Rohde & Schwarz ESRP Series, Руководство пользователя

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Receiver Mode
R&S
®
ESRP
142 User Manual 1175.7445.02 ─ 08
● Measurement Bandwidth ...................................................................................... 142
● Detectors ...............................................................................................................143
● Trace Modes ......................................................................................................... 147
● AF Demodulation .................................................................................................. 148
● V-Networks Control (LISN) ....................................................................................149
● Transducers .......................................................................................................... 150
● Preamplifier ...........................................................................................................151
● Exported Peak List ................................................................................................152
● Formats for Returned Values: ASCII Format and Binary Format ..........................153
5.2.1 Measurement Bandwidth
The measurement bandwidth ("RES BW") defines the bandwidth of the resolution filter.
The RF signal is evaluated and displayed according to the bandpass characteristics of
the resolution filter.
The receiver mode supports the following types of resolution filter.
●
Filters with a 3 dB bandwidth ( normal filters).
●
Filters with a 6 dB bandwidth ( EMI filters).
The 6 dB bandwidths are designed and required for EMI tests and measurements.
Note that the available bandwidth is limited by the current receiver frequency. The
measurement bandwidth must be less than or equal to half of the current receiver fre-
quency:
BW
≤
f
in
/ 2
Additional 6 dB bandwidths
Installing option R&S ESRP-B29 adds additional 6 dB bandwidths that are specified for
and comply to MIL, DO and automotive standards.
The resolution filters are implemented as digital Gaussian bandpass filters. Concerning
the attenuation characteristic, the filters behave like analog filters, but their measure-
ment 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.
The highest sensitivity is obtained at the smallest bandwidth (10 Hz). If the bandwidth
is increased, the reduction in sensitivity is proportional to the change in bandwidth.
Increasing the bandwidth by a factor of 3 increases the displayed noise by approx.
5
dB (4.77 dB precisely). If the bandwidth is increased by a factor of 10, the displayed
noise increases by a factor of 10, i.e. 10 dB.
The higher spectral resolution with smaller bandwidths leads to longer measurement
times at each frequency, because the measurement time has to allow the resolution fil-
ters to settle during a sweep at all signal levels and frequencies to be displayed.
For large measurement bandwidths, signal parts that are very far away (e.g. from a dif-
ferent signal) are considered in the measurement and distort the results. The displayed
noise increases.
Measurement Basics