where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -
2745 views
Technical Discussions
Pim van Andel
Pim van Andel
04:11 Jun-02-1998
pulse repetition frequency

I am working on the design for electronics of a PC based ultrasonic
instrument.

For manual weld inspection the pulse repetition rate must be rather high
(250Hz?) in view of the probe speed (150mm/sec) and the requirement that
you do not want to miss defect echos. The problem is that a PC screen
can only display A-scans at a rate of e.g. 20 A-scans/sec.

My question: How to reduce 250 Hz prf to 20 A-scans/sec; how is this
solved in digital UT instruments?



 
 Reply 
 
Eugene Suchcicki
Eugene Suchcicki
02:25 Jun-03-1998
Re: pulse repetition frequency
My private( I am not an expert in this field) it would
be to make "average" of let say 25 scans and calculate
one PC screen of information. This "average" could be
inteligent enough to represent miningfull data.
In its simplest form it could be just average.
But having 25 sets of data to be reperented by "one"
event you could for example display such values as
1. min
2. max
3. average
The other alternative is to make the probe movment slower
to match speed( refresh rate) of PC screen. But even so
can anyone spot the problem on the screen if the refresh
rate is high (and probe speed is high). ( Actual information
is on the sceen for fraction of a sec only)
So real time data on the PC screen is of little benefit.
More static screen with recalculated(evaluated)data is what
I would aim for.


: I am working on the design for electronics of a PC based ultrasonic
: instrument.

: For manual weld inspection the pulse repetition rate must be rather high
: (250Hz?) in view of the probe speed (150mm/sec) and the requirement that
: you do not want to miss defect echos. The problem is that a PC screen
: can only display A-scans at a rate of e.g. 20 A-scans/sec.

: My question: How to reduce 250 Hz prf to 20 A-scans/sec; how is this
: solved in digital UT instruments?




 
 Reply 
 
Rainer Meier
R & D
retired from intelligeNDT Systems & Services, Germany, Joined Nov 1998, 15

Rainer Meier

R & D
retired from intelligeNDT Systems & Services,
Germany,
Joined Nov 1998
15
02:46 Jun-03-1998
Re: pulse repetition frequency
: I am working on the design for electronics of a PC based ultrasonic
: instrument.

: For manual weld inspection the pulse repetition rate must be rather high
: (250Hz?) in view of the probe speed (150mm/sec) and the requirement that
: you do not want to miss defect echos. The problem is that a PC screen
: can only display A-scans at a rate of e.g. 20 A-scans/sec.

: My question: How to reduce 250 Hz prf to 20 A-scans/sec; how is this
: solved in digital UT instruments?

For my opinion, it is very important to avoid the suppression of relevant
data. Therefore I would suggest, to show a kind of envelope of the A-scans,
that means to view at each point of time of flight the maximal as well
as the minimal amplitude.
Advandages: - No significant information lost
- You can easily adept your mooving speed to the local
UT-result at your component: The speed is slow enough,
if there is only a small difference bedween minimum
and maximum amplitude.

Rainer Meier


 
 Reply 
 
Linas Svilainis
R & D,
Kaunas University of Technology, Lithuania, Joined Nov 1998, 67

Linas Svilainis

R & D,
Kaunas University of Technology,
Lithuania,
Joined Nov 1998
67
01:18 Jun-03-1998
Re: pulse repetition frequency
: For manual weld inspection the pulse repetition rate must be rather high
: (250Hz?) in view of the probe speed (150mm/sec) and the requirement that
: you do not want to miss defect echos. The problem is that a PC screen
: can only display A-scans at a rate of e.g. 20 A-scans/sec.
The alarm suppose to be automated in order not to miss echoes.

: My question: How to reduce 250 Hz prf to 20 A-scans/sec; how is this
: solved in digital UT instruments?
As already was mentioned, use minimal, maximal,average or trailing envelope
of desired number of A-scans.



 
 Reply 
 
rysiek
rysiek
01:42 Sep-01-1999
Re: pulse repetition frequency
: My private( I am not an expert in this field) it would
: be to make "average" of let say 25 scans and calculate
: one PC screen of information. This "average" could be
: inteligent enough to represent miningfull data.
: In its simplest form it could be just average.
: But having 25 sets of data to be reperented by "one"
: event you could for example display such values as
: 1. min
: 2. max
: 3. average
: The other alternative is to make the probe movment slower
: to match speed( refresh rate) of PC screen. But even so
: can anyone spot the problem on the screen if the refresh
: rate is high (and probe speed is high). ( Actual information
: is on the sceen for fraction of a sec only)
: So real time data on the PC screen is of little benefit.
: More static screen with recalculated(evaluated)data is what
: I would aim for.

:
: : I am working on the design for electronics of a PC based ultrasonic
: : instrument.

: : For manual weld inspection the pulse repetition rate must be rather high
: : (250Hz?) in view of the probe speed (150mm/sec) and the requirement that
: : you do not want to miss defect echos. The problem is that a PC screen
: : can only display A-scans at a rate of e.g. 20 A-scans/sec.

: : My question: How to reduce 250 Hz prf to 20 A-scans/sec; how is this
: : solved in digital UT instruments?
POWODZENIA GIENEK



 
 Reply 
 

Product Spotlight

Robotic laser shearography enables 100% inspection of complex, flight-critical composite structures

An article in “Composites World Magazine” showcases Non Destructive Testing of aero-structures
...
with Laser Shearography. Over the years Dantec Dynamics has supplied many solutions for the aerospace industry. Referring to specific customer projects several of these cases are examined to outline the advantages of using Laser Shearography for automated defect detection.
>

Research Center IDEKO develops an ultrasonic train wheel inspection system for CAF

The Basque Research centre IK4-IDEKO has developed a state-of-the-art ultrasonic inspection system f
...
or the train wheel. This system secures a sound condition of train wheels and is thus a significant contribution to rail transport safety. The device was delivered to CAF recently and its use allows the manufacturer to become an approved supplier of rolling stock in Italy, as it meets the demanding homologation standards of this country. \\\\r\\\\n
>

NOVO Armor 15 & NOVO Armor 22

The Armor Kit Contains the NOVO Armor, which provides additional mechanical protection to the NOVO 1
...
5WN & NOVO 22WN Detectors, the Armor Stand and a traveling soft cover. - Newest shock absorbent technology case - Water resistant design - Supports wired & wireless communication - Multiple positioning options - Tripod connection using the Built-in 1/4” threads - Simple Detector battery replacement
>

NEOS III

NEOS III is Logos Imagings lightest DR system. With a built-in battery and internal wireless commu
...
nication, the NEOS III is perfect for users that want to quickly assess an item.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window