Stereo System User Manual

Chapter 1 45
Agilent EXA Signal Analyzer
Dynamic Range
c. Setting the IF Gain to Low is often desirable in order to allow higher power into the mixer
without overload, better compression and better third-order intermodulation. When the Swept
IF Gain is set to Low, either by auto coupling or manual coupling, there is noise added above
that specified in this table for the IF Gain = High case. That excess noise appears as an addi-
tional noise at the input mixer. This level has sub-decibel dependence on center frequency. To
find the total displayed average noise at the mixer for Swept IF Gain = Low, sum the powers
of the DANL for IF Gain = High with this additional DANL. To do that summation, compute
DANLtotal = 10 × log (10^(DANLhigh/10) + 10^(AdditionalDANL / 10)). In FFT sweeps,
the same behavior occurs, except that FFT IF Gain can be set to autorange, where it varies
with the input signal level, in addition to forced High and Low settings.