Recent History, Current Status, and Latest PT Results of ACE-PT Inc. EMC Proficiency Testing (PT) Programs

Transcription

1 Recent History, Current Status, and Latest PT Results of ACE-PT Inc. EMC Proficiency Testing (PT) Programs Presented to the Accredited Standards Committee C63 during the May 2017 Meeting By: Harry H. Hodes, NCE ACE-PT Inc. EMC PT Program Technical Manager 1

2 Presentation Outline Why we should care about EMC Proficiency Testing [PT] Brief History & Current Status of the ACIL / ACE-PT Inc. EMC PT Program ACE-PT Inc. s ISO/IEC Certificate & Scope of Accreditation EMC PT Test Artifacts Technical Approach & Statistical Methods used in all EMC PT Schemes Participation Rates and Participant Profiles Results of the 150 khz to 1 GHz EMC PT Scheme Results of the 1 GHz to 18 GHz EMC PT Scheme Observations, Conclusions & Recommendations 2

3 Why should a Test Lab care about doing EMC Proficiency Testing? - I From a Quality System Management Standpoint: Except for Clause 5.9, all other Clauses of ISO/IEC 17025:2005 concern themselves with process, not with actual results! The underlying presumption of ISO/IEC 17025:2005 is that if you properly control the processes, the outcomes (i.e., the results) will also be controlled. This presumption is almost a dogma, and is easily rebutted by the facts. An across-the-board Passing result of a Proficiency Test provides the strongest proof (i.e., directly relevant objective evidence, rather than indirect evidence) that the Test Lab can get the correct results. Such evidence fully satisfies Clause 5.9 of ISO/IEC 17025:

4 Why should a Test Lab care about doing EMC Proficiency Testing? - II From a Technical Standpoint: It is not possible for a single EMC Test Lab to assess its own Bias. In other words, a Test Lab cannot (by its own efforts) determine whether it is consistently measuring amplitudes that are hot or cold as a function of frequency. It is quite difficult for a single EMC Test Lab to assess (by its own efforts) whether or not its test processes are fully in control (i.e., Are the variations in measured amplitude as a function of frequency reasonable, given their Measurement Uncertainties?) [Note: Daily confidence checks help, and trending analysis helps even more, but this is far from a formal inter-lab comparison]. Failing EUTs that should pass (i.e., making a Type I Error) and/or Passing EUTs that should fail (i.e., making a Type II Error) is not good for an EMC Lab s Customers, nor for the specific EMC Lab that made the Pass/Fail Classification Error, nor for the reputation of the EMC Test Laboratory industry as a whole. Conclusion: Participating in, and passing a well-run EMC PT Program provides objective (and comprehensive) proof that an EMC Test Lab is competent i.e., that it can consistently make good measurements, and thus can be relied upon to correctly classify EUT s as having Passed or Failed. [ Good Measurements are measurements made with acceptable bias and with a process that is In Control ]. 4

5 Why should an AB care about requiring EMC Proficiency Testing? THE USES OF PT ANALYSIS RESULTS TO ACCREDITING BODIES (ABs) 1. Adherence to ILAC Policy P9: 6/2014 The mandated use of the PT Analysis Results for evaluating the competence of EMC testing laboratories as part of the accreditation process of laboratories is stated in ILAC Policy P9 6/2014 which is imposed upon all ABs that are signatories to the ILAC Multilateral Recognition Arrangement (MRA). [Emphasis Added]. 2. Adherence to ISO/IEC 17011:2004 ISO/IEC 17011:2004 {quoted in ILAC Policy P9 6/2014} requires ABs to take into account during Assessment and the Decision Making process Participation and Performance in Proficiency Testing. [Emphasis Added]. 5

