AV1 (serv.man2) - JBL Audio EMC - CB Certificate (repair manual). Page 12

Report #70112.e1 

 
 

 
The following is a description of terms and a sample calculation, as appears in the radiated 
emissions data table. The numbers used in the calculation are for example only. There is no direct 
correlation to the specific data taken for the product described in this document: 
 
Reading:  This is the reading obtained on the spectrum analyzer in dB

µV. Any external 

preamplifiers used are taken into account through internal analyzer settings. 

 
A.F.: 

This is the antenna factor for the receiving antenna. It is a conversion factor, which 
converts electric fields strengths to voltages, which can be measured directly on the 
spectrum analyzer. It is treated as a loss in dB. Cable losses have been included with 
the A.F. to simplify the calculations. The antenna factor is used in calculations as 
follows: 

 
 

 

µ

µ

V/m) 

 
Net: 

This is the net field strength measurement (as shown above). 

 
Limit: 

This is the FCC Class B radiated emission limit (in units of dB

µV/m). 

 
Margin:  This is the margin of compliance below the FCC limit. The units are given in dB. A 

negative margin indicates the emission was below the limit. A positive margin indicates 
that the emission exceeds the limit. 

 
Example for an emission measuring 20.5 dB

µV on the spectrum analyzer at 592 MHz: 

(Note: This shows a passing result (i.e. a negative margin)) 
 
Example only: 
 

Reading A.F. 

    Net Reading           Net Reading      FCC limit             Margin 

20.5dB

µV   +    25 dB    =  45.5 dBµV/m   :   45.5 dBµV/m  -  57 dBµV/m =     -11.5 dB