How do I Make Rach Measurements?
Last updated: December 2, 2008
This section details how to make RACH measurements for the different operating modes the test set offers. These procedures assume that the BCH parameter for Cell Band is set up correctly for your mobile station and that the appropriate RF IN/OUT Amplitude Offsets have been set to offset loss between the mobile station and the test set. An example scenario is given.
Overview of Measurement Procedure in Active Cell Mode
-
Set operating mode to Active Cell.
-
Press Receiver Control (F12).
-
Set the Expected Power Control to Manual and set the Manual Burst Power.
-
Set the test set's Measurement Frequency to the frequency the RACH will arrive on. The simplest way to do this is to set the manual channel (that is, the expected ARFCN) to the ARFCN of the BCH. Alternatively, you could set the expected frequency to the uplink frequency of the BCH ARFCN.
-
Ensure trigger mode is set to Auto.
Once the RACH measurement is completed, in order to make further measurements on the TCH, ensure you reset the receiver control to Auto.
Overview of Measurement Procedure in Test Mode
This procedure assumes that the BCH parameter for the cell band is set up correctly for your mobile station and the appropriate RF IN/OUT Amplitude Offsets have been set to offset loss between the mobile station and the test set.
-
Press
CALL SETUP
-
Set
Operating Mode
to any non-Active Cell mode that has a Broadcast Channel (BCH). These operating modes include:
GSM BCH
,
GSM BCH+TCH
,
GPRS BCH
,
GPRS BCH+PDTCH
,
EGPRS BCH
and
EGPRS BCH+PDTCH
.
-
Press
Receiver Control
(
F12
)
-
Set the
Expected Power Control
parameter to
Manual
. and set the Manual Power for each uplink burst in the multislot configuration.
-
Set the
Measurement Frequency
to the expected BCH receiver frequency.
-
Press
Close Menu
(
F6
)
-
Press
Measurement selection
-
Select
Power vs Time
.
-
Press
Change View
(
F2
)
-
Press
Burst 1 Numeric Results
(
F2
). Note: Changing views after the measurement is complete will loose your measurement results.
-
Using your proprietary commands, initiate the mobile to generate a sequence of RACH bursts on the BCH, or set the
Expected Power Control
parameter to
Manual
.
-
Set the
Measurement Frequency
to the expected BCH receiver frequency.
-
Start the appropriate measurement.
-
Make a mobile originated call. While the Operating Mode is set to one of the modes in step 1, the test set will not respond to a random access burst which allows the mobile station to generate additional random access bursts.
Example Procedure
The following procedure details how to manually make a GSM power versus time RACH measurement while the Operating Mode is GSM BCH+TCH.
-
Press
CALL SETUP
-
Press
Operating Mode
(
F1
) and choose
GSM BCH+TCH
from the Operating Mode menu.
-
Press
Receiver Control
(
F12
)
-
Set the
Expected Power Control
parameter to
Manual
.
-
Set the
Measurement Frequency
to the expected BCH receiver frequency.
-
Press
Close Menu
(
F6
)
-
Press
Measurement selection
-
Select
Power vs Time
.
-
Press
Change View
(
F2
)
-
Press
Burst 1 Numeric Results
(
F2
). Note: Changing views after the measurement is complete will loose your measurement results.
-
Originate a call from the mobile station. The results are automatically displayed on the front panel. You can confirm the measurement was on the random access burst by observing the burst is shorter than a normal burst. The useful part of a RATCH burst is 312.2 µs. The results should be similar to the figure below.
-
Press Graph (F4). This shows the graphical representation of the data. The display should look similar to the figure below.This clearly shows the random access burst is shorter than a normal traffic channel burst, as the green lines show boundaries for a normal burst.
-
To make further measurements on the TCH ensure that the Receiver Control is returned to Auto.
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