Rohde & Schwarz ESW Series, User Manual

Page: 333 / 759

General Instrument Setup
R&S
®
ESW
333 User Manual 1177.6298.02 ─ 08
"Switch to
internal refer-
ence" The instrument automatically switches back to the internal reference
if no external reference is available. Note that you must re-activate
the external reference if it becomes available again at a later time.
Remote command:
[SENSe:]ROSCillator:SOURce
on page 623
[SENSe:]ROSCillator:SOURce:EAUTo?
on page 624
Tuning Range ← Reference Frequency Input
The tuning range is only available for the variable external reference frequency. It
determines how far the frequency may deviate from the defined level in parts per mil-
lion (10
-6 ).
"+/- 0.5 ppm" With this smaller deviation a very narrow fixed loop bandwidth of 0.1
Hz is realized. With this setting the instrument can synchronize to an
external reference signal with a very precise frequency. Due to the
very narrow loop bandwidth, unwanted noise or spurious components
on the external reference input signal are strongly attenuated. Fur-
thermore, the loop requires about 30 seconds to reach a locked state.
During this locking process, "NO REF" is displayed in the status bar.
"+/- 6 ppm" The larger deviation allows the instrument to synchronize to less pre-
cise external reference input signals.
Remote command:
[SENSe:]ROSCillator:TRANge
on page 625
Frequency ← Reference Frequency Input
Defines the external reference frequency to be used (for variable connectors only).
Loop Bandwidth ← Reference Frequency Input
Defines the speed of internal synchronization with the reference frequency. The setting
requires a compromise between performance and increasing phase noise.
For a variable external reference frequency with a narrow tuning range (+/- 0.5 ppm),
the loop bandwidth is fixed to 0.1 Hz and cannot be changed.
Remote command:
[SENSe:]ROSCillator:LBWidth
on page 622
Reference Frequency Output
A reference frequency can be provided by the R&S ESW to other devices that are con-
nected to this instrument. If activated, the reference signal is output to the correspond-
ing connector.
"Output 100 MHz"
Provides a 100 MHz reference signal to the REF OUTPUT 100 MHz
connector.
"Output 640 MHz"
Provides a 640 MHz reference signal to the REF OUTPUT 640 MHz
connector.
"Output Sync Trigger"
Provides a 100 MHz reference signal to the SYNC TRIGGER OUT-
PUT connector.
Reference Frequency Settings