6 HISTORY - I ACIL s EMC Proficiency Testing (PT) Program dates from Two EMC PT Test Artifacts were ultimately acquired in late a York CNE III Broadband Noise Source (frequency range: 150 khz to 1 GHz), and, a WD Test Solutions EM-18 Spectrally Broadened Comb Generator (frequency range: 1 GHz to 18 GHz). These Artifacts are still in use, and still have essentially identical RF Outputs to what they were when new! Preliminary experiments with EMC PT Testing began in 1999 using borrowed Test Artifacts.. Formal EMC PT Testing began in 2004 used ACIL-owned Test Artifacts. An outside contractor (statistician) was paid to perform elementary statistical analyses on the PT Data received from the Participating Labs. Between 2004 and 2009, ACIL made numerous modifications to its User Instructions, Test Procedures, and Data Collection Procedures for the purpose of improving the usefulness of its program. In 2009, it was recognized that the statistical analyses being provided were technically inadequate. Acme Testing Co. (an ACIL Member Laboratory) volunteered to take over the technical management of the ACIL PT Program. To preserve confidentiality, the procedures were changed such that Participants sent their PT Data to the ACIL Section Executive Officer, who then anonymized their data and gave each data set a unique 3-character Lab Code as an identifier before sending the data to Acme Testing Co. s statistician for analysis. 6

7 HISTORY - II Acme Testing Co. s statistician immediately realized that the analytical methods used up to that point were unsatisfactory, and needed to be replaced. Several significant improvements were made, including: A rigorous statistical analysis methodology was developed and implemented, based upon the guidance given in ISO In particular: o the Assigned Values (i.e., the robust estimators of the true values ) are determined by consensus of participants using the so-called Robust Average Method per Algorithm A of ISO 13528, and, o the Performance Evaluation Parameters used for Pass/Fail determination are based upon the applicable U CISPR values (from CISPR ) for a k=2 Coverage Factor.] Standardized Data Collection Templates were developed, introduced and mandated for use, in order to ensure that all participants provide data in the same format, so as to allow for faster and more accurate data analysis); and, Updated User Instruction Manuals [UIMs] were developed and provided with the PT Test Artifacts. These UIMs covered the setup and operation of the Test Artifacts, the procedures to be used for PT Data Collection, and a summary of the Data Analysis Techniques to be used to analyze PT data). Rigorous procedures for periodic (annual) re-characterizations of the Test Artifacts were developed and implemented, in order to confirm the stability and repeatability of their RF Outputs. The result of these changes was that ACIL s EMC PT Program achieved the status of a wellorganized inter-laboratory comparison (ILC).. 7

8 HISTORY - III In 2011, it was decided that ACIL would try to obtain ISO/IEC Accreditation for its EMC PT Program. To that end, ACIL created a wholly-owned subsidiary, called the ACIL Corporation for EMC Proficiency Testing Inc. ( ACE-PT Inc. ), and transferred EMC PT related assets and responsibilities to it. On 12 July 2012, ACE-PT Inc. became the worlds only ISO/IEC accredited provider of EMC PT Services. ACE-PT Inc. was accredited by A2LA, under Certificate # The ACE-PT Inc. EMC PT Program was organized into two basic PT Schemes one from 150 khz to 1 GHz (using the York CNE III Test Artifact), and the other from 1 GHz to 18 GHz (using the WD Test Solutions EM-18 Test Artifact). Each PT Scheme operated continuously, but PT Analysis Results were originally generated only at the end of each PT Scheme Round. A Round was typically declared after about 10 Participating Laboratories had submitted measurements for the Scheme. This resulted in very lengthy delays. Starting in mid 2015, ACE-PT Inc. was authorized to issue Participants Interim Statement of Performance Letters, using Assigned Values and Control Limits derived from consolidated measurement data from from the previous Rounds. Since this change was made, Participants get their Results within 7 days after they submit their PT measurements. 8

9 CURRENT STATUS On 01 March 2017, ACE-PT Inc. was re-accredited as a Proficiency Testing Provider. It is still the worlds only ISO/IEC accredited PT Provider of EMC PT Services. Its current Certificate and Scope of Accreditation are shown on the next two Slides. As of now, ACE-PT Inc. is offering two PT Schemes based on the ANSI C and ANSI C63.10 Standards. Among other things, these new Schemes now explicitly allow Participants to: use either FFT-based EMI Receivers / Spectrum Analyzers or frequency-domain EMI Receivers / Spectrum Analyzers; and, use EPS (e.g., Styrofoam ) Support Tables as well as those made from other materials. ACE-PT Inc. s two EMC PT Schemes are available on a world-wide basis to any EMC and/or Wireless/RF Test Lab that has (or wants to have) ANSI C and/or ANSI C in their ISO/IEC Scope of Accreditation. 9

