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ipad app development

301 Views 4 Replies Latest reply: Apr 24, 2012 8:48 AM by Keith Barkley RSS
th0mh Calculating status...
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Apr 24, 2012 6:19 AM

Hello ive got a question for all of you out there that can code properly.

Ive got to make an ipad application, The point of the application is to show the current mhz (toons) that are

comming in by the ipad mic.(or external mic). But I have no idea how i can display the mhz on a live meter like a frequency meter.

Does anyone got some ideas for me or knows how to help me out. If you dont understand what type of program I'm meaning by this feel free to leave a comment aswell and I will try to explain it beter.

 

Thanks,

  Th0mh

  • FluBBa Calculating status...
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    Apr 24, 2012 6:53 AM (in response to th0mh)

    I guess you want to measure the frequency (mhz?)? Though I don't think the mic or the ADC (analog to Digital converter) in the iPad is able to work in the Mega Hertz range, probably up 20-40 kilo Hertz.

    Look up frequency analasys, FFT and so on, should give you some idea what you need to do.

  • Keith Barkley Level 5 Level 5 (5,140 points)
    Currently Being Moderated
    Apr 24, 2012 8:39 AM (in response to th0mh)

    You need to use the divide and conquer approach.

     

    (FluBBa's confusion comes because mHz stands for "milliHertz", or 1/1000 of a Hz. For audio frequencies you would use plain Hz or KHz [kiloHertz]. FluBBa [reasonably] assumed you meant MHz or MegaHz, which is millions of Hz, usually used for RF signals and way beyond the iPads capability.)

     

    First learn how to write a basic app that displays a number.

    Next read the microphone and determine when there is a signal.

    Lastly, perform an FFT to turn the signal samples into a set of frequencies.

     

    I suggest you get something like MatLab to experiment with the signal processing.

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