Ronde & Schwarz 1304.0004.03, User Manual

Page: 276 / 1076

The Spectrum Application (RF Measurements)
R&S
®
FPL1000
276 User Manual 1178.3370.02 ─ 09
RF Input Protection
The RF input connector of the R&S FPL1000 must be protected against signal levels
that exceed the ranges specified in the data sheet. Therefore, the R&S FPL1000 is
equipped with an overload protection mechanism. This mechanism becomes active as
soon as the power at the input mixer exceeds the specified limit. It ensures that the
connection between RF input and input mixer is cut off.
The RF input connector of the R&S
FPL1000 must be protected against signal levels
that exceed the ranges specified in the data sheet. Therefore, the R&S FPL1000 is
equipped with an overload protection mechanism for DC and signal frequencies up to
30
MHz. This mechanism becomes active as soon as the power at the input mixer
exceeds the specified limit. It ensures that the connection between RF input and input
mixer is cut off.
When the overload protection is activated, an error message is displayed in the status
bar ("INPUT OVLD"), and a message box informs you that the RF Input was discon-
nected. Furthermore, a status bit (bit 3) in the
STAT:QUES:POW
status register is set.
In this case you must decrease the level at the RF input connector and then close the
message box. Then measurement is possible again. Reactivating the RF input is also
possible via the remote command
INPut<ip>:ATTenuation:PROTection:RESet
.
Radio Frequency State ............................................................................................... 276
Impedance .................................................................................................................. 276
SAW filter .................................................................................................................... 276
Radio Frequency State
Activates input from the "RF Input" connector.
Remote command:
INPut<ip>:SELect
on page 790
Impedance
For some measurements, the reference impedance for the measured levels of the
R&S
FPL1000 can be set to 50
Ω
or 75
Ω
.
Select 75
Ω
if the 50
Ω
input impedance is transformed to a higher impedance using a
75
Ω
adapter of the RAZ type. (That corresponds to 25
Ω
in series to the input impe-
dance of the instrument.) The correction value in this case is 1.76 dB = 10 log (75
Ω
/
50
Ω
).
This value also affects the unit conversion (see "Reference Level" on page 311).
Remote command:
INPut<ip>:IMPedance
on page 790
SAW filter
The R&S FPL1000 hardware contains both a wide and a narrow IF path. Depending on
the used analysis bandwidth, the R&S FPL1000 determines which IF path to use auto-
matically. The wide IF path allows for a smoother signal at the center frequency, while
the narrow IF path supresses possibly distorting signals further away from the center
frequency. Using this setting, you can affect which IF path is used.
Receiving Data Input and Providing Data Output