OFDM Error Summary table (Custom OFDM)
table contains signal quality metrics of the signal. This data can be averaged over multiple measurements and can also be queried programmatically through a .NET API 1) Access Preamble Indicator, or 2) Application Programming Interface interface. This topic contains the following information:
- Available Error Summary Results
- Averaging and Error Summary Data
- Using Band Power markers to limit Error Information
- Querying summary table data results programmatically
Available Error Summary Data
A list of the available error data is provided in the Available Error Summary Data topic, which also links to detailed descriptions for each error result.
Averaging and Error Summary Data
When averaging is on, averaging is applied to the numeric error data in the symbol/errors table with the following exception. Averaging applies only to 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 data for the Peak Hold/Continuous Peak Hold averaging types.
Error data from the current scan is not included in the average if any of these conditions exist:
- Pulse Not Found
- Sync Not Found
- Carrier Unlock.
- DATA?
- Pulse too Short
For more information see Averaging with Digital Demodulation.
Using Band Power markers to limit Error Information
If you want EVM error information for all points over a selected region, you can use the band-power markers with the Error Vect vs. Carrier and Error Vect vs. Sym trace data. The Error Vect vs. Carrier trace data will compute the EVM for all symbols within a specified subcarrier region and Error Vect vs. Sym trace data with compute the EVM for all subcarriers within a specified symbols region.
For example, here's how you could compute the symbol EVM for OFDM Orthogonal Frequency Division Multiplexing: OFDM employs multiple overlapping radio frequency carriers, each operating at a carefully chosen frequency that is Orthogonal to the others, to produce a transmission scheme that supports higher bit rates due to parallel channel operation. OFDM is an alternative tranmission scheme to DSSS and FHSS. subcarriers 11, 12, and 13. Click to display the Error Vect vs. Carrier trace data, then click , select the Band Power check box to turn on the band-power markers.
Now position the band-power markers to select the region of interest; place the markers so that they are exactly on or close to the specific subcarriers of interest. Center the marker at subcarrier 12, enter 12 in the Center text box, and set the width to two carriers, enter 2 in the Width text box, this encloses the region of interest (subcarriers 11, 12, and 13). Then select RMS () to display the EVM in %rms, this is the EVM (%rms) for all symbols within subcarriers 11, 12, and 13.
You can use the same procedure with the Error Vect vs. Sym trace data display to find the EVM (%rms) for all subcarriers within a specific range of symbols.
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
