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- since 1996 -
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Technical Discussions
Vinny
Vinny
04:04 Mar-17-2004
RF Display

When and why would you use the RF display when performing ultrasonic thickness measurements?


    
 
 Reply 
 
Richard Kazares
Richard Kazares
06:11 Mar-18-2004
Re: RF Display
The A-Scan is needed for thickness measurements when you want to be able to discriminate between corrosion (plate thinning) and possible delamination (linear internal cracking).

Without the A-Scan (or an Amplitude-based C-Scan image) it would be impossible to tell the difference - and could result in incorrect conclusions and repair actions.

----------- Start Original Message -----------
: When and why would you use the RF display when performing ultrasonic thickness measurements?
------------ End Original Message ------------




    
 
 Reply 
 
Phil
Sales, -
MISTRAS Products & Systems, USA, Joined Feb 2002, 12

Phil

Sales, -
MISTRAS Products & Systems,
USA,
Joined Feb 2002
12
09:20 Mar-18-2004
Re: RF Display
I concur

----------- Start Original Message -----------
: The A-Scan is needed for thickness measurements when you want to be able to discriminate between corrosion (plate thinning) and possible delamination (linear internal cracking).
: Without the A-Scan (or an Amplitude-based C-Scan image) it would be impossible to tell the difference - and could result in incorrect conclusions and repair actions.
: : When and why would you use the RF display when performing ultrasonic thickness measurements?
------------ End Original Message ------------




    
 
 Reply 
 
Vinny
Vinny
00:53 Mar-19-2004
Re: RF Display
I think you misunderstood the question. I realize you need the A-scan for identification of indications but what I was wondering is why would you use a RF display on the A-scan as opposed to using the full wave rectified or half wave + or half wave -.

My understanding is it is more accurate especially at high frequencys but I am not sure if this is right and if it is right why.

Can anyone please explain the purpose of the RF display.

Thanks.

----------- Start Original Message -----------
: I concur
: : The A-Scan is needed for thickness measurements when you want to be able to discriminate between corrosion (plate thinning) and possible delamination (linear internal cracking).
: : Without the A-Scan (or an Amplitude-based C-Scan image) it would be impossible to tell the difference - and could result in incorrect conclusions and repair actions.
: : : When and why would you use the RF display when performing ultrasonic thickness measurements?
------------ End Original Message ------------




    
 
 Reply 
 
Ahmed Yamani
Director, - President & CEO
Yamani Institute of Technology, Algeria, Joined Nov 2001, 23

Ahmed Yamani

Director, - President & CEO
Yamani Institute of Technology,
Algeria,
Joined Nov 2001
23
06:36 Mar-19-2004
Re: RF Display

RF (Radio Frequency) signal is needed if one is interested in advanced signal processing that uses phase information as well as amplitude,(such as defect identification/classification). However, if amplitude based signal processing is used one can used the rectified version of the A-scan.
Good Luck

----------- Start Original Message -----------
: I think you misunderstood the question. I realize you need the A-scan for identification of indications but what I was wondering is why would you use a RF display on the A-scan as opposed to using the full wave rectified or half wave + or half wave -.
: My understanding is it is more accurate especially at high frequencys but I am not sure if this is right and if it is right why.
: Can anyone please explain the purpose of the RF display.
: Thanks.
: : I concur
: : : The A-Scan is needed for thickness measurements when you want to be able to discriminate between corrosion (plate thinning) and possible delamination (linear internal cracking).
: : : Without the A-Scan (or an Amplitude-based C-Scan image) it would be impossible to tell the difference - and could result in incorrect conclusions and repair actions.
: : : : When and why would you use the RF display when performing ultrasonic thickness measurements?
------------ End Original Message ------------




    
 
 Reply 
 
Csaba Hollo
Csaba Hollo
04:29 Mar-27-2004
Re: RF Display
----------- Start Original Message -----------
: When and why would you use the RF display when performing ultrasonic thickness measurements?
------------ End Original Message ------------

Sorry if this is a bit of a diatribe...

Many a-scan instruments, including digital flaw detectors utilize gate intercept techniques for time of flight measurements. Observation of the back wall echo characteristics using the unrectified (RF) signal often leads to a more accurate measurement. The operator is able to select a more "clean" echo to trigger the measurement gate. Historically, I have used RF to take thickness measurements on high temperature materials using non hi temp couplants. The couplant would "flash", allowing a few seconds to take the measurement. With limited time for recognition of true back wall echos versus noise, the RF display helps a lot to determine the true back wall echoes.
RF displays will help in making more accurate measurements when transducer selection is less than optimal.


    
 
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