ON STAGEII (serv.man2) - JBL Audio EMC - CB Certificate (repair manual). Page 15

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REPORT  # 56050AF 
 1 5   
4.  APPENDIX SECTION 
 
4.1  APPENDIX A:  UNCERTAINTY TOLERANCE 
 
DNB Engineering’s Utah Facility is within acceptable uncertainty tolerances per ANSI C63.4 
sections 5.4.6.1 and 5.4.6.2 as well as CISPR 16-1 Annex M, section M.2. 
 
ANSI C63.4  
 
5.4.6.1 Site Attenuation. A measurement site shall be considered acceptable for radiated 
electromagnetic field measurements if the horizontal and vertical NSA derived from 
measurements, i.e., the “measured NSA,” are within +4 dB of the theoretical NSA 
(5.4.6.3) for an ideal site. 
 
5.4.6.1 NSA Tolerance. The +4 dB tolerance in 5.4.6.1 includes instrumentation 
calibration errors, measurement technique errors, and errors due to site anomalies.  
These errors are analyzed in ANSI C63.6-[3], wherein it is shown that the performance 
of a well-built site contributes only 1 dB of the total allowable tolerance. 
 
CISPR 16-1  
 
M.2  Error analysis 
 
. . . The total estimated errors are the basis for the + 4 dB site acceptability criterion 
consisting of approximately 3 dB measurement uncertainties and an additional allowable 
1 dB for site imperfections. 
4.2  APPENDIX B:  SITE CHARACTERISTICS,  
CHALK CREEK EMI TEST SITE
 
The DNB Engineering test facility is located in Chalk Creek Canyon near Coalville, Utah.  
Site characteristics were measured according to the procedures outlined in ANSI C63.4 
“Characteristics of Open Field Test Site”.  The results of these characterizations indicate 
that the Chalk Creek site is an outstanding facility to perform accurate and repeatable 
EMI tests. 
 
4.2.1  Ambient Emissions 
 
Ambient Emission measurements were made to determine the level of the ambient 
emanations at the DNB test facility.  The results indicate that all ambient signals are 
below the FCC Radiated Emission limits or that each can easily be identified as an 
ambient signal. 
 
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