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12 ANSI C / ANSI C (150 khz 1 GHz) EMC PT Scheme York CNE III Test Artifact configured for Radiated Emissions V Polarization EMC PT Measurements 12

13 ANSI C / ANSI C (150 khz 1 GHz) EMC PT Scheme York CNE III Test Artifact configured for Radiated Emissions H Polarization EMC PT Measurements 13

14 ANSI C / ANSI C (1 GHz 18 GHz) EMC PT Scheme WD Test Solutions EM 18 Test Artifact configured for Radiated Emissions V Polarization EMC PT Measurements 14

15 ANSI C / ANSI C (1 GHz 18 GHz) EMC PT Scheme WD Test Solutions EM 18 Test Artifact configured for Radiated Emissions H Polarization EMC PT Measurements 15

16 The Canonical Question Q: If we distributed an EUT to a series of Test Labs, and then somehow aggregated all of their measurements, could we collectively estimate what God would have measured? A. YES! Using a large number of independent measurements, and the appropriate statistical techniques, we can estimate the true answer (i.e., the value of the correct, error-free measurement). Additionally, we can estimate the uncertainty of our estimate of the true answer. The estimate of the true answer is called the Assigned Value. The estimate of the uncertainty of the Assigned Value is called the Standard Uncertainty of the Assigned Value. 16

17 The Technical Approach - I ISO states that when the Assigned Value is to be determined as a Consensus Value from the Participants, the ISO Algorithm A is an appropriate method for determining the Assigned Value. The ISO Algorithm A specifies the method to be used to compute the: Robust Average, X* (i.e., the Assigned Value), Standard Deviation of the Robust Average, S* Standard Uncertainty of the Assigned Value, u x Important Note: In EMC PT Programs, the Standard Uncertainty of the Assigned Value is almost always significant, and thus must never be ignored. 17

18 The Technical Approach - II All of the EMC PT Schemes operated by ACE-PT Inc. employ the ISO Prescribed Value Method for determining the Standard Deviation for Proficiency Assessment. Specifically, Measurement Uncertainty [MU] values stated in various Normative EMC Standards are used (e.g., U CISPR (k=2) values from the latest version of CISPR ). 18

19 Procedure for computing the Control Limits in natural db Units In all of ACE-PT Inc.'s EMC Standards-based EMC PT Schemes, when using db units (i.e., either dbμv or dbμv/m as applicable), each Upper Control Limit [UCL] and each Lower Control Limit [LCL] is computed as follows: UCL = X* + (U p + u x ) LCL = X* - (U p + u x ) where, X* is the Robust Average derived using Algorithm A from ISO for the i th RF Frequency in a given EMC PT Data Set; and, U p is the prescribed measurement uncertainty that is treated as having a fixed value (i.e., is a constant) for a specific EMC PT Test Process in a given EMC PT Data Set; and, u x is the Standard Uncertainty of the Assigned Value (i.e., of the Robust Average) for a specific EMC PT Test Process being examined in a given EMC PT Data Set. 19

20 In all of ACE-PT Inc.'s EMC Standards-based EMC PT Schemes, the results are determined by comparing each participating EMC Laboratory s measurements with the computed UCL and LCL values, as follows: where, Procedure for determining Laboratory Performance (in db Units) LCL X i UCL PASS X i > UCL FAIL on the hot side (i.e., the measurement had a higher value than the UCL) X i < LCL FAIL on the cold side (i.e., the measurement had a lower value than the LCL) X i is the measurement made at i th RF Frequency in a given EMC PT Data Set Any measurements which are between the Upper Control Limit [UCL] and the Lower Control Limit [LCL] are defined as being "acceptable" measurements and are therefore deemed to have Passed. Any measurements which are either above the Upper Control Limit [UCL] or are below the Lower Control Limit [LCL] are defined as being Unacceptable Measurements. Unacceptable Measurements are also defined to be outliers and are therefore deemed to have "Failed". 20

