Baseband File Writer

R2026b

Write baseband signals to file

• 

Baseband File Writer block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Communications Toolbox / Comm Sinks

Description

The Baseband File Writer block writes a baseband signal to a specific type of binary file. Baseband signals are typically down-converted from a nonzero center frequency to 0 Hz. Sample rate, which is determined by the input signal sample time and frame size, and center frequency are saved when the signal is written to a file.

Examples

Write Baseband Signal to File in Simulink

Generate and write a QPSK-modulated signal to a file. Then, read the file and plot the constellation diagram of the signal.

The model cm_baseband_writer_ex1 generates a QPSK-modulated signal and writes the noisy QPSK signal to a file named bbw_example.bb.

Open a second model, cm_baseband_writer_ex2, to read the signal from the file and display the constellation diagram.

Ports

Input

Port_1 — Baseband signal

scalar | vector | matrix

This port accepts a baseband signal to be saved under the filename specified by the Baseband file name parameter. The saved signal is always complex.

Data Types: single | double
Complex Number Support: Yes

Parameters

To edit block parameters interactively, use the Property Inspector. From the Simulink^® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Baseband file name — Name of baseband file to write

untitled.bb (default) | character vector

Name of the baseband file to write, specified as a character vector.

To specify the location where the file is saved, click Browse.

Center frequency (Hz) — Center frequency of baseband signal

1e8 (default) | nonnegative scalar

Center frequency of the baseband signal in Hz, specified as a positive scalar or row vector. When this property is a row vector, each element is the center frequency of a channel in a multichannel signal. The vector length equal the number of columns in the input signal Port_1.

Metadata (structure or object) — Data describing baseband signal

empty structure (struct()) (default) | structure | object

Data describing the baseband signal, specified as a scalar structure or object.

Data Types: struct | object

Number of latest samples to write — Number of samples to write

inf (default) | positive integer

Number of samples to save, specified as a positive integer or Inf.

• To write all of the baseband signal samples to a file, set this property to inf.

• To write only the last NumSamplesToWrite samples to a file, set this property to a positive integer.

Simulate using — Select simulation mode

Code generation (default) | Interpreted execution

Code generation

On the first model run, simulate and generate code for the block using only MATLAB^® functions supported for code generation. If the structure of the block does not change, subsequent model runs do not regenerate the code.

Interpreted execution

Simulate model using all supported MATLAB functions. Choosing this option can slow simulation performance.

Block Characteristics

Data Types	double | integer | single
Multidimensional Signals	no
Variable-Size Signals	no

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"commsink2/Baseband File Writer"

Example: add_block("commsink2/Baseband File Writer","myModel/myBlock",MakeNameUnique="on")

Tips

• The Baseband File Writer block writes baseband signals to uncompressed binary files. To share these files, you can compress them to a zip file using the zip function. For more information, see Create and Extract from Zip Archives.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2016b

R2024a: Support writing objects to metadata

The Baseband File Writer block now supports writing objects and structures-of-structures to the saved metadata.