Rohde & Schwarz R&S FSP Series, Operating Manual

Page: 238 / 796

R&S FSP Instrument Functions
Basic Settings
4.166 Operating Manual 1164.4556.12 - 06
In the setting REFERENCE EXT , the connector REF IN is used as input connector
for an external frequency standard. In this case all internal oscillators of the
R&S FSP are synchronized to the external reference frequency.
REFERENCE
FREQUENCY
As of firmware version 4.4x, the firmware provides the REFERENCE FREQUENCY
softkey. This softkey opens a submenu to configure the reference more precisely.
To maintain the setup of a test system, the reference settings do not change if a pre-
set is performed.
REFERENCE
INTERNAL /
EXTERNAL
The REFERENCE INTERNAL / EXTERNAL softkey activates the internal or exter-
nal reference.
If the external reference is selected, you can set the frequency of the external refer-
ence with the
REFERENCE FREQUENCY softkey.
Remote command:
ROSC:SOUR EXT
ROSC:SOUR INT
REFERENCE
EXT (INT)
The REFERENCE EXT (INT) softkey provides a fail-safe if the external reference
signals fails for any reason.
The softkey activates the use of an external reference signal. However, if the
R&S FSP detects an unlock due to a missing external reference signal, the refer-
ence signal source automatically switches to use the internal reference signal.
Once the R&S FSP has switched to the internal reference signal it stays with the
internal reference. You have to switch back to the external reference signal manually
(press
REFERENCE EXTERNAL and then activate REFERENCE EXT (INT) again).
The current source (internal or external) is indicated in the lower part of the softkey.
Remote command:
ROSC:SOUR EAUT
REFERENCE
FREQUENCY
The REFERENCE FREQUENCY softkey sets the frequency of the external refer-
ence. The range is from 1 MHz to 20 MHz with the default value being 10 MHz.
The reference frequency does not change after a preset to maintain the setup of a
test system.
Remote command:
ROSC:EXT:FREQ 10 MHZ
REF BW (NORM
WIDE)
The REF BW (NORM WIDE) softkey controls the PLL bandwidth used to sznchro-
nize with the external reference signal. Possible settings are NORM (PLL bandwidth
about 3 Hz) or WIDE (PLL bandwidth about 30 Hz). The default setting is NORM.
The reference settings do not change after a preset to maintain the setup of a test
system.
The softkey is available only if the external reference frequency is 10 MHz.
This function requires a synthersizer board revision with hardware code 7 or above .
You can check this information in the “HWC” column of the hardware info window
(see
“HARDWARE INFO” on page 4.186 ).
Remote command:
ROSC:EXT:PLL NORM | WIDE