21 Procedure for evaluation of Laboratory Bias (using D-Statistics) In all of ACE-PT Inc.'s EMC Standards-based EMC PT Schemes, the Bias (denoted as D ) of the measurement made at the i th RF Frequency in a given EMC PT Data Set from a given "round" of a given EMC PT Program is evaluated as follows: D = X i - X* where, D is the Bias; X i is the measurement made at i th RF Frequency in a given EMC PT Data Set X* is the Robust Average derived using Algorithm A from ISO for i th RF Frequency in a given EMC PT Data Set Bias is most easily visualized by plotting the computed Bias values (for a given EMC PT Data Set) as a function of RF Frequency, with Bias = 0.00 being in the middle of the Y-Axis of each plot. (In other words, the plots are formatted similar to those used in plotting the Deviations from Zero Normalized Site Attenuation). 21

22 Procedure for evaluation of Laboratory Ranking (using Z-Scores) In all of ACE-PT Inc.'s EMC Standards-based EMC PT Schemes, the performance of each EMC Laboratory can be ranked against all other participating EMC laboratories by standardizing each participating EMC Laboratory s Bias (i.e., D = X i X*), as follows: Z-Score = (X i X*) / S* where: X i is the measurement made at i th RF Frequency in a given EMC PT Data Set X* is the Robust Average derived using Algorithm A from ISO for the i th RF Frequency in a given EMC PT Data Set. S* is the standard deviation of the assigned value (the Robust Average) for the i th RF Frequency in a given EMC PT Data Set. Note: the Z-Score (Z-Score = Bias/S*) is the standardized method for scoring participants against each other; there is no underlying normality assumption. In contrast, the Z-Value [i.e., Z-Value = (X i X*)/ σ x ] is the standard deviation for proficiency testing, and explicitly carries with it an underlying assumption of normality. Care should be taken to avoid confusing the term Z-Score with the term Z-Value. ACE-PT Inc. s EMC PT Schemes are NOT concerned with (and do not rely upon) the computation of Z-Values. 22

23 Guaranteed Consistency of Results It is important to note that all three methods just described (i.e., computation of results in natural units, computation of results using D-statistics, and computation of results using Z-Scores) for evaluating participant performance MUST yield the same (qualitative) Pass / Fail results. If the Pass / Fail Results are NOT identical, then a computational error has been made. 23

24 GROSS PARTICIPATION RATES OF EMC TEST LABORATORIES (during the 4 year period between 2012 and 2016) Of Test Labs accredited to ANSI C63.4 by A2LA: Of the approximately 80 EMC Test Laboratories (having unique locations) in the USA and in Canada that are currently accredited to ANSI C63.4 by A2LA, only 25 of them (representing ~31% of the total) have partially or fully satisfied the participation requirements of Clause b) of ISO/IEC 17025:2005 over the last four years. Of the approximately 50 EMC laboratories (having unique locations) outside of the US and Canada (e.g., in Japan, Taiwan, South Korea, China, etc.) that are currently accredited to ANSI C63.4 by A2LA, only 2 of them (representing 4%) have partially or fully satisfied the participation requirements of Clause b) of ISO/IEC 17025:2005 over the last four years. Thus taken together, of the approximately 130 EMC laboratories (having unique locations) that are currently accredited to ANSI C63.4 by A2LA, the gross participation rate of ACE-PT Inc.'s ANSI C63.4 accredited PT Schemes is only 20.8% - i.e., 27 unique Laboratory Participants - over 4 years). In other words, the gross non-participation rate is almost 80% - i.e., about 4 out of 5 EMC Labs have never participated. 24

25 GROSS PARTICIPATION RATES OF EMC TEST LABORATORIES (during the 4 year period between 2012 and 2016) Of Test Labs accredited to ANSI C63.4 by NIST/NVLAP: Of the approximately 93 EMC Test Laboratories that are currently ISO/IEC accredited by NVLAP to ANSI C63.4, only 1 of them participated in an ACE-PT Inc. EMC PT Scheme over the last 4 year period, and thereby satisfied the participation requirements of Clause b) of ISO/IEC 17025:2005. (Specifically, we identified some 48 EMC Test Labs located in the USA and Canada and another 45 EMC Test Labs located outside the USA and Canada that are ISO/IEC accredited by NVLAP to ANSI C63.4). Thus taken together, of the approximately 93 EMC laboratories (having unique locations) that are currently accredited to ANSI C63.4 by NIST / NVLAP, the gross participation rate of ACE-PT Inc.'s ANSI C63.4 accredited PT Schemes is only 1.08%. In other words, the gross non-participation rate is almost 99%! 25

