3 53210A Measurements
82 Keysight 53210A User’s Guide
–
INTernal selects the counter’s internal 10 MHz oscillator. The signal is a
0.5 Vrms (into 50
Ω) sine wave. The internal oscillator signal is also present on
the counter’s rear panel Int Ref Out connector.
–
EXTernal selects an external reference signal applied to the rear panel Ext Ref
In connector. The signal must be:
– 1 MHz, 5 MHz, or 10 MHz
– 100 mVrms to 2.5 Vrms
–sine wave
and the frequency must be specified by the
SENSe:ROSCillator:EXTernal:FREQuency command.
–
:AUTO ON enables automatic selection of the reference oscillator source. If a 1,
5, or 10 MHz signal is present on the counter’s Ext Ref In connector, source
EXTernal is set. If a valid signal is not present or is lost, the source
automatically switches to INTernal.
Note that specifying an oscillator source (
INTernal or EXTernal) using
[
SENSe:]ROSCillator:SOURce disables automatic selection.
–
:AUTO Off disables automatic selection of the oscillator source. The source is
then set by the [
SENSe:]ROSCillator:SOURce command.
The reference oscillator source is set to
INTernal with automatic selection
enabled (
On) when the counter is shipped from the factory or following the
SYSTem:SECure:IMMediate command. Settings are stored in non-volatile memory
and are not changed after a reset (
*RST) or instrument preset (SYSTem:PREset or
Preset key).
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:
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