WCDMA3G_ErrorVector
Description: EVM error vector
Library: 3GPPFDD 10-99, Measurement
Class: SDFWCDMA3G_ErrorVector
Parameters
Name | Description | Default | Type | Range |
---|---|---|---|---|
StartSym | start symbol | 2560 | int | [0, 10000] |
SymBurstLen | number of symbols within burst to be measured | 2560 | int | [1, 10000] |
SampPerSym | number of samples per symbol | 16 | int | [1, 512] |
SymDelayBound | upper bound of delay detection, in symbol, -1 for no detection | -1 | int | [-1, 1000] † |
NumBursts | number of bursts to be measured | 1 | int | [1, ∞) |
FilterLength | Number of taps | 64 | int | [2, 128] |
† -1 means no synchronization is needed |
Pin Inputs
Pin |
Name |
Description |
Signal Type |
---|---|---|---|
1 |
in |
signals to be measured for EVM |
complex |
2 |
ref |
reference signals for EVM measurement |
complex |
Notes/Equations
- This subnetwork is used to calculate EVM error vector according to the tested and reference signals. The following figure shows the schematic of this subnetwork.
WCDMA3G_ErrorVector Schematic
- Each firing, one input token is consumed at each input pin while one output token is produced at the output token. The data sequence size that represents the valid error vector is SymBurstLen × NumBursts. The error vector is measured at each symbol instead of each sample.
Results are split into Real and Imag parts and saved in the Realerror.txt and Imagerror.txt files, respectively. - The error vector is obtained by calculating the EVM. Let Z(k) be the complex vectors produced by observing the real transmitter through a specified measuring receiver filter at instant K, one symbol period apart. S(k) is defined to be an ideal transmitted signal observed through the measuring filter and sampled at time k. With the transmitter modeled as:
where
The error vector E(k)W = e^{dr + jda} accounts for both a frequency offset giving da radians per symbol phase rotation and an Amplitude change of dr nepers per symbol;
C0 is a constant origin offset representing quadrature modulator imbalance;
C1 is a complex constant representing the arbitrary phase and output power of the transmitter;
E(k) is the residual vector error on sample S(k).
is measured and calculated for each instant k.