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Newbie question re. buffer memory

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Newbie question re. buffer memory

Postby Steve Thackery » Wed Jun 22, 2011 10:47 pm

Hi,

I'm struggling with what is probably a very basic concept: buffer memory.

Having used a traditional digital storage scope, I've got used to each scope having a certain storage capacity for samples. For example, one which stores 10,000 samples will record that many samples when triggered. I can then move back and forth through the stored data looking at the waveform.

The problem is, I thought it was the PicoScope software on the PC that stored the captured samples. So what relevance does the "buffer memory" have which is quoted for the various different PicoScopes. For instance, the 2105 has a buffer memory of 24Ks. But why do I care about that, when all the data is streaming back to the PC and (presumably) being recorded by the PicoScope software?

Thanks for what is probably a very daft question!

Steve
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Re: Newbie question re. buffer memory

Postby ziko » Thu Jun 23, 2011 3:09 pm

Hi Steve, the device operates in two modes:

1) Block mode
2) Streaming mode

1) Block mode, the device can sample at very high rates to the memory of the device and then trasnfer to the PC
2) Streaming mode is when it streams directly to the PC.

In block mode you can achieve very high sample rates in the 2105s case 100MS/s this cannot be achieved in streaming mode. In streaming mode the 2105 streams at 1kS/s.

On our newer products the streaming rate is much higher in MS/s.

Kind regaerds
Ziko

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Re: Newbie question re. buffer memory

Postby Steve Thackery » Thu Jun 23, 2011 9:27 pm

Hi Ziko,

Thank you for that information - it explains it all perfectly. I assume I can switch it between block and streaming using the PicoScope software?

By the way, I can't find the block/streaming rates for the various products so I can compare them. Could you point me to the relevant page?

Many thanks,

Steve
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Re: Newbie question re. buffer memory

Postby ziko » Mon Jun 27, 2011 10:21 am

Apart from the 2104/2105 all our current USB products support fast streaming modes, which can give you 1MS/s or more. There are no exact figures of what you can get them to stream at as it is PC dependant.

All our USB scopes including the 2104/2105 support block mode, the length of time these devices can sample at high rates is dependant on the devices memory.

The following link gives a brief overview of the range, ignore the 9000 series as this is a Sequential Sampling Oscilloscope and is not a real time oscilloscope:

http://www.picotech.com/oscilloscope-sp ... tions.html

Kind regards
Ziko

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Re: Newbie question re. buffer memory

Postby Jeff » Fri Jul 01, 2011 1:13 pm

We also have a technical note on block-mode and streaming-mode speeds, which covers our scopes up to the 5000 Series:

kb/kbfiles/PicoScopeUSBStreaming.pdf
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Re: Newbie question re. buffer memory

Postby forjack842 » Wed Jul 20, 2011 10:43 pm

I would like to record the streaming data to a file for possibly hours. Does the 2203 software suport this if the PC is capable?
Thanks
Jack
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Re: Newbie question re. buffer memory

Postby ziko » Thu Jul 21, 2011 11:24 am

Hi that really does depend on the sampling rate, the article Jeff pointed out will give you some idea.

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