VCO

VCO - Voltage controlled oscillator. Produces a sinusoid of frequency based on the amplitude of the input. See VCO (complex) for a complex sinusoidal output.

input: float stream of control voltages;

output: float oscillator output

Parameters

Sample Rate

sampling rate (Hz)

Sensitivity

units are radians/sec/(input unit)

Amplitude

output amplitude

Example Flowgraph

This flowgraph can be found at [1]

For this flowgraph, the standard RTTY tones of 2295 (mark) and 2125 (space) are generated. The calculations for this follow:

• Choosing a full-scale frequency of 2500Hz with an input of +1.0, the VCO Sensitivity = (2 * math.pi * 2500 / 1.0) = 15708
• At the output of the Low Pass Filter, a Mark has a value of +1.0 and a Space has a value of 0.0
• When the output of the Low Pass Filter is +1.0, the input of the VCO is (1.0 * 0.068) + 0.850 = 0.918  That generates a frequency of 0.918 * 2500 => 2295
• When the output of the Low Pass Filter is 0.0, the input of the VCO is (0.0 * 0.068) + 0.850 = 0.850  That generates a frequency of 0.850 * 2500 => 2125

See Sample_Rate_Tutorial#Sink_hardware_example for a discussion of the timing involved in a similar flowgraph.

Source Files

C++ files

vco_c_impl.cc

vco_f_impl.cc

Header files

vco_c_impl.h

vco_f_impl.h

Public header files

vco_c.h

vco_f.h

Block definition

blocks_vco_c.block.yml

blocks_vco_f.block.yml