Comp IQ Meas Spec and IQ Ref Spec (W-CDMA(3GPP)/HSPA)

When W-CDMA Code Division Multiple Access: One of several digital wireless transmission methods in which signals are encoded using a specific pseudo-random sequence, or code, to define a communication channel. A receiver, knowing the code, can use it to decode the received signal in the presence of other signals in the channel. This is one of several "spread spectrum" techniques, which allows multiple users to share the same radio frequency spectrum by assigning each active user an unique code. CDMA offers improved spectral efficiency over analog transmission in that it allows for greater frequency reuse. Other characteristics of CDMA systems reduce dropped calls, increase battery life and offer more secure transmission. See also IS-95.(3GPP) Demodulation is enabled, the composite IQ Meas Spec and composite IQ Ref Spec traces show the spectrum of the composite IQ Meas Time and composite IQ Ref Time signals respectively. The VSA produces the spectrum by windowing and FFTing the composite I/Q measured or composite I/Q reference signal.

MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. Measurements ( only): There is a seperate trace result for each measurement Antenna (x).

The trace data is computed from the first slot in the Measurement Interval after the Measurement Offset (see Measurement Interval and Offset).

The VSA's demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, the carrier-frequency error must be added to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in Composite Error Summary Table.

The spectrum represents the signal AFTER filtering.

By default, the VSA shows the log(dB) magnitude when IQ measured Spectrum is selected. The same is true for I/Q reference.