Re: Ultrasonic Heterodyning

Kenneth Carrigan ( (no email) )
Mon, 1 Feb 1999 09:04:00 -0500

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In order for waves to mix, there needs to be a nonlinear junction. As =
in a 'diode'
function for electrons, and ferrous products that contain oxides or =
dissimilar
metals.. all have some non linear juntions. For sounds waves to mix, =
there also
must be some non linear materials. I hear that air is non linear when a =
high
enough power and high frequency is utilized.. but do not know this for =
certain.
v/r Ken Carrigan

Hi all!
I know that if two sound waves are beat together, you get the =
two originals, the sum and difference waves.=20
Question: If you beat the output of two ultrasonic transducers, =
can the difference be heard if it is within the audible range? =20
EXAMPLE: Two transducers, 1 at 40KHz, the other at 39KHz are =
next to each other pinging away. Will you hear the 1KHz difference, or =
must your acoustic detection abilities be in the ultrasonic to hear the =
beat?
BillP
=20

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In order for waves to =mix, there needs=20to be a nonlinear junction.  As in a 'diode'
function for=20electrons, and ferrous products that contain oxides or=20dissimilar
metals.. all have=20some non linear juntions.  For sounds waves to mix, there=20also
must be some non=20linear materials.  I hear that air is non linear when a=20high
enough power and=20high frequency is utilized.. but do not know this for=20certain.
v/r Ken Carrigan
Hi=20 all!
    I know that if two sound waves are beat =together,=20 you get the two originals, the sum and difference waves.=20
Question:     If you beat the output of two=20 ultrasonic transducers, can the difference be heard if it is within =the=20 audible range? 
EXAMPLE:     Two =transducers, 1=20 at 40KHz, the other at 39KHz are next to each other pinging away. =Will you=20 hear the 1KHz difference, or must your acoustic detection abilities =be in=20 the ultrasonic to hear the=20beat?
BillP

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