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Topic: Time Difference between Two Microphones (Read 10557 times) previous topic - next topic

jremington

I could not make much sense out of the microphone data sheet that you posted, so I think what you need to do is make sure that you have a good, clean signal from the microphones -- with amplitude changes of a VOLT or so when the sound of interest is present. If you have access to an oscilloscope, use it. If possible, post a picture of the signal.

You will probably need an amplifier and possibly also a low pass filter between the microphone and the Arduino input. Your chances of successfully analyzing a clean, strong signal are fantastically better than analyzing a weak, noisy signal.Just being able to correctly identify a frequency is *not* strong evidence that your signal is clean and strong.

michinyon

How do you propose the read the output of the microphone you posted a link to,  without an opamp ?

sventar

How are you getting on with the project? I am doing something similar, if you have finished it can you please send my your or code? If not, let's exchange emails and try to find a solution together :)

sesmd

Hi- I haven't read all posts, hope I'm not 'reinventing the wheel'.....
One possible approach, would be to run each mic thru a gain amp,
goal being output between 0 - 5 vdc for sound input into either mic.
Then run each amp output to a comparator, giving either a 0V or
5V signal for no sound/ sound.  Run each comparator output to a
hc86 XOR gate (each gate has two inputs), one hc86 input hooked
directly to comparator output,  other hc86 input having a small
capacitor (perhaps 0.1 uF) to gnd, and resistor to comparator out.
This circuit essentially 'splits' each comparator output into two
signals, slightly delaying one. The result is a positive going comparator
output signal yields a brief pulse from the HC86.  Overall effect is
for leading edge of sound signal, a brief digital pulse is generated
for each mic. (might also need a flip-flop, i.e. HC74, in circuit to
prevent repetitive pulses from a sound: use HC86 out to set HC74.
Run HC86 output, and -Q HC74 to AND gate. AND gate out is
single pulse/ sound.  Reset HC74 before next sound).  Then use
these digital pulses to start and stop a counter, and read counter
for sound delay mic 1 to mic 2.  Much of this could be done in
software on Arduino processor.

Hope this helps a little.

Stan Smale  (SESMD)
stanleysmd@gmail.com

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