Hold-Over Mode; Frequency Reference Status; Reference Out - Keysight A Series User Manual

System Settings
System Configuration

Hold-over mode

When the GPS signal is lost, the last GPS reading is used as a hold-over
correction value for the internal reference. The hold-over correction value is no
longer used, but instead the factory-set correction value is used, when any of
the following occur:
— when GPS is disabled.
— when Reference Source is set to Internal.
— when the FieldFox resumes from Standby mode or shut down.

Frequency Reference Status

When switched to Ext or GPS, one of the following annotations appears in the
lower-left corner of the screen:
—
—
—
If the FieldFox does NOT find an appropriate Ext or GPS reference signal, then
Ext Ref UNLOCKED
This can occur when any of the following conditions exist:
— NO reference signal is present.
— A low or very high-level external reference signal is present. For best
— The external reference is off-frequency.
To learn the expected measurement accuracy when connected to a frequency
reference source, see the FieldFox specifications in
"Specifications/Data

Reference OUT

The internal 10 MHz frequency reference is available from the Ref/Trig output
connector on the right-side panel. Use this signal as a common frequency
reference when making measurements using external equipment. See this
connector in
764
— GPS Available ONLY with Built-in GPS (Opt. 307). When selected,
the internal GPS is immediately enabled and a search for satellites
begins. When satellites are found, the precision timing signal is NOT
used directly, but is used to correct the absolute frequency of the
internal reference many times per second.
EXT R – External reference is selected.
GPS R – GPS reference is selected.
GPS H – Internal Reference is used with last 'hold-over' correction reading.
is displayed in the lower-left corner of the graticule area.
results, the signal should be between –5 dBm and +5 dBm.
Sheet".
"Top Panel" on page
Appendix B:
51.
Keysight N9927-90020 User's Guide