Channel Error Summary Data (TD-SCDMA)
The upper half of the symbol table shows Error Summary trace data for the specified . This topic discusses the Channel Error Summary data results, the Symbol data is discussed in About the Channel Symbol Table. The following Error Data topics are discussed and presented as listed:
- Available Channel Error Summary Data
- Selecting the Code Channel and Layer
- Averaging and Error Data Results
- Using Band Power markers to limit Error Information
- How EVM and Magnitude Error data results are calculated (%RMS)
- Additional Error Summary Data
- Querying summary table data results programmatically
Selecting Code Channel and Layer
The and parameters are specified in ( > > tab). The and Code Layer are specified in ( > > tab).
From the Overall Time trace data display use the marker feature to automatically specify the and information (Right click on the trace ).
From the trace data display use the marker feature to automatically specify the Despread-Channel and settings (Right click on the trace).
Averaging and Error Data results
If averaging is on, averaging is applied to most numeric error data in the error summary table with the following exceptions. The peak data values, such as peak EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format., peak Magnitude and peak Phase error are averaged only for the averaging types. The Slot number is never averaged. For more information see Averaging with Digital Demodulation.
Error data from the current scan is not included in the average if any of these conditions occur:
- CARRIER LOCK?.
- DATA? (if caused by a temporary condition like partial data record)
Using Band Power markers to limit Error Information
For error information for all points over a selected region, use the band-power markers with an error trace.
For example, here's how to compute the phase error for all points within a region. Click to display the IQ phase-error trace, then click and select the check box to turn on the band-power markers.
Now position the band-power markers to select the region of interest and Calculate to to display the phase error for the selected region.
At this point, simply click to display the magnitude error for the same region.
How EVM (%rms) and Magnitude Error (%rms) data results are calculated (%RMS)
In the channel error summary table, the VSA shows the error-vector magnitude and magnitude error as a percentage. Before computing this percentage, the VSA normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.
The VSA computes the overall, percent error by first computing the error-vector magnitude and magnitude error at each symbol time.
Next, the VSA derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the VSA takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.
Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.
Additional Error Summary Data
TD-SCDMA demodulation also provides these additional Error Summary data tables:
- Composite Error Summary table provides error data for the composite signal for a specific timeslot and sub-frame.
- Overall Error Summary table provides chip timing error data and Total power, Data power and Midamble power for each timeslot within the burst.
Querying summary table data results programmatically
To programmatically query the Trace Summary Table data results using the Summary() and SummaryUnit() methods in the MeasurementData object.
See the How To Query Summary Table Data Results topic for more information.
See Also
