JBL ON TOUR XTB (serv.man6) EMC - CB Certificate ▷ View online
Nemko USA, Inc.
11696 Sorrento Valley Road, Suite F, San Diego, CA 92121
Phone (858) 755-5525 - Fax (858) 452-1810
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Harman Multimedia - On Tour XTB - RTTE Test Report
2009 11138368 EMC
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Template 7-09aal
3. Practical Explanation of the Meaning of Radiated Emissions Measurement Uncertainties
In general, a “Statement of Measurement Uncertainty” means that with a certain (specified) confidence level,
the “true” value of a measurand will be between a (stated) upper bound and a (stated) lower bound.
In the specific case of EMC Measurements in this test report, the measurement uncertainties of the conducted
emissions measurements and the radiated emissions measurements have been calculated in accordance with the
method detailed in the following documents:
In general, a “Statement of Measurement Uncertainty” means that with a certain (specified) confidence level,
the “true” value of a measurand will be between a (stated) upper bound and a (stated) lower bound.
In the specific case of EMC Measurements in this test report, the measurement uncertainties of the conducted
emissions measurements and the radiated emissions measurements have been calculated in accordance with the
method detailed in the following documents:
o
ANSI Z540.2 (2002) Guide to the Expression of Uncertainty in Measurement
o
NIS 81:1994, The Treatment of Uncertainty in EMC Measurements (NAMAS, 1994)
o
NIST Technical Note 1297(1994), Guidelines for Evaluating and Expressing the Uncertainty of NIST
Measurement Results (NIST, 1994)
The calculation method used in these documents requires that the stated uncertainty of the measurements be
expressed as an “expanded uncertainty”, U, with a k=2 coverage factor. The practical interpretation of this
method of expressing measurement uncertainty is shown in the following example:
EXAMPLE: Assume that at 39.51 MHz, the (measured) radiated emissions level was equal to +26.5
dBuV/m, and that the +/- 2 standard deviations (i.e. 95% confidence level) measurement uncertainty was
+/- 3.4 dB.
In the example above, the phrase “k = 2 Coverage Factor” simply means that the measurement uncertainty is
dBuV/m, and that the +/- 2 standard deviations (i.e. 95% confidence level) measurement uncertainty was
+/- 3.4 dB.
In the example above, the phrase “k = 2 Coverage Factor” simply means that the measurement uncertainty is
stated to cover +/-2 standard deviations (i.e. a 95% confidence interval) about the measurand. The measurand is
the radiated emissions measurement of +26.5 dBuV/m at 39.51 MHz, and the 95% bounds for the uncertainty
are –3.4 dB to + 3.4 dB. One can thus be 95% confident that the “true” value of the radiated emissions
measurement is between +23.1 dBuV/m and +29.9 dBuV/m. In effect, this means that in the above example
there is only a 2.5% chance that the “true” radiated emissions value exceeds +29.9 dBuV/m.
Nemko USA, Inc.
11696 Sorrento Valley Road, Suite F, San Diego, CA 92121
Phone (858) 755-5525 - Fax (858) 452-1810
DATE
DOCUMENT NAME
DOCUMENT #
PAGE
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Harman Multimedia - On Tour XTB - RTTE Test Report
2009 11138368 EMC
B1 of 73
APPENDIX B
B. Nemko USA, Inc. Test Equipment & Facilities Calibration Program
Nemko USA, Inc. operates a comprehensive Periodic Calibration Program in order to ensure the validity of all
test data. Nemko USA’s Periodic Calibration Program is fully compliant to the requirements of NVLAP Policy
Guide PG-1-1988, ANSI/NCSL Z540.1-1994 (R2002), ISO 10012:2003, ISO/IEC 17025:2005, and ISO-9000:
2000. Nemko USA, Inc.’s calibrations program therefore meets or exceeds the US national commercial and
military requirements [N.B. ANSI/NCSL Z540-1-1994 replaces MIL-STD-45662A].
Specifically, all of Nemko USA’s primary reference standard devices (e.g. vector voltmeters, multimeters,
attenuators and terminations, RF power meters and their detector heads, oscilloscope mainframes and plug-ins,
spectrum analyzers, RF preselectors, quasi-peak adapters, interference analyzers, impulse generators, signal
generators and pulse/function generators, field-strength meters and their detector heads, etc.) and certain
secondary standard devices (e.g. RF Preamplifiers used in CISPR 11/22 and FCC Part 15/18 tests) are
periodically recalibrated by:
o
A Nemko USA-approved independent (third party) metrology laboratory that uses NIST-
traceable standards and that is ISO Guide 25-accredited as a calibration laboratories by NIST; or,
o
A Nemko USA-approved independent (third party) metrology laboratory that uses NIST-
traceable standards and that is ISO Guide 25-accredited as a calibration laboratory by another
accreditation body (such as A2LA) that is mutually recognized by NIST; or,
accreditation body (such as A2LA) that is mutually recognized by NIST; or,
o
A manufacturer of Measurement and Test Equipment (M&TE), if the manufacturer uses NIST-
traceable standards and is ISO Guide 25-accredited as calibration laboratory either by NIST or by
another accreditation body (such as A2LA) that is mutually recognized by NIST; or
another accreditation body (such as A2LA) that is mutually recognized by NIST; or
o
A manufacturer of M&TE (or by a Nemko USA-approved independent third party metrology
laboratory) that is not ISO Guide 25-accredited. (In these cases, Nemko USA conducts an annual
audit of the manufacturer or metrology laboratory for the purposes of proving traceabilty to
NIST, ensuring that adequate and repeatable calibration procedures are being applied, and
verifying conformity with the other requirements of ISO Guide 25).
audit of the manufacturer or metrology laboratory for the purposes of proving traceabilty to
NIST, ensuring that adequate and repeatable calibration procedures are being applied, and
verifying conformity with the other requirements of ISO Guide 25).
Nemko USA, Inc.
11696 Sorrento Valley Road, Suite F, San Diego, CA 92121
Phone (858) 755-5525 - Fax (858) 452-1810
DATE
DOCUMENT NAME
DOCUMENT #
PAGE
Error! Reference
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found.
Harman Multimedia - On Tour XTB - RTTE Test Report
2009 11138368 EMC
B2 of 73
Nemko USA, Inc.
11696 Sorrento Valley Road, Suite F, San Diego, CA 92121
Phone (858) 755-5525 - Fax (858) 452-1810
DATE
DOCUMENT NAME
DOCUMENT #
PAGE
Error! Reference
source not
found.
Harman Multimedia - On
Tour XTB
- RTTE Test Report
2009 11138368 EMC
C1 of 73
APPENDIX C
C. NVLAP Accrediation
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