The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
Subject: Re: Ultrasonics basics
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Fri, 22 Nov 2002 09:46:20 -0000
NNTP-Posting-Date: Fri, 22 Nov 2002 09:46:26 GMT
> "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 the 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 reflected pulse the receiver looks for is surely the
>> reflection of the last pulse transmitted?
>> Is the reason for the 6 inch minimum distance because the
>> transducers "ring" and so swamp any reflected pulses? If so would a
>> higher frequency be the answer?
>> If this is the case are any standard transducers available other
>> than 40KHz? So many questions! Does anyone know the answers please?
>> Thanks in anticipation, Dave.
> Thanks for all the replies.
> I must have my decimal point in the wrong place somewhere.
> Wavelength = velocity / frequency = 330 / 40000 = 8.25mm ?
Seems ok to me.
> Also how would you go about measuring the phase difference? Can
> someone point me towards some reading material please!
I would not bother if I were you. Its just an added complication.
Extracting phase info from a few cycles in a burst is going to get you
into all that digital processing sort of stuff.
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup