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Subject: Re: Ultrasonics basics
Date: Fri, 22 Nov 2002 09:36:47 -0000
NNTP-Posting-Date: 22 Nov 2002 09:34:39 GMT
X-Newsreader: Microsoft Outlook Express 5.50.4133.2400
Thanks for all the replies.
I must have my decimal point in the wrong place somewhere.
Wavelength = velocity / frequency = 330 / 40000 = 8.25mm ?
Also how would you go about measuring the phase difference? Can someone
point me towards some reading material please!
"Dave" wrote in message
> Hello all,
> I want to measure short distances (1 to 2 inches) using reflected
> ultrasonics (i.e. a Tx bouncing back to an Rx). Using 40KHz transducers
> minimum achievable seems to be about 6 inches.
> Looking at existing circuits the transmitter usually sends a burst of 6 to
> 10 pulses? What is the reason for this i.e. why not one pulse? The
> pulse the receiver looks for is surely the reflection of the last pulse
> Is the reason for the 6 inch minimum distance because the transducers
> and so swamp any reflected pulses? If so would a higher frequency be the
> If this is the case are any standard transducers available other than
> So many questions! Does anyone know the answers please?
> Thanks in anticipation, Dave.
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