Keysight Technologies E8740A-060, Startup Manual

Page: 15 / 35

Keysight E8740A-060 Start-up Guide 15
Power Spectral Density Measurement with N9041B
Specifications for automotive radar usually states the average radiated power
spectral density (PSD) limits in dBm/MHz. The PSD can be viewed approximately
on screen by sweeping with a resolution bandwidth (RBW) of 1 MHz. However, if
larger RBW are required, the N9041B’s band power marker function can be used
to read the power spectral density. The following steps illustrates how to set the
center frequency, change the RBW and use Marker functions from the N9041B
user interface.
Step Action Notes
1 Change center frequency to 79 GHz a Select the Frequency panel or press
the FREQ key. Select the Center
Frequency control and enter 79.0 GHz.
b Select the Span control and enter
5.0 GHz.
Ensure that the detector is already in
RMS average mode. See step 6 of
“Viewing the noise floor of the N9041B”
on page 9 .
2 Change analyzer resolution bandwidth
(RBW).
a Select the BW panel or press the BW
key.
b Select the Res BW control and enter
1.0 MHz.
3 Select the Video BW control and enter
3.0 MHz.
4 Use Marker Function to measure
power spectral density.
a Select the Marker panel or press the
Marker key and select the Settings
tab.
b Choose Marker Mode to Normal . Tap
on the Marker Frequency and enter
79.0 GHz.
5 Switch to the Marker Function tab.
Tap Band Function control and select
Band Power from the drop down list.
6 Enter the Band Span as 1.0 MHz and
read the readout on the screen.
When using RBW that is not 1 MHz, the
marker function is required to read the
spectral density. The Band Density
marker function can also be used to read
spectral density directly in dBm/Hz. A
conversion factor of 60 dB can be added
for 1 MHz bandwidth.