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HOW TO MEASURE TIME OF FLIGHT

Hello,
I'm trying to message a transducers time of flight. The transducer has
two leads and has an operating frequency of 40 kHz. I would like to
see the reflected wave vary when I move the target with respect to the
initial pulse . I just don't know how to setup my equipment to do
this. Could someone please tell me how to do this and if is the wrong
forum please let me know where I should post this question.
Thanks for any and all help.

Best regards,
Ken

I have the following equipment:
Tektronix TDS 3012B scope
Tektronix 2246 scope
B&k 3011 2MHz function generator
Wavetek 4 MHz sweep/ function generator
101 Pulse generator
 
B

BobG

Jan 1, 1970
0
Speed of sound is about 1120 ft/sec at std temperature and
pressure.... about 1ms per foot
 
J

John Popelish

Jan 1, 1970
0
Hello,
I'm trying to message a transducers time of flight. The transducer has
two leads and has an operating frequency of 40 kHz. I would like to
see the reflected wave vary when I move the target with respect to the
initial pulse . I just don't know how to setup my equipment to do
this. Could someone please tell me how to do this and if is the wrong
forum please let me know where I should post this question.
Thanks for any and all help.

Best regards,
Ken

I have the following equipment:
Tektronix TDS 3012B scope
Tektronix 2246 scope
B&k 3011 2MHz function generator
Wavetek 4 MHz sweep/ function generator
101 Pulse generator

I think the scope and pulse generator may be most of what
you need. The biggest problem, after finding the best burst
waveform will be the fact that the outgoing signal is
thousands of times larger than the received signal. You use
one trace, that triggers the scope sweep, on the outgoing
burst, then use a second trace with a much higher gain, to
see the returned signal. I think this trace should also
have a series resistor and a pair of diodes across the scope
input, to clamp the large outgoing signal, so that you don't
severely overload the high gain vertical amplifier. If the
scope has delayed sweep, you will have finer resolution on
the timing measurement.

If this sort of simple hook up does not have the gain to see
the returned echo, you will have to build some sort of
limiting amplifier to boost the signal and handle the huge
overload of the outgoing burst.

Can the target be a corner reflector, so that you have good
reflection efficiency?
 

neon

Oct 21, 2006
1,325
Joined
Oct 21, 2006
Messages
1,325
if you ever figure it out let me know the wavelengt is 3x10-10 cm does that help. if you are going to get a delay it will be because of you time delay in the electronics not from light shift you want to test that just short the input and measure it.dhh?
 
I think the scope and pulse generator may be most of what
you need. The biggest problem, after finding the best burst
waveform will be the fact that the outgoing signal is
thousands of times larger than the received signal. You use
one trace, that triggers the scope sweep, on the outgoing
burst, then use a second trace with a much higher gain, to
see the returned signal. I think this trace should also
have a series resistor and a pair of diodes across the scope
input, to clamp the large outgoing signal, so that you don't
severely overload the high gain vertical amplifier. If the
scope has delayed sweep, you will have finer resolution on
the timing measurement.

If this sort of simple hook up does not have the gain to see
the returned echo, you will have to build some sort of
limiting amplifier to boost the signal and handle the huge
overload of the outgoing burst.

Can the target be a corner reflector, so that you have good
reflection efficiency?

Hi and thank you fog your reply. I've never done anything like this
would it be too much to ask to send me a schematic of the gen. and
scope hook up along with the resistor/diode network.
Once again thanks for taking the time to reply.
Regards,
Ken
email address: [email protected]
 
J

John Popelish

Jan 1, 1970
0
Hi and thank you fog your reply. I've never done anything like this
would it be too much to ask to send me a schematic of the gen. and
scope hook up along with the resistor/diode network.
Once again thanks for taking the time to reply.
Regards,
Ken
email address: [email protected]

Sorry, I think I will bow out, now. If you are not familiar
enough with both the equipment and the transducer to take an
educated guess as to how they should be connected, I doubt
that my guesses that will have to be refined by
experimentation will do you much good.
 
P

Phil Allison

Jan 1, 1970
0
I've never done anything like this
would it be too much to ask to send me a schematic of the gen. and
scope hook up along with the resistor/diode network.


** You had better get a second transducer and use that for receive only.

Then ask one of the PAID STAFF at that lab to show you what to do.




.......... Phil
 
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