Hardware Interfaces  CMU 
1100.4903.12 8.12  E-8 
Signal Inputs and Outputs 
RF Connectors  
The N sockets on the front panel labeled RF1, RF 2, RF 3 OUT and RF4 IN are used as inputs and 
outputs for RF signals. 
 
RF 2 RF 1
 
 
Bidirectional RF connectors 
 
 
RF4 IN RF 3 OUT
 
Unidirectional RF connectors  
Fig. 8-8  RF connectors 
 
 
Inputs and Outputs for the Reference Frequency (REF...) 
The BNC sockets on the rear panel labeled REF IN, REF OUT 1 and REF OUT2 are used for 
synchronization of the CMU with external devices. 
 
REF IN REF OUT 1 REF OUT 2
 
REF IN  This input is used to synchronize the CMU to other 
instruments. The frequency of the external reference 
signal fed in at REF IN must be set in the Sync. index card 
of the Connection Control menu or via the 
CONFigure:SYNChronize:FREQuency:REFerence 
command. 
REF OUT 1 A signal for synchronization of other instruments is 
available at this output connector. This signal is either the 
reference frequency of the CMU or the signal applied to 
the input REF IN (see Sync. index card of the Connection 
Control menu).  
REF OUT 2  A clock signal applied to this output and can be used for 
synchronizing external devices. The clock frequency can 
be selected from a list of network-specific frequencies in 
the Sync. index card of the Connection Control menu. 
 
Fig. 8-9  Inputs and outputs for reference frequency