Signal Source

Signal generator: generates a variety of waveforms.

Supports an output of type complex, float, int, and short

Parameters

(R): Run-time adjustable

Sample Rate (R)

Default value: samp_rate

Sample rate (fs) is the average number of samples obtained in one second. Its units are samples per second or hertz e.g. 48,000 sample rate is 48 kHz.

Waveform (R)

options: [Constant, Sine, Cosine, Square, Triangle, Saw Tooth]

For selection with a variable, the following values should be used:

 * Constant = 100
 * Sine = 101
 * Cosine = 102
 * Square = 103
 * Triangle = 104
 * Sawtooth = 105

Frequency (R)

Frequency of the waveform (default: 1000)

Amplitude (R)

Amplitude of the output (default: 1)

Offset (R)

Offset from zero (default: 0)

Initial Phase (Radians) (R)

Default: 0

Message Ports

cmd

The 'cmd' message port accepts message pairs.

• 'freq' . float value
• 'ampl' . float value
• 'phase' . float value
• 'offset' . float value

For GNU Radio 3.8, the messages dont work correctly with pairs, but they do work fine with a dictionary. This issue is explained here.

For GNU Radio 3.8, the amplitude of the signal source can be changed to 0.5 by adding the following PMT to the message strobe block.

pmt.dict_add(pmt.make_dict(), pmt.intern("ampl"), pmt.from_double(0.5))

This PMT creates a dictionary and adds a pmt pair of ("ampl", 0.5) to the dictionary.

freq

The value of frequency in the signal source can be changed by connecting a message strobe. The Message PMT parameter can be set to pmt.from_float(new_freq). In this way, the frequency of the signal source will be changed to new_freq value after the specified period in the message strobe. In the following example, the frequency of the signal source is changed to 1kHz after 5 seconds.

The 'freq' message port has been deprecated in 3.9 in favor of the 'cmd' message port.

Example Flowgraph

This flowgraph is for version 3.9+.

Example Output

Types of Waveforms:

Cosine (complex):

Constant:

Square:

Triangle:

Sawtooth:

Source Files

C++ files

[1]

Header files

[2]

Public header files

Base

Waveforms

Block definition

[3]