The noise marker function calculates the 
average noise level over a bandwidth of 1Hz, 
referenced from the marker position. 
> Select Marker[F1] and select a 
marker number. 
2.  Press [F2] to turn the selected marker on. 
3.  Press Normal[F3] and then position the marker 
to the desired location.  
4.  Press Function[F5]>Marker Noise and turn 
Marker Noise on. 
5.  The display will show the noise level 
measurement at the top of the screen in 
dBm/Hz.