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PicoScope Beta 6.9.5: New filter options

Forum for discussing PicoScope version 6 (non-automotive version)

PicoScope Beta 6.9.5: New filter options

Postby alan » Thu May 22, 2014 11:45 am

Beta releases have NOT been fully tested by us. If you choose to install and use the beta software you should expect to run into bugs. These bugs may range in severity from minor features that don’t work to problems that may cause your PC to crash.

This forum post is intended to provide a brief introduction to a new feature prior to full instructions being added to the manual. If you have any questions / comments about its use (including just wanting to thank the developers for adding the feature :D) then please post below.

Most PicoScope oscilloscopes have both hardware-based low pass filters (bandwidth limiters) and software-based low pass filters (digital filters). Each type of filter has different advantages and disadvantages that are described in the manual. These filters can be used independently or combined for maximum flexibility.

As low pass filters are the ones most commonly used, they are available in the channel options as shown below:

oscilloscope filtering ui.jpg


In PicoScope 6.9.4 we have added more digital filters (high pass, band pass etc.) and made them available as maths channels. The advantage of using maths channels is that you can now display the original (unfiltered) waveform at the same time as the filtered waveform. In the example below I have used the built-in AWG on a PicoScope 3406B to create a sine wave corrupted with a higher-frequency square wave (blue trace at top). The filtered version (black at bottom) shows the sine wave with the higher-frequency noise removed.

oscilloscope filtering ui 2.jpg


To use these new functions follow these steps:

1. Create a new maths channel (Tools > Maths Channels > Create)

2. Select Advanced in the maths channel equation editor and on the left choose the filters option. You then have a choice of

* High pass
* Low pass
* Band pass
* Band stop

oscilloscope filtering ui 3.jpg


You can select the filter type using the icons, then select the channel and frequency in Hz. The correct format for a 10 kHz low pass filter on channel A is as follows:

LowPass(A,10000)

The filter options can be combined with other maths channel operators to make some incredibly powerful functions. For example the equation below takes channel A and subtracts channel C multiplied by the square root of channel D. It then bandpass-filters the result between 1 kHz and 2 kHz:

BandPass(A-(C*sqrt(D)),1000, 2000)

3. Once you have chosen your filter, click Next to choose the maths channel name and trace color. Click Next again to choose your units and ranges.

4. The filter you have created should now appear in the library and can be selected and used.
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Re: PicoScope Beta 6.9.5: New filter options

Postby Ax2_ » Tue Sep 02, 2014 4:54 pm

Please enable digital filtering as channel options for 2000-series scopes too. A lot can be done with math channels but there are few essential use cases which are not possible. Triggering is one - as an example. Maybe adding triggering possibility from math channel too, but it is worse workaround IMHO. The comprehensive solution would allow digital filtering - or.... a selection from math channels as a pre-processing function in channel options. THAT would be something!

BTW: Noticed few limitations in combining average and filtering in one math channel.

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Re: PicoScope Beta 6.9.5: New filter options

Postby Martyn » Thu Sep 11, 2014 10:07 am

This is currently being considered by the development team, thank you for your feedback.
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Re: PicoScope Beta 6.9.5: New filter options

Postby Ax2_ » Thu Sep 11, 2014 8:19 pm

Thanks for the information.
Very good, very good...

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