Not fully using the sample buffer

Forum for discussing PicoScope version 6 (non-automotive version)
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jacob.larsen
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Not fully using the sample buffer

Post by jacob.larsen » Tue Nov 11, 2014 1:13 pm

It seems like the PicoScope software does not fully utilize the sample buffer. I have a PicoScope 6404D, which should have a 2GS sample buffer. But I can only get 1GS by shifting various settings. It looks like it could be a one-off bug in the software. If I set a single channel with the maximum settings, it shows that it is capturing 1,000,000,001 samples, suggesting that there is a bug there preventing it from doubling the buffer use.

I think the user interface could do with a tune-up in this area. It should be possible to configure these sets of parameters directly:

- Capture for x ms with sample rate y. Sample buffer size z is calculated from this.
- Capture z samples with sample rate y. Sample time x is calculated from this.
- Capture z samples for x ms. Sample rate y is calculated from this.

You would often use the constraints that sample buffer is set to max (2GS for 6404D). Sample rate will be limited to a fixed number that is specific to the setup being measured. For digital signals, this will most likely be 4x the fastest clocked line being measured.

Hitesh
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Re: Not fully using the sample buffer

Post by Hitesh » Tue Nov 18, 2014 12:21 pm

Hello Jacob,

The reason why PicoScope 6 is not able to collect the full 2GS in a single shot capture is due to the timebases available in the software.

In order to collect 2GS at the fastest sampling rate (5GS/s - 200ps sample interval), this would require a collection time of

200000000 * 200e-12 = 0.4s (400ms)

This would require a timebase of 40ms/div which is not supported. However, you should be able to achieve a collection of 1.25GS in a single shot capture using a sampling interval of 400ps and a timebase of 50ms/div.

If you are using the Software Development Kit, then you should be able to collect the full 2GS.

I will pass on your suggestions to the Development Team for consideration.

Regards,
Hitesh

Technical Support Engineer

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