a part of oscilloscope but have a look at many of them having measurements and math functions included. Take it as a good suggestion.

Thank you for advise about filters. I will see what LabView has regarding FIR filter.

True I can do zero offset by shorting the input, average big sample to calculate offset value then feedback the value to offset input of ps5000aSetChannel. The problem here is shorting the input - seems that PicoScope has no such function so input shorting from external side is required and that is not easy when unit is installed as a part of bigger system.

I was referring to input coupling AC/DC/GND (where no GND at PicoScope), not how ground of PicoScope is connected to PC and/or power supplies. That is shorting input to ground (required for offset in this case).

Kind Regards,

Mirko

Hitesh
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Re: PicoScope PS5000a and traditional oscilloscope

Post by Hitesh » Wed May 23, 2018 11:48 am

Hi Mirko,

Thank you for your reply.

I have logged your comments on one of our systems so we will see what we can provide in the future.

I will also add a new feature request for zero offset application via the driver. When using the zero-offset feature in PicoScope 6, the channel inputs are short-circuited normally by connecting the centre pin to the outer part of the BNC connector, as this is normally grounded via the connection to the PC (assuming it is on mains power).

The only coupling options for the PicoScope 5000 Series is AC or DC.

Regards,
Hitesh

Technical Support Engineer

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