Composite Error Summary (TEDS)

The composite Error Summary trace shows quality metrics for the composite TEDS signal (all valid TEDS subcarriers). All measurements, except IQ Offset, IQ Offset Max, Reference Power, and Droop Rate, depend on the symbols in the calculation. You can choose which symbols to include in the calculation using the Include Sync/Pilot Symbols and Include Header Symbols settings plus the effects of droop using Include Droop and also Pilot Tracking.

The trace below is for a Normal Uplink, 50kHz channel bandwidth, 16QAM signal.

The Error Summary trace provides the following information:

Parameter

Description

EVM

A summary of the composite EVM in %rms where the Root Mean Square (rms) of the error vectors is computed and expressed as a percentage of the square root of the mean power of the ideal signal.

EVM Max

Subcarrier with the maximum EVM in %rms and the TEDS subcarrier location.

EVM Pk

Symbol with the peak EVM in % and the symbol location on the specific TEDS subcarrier.

Mag Err

Composite symbol magnitude error in %rms. Magnitude error is the difference in amplitude between the I/Q measured signal and the I/Q reference signal and is an indicator of the quality of the modulated signal amplitude component. A high magnitude error might indicate, for example, incidental AM modulation on the signal.

Mag Err Max

Maximum symbol magnitude error in % and the specific TEDS subcarrier location.

Mag Err Pk

Peak symbol magnitude error in % and the symbol on the specific TEDS subcarrier location.

Phase Err

Composite IQ phase error in degrees. Phase error is the difference in phase between the I/Q measured signal and the I/Q reference signal and is an indicator of the quality of the modulated signal phase component. A high phase error might indicate, for example, incidental FM modulation on the signal.

Phase Err Max

Maximum IQ phase error in degrees and the specific TEDS subcarrier location.

Phase Err Pk

Peak IQ phase error in degrees and the symbol on the specific TEDS subcarrier location.

Freq Err

Composite frequency error in Hertz (or fractions of Hertz). This value is not subject to the symbols in the EVM calculation or Droop or Pilot Tracking.

Freq Err Max

Maximum frequency error in Hertz (or fractions of Hertz), and the specific TEDS subcarrier. This value is not subject to the symbols in the EVM calculation or Droop or Pilot Tracking.

Freq Err Pk

Peak frequency error in Hertz (or fractions of Hertz), and the symbol on the specific TEDS subcarrier location. This value is not subject to the symbols in the EVM calculation or Droop or Pilot Tracking.

IQ Offset

Composite IQ Offset is the average of all subcarrier IQ offsets.

For a single-carrier signal, IQ offset would indicate the magnitude of the carrier feedthrough, which is caused by offsets in the modulation inputs to the quadrature modulator. However, since composite IQ Offset is based on the subcarrier IQ offsets (and the center of an individual subcarrier is not aligned with the carrier center (0 Hz) of the combined signal), composite IQ Offset does not represent the magnitude of the carrier feedthrough.

This value is not subject to the symbols in the EVM calculation or Droop or Pilot Tracking.

IQ Offset Max

Maximum IQ Offset (also called I/Q origin offset) for a particular specific TEDS subcarrier. This value is not subject to the symbols in the EVM calculation or Droop or Pilot Tracking.

Ref Pwr

Average power of all sync and pilot symbols.

Droop Rate

Droop Rate refers to a transmission signal impairment that measures the amplitude difference between the start and end of a TDMA burst. It is calibrated in dB/symbol, typically in fractions, that is mdB/symbol (millidB) or udB/symbol (microdB). To remove droop correction from your measurements, clear the Include Droop checkbox. The droop rate is displayed regardless of whether Include Droop is selected.

See Also

About TEDS Trace Data

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