Modulation Accuracy Troubleshooting
Last updated: December 3, 2008
This section is applicable only to EGPRS
Possible Setup Issues
The serving cell must be set to EGPRS and an EGPRS data connection must be active. The test set's default serving cell is GPRS. See
Serving Cell
for more information.
The modulation accuracy measurement can only be used on signals using 8PSK modulation. Therefore, the modulation and coding scheme used must be MCS-5, MCS-6, MCS-7, MCS-8, or MCS-9, which all use 8PSK modulation. (See
CALL:(PDTCH|PDTChannel):MCSCheme
. The other MCS use GMSK modulation.
If you are using a connection type other than Auto, you must have the mobile station configured to perform a GPRS attach automatically or you must force one before you can start a data connection from the test set. The mobile station may have a connectivity setting for GPRS that allows you to configure it to always be on-line rather than use GPRS as needed.
During remote operation of the modulation accuracy measurement you should configure the trigger arm to single, see
SETup:EMACcuracy:CONTinuous
.
If the trigger arm is not set to single, the measurement may not return a result. When trigger arm is continuous the measurement rearms itself and starts another measurement cycle, during remote operation the FETCh query may not be synchronized to the measurement cycle, see
Measurement States
.
If the Trigger Source is set to RF Rise and the signal measured is not burst modulated the measurement will wait until aborted or timed out.
If the input signal does not rise above the threshold set at 20 to 30 dB below the Expected Power, see
Expected Power Control
there is not enough power to generate an RF Rise trigger so the measurement may hang.
Interpreting Integrity Indicator values
See
Integrity Indicator
.
If over range (5) is returned; the input power has exceeded the test set's internal sampler maximum value during some part of the sampling or the input power has exceeded the calibrated range of the test set's power detector for the RF Range setting. RF Range is automatically set based on the input power setting. Input power is a combination of amplitude offset and expected power settings. See
Mobile Station Receiver Example
.
If the signal has both over range and under range conditions only the over range (5) will be indicated.
If under range (6) is returned; the input power is more than 2 dB below the calibrated range of the test set's power detector for the RF Range setting. RF Range is automatically set based on the input power setting. Input power is a combination of amplitude offset and expected power settings. See
Mobile Station Receiver Example
.
Sync Not Found (11) is returned if a valid midamble cannot be found. In test mode, you must set the midamble to be used with the burst type parameter. See
CALL:BURSt:TYPE[:SELected]
. You may also see this error if you do not have the amplitude offsets configured correctly. See
Amplitude Offset
for more information.
If the burst is not continuous in a flexible timeslot configuration, for example, if the total number of uplink bursts is 6 and the bursts are transmited in TS0, TS1, TS2, TS4, TS5 and TS6 respectively, then valid results will be returned for burst 1, 2, and 3, Sync Not Found (11) will be returned for burst 4, 5, 6 and 7.
Unsupported Configuration (22) is returned if a base station emulator parameter is set incorrectly for this measurement. This error is returned if the modulation and coding scheme parameter is set to an MCS which does not use 8PSK modulation. Additionally, this error is returned if the connection type is set to BLER, as the PACCH is used for all signaling and control channels all use GMSK modulation.
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