26 5 th Continuation (Most Recent) Round PT Scheme Collateral Data (150 khz 1 GHz) 26

27 4 th Continuation Round PT Scheme Collateral Data (150 khz 1 GHz) 27

28 3 rd Continuation (Most Recent) Round PT Scheme Collateral Data (1 GHz 18 GHz) 28

29 2 nd Continuation Round PT Scheme Collateral Data (1 GHz 18 GHz) 29

30 Initial and 1 st Continuation Round PT Scheme Collateral Data (1 GHz 18 GHz) 30

31 PT Results (150 khz to 30 MHz) Direct Antenna Conducted Emissions Participants: 51 Overall Failure Rate (%): Acrossboard Failure Rate:

32 5 th Rnd PT Results: Direct Ant. Conducted Emissions (150 khz 30 MHz) Participants: 12 Overall Failure Rate (%): 8.33 Acrossboard Failure Rate (%):

33 5 th Rnd PT Results: Direct Ant. Conducted Emissions (150 khz 30 MHz) 33

34 PT Results (30 MHz to 1000 MHz) Direct Antenna Conducted Emissions Participants: 50 Overall Failure Rate (%): Acrossboard Failure Rate (%):

35 5 th Rnd PT Results: Direct Ant Conducted Emissions (30 MHz 1000 MHz) Participants: 12 Overall Failure Rate (%): 8.33 Acrossboard Failure Rate (%):

36 5 th Rnd PT Results: Direct Ant Conducted Emissions (30 MHz 1000 MHz) 36

37 PT Results (30 MHz to 1000 MHz) Radiated Emissions (3m H Pol) Participants: 49 Overall Failure Rate (%): Acrossboard Failure Rate (%):

38 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 3m H Pol Participants: 7 Overall Failure Rate (%): Acrossboard Failure Rate (%):

39 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 3m H Pol 39

40 PT Results (30 MHz to 1000 MHz) Radiated Emissions (3m V Pol) Participants: 49 Overall Failure Rate (%): Acrossboard Failure Rate (%):

41 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 3m V Pol Participants: 7 Overall Failure Rate (%): Acrossboard Failure Rate (%):

42 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 3m V Pol 42

43 PT Results (30 MHz to 1000 MHz) Radiated Emissions (10m H Pol) Participants: 33 Overall Failure Rate (%): Acrossboard Failure Rate (%):

44 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 10m H Pol Participants: 7 Overall Failure Rate (%): Acrossboard Failure Rate (%):

45 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 10m H Pol 45

46 PT Results (30 MHz to 1000 MHz) Radiated Emissions (10m V Pol) Participants: 33 Overall Failure Rate (%): Acrossboard Failure Rate (%):

47 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 10m V Pol Participants: 7 Overall Failure Rate (%): 0.00 Acrossboard Failure Rate (%):

48 5 th Rnd PT Results: Radiated Emissions (30 MHz 1000 MHz) 10m V Pol 48

49 PT Results (1 GHz to 18 GHz) Direct Ant. Conducted Emissions (Peak) Participants: 35 Overall Failure Rate (%): Acrossboard Failure Rate (%):

50 3 rd Rnd PT Results (1 18 GHz): Direct Ant. Conducted Emissions (Peak) Participants: 13 Overall Failure Rate (%): Acrossboard Failure Rate (%):

51 3 rd Rnd PT Results (1 18 GHz): Direct Ant. Conducted Emissions (Peak) 51

52 PT Results (1 GHz to 18 GHz) Direct Ant. Conducted Emissions (Avg) Participants: 35 Overall Failure Rate (%): Acrossboard Failure Rate (%):

53 3 rd Rnd PT Results (1 18 GHz): Direct Ant. Conducted Emissions (Avg) Participants: 13 Overall Failure Rate (%): Acrossboard Failure Rate (%):

