WCDMA PRACH Measurement
R&S
®
CMW-KG4xx/-KM4xx/-KS4xx
849
User Manual 1173.9657.02 ─ 11
Fig. 5-1: Connecting an RF transmitter to the instrument
5.2.2 How to Perform a Measurement
The measurement expects a WCDMA PRACH UL signal. Any other signals, e.g. a
WCDMA UL signal without preambles (established connection) will not yield measure-
ment results.
After preparing the physical test setup, you have to adjust at least the following ana-
lyzer settings to the properties of the analyzed PRACH signal:
●
Analyzer "Frequency"
●
"Expected Nominal Power", "User Margin" (optional) and "External Attenuation
(Input)"
Recommended values: "Expected Nominal Power" = peak power of the first pre-
amble; "User Margin" = 0 dB. The smallest possible value of the "Expected Nomi-
nal Power" plus the "User Margin" ensures maximum dynamic range.
When using the combined signal path scenario, let the signaling application calcu-
late the expected nominal power from the UL power control settings (expected
nominal power mode = "According to UL Power Control Settings"). Do not use the
manual mode.
●
"UE Signal Info" setting "DL Scrambling Code"
Configure this parameter for a standalone measurement. For the combined signal
path scenario it is set automatically.
●
Power step limit setting "Preamble Power Steps"
For a standalone measurement, configure the power step size expected for con-
secutive preambles. The value is used to calculate the expected nominal power of
the second preamble and of subsequent preambles.
For the combined signal path scenario the value is set automatically.
The default trigger settings are usually appropriate and don't need to be modified, see
chapter 5.2.5, "Trigger Modes"
Start the measurement before switching on the UE. This ensures that the measure-
ment starts with the first preamble of the preamble cycle.
General Description
深圳德标仪器
135-1095-0799