ultrasonic defectoscope

Discussion in 'Homework Help' started by c e z a r, Dec 16, 2010.

  1. c e z a r

    Thread Starter New Member

    Dec 16, 2010
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    hello! i'm currently working to develop a device that can generate an ultra sonic 2MHz signal to a transmiter/receiver transducer (made especially for this kind of work) used for detecting cracks in metals. normally, this kind of operation is made by a special device which looks like an osciloscope. i allready have the transducer so my plans are to build a device that can generate short blips with this kind of signal 3 times the period (of blip) between the blips. one blip should be minus the cube of 10 in seconds. the device should be able to receive back the signals produced by echos returned from the metal piece that is analized. this signal i would like to see on one of those oscilloscope software type that are available on the internet, so the whole device can be controled by computer. more by token, the device will have two essential parts, the signal generator and the signal receiver which i would like to connect to the computer through the usb or serial port. for starters, a 2MHz signal generator scheme is needed. if anybody can help me pls post here!
     
    Last edited: Dec 16, 2010
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    School assignment?
     
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Sounds similar to the function of a TDR (Time Domain Reflectometer) used to find how long a cable is, or the location of a fault in a cable.

    If you search for DIY TDR, you may find some schematics close to what you are looking for.

    Have you got any start on it, or just the assignment/idea?
     
  4. wayneh

    Expert

    Sep 9, 2010
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    I could be wrong but I think software oscilloscopes receiving data over USB will not be able to handle a signal at 2MHz. Audio range, yes. There is data acquisition hardware available that could handle this easily.
     
  5. shortbus

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    Sep 30, 2009
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  6. Wendy

    Moderator

    Mar 24, 2008
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    Last I checked you are wrong, you are confusing a USB coupled digital oscope with a sound card oscope. The USB variety are very capable units, spend the money an they can go to the gigahertz range.
     
  7. c e z a r

    Thread Starter New Member

    Dec 16, 2010
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    hi all! Thanks for all posts on this thread! Yes it is a school assignment , I'm in the last year of college, and this is an optional "homework project" and, yes, i know too, that this kind of devices already exist cause i've learned about them at school,from there I got the idea to build one . Now,i have already the electrical diagram of a pulse generator based on one 555, one 7400 and one 7474 IC, which can generate an impulse with 2Mhz frequency and 1 milisecond long with 3 miliseconds between the impulses. Now the problem is to receive back and read the impulses created by the quartz crystal. how should i do that by way of USB? any ideas?
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    USB is only a communications protocol (with a physical implementation). It send data back and forth, say between a microprocessor and a desktop computer.

    To "read" the pulses means you need a transducer that can resolve the ultrasonic pulses reflected back in amplitude and time from the originating pulse. Once that information has been digitized, it can be sent via USB.
     
  9. c e z a r

    Thread Starter New Member

    Dec 16, 2010
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    hello! yes i understand that. So, that means i must use like arduino platform or something like that? Doesn't an easier way exist?
     
  10. beenthere

    Retired Moderator

    Apr 20, 2004
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    You might help out and state the full system you are constructing. If it will be a local microprocessor collecting data and sending it to a larger computer, USB is very attractive in that every computer has USB ports.
     
  11. thatoneguy

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    Feb 19, 2009
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    What you will be building is essentially a limited version of an oscilloscope. Essentially, nearly all of the processing is done in that package, usually a processor and RAM, and only the display data is sent to the computer.

    An Arduino wouldn't be capable of the speeds and power you need. Using even an AVR or PIC would give the speeds you are looking for unless they are controlling external flash ADCs.

    The solution will be closer to a full processor with RAM, which then sends results to the PC via USB Protocol, the PC program will then render the data received into a graph. This is the reason good Digital scopes, especially Ghz + scopes, are as spendy as they are.
     
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