Keysight x-series User Reference Manual page 198

4 Input/Output Functions
Input/Output
to Sense and there is a valid external reference present) this information is used by the analyzer to
determine the internal settings needed to lock to that particular external reference signal.
For the instrument to stay locked, the value entered must be within 5 ppm of the actual external reference
frequency. So it is important to get it close, or you risk an unlock condition.
Note that this value only affects the instrument's ability to lock. It does not affect any calculations or
measurement results. See "Freq Offset" in the Frequency section for information on how to offset
frequency values.
Key Path
Remote Command
Example
Dependencies
Preset
Min
Max
Default Unit
Initial S/W Revision
Modified at S/W Revision
198
Input/Output, Freq Ref In
[:SENSe]:ROSCillator:EXTernal:FREQuency <freq>
[:SENSe]:ROSCillator:EXTernal:FREQuency?
ROSC:EXT:FREQ 20 MHz sets the external reference frequency to 20 MHz, but does not select the
external reference.
ROSC:SOUR:TYPE EXT selects the external reference.
Still available with Internal or Pulse selected, to allow setup for when External is in use. However, the
setting has no effect if the Internal Reference is in use (Freq Ref In set to Internal, Pulse, or
SENSE:INT or SENSE:PULSE).
This is unaffected by a Preset but is set to 10 MHz on a "Restore Input/Output Defaults" or "Restore
System Defaults->All"
CXA: 10 MHz
EXA: 10 MHz
MXA: 1 MHz
PXA: 1 MHz
N8973B, N8974B, N8975B, or N8976B: 10 MHz
CXA: 10 MHz
EXA: 10 MHz
EXA with option R13: 20 MHz
MXA: 50 MHz
PXA: 50 MHz
N8973B, N8974B, N8975B, or N8976B: 10 MHz
Hz
Prior to A.02.00
A.14.00
EMI Receiver Mode Reference