R&S ESU Series - Setting the if Bandwidth - BW Key

Operating Manual 1302.6163.12 - 03 4.21
R&S ESU Instrument Functions
Receiver Mode
4.5.3 Setting the IF Bandwidth – BW Key
R&S ESU offers the IF bandwidths (3 dB bandwidths) from 10 Hz to 10 MHz avail-
able in steps of 1/2/3/5/10 and the IF bandwidths (6 dB bandwidths) 10 Hz, 100 Hz,
200 Hz, 1kHz, 9 kHz, 10 kHz, 100 kHz, 120 kHz, and 1 MHz.
The resolution bandwidths up to 120 kHz are implemented by digital Gaussian
bandpass filters. Concerning the attenuation characteristic, the filters behave like
analog filters, but their measurement speed is much higher than the measurement
speed of comparable analog filters. This is due to the fact that the transient
response can be compensated because the filters have an accurately defined
behavior.
Bandwidths of 200 kHz and higher are implemented by decoupled LC filters. These
filters contain 5 filter circuits.
BW
The BW key calls a menu for setting the resolution bandwidth (RES BW) for the
receiver.
RES BW
The RES BW softkey activates the manual entry mode for the resolution bandwidth.
For filter type NORMAL (3dB), the bandwidth can be set from 10 Hz to 10 MHz in
steps of 1/2/3/5/10. For filter type EMI (6dB), the 6-dB bandwidth 10 Hz, 100 Hz, 200
Hz, 1kHz, 9 kHz, 10 kHz, 100 kHz, 120 kHz, and 1 MHz can be set. Softkeys are
only available for the CISPR bandwidths 200 Hz, 9 kHz a nd 120 kHz and for the 6-
dB bandwidth 1 MHz. The other bandwidths have to be set by numerical input or by
rotary knob..
For numerical inputs, the values are always rounded up to the next valid bandwidth.
For rotary knob or the UP/DOWN key entries, the bandwidth is adjusted in steps
either upwards or downwards.
For the CHANNEL and RRC filter types, the bandwidth is selected from a list of
available channel filters, which is included at the end of this section. The list can be
scrolled with the Uu and Ud keys to select a filter (see section “List of Available
Channel Filters” on page 4.23).
RES BW
200 Hz
9kHz
120 kHz
1MHz
CISPR RBW
UNCOUPLED
FILTER TYPE
! NORMAL (3dB)
EMI (6dB)
CHANNEL
RRC