3 53220A/53230A Measurements
80 Keysight 53220A/53230A User’s Guide
Specifying the external reference frequency
When the reference oscillator source is EXTernal as set by either
SENSe:ROSCillator:SOURce or SENSe:ROSCillator:SOURce:AUTO, the lock
frequency of the external signal (to which the internal oscillator is tuned) must be
indicated using the command:
[SENSe:]ROSCillator:EXTernal:FREQuency
{1E6|5E6|10E6|MINimum|MAXimum|DEFault}
[SENSe:]ROSCillator:EXTernal:FREQuency? [{MINimum|MAXimum|DEFault}]
(query form)
The external reference frequency setting is 10 MHz when the counter is shipped
from the factory or following the SYSTem:SECure:IMMediate command. The
setting is stored in non-volatile memory and is not changed after a reset (*RST) or
instrument preset (SYSTem:PREset or Preset key).
External Reference Example
The following example configures the counter to tune to an external reference if
present, and the expected external frequency is 10 MHz.
SENS:ROSC:SOUR:AUTO ON // tune to external ref if present
SENS:ROSC:EXT:FREQ 10E6 // signal will be 10 MHz
Detecting a valid external reference signal
ExtRef will appear in the top, right corner of the display when a valid (external)
reference is present. If a valid frequency is not present or was not specified, the
message “No valid external timebase” is displayed. The error is also logged in the
error queue.
The presence of a valid external reference can be determined programmatically
with the command:
[SENSe:]ROSCillator:EXTernal:CHECk ONCE
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