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Technical Discussions
Mitsuyoshi Uematsu
Mitsuyoshi Uematsu
01:44 Jan-19-2009
Signal-to-noise Ratio requirement in AMS-STD-2154

Can anyone help me with the intepretation of Signal-to-noise Ratio requirement in AMS-STD-2154?
The minimum requirement for Signal-to-noise Ratio is 100:1 using 5MHz and ASTM reference block 1-0300, which has a 1/64 in. diameter FBH with 3 in metal distance. It seems not realistic and not acheivable.
And it seems referenced document ASTM E 317 does define "sensitivity" and "noise", but does not "Signal-to-noise Ratio".

Thank you for your cooperation.

 
 Reply 
 
Michel Couture
NDT Inspector,
consultant, Canada, Joined Sep 2006, 888

Michel Couture

NDT Inspector,
consultant,
Canada,
Joined Sep 2006
888
16:44 Jan-19-2009
Re: Signal-to-noise Ratio requirement in AMS-STD-2154
In Reply to Mitsuyoshi Uematsu at 01:44 Jan-19-2009 (Opening).

Signal-to-noise Ratio is the Ratio between the Signal on your screen from your FBH and the grass indication (noise) at the bottom of your screen. In this case when your FBH is at 100% Full Screen Height, the noise (grass) at the bottom of your screen should not exceed 1%. If you have problem to achieve this, you may want to get a transducer that would ring less and a better cable.

Good Luck!!!

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1300

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1300
00:26 Jan-20-2009
Re: Signal-to-noise Ratio requirement in AMS-STD-2154
In Reply to Mitsuyoshi Uematsu at 01:44 Jan-19-2009 (Opening).

Mitsuyoshi san
Some years ago ASTM ultrasonic subcommittee was requested to review the MIL-STD 2154. This took a long time in ASTM and in the meantime AMS-STD-2154 was published as a direct copy of that MIL-STD document without any regard for the sort of updates that a dynamic Standard undergoes. ASTM eventually developed the revised document and it is identified as ASTM E-2375. In the footnote of the ASTM document it states that "When accepted by DoD this document is expected to replace MIL-STD 2154." Last year, the US Navy made 2 announcements of the cancellation of MIL-STD-2154. If this is a contractual document I suggest you check on the suitability of the proposed replacement (i.e. ASTM E-2375).

 
 Reply 
 
David Harvey
Engineering
ATI - Wah Chang, USA, Joined Nov 2002, 42

David Harvey

Engineering
ATI - Wah Chang,
USA,
Joined Nov 2002
42
20:40 Jan-22-2009
Re: Signal-to-noise Ratio requirement in AMS-STD-2154
In Reply to Mitsuyoshi Uematsu at 01:44 Jan-19-2009 (Opening).

In my humble opinion, this is only one of the unrealistic requirements in 2154. I was never quite able to work a way to succeed on this requirement, and thus we simply rejected 2154 when it was called out and offered other documents in its stead. Since the large majority of our product uses ASTM specs, this was not too horribly difficult.

If I remember correctly, there was one UT instrument manufacturer who actually had a "built-in" 5% reject in order to meet this requirement.

 
 Reply 
 
Chuck Garner
Chuck Garner
23:17 Sep-10-2009
Re: Signal-to-noise Ratio requirement in AMS-STD-2154
In Reply to Mitsuyoshi Uematsu at 01:44 Jan-19-2009 (Opening).

I just stumbled on to this series of comment and wanted to add my observations, having just written a calibration procedure to "meet" the requirements of ASTM E317 & AMS-STD-2154. The test methods outlined in 317 do not match the requirements in 2154. The upper & lower linearity limits have no tolerance to indicate how linear the response must be between 10% & 95%.
Sensitivity and noise requirements have no obvious connection to the test methods in 317.
Gain control requirements must be backed out of calibrated attenuator requirements.

If anyone has a clear interpretation of how to implement these requirements I would like to hear it.

I notice that ASTM E2375 has not included sensitivity & noise in its list of instrument test and does a better job of defining the requirements forthe other measurements.

 
 Reply 
 
Jay Amos
Engineering,
Textron Aviation, USA, Joined Aug 2000, 3

Jay Amos

Engineering,
Textron Aviation,
USA,
Joined Aug 2000
3
17:11 Mar-04-2011
Re: Signal-to-noise Ratio requirement in AMS-STD-2154
In Reply to Chuck Garner at 23:17 Sep-10-2009 .

Hoping to renew this discussion of 2154 vs. E2375.

Since the instrument calibration requirements of 2154 appear to be incorrect for SNR, does anyone have an opinion on appropriate SNR requirements? E317 indicates a minimum of 3:1, but seems to have no hard requirements with respect to hole size & frequency?

Thanks,

 
 Reply 
 
Sudheer Jai Krishnan
NDT Inspector, -
bluestarindia, India, Joined Mar 2011, 30

Sudheer Jai Krishnan

NDT Inspector, -
bluestarindia,
India,
Joined Mar 2011
30
12:50 Mar-17-2011
Re: Signal-to-noise Ratio requirement in AMS-STD-2154
In Reply to Chuck Garner at 23:17 Sep-10-2009 .

Dear Chuck,

I beleive E317 mentions that the linearity is +or- 5%.But some forging manufacturers who do components for aerospace says that it should be +or- 3%

 
 Reply 
 

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