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Picosocpe 2000 series - Downsampling

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Picosocpe 2000 series - Downsampling

Postby akilanakil » Tue Feb 05, 2013 6:37 am

In Picosocope 2205, does the downsampling occour on the scope Hardware or in the computer (driver)?
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Re: Picosocpe 2000 series - Downsampling

Postby Hitesh » Tue Feb 05, 2013 10:26 am

Hi,

The downsampling (aggregation) is carried out by the driver.

Hope this helps.
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Re: Picosocpe 2000 series - Downsampling

Postby akilanakil » Fri Feb 08, 2013 8:42 am

Thanks for the help Hitesh :D
My application requires downsampling at scope hardware and hence I have to go for one which supports it. Does any other device in 2200 & 3200 series support downsampling at hardware :?:
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Re: Picosocpe 2000 series - Downsampling

Postby Hitesh » Fri Feb 08, 2013 5:02 pm

Hi,

I'm afraid both the 2200 and 3200 devices use the driver to downsample data as required. The following article may be of interest - please see the Aggregation mode section:

http://www.picotech.com/support/kb/kbfiles/PicoScopeUSBStreaming.pdf

Regards,
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Re: Picosocpe 2000 series - Downsampling

Postby akilanakil » Sun Feb 10, 2013 10:03 am

Oh :(
Anyway thanks & I'm enjoying my 2205 and probably would put it to use in some other application.

But In section 2.11.18.1 (page #43) of the document 'Picoscope 2000 Series Programmer's guide (A API) ' (ps2000apg.en.pdf available in the SDK zip) the following is said about downsampling:
Various methods of data reduction, or downsampling, are possible with the
PicoScope 2000 Series oscilloscopes. The downsampling is done at high speed by
dedicated hardware inside the scope, making your application faster and more
responsive than if you had to do all the data processing in software.


Also in section 2.1.12.20.1 (page #49) of 'Picoscope 3000 Series Programmer's guide (A API) ' (ps3000abpg.en.pdf), the same thing is repeated
Various methods of data reduction, or downsampling, are possible with the
PicoScope 3000A Series oscilloscopes. The downsampling is done at high speed by
dedicated hardware inside the scope, making your application faster and more
responsive than if you had to do all the data processing in software.


Downsampling.png
The portion of 'Picoscope 3000 Series Programmer's guide' about downsampling


:?
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Re: Picosocpe 2000 series - Downsampling

Postby Hitesh » Mon Feb 11, 2013 10:22 am

Hi,

Sorry about the mix-up :oops:

The PicoScope 2205 uses a different driver to the PicoScope 2205 MSO, 2206, 2207, 2208 - these last few devices use the 2000 A API rather than the old PicoScope 2000 series API.

The PicoScope 2205 has a different feature called oversampling, which is carried out by the hardware:

When the oscilloscope is operating at sampling rates less than the maximum, it is
possible to oversample. Oversampling is taking more than one measurement during
a time interval and returning an average. If the signal contains a small amount of
noise, this technique can increase the effective vertical resolution of the oscilloscope
by the amount given by the equation below:
Increase in resolution (bits) = (log oversample) / (log 4)


However, this is available for block mode capture only.

The PicoScope 2200 devices using the A API and the PicoScope 3X0XA/B and MSO devices have the downsampling feature in hardware which is called by the driver. There are 3 modes of downsampling as described in the Programmer's manual:

  • Aggregation
  • Averaging
  • Decimation

Additionally, you set up the data buffers (if you are writing your own software) according to the modes of downsampling that you are using (it is possible to set up more than one data buffer for a channel for different modes of downsampling).

I hope this helps :D
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Re: Picosocpe 2000 series - Downsampling

Postby akilanakil » Mon Feb 11, 2013 2:07 pm

Well then 3X0X A series looks good to me. Thanks for information Hitesh :D Have a nice Day!
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