Streaming mode at high sampling rate

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mattou
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Streaming mode at high sampling rate

Post by mattou » Tue Oct 22, 2019 3:42 pm

Hello,

For my experiment, I am using a picoscope 6407 to capture electromagnetic emanations. I need to capture the data in real time during long periods of time, so I am using the streaming mode of the picoscope. I am encountering several problems in the process.

First of them is the API itself does not let me define a sample rate > 150 MS/s, when I would need to get data at 1GS/s (the picoscope has a capacity of 5GS/s according to the specs).

Second is I can only connect an usb2 cable, which is probably limiting the amount of data I can transfer to my computer. I can see here that it should be compatible with usb3. Am I missing something?

Finally, since data quickly get bigger than the memory, I need to write them in a file stored in the hard drive. The thing is 1GS/s is faster than the HDD write speed. Do you guys have any solution for this kind of problem? Would upgrading to a SSD be enough? Should I buy a huge RAM amount?

Thanks a lot by advance.

bennog
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Re: Streaming mode at high sampling rate

Post by bennog » Wed Oct 23, 2019 5:48 am

From here
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.
Each sample is (most of the times 16bits or 2 bytes) so the max you is theoretical 200MS/s.
There are a lot of other things hindering the speed of the USB (CPU speed) disk acces, video acces, ....
Even if there is a slight hiccup in windows you have a big backlog in the USB data witch can not run in because you are using the USB at max speed.

so 150MS/s on a fast PC 4+ cores 4+ Ghz and a lot of memory is probably the fastest you can get.

Benno

Martyn
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Re: Streaming mode at high sampling rate

Post by Martyn » Wed Oct 23, 2019 6:25 am

The 6407 is not part of the PicoScope 6000 series that use USB3 which is why there are two tabs here it is a USB2 only device.

Continuous streaming is limited to 9.7MS/s using our PicoScope 6 software, and a bit higher if you write your own application, and this is shared amongst the active channels. You can find the full specifications here

Your intended use is not possible with the 6407 or any of the devices in our range. The fastest streaming rates are around 150MS/s shared between active channels for the USB3 devices, and 15MS/s for the USB2 devices.
Martyn
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mattou
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Re: Streaming mode at high sampling rate

Post by mattou » Wed Oct 23, 2019 10:41 am

Thank you for your answers, I was apparently clearly overoptimistic about the performances of the pico 6407.
I will try to see if the block mode would be a suitable alternative for what I am trying to achieve.

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