NTi Audio Digilyzer DL1 - Manual (Page 40)

40
Measurement Functions
Application hint:
Broadcast levels are limited to a maximum output peak level. This
is in order to not to overload the transmission lines and to avoid
unpleasant and audible distortions. During tuning through the radio
stations it is clearly noticeable, that some channels are much louder
than others; purposely to increase awareness!
This is accomplished by using compressors and other dynamic
signal processing devices. The intention is to make the material as
loud as possible without exceeding the maximum peak level. Simply
feed the digital audio signal into the Digilyzer and it displays for both
channels the peak- and VU-levels. The closer the VU level is to the
PPM level, the higher is the compression of the audio material.