Test and Measurement

Waveform generation, file IO formats, visualization, and performance analysis

Generate waveforms and use quantitative tools to measure system performance. Use graphical utilities such as constellation and eye diagrams to visualize the effects of various impairments and corrections.

Supported file formats to process captured signals include binary baseband signal and NI™ technical data management solution (TDMS) format files. You can read data into tables or timetables by reading TDMS-files individually, or by reading collections of TDMS-files simultaneously.

Apps

Wireless Waveform Generator	Create, impair, visualize, and export modulated waveforms
Bit Error Rate Analysis	Analyze BER performance of communications systems

Functions

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Bit Error Rate Calculation and Estimation

`biterr`	Number of bit errors and bit error rate (BER)
`symerr`	Compute number of symbol errors and symbol error rate
`berawgn`	BER and SER for uncoded data over AWGN channels
`bercoding`	BER for coded AWGN channels
`berconfint`	Error probability estimate and confidence interval of Monte Carlo simulation
`berfading`	BER and SER for uncoded data over Rayleigh and Rician fading channels
`berfit`	Fit curve to nonsmooth empirical BER data
`bersync`	BER for imperfect synchronization
`semianalytic`	BER using semianalytic technique

Measurements

powermeter Measure power and CCDF of the power of voltage signal

Visualization

`scatterplot`	Display input signal in IQ-plane
`eyediagram`	Generate eye diagram
`plotPhaseNoiseFilter`	Plot response of phase noise filter block

Utilities

`marcumq`	Generalized Marcum Q-function
`noisebw`	Equivalent noise bandwidth of digital lowpass filter
`qfunc`	Q function
`qfuncinv`	Inverse Q function
`showcommblockdatatypetable`	Communications Toolbox block characteristics

File IO

`tdmsread`	Read data from TDMS-file
`tdmswrite`	Write data to TDMS-file
`tdmsinfo`	Information about TDMS-file
`tdmsreadprop`	Read properties as single row table from TDMS-file
`tdmswriteprop`	Write properties to TDMS-file

Objects

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Measurements

`comm.ACPR`	Measure adjacent channel power ratio (ACPR)
`comm.CCDF`	Complementary cumulative distribution function (CCDF) measurements
`comm.ErrorRate`	Compute bit or symbol error rate of input data
`comm.EVM`	Measure error vector magnitude (EVM) of received signal
`comm.MER`	Measure modulation error ratio of received signal

Visualization

`comm.ConstellationDiagram`	Display and analyze input signals in IQ-plane
`spectrumAnalyzer`	Display frequency spectrum of time-domain signals
`timescope`	Display time-domain signals
`dsp.ArrayPlot`	Display vectors or arrays

File IO

`comm.BasebandFileReader`	Read baseband signal from file
`comm.BasebandFileWriter`	Write baseband signal to file
`tdmsDatastore`	Datastore for collection of TDMS-files

Blocks

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Measurements

Error Rate Calculation	Compute bit error rate or symbol error rate of input data
EVM Measurement	Measure error vector magnitude (EVM)
MER Measurement	Measure modulation error ratio in digital modulation applications
Power Meter	Measure power and the CCDF of the power of voltage signal in Simulink

Visualization

Constellation Diagram	Display and analyze input signals in IQ-plane
Eye Diagram	Display eye diagram of time-domain signal
Time Scope	Display and analyze signals generated during simulation and log signal data to MATLAB
Spectrum Analyzer	Display frequency spectrum

Waveform Generation

Waveform From Wireless Waveform Generator App

Wireless waveform source exported to Simulink

File IO

Baseband File Writer	Write baseband signals to file
Baseband File Reader	Read baseband signals from file

Topics

Bit Error Rate Analysis Techniques
Obtain bit error rate results and statistics.
Analyze Performance with Bit Error Rate Analysis App
Learn how to use the Bit Error Rate Analysis app.
Create Waveforms Using Wireless Waveform Generator App
Create, impair, visualize, and export modulated waveforms.
Adjacent Channel Power Ratio (ACPR)
Learn about ACPR Measurements.
Measure Modulation Accuracy
Learn about EVM and MER for measuring modulation accuracy.
Scatter Plots and Constellation Diagrams
Display digitally modulated signals in the IQ-plane.
Visualize RF Impairments
Apply various RF impairments to a QAM signal.
Plot Signal Constellations
This example shows how to plot a PSK constellation having 16 points.
Eye Diagram Analysis
In digital communications, an eye diagram provides a visual indication of how noise might impact system performance.
Selected Bibliography for Measurements
List of references for further reading.

Related Information

The NI TDMS File Format
Datastore

Featured Examples

Link Budget Analysis

In the design of wireless communications links between two sites, issues of range, throughput, and received signal quality are of critical importance to the system engineer. Link budget analysis accounts for all gains and losses in the communication link. Some factors and design choices, such as propagation path length, signal polarization, and antenna feed cable, degrade signal quality, while others, such as the power amplifier and antenna size, can increase transmitted signal strength.

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Measure EVM for 802.15.4 (ZigBee) System

Measure the error vector magnitude (EVM) of a simulated IEEE® 802.15.4 [ 1 ] transmitter by using a comm.EVM System object™. The EVM measurement quantifies the modulation accuracy of a transmitter by measuring the difference between an error-free modulated reference waveform and an impaired waveform. IEEE 802.15.4 specifies the protocols to use for ZigBee® wireless personal area networks. Section 6.7.3.1 of IEEE® 802.15.4 [ 1 ] specifies: "... An IEEE 802.15.4 transmitter shall have EVM values of less than 35% when measured for 1000 chips. The error-vector measurement shall be made on baseband I and Q chips after recovery through a reference receiver system. The reference receiver shall perform carrier lock, symbol timing recovery, and amplitude adjustment while making the measurements. ...". Here, the receiver processing does not require carrier lock, symbol timing recovery, and amplitude adjustment because the only impairment applied in the simulation is additive white Gaussian noise (AWGN).

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Frequency Offset Calibration for Receivers

At the receiver, measure and calibrate to remove the frequency offset between a transmitter and a receiver.

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Frequency Offset Calibration for Receivers in Simulink

Measure and calibrate for transmitter/receiver frequency offset at the receiver using Simulink® and Communications Toolbox™. You can either use captured signals or receive signals in real time using the Communications Toolbox Support Package for RTL-SDR Radio. The receiver monitors the received signal, calculates and display the transmitter/receiver frequency offset.

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Spectrum Analysis of Signals

Downstream spectrum analysis of signals using MATLAB^®, Communications Toolbox™ and DSP System Toolbox™.

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Spectral Analysis of signals in Simulink®

Use the captured signals, or receive signals in real time using RTL-SDR, ADALM-PLUTO or USRP™ radio, as a data source for downstream spectrum analysis with MATLAB and Simulink^®.

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