Analog Demodulation (Option K7)  R&S FSL  
1300.2519.12 4.140  E-11 
Analog Demodulation (Option K7) 
The digital signal processing in the R&S FSL, used in the analyzer mode for digital IF filters, is also 
ideally suited for demodulating AM, FM, or PM signals. The firmware option R&S FSL–K7 provides the 
necessary measurement functions. 
The R&S FSL is equipped with a demodulator that is capable of performing AM, FM, and PM 
demodulation at a time. Additionally maximum, minimum and average or current values can be 
obtained parallelly over a selected number of measurements.  
By sampling (digitization) already at the IF and digital down–conversion to the baseband (I/Q), the 
demodulator achieves maximum accuracy and temperature stability. There is no evidence of typical 
errors of an analog down–conversion and demodulation like AM to FM conversion and vice versa, 
deviation error, frequency response or frequency drift at DC coupling. 
This option is available from firmware version 1.10. 
To open the analog demodulation menu 
 If the Analog Demodulation mode is not the active measurement mode, press the MODE key and 
activate the Analog Demodulation option. 
 If the Analog Demodulation mode is already active, press the MENU key. 
The analog demodulation menu is displayed. If the tracking generator (models 13, 16 and 28) or the 
power meter (option Power Sensor Support, K9) is available, softkeys for these functions are also 
provided. 
Menu and softkey description 
– "Softkeys of the analog demodulation menu" on page 4.144 
– "Softkeys of the frequency menu (Analog Demodulation mode)" on page 4.150 
– "Softkeys of the span menu (Analog Demodulation mode)" on page 4.152 
– "Softkeys of the amplitude menu (Analog Demodulation mode)" on page 4.153 
– "Softkeys of the bandwidth menu (Analog Demodulation mode)" on page 4.155 
– "Softkeys of the sweep menu (Analog Demodulation mode)" on page 4.155 
– "Softkeys of the trigger menu (Analog Demodulation mode)" on page 4.156 
Apart from the power measurement menu that is not available in the Analog Demodulation mode, all 
other menus are provided as described for the base unit. For details refer to the corresponding menu 
descriptions.  
To display help to a softkey, press the HELP key and then the softkey for which you want to display 
help. To close the help window, press the ESC key. For further information refer to section "How to use 
the Help System". 
Further information 
– "Circuit description – block diagrams" on page 4.141 
– "Demodulation bandwidth" on page 4.142 
– "AF trigger" on page 4.142 
– "Stability of measurement results" on page 4.142 
– "Sample rate, measurement time and trigger offset" on page 4.143