Spectrum Measurements
R&S
®
ESR
454
User Manual 1175.7068.02 ─ 12
Figure 6-35: The R&S
ESR's dynamic range for adjacent channel power measurements on W-CDMA
uplink signals is a function of the mixer level.
The level of the W-CDMA signal at the input mixer is shown on the horizontal axis, i.e.
the measured signal level minus the selected RF attenuation. The individual compo-
nents which contribute to the power in the adjacent channel and the resulting relative
level (total ACPR) in the adjacent channel are displayed on the vertical axis. The opti-
mum mixer level is -18 dBm. The relative adjacent channel power (ACPR) at an opti-
mum mixer level is -77 dBc. Since, at a given signal level, the mixer level is set in 5 dB
steps with the 5 dB RF attenuator, the optimum 10 dB range spreads from -17 dBm to
-22 dBm. In this range, the obtainable dynamic range with noise correction is 77 dB.
To set the attenuation parameter manually, the following method is recommended:
► Set the RF attenuation so that the mixer level (= measured channel power – RF
attenuation) is between -16 dBm and -22 dBm.
This method is automated with the "Adjust Ref Level" function. Especially in remote
control mode, e.g. in production environments, it is best to correctly set the attenuation
parameters prior to the measurement, as the time required for automatic setting can be
saved.
To measure the R&S
ESR's intrinsic dynamic range for W-CDMA adjacent channel
power measurements, a filter which suppresses the adjacent channel power is
required at the output of the transmitter. A SAW filter with a bandwidth of 4 MHz, for
example, can be used.
Advanced Measurement Examples