54 3 rd Rnd PT Results (1 18 GHz): Direct Ant. Conducted Emissions (Avg) 54

55 PT Results (1 GHz to 18 GHz) Radiated Emissions (3m H Pol Peak) Participants: 37 Overall Failure Rate (%): Acrossboard Failure Rate (%):

56 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m H Pol Peak) Participants: 12 Overall Failure Rate (%): Acrossboard Failure Rate (%):

57 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m H Pol Peak) 57

58 PT Results (1 GHz to 18 GHz) Radiated Emissions (3m H Pol Avg) Participants: 38 Overall Failure Rate (%): Acrossboard Failure Rate:

59 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m H Pol Avg) Participants: 12 Overall Failure Rate (%): Acrossboard Failure Rate (%):

60 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m H Pol Avg) 60

61 PT Results (1 GHz to 18 GHz) Radiated Emissions (3m V Pol Peak) Participants: 38 Overall Failure Rate (%): Acrossboard Failure Rate:

62 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m V Pol Peak) Participants: 12 Overall Failure Rate (%): Acrossboard Failure Rate (%):

63 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m V Pol Peak) 63

64 PT Results (1 GHz to 18 GHz) Radiated Emissions (3m V Pol Avg) Participants: 37 Overall Failure Rate (%): Acrossboard Failure Rate (%):

65 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m V Pol Avg) Participants: 12 Overall Failure Rate (%): Acrossboard Failure Rate (%):

66 3 rd Rnd PT Results (1 18 GHz): Radiated Emissions (3m V Pol Avg) 66

67 Consolidated Results: Failure Rate Summary: 150 khz 1 GHz 67

68 Consolidated Results: Failure Rate Summary: 1 GHZ - 18 GHz 68

69 Using Histograms to check the Data Distributions Non-Normal! The severely non-normal data distributions shown above (merely as exemplars) are the aggregated result of Egregious Errors in the measurement processes used by many Test Labs. Severely non-normal, multi-modal distributions of measured amplitudes are a sure indicator of high PT failure rates. 69

70 FINAL CONCLUSIONS Based on the EMC Proficiency Testing Results presented herein, it is clear that a large percentage of Test Laboratories still have very serious problems with making correct measurements. Specifically: There is abundant objective evidence that a some Test Labs are unable to verify the correctness of their end-to-end measurement chains. There is abundant objective evidence that a very considerable number of Test Labs exhibit severe and consistent bias errors in their measurements. There is abundant objective evidence that a very significant number of Test Labs have test processes that are out-of-control. Below 1 GHz, the majority of the Test Labs whose processes were out-of-control were measuring cold (i.e., were likely to make Type II [False Pass] Errors). Above 1 GHz, Test Labs whose processes were out-of-control were about equally likely to measure hot (i.e., were likely to make Type I [False Fail] Errors) as they were to measure cold (i.e., were likely to make Type II [False Pass] Errors). 70

71 RECOMMENDATIONS to ensure competency and eliminate amateurism In order to ensure that Emissions Compliance Tests are being performed only by those Test Laboratories that are competent, Regulators (e.g., the FCC and ISED Canada) should require that Accrediting Bodies (e.g., A2LA, ANAB, NIST/NVLP) obtain actual direct objective evidence of each Test Laboratory s competency in making correct Emissions measurements as a condition of their granting an ISO/IEC accreditation with a Scope that includes Regulatory Body Recognition of their ANSI C63.4 and/or ANSI C63.10 Test Methods. In order to fulfill their ILAC Policy P9 (6/2014) mandate, Accrediting Bodies (e.g., A2LA, ANAB, NIST/NVLP) should in all cases, require that Test Laboratories (having or wanting ANSI C63.4 and/or ANSI C63.10 on their ISO/IEC Scopes of Accreditation), participate in, and pass, at least one ISO/IEC accredited 150 khz to 1 GHz EMC PT Scheme and one 1 GHz to 18 GHz EMC PT Scheme within the two year interval corresponding to their ISO/IEC on-site Assessments. 71

72 Any Any Questions? Contact Harry H. Hodes ACE-PT Inc. PT Program Technical Manager by telephone at : or by at: hhhodes@yahoo.com 72