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Buffered High Speed ADC for embedded oscilloscope

Discussion in 'General Electronics Discussion' started by MBrantley, Jan 21, 2015.

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  1. MBrantley


    Jan 21, 2015

    I am working on a project that involves applying an RF (6-14MHz) sine wave and our project design goal was to have an oscilloscope embedded in the device to monitor signal intensity and integrity. Our signal is a pulsed RF that we are interested in knowing the Vpp and basic visualization of the sine wave for visual inspection.

    Initially I purchased a Bitscope Micro (BS05) but based on the feedback from the company, their super sampling techniques don't quiet extend to the higher end of their advertised bandwidth (20MHz). Now I am trying to find a new approach and wanted to discuss an idea with some more experienced people (I am a chemist, not an EE).

    Because our signal is 6-14MHz I suspect we need a sampling rate of atleast 200MSps. I'm not finding any off the shelf USB oscilloscopes that have that capture speed (and fit in our control module) - I suspect due to limitations in USB transfer rates? If you know of a prepackaged solution that could integrated with a Raspberry Pi or comparable device please let me know.

    The idea I would like to discuss is the ability to take a high speed ADC, use that to write to some embedded memory (this would be the capture window at at least 200MHz) at a set frequency (maybe capture the full window 1000x per second or so) and then push those captures through USB or I2C to the micro controller. I understand this would be absolutely useless for non-continuous signals as no information would be stored in between full window captures - but it would fit the design goals of displaying the sine wave to the user and monitoring frequency/Vpp. I feel like there are probably already ways to do this - but I haven't been able to locate them yet.

    Do devices like this exist already? Is there possibly a simpler way to approach this? I have no experience with FPGA but I'm confident I could learn them if needed. What about the PCUs on a Beaglebone black?

    Any insight or discussion is appreciated!

  2. BobK


    Jan 5, 2010
    There are fast buffered ADC chips out there that would do what you need (at least the capture portion of it). I don't remember who makes them, but if you search at Mouser or DIgi-key, I am sure you can find one.

  3. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Fast sampling oscilloscopes with deep memory are pricey. For a USB device, check out this manufacturer. Not cheap, but less costly than a comparable bench 'scope from Tektronix, Agilent, or Rohde & Schwarz. USB bandwidth is not generally a consideration. Accquisition occurs in the box and results are sent via USB for display on an attached computer. Not even close to being real-time, but usually adequate for most purposes.
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