Variables in Flowgraphs

This page describes the fundamentals of a flowgraph: how to make and edit variables, and data types. The flowgraph from the previous guide (Your First Flowgraph) will be used as a reference.

Variables

A GNURadio flowgraph is a .py Python file. Just as Python code can have variables so too can a GNURadio flowgraph by using the Variable block.

Every new flowgraph starts with the samp_rate variable:

GNURadio blocks are implemented as functions and can take parameters which modify their behavior. All of the blocks in the flowgraph above use samp_rate as a parameter. Create a new variable block by dragging and dropping it from the block library on the right:

Double-click the variable_0 block to view and modify it's parameters.

Double-click the Signal Source block to :

You'll notice that samp_rate is the variable being used for the Sample Rate but Frequency is hard coded to 1000.

TODO: make/edit variables complex vs float (blue vs orange) compare the python .py code with the visual GRC flowgraph