CONTENTS

ANNEX  1    
Use of the decibel and the neper    
 1     Definition of the decibel    
 2     Definition of the neper      
 3     Use of the decibel and neper        
 4     Rules for the use of the symbols where dB is included       
        4.1     The symbol dB without additional indication           
        4.2     The symbol dB followed by additional information within parenthesis           
        4.3     The symbol dB followed by additional information without parenthesis        
 5     Loss and gain   
        5.1     Transmission loss   
        5.2     Antenna gain          
 6     Levels 
        6.1     Absolute power level         
        6.2     Relative power level and related concepts  
                  6.2.1     Definition  
                  6.2.2     Transmission reference point (see ITU-T Recommendation G.101)
                  6.2.3     Meaning of “dBm0”          
        6.3     Power density        
        6.4     Absolute power density level          
        6.5     Absolute voltage level        
        6.6     Audio frequencies  
                  6.6.1     Absolute audio-frequency noise level         
                  6.6.2     Relative voltage levels       
                  6.6.3     Use of the decibel, by extension, for ratios of quantities not connected with power 
        6.7     Absolute level of an electromagnetic field    
        6.8     Sound pressure level          
 7     Ratios expressing transmission quality       
        7.1     Signal-to-noise ratio           
        7.2     Protection ratio      
        7.3     Carrier to spectral noise density ratio (C / N0)        
        7.4     Energy to spectral noise density ratio          
        7.5     Figure of merit (M)
 8     Special notations  
APPENDIX  1    
Notation for expressing the reference of a level