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Technical Discussions
George Trieu
George Trieu
00:27 Aug-14-2003
Signal Recovery

Can someone recommend an instrument that can recover a pulsed sinusoidal signal buried in noise? The signal is a pulse-echo excitation response. It is generated by a receiving transducer in an ultrasonics experiment. Any help is appreciated.




 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1292

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1292
03:33 Aug-14-2003
Re: Signal Recovery
Mr. Trieu:
The origin of noise in an ultrasonic setup can be from various sources. Some of the noise may be reduced by using bandpass filters and these are often incorporated into some instruments. You might also try tuning the pulse to the transdcer. This would attempt to increase the efficiency of transmission so the amplitude of the pulse is greater than the surrounding noise component. But often the noise is not so easy to get rid of by simple electronics hardware. Some instruments are equipped with software that allows Digital Signal Processing (DSP). Possibly the most common option for noise reduction uses signal averaging. Most TOFD systems have this feature and averaging of 2, 4 or 8 times will average out the noise and at the same time enhance a real signal of interest.

If that is not sufficient then you may also resort to other DSP options (like Weiner Filtering) where you would process captured signals to extract the signals of interest.
Ed
----------- Start Original Message -----------
: Can someone recommend an instrument that can recover a pulsed sinusoidal signal buried in noise? The signal is a pulse-echo excitation response. It is generated by a receiving transducer in an ultrasonics experiment. Any help is appreciated.
------------ End Original Message ------------




 
 Reply 
 
Joerg Schulze-Clewing
Joerg Schulze-Clewing
03:12 Aug-15-2003
Re: Signal Recovery
George, you also need a good range gate that only opens
for the short time where you receive the pulse echo.
This range gate should have a good off isolation and
also should not inject noise when switching in and out.
In tech terms this is called "low charge injection
noise".

----------- Start Original Message -----------
: Can someone recommend an instrument that can recover a pulsed sinusoidal signal buried in noise? The signal is a pulse-echo excitation response. It is generated by a receiving transducer in an ultrasonics experiment. Any help is appreciated.
------------ End Original Message ------------




 
 Reply 
 
George Trieu
George Trieu
00:21 Aug-19-2003
Re: Signal Recovery

Thank you all for the helpful inputs. Can you guys recommend a good signal averager and a good range gate. Thank you again.

George


----------- Start Original Message -----------
: George, you also need a good range gate that only opens
: for the short time where you receive the pulse echo.
: This range gate should have a good off isolation and
: also should not inject noise when switching in and out.
: In tech terms this is called "low charge injection
: noise".
: : Can someone recommend an instrument that can recover a pulsed sinusoidal signal buried in noise? The signal is a pulse-echo excitation response. It is generated by a receiving transducer in an ultrasonics experiment. Any help is appreciated.
------------ End Original Message ------------




 
 Reply 
 
Joerg Schulze-Clewing
Joerg Schulze-Clewing
00:08 Aug-19-2003
Re: Signal Recovery
George, in the past I never found a commercial range gate and always built my own. You can use FET arrays such as the SD5000 (Siliconix) series or quad diode (HP/Agilent)arrays. This was a long time ago so things might have changed.

Averager: I sometimes used digital scopes. You might want to talk to the folks at the RF institute at your university. There are also very fast digital acquisition cards (mostly called AD cards) for PCs, for example from a company named Gage. When you use one of those you might be able to do a lot in software to control how things get acquired and averaged.

Good luck, Joerg.

----------- Start Original Message -----------
:
: Thank you all for the helpful inputs. Can you guys recommend a good signal averager and a good range gate. Thank you again.
: George
:
: : George, you also need a good range gate that only opens
: : for the short time where you receive the pulse echo.
: : This range gate should have a good off isolation and
: : also shouldnot inject noise when switching in and out.
: : In tech terms this is called "low charge injection
: : noise".
: : : Can someone recommend an instrument that can recover a pulsed sinusoidal signal buried in noise? The signal is a pulse-echo excitation response. It is generated by a receiving transducer in an ultrasonics experiment. Any help is appreciated.
------------ End Original Message ------------




 
 Reply 
 

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