Comp IQ Meas Time and IQ Ref Time (cdma2000/1xEV-DV)
When cdma2000/1xEV-DV demodulation is enabled, the and traces are the time data results of cdma2000/1xEV-DV demodulation for the composite signal. is the data results for the measured input signal. trace data is the data results that would be derived from an ideal input signal (reference signal).
The trace data is computed from the first PCG in the measurement and the and parameter settings are ignored.
Concepts
The VSA's demodulator produces two signals: I/Q Measured and I/Q Reference.
IQ measured signal
The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset compensation, filtering and system gain normalization to the incoming signal.
IQ reference signal
IQ reference signal is the ideal signal that the VSA generates from the IQ measured signal demodulated data bits. The VSA detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.
Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.
Time-Domain Displays
The VSA's demodulator produces time-domain data. If is selected, the VSA shows the composite IQ measured signal in the time domain. Likewise, if is selected, the VSA shows the composite IQ reference signal in the time domain.
The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)).
If normalization is OFF, the VSA shows the instantaneous magnitude. If normalization is ON, the VSA scales the composite IQ measured and composite IQ reference traces so that the RMS level is one, which produces a unitless y-axis.
For further details about normalization, see Normalize IQ Traces.
See Also
