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What exactly is its sample rate?

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What exactly is its sample rate?

Postby Ben321 » Sun Feb 25, 2018 8:50 am

With the Picoscope 5000, what exactly is its maximum sample rate? I'm looking at the different sources of info on it from the various pages on your site. On this page https://www.picotech.com/library/oscill ... aming-mode it says that the maximum USB streaming sample rate for the 5000 series is 10MS/s when using the SDK. However when looking at https://www.picotech.com/oscilloscope/5 ... ifications it says that the maximum sample rate for USB streaming when using the SDK is >(greater than) 10MS/s. So which is it? Is it capped at 10MS/s or not?

Also which bit-depth is this documentation referring to? I assume it can stream faster when using 8 bit mode than when using 12, 14, or 16 bit mode, simply because it has less data that it needs to send. Can anybody write out exactly what the specs are here? Because I'm not going to be buying any of these more expensive scopes (like a 4000 series or 5000 series Picoscope unit) until I'm sure exactly what the specs are.

My intent is to use USB streaming only (not block transfer mode), and to use the SDK (not Picoscope 6 software) to write my own program to use a sample rate that is not limited by the Picoscope 6 software. However I also need reasonable bit-depth (greater than 8-bits).

Specifically, when using the SDK, the USB streaming mode of the scope I will purchase must be able to run at at least 12MS/s when using one channel (I know it slows down when using more than one channel). Also, it must be able to do this 12MS/s when running at a bit-depth greater than 8-bits-per-sample. And I want to spend the least amount of money needed to meet these requirements.
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Re: What exactly is its sample rate?

Postby bennog » Sun Feb 25, 2018 9:02 am

It is usb3 you can go far beyond the 12Ms/s

from this page https://www.picotech.com/library/oscilloscopes/streaming-mode

USB 3.0 is about ten times faster, with a theoretical maximum transfer rate of about 400 MB/s. USB 3.0 PicoScopes have exceeded 150 MS/s in tests.


And if I remember correctly, data is always as 16bit words transferred over USB.

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Re: What exactly is its sample rate?

Postby Ben321 » Sun Feb 25, 2018 9:19 am

bennog wrote:It is usb3 you can go far beyond the 12Ms/s

from this page https://www.picotech.com/library/oscilloscopes/streaming-mode

USB 3.0 is about ten times faster, with a theoretical maximum transfer rate of about 400 MB/s. USB 3.0 PicoScopes have exceeded 150 MS/s in tests.


And if I remember correctly, data is always as 16bit words transferred over USB.

Benno



Thanks for the info. So Picoscope 5000series units do use USB3? I was considering a 5242A or 5242B. Does this unit's USB stream slow down when running running over 8-bits-per-sample? Has anybody tested a 5242A or 5242B using the SDK, and run it at different bit-depths, to see how much the sample rate is slowed down when the bit depth is increased over 8-bits-per-sample?

You cited over 150MS/s for the USB3 Picoscopes? Which model exactly was that tested on? Was it the 5242A/5242B model, or one of the more expensive ones? Also, was this test using 8-bit mode, or a higher bit depth? And how many channels were used in the test, just one, or all the channels?
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Re: What exactly is its sample rate?

Postby bennog » Sun Feb 25, 2018 2:35 pm

Sorry misred the 5000 series is USB2 and so limited to max USB2 streaming speed.

So your best bet is about 15MS/sec for usb2 and the SDK, depending on hardware config of your PC.
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Re: What exactly is its sample rate?

Postby Ben321 » Sun Feb 25, 2018 7:43 pm

bennog wrote:Sorry misred the 5000 series is USB2 and so limited to max USB2 streaming speed.

So your best bet is about 15MS/sec for usb2 and the SDK, depending on hardware config of your PC.


Thanks. And does increasing its bit-depth from 8-bits-per-sample to 12-bits-per-sample slow this down? Or can I expect to get about 15MS/s over USB2 regardless of what bit-depth I'm using?
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Re: What exactly is its sample rate?

Postby Martyn » Mon Feb 26, 2018 8:57 am

USB2 line rate is approximately 48MB/s.

With the 5000 series devices it is possible to continuously stream on a single channel at 15.625 MS/s with the full 16 bit resolution using the SDK. You can set a faster streaming rate, up to 62.5MS/s, but this is only sustainable for very short time frames making use of the internal memory of the device to prevent data loss.

If you can give some more details on your requirements, either here or to support@picotech.com, then we can advise on the best PicoScope for your needs.
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Re: What exactly is its sample rate?

Postby Ben321 » Mon Feb 26, 2018 11:13 pm

Martyn wrote:USB2 line rate is approximately 48MB/s.

With the 5000 series devices it is possible to continuously stream on a single channel at 15.625 MS/s with the full 16 bit resolution using the SDK. You can set a faster streaming rate, up to 62.5MS/s, but this is only sustainable for very short time frames making use of the internal memory of the device to prevent data loss.

If you can give some more details on your requirements, either here or to support@picotech.com, then we can advise on the best PicoScope for your needs.


Thank you for that info. It was very useful. I probably will be getting a 5000 series Picoscope then later this year or next year, as it sounds like it will fit all my requirements.
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