GNUradio Basics

Sine §

• Signal source block ▶️ complex signal creation
• QT GUI freq sink ▶️ display magnitude of the freq spectrum
• QT GUI time ▶️ display time domain
• Throttle ▶️ flow control in the absence of radio h/w

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Variables §

• python data types for vars

  floatNumber=0.1
  intnumber=2
   
  floatnumber=float(2)
  intNumber=int(0.1)

• Use variable blocks

• Same for strings, Lists and tuples

• List comprehension

  • functions can be written in variables too

    listvar=[0,1,2,3]
    listcomp=[(i+1)*2 for i in listvar]

    

• the blocks are implemented as functions

• parameters modify the behavior

• variables can be dependent on other vars

  freq=30000
  sample_rate=freq*2

  • here, variable names are treated as ID and values as Value in GNURadio

• Runtime updating variables

  • QT GUI Range

    • works as variable block
    • needs default parameters

    

  • QT GUI Chooser

    • drop down list options

    

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Signal data types §

• complex
  • uses pair of 32-bit float to represent the real and imaginary portions
  • Signal 1 and Singnal 2 are real and imaginary components, simultaneously (see output of the diagram).
• type can be changed to have a single signal “source”.
• to convert data-types use block provided, note the conversion feasibility.

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Packing bits §

• packing bits generated by a random source to byte.

  GnuRadio_basics 2023-11-25 23.50.47.excalidraw

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Unpacking bits §

• unpacking packed bits.

  • unpacks from LSB to MSB
  • perfectly reverses the packing

• vis

  • perfect rev (sig1 and sig2 perfect overlapping)

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Streams and Vectors §

• Streams

  • carries 1 sample per time instance
  • serialized data
  • scalar at each time instance

• Vectors

  • multiple sample per time instance
  • represent data in parallel
  • array at each time instance

• Streams to vector flowgraph

• Vectors to stream flowgraph

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Hier blocks(hierarchical) and Parameters §

• wrapper to simplify multiple GNU radio blocks into a single block
• var vs parameter
  • parameter creates an interface for the hier block to accept a value from an external source.
  • variable exists only internally to a block. (block here might be the hier block)
• Pads source and pad sink represents the connection points (input and output) to the hier block in reference to the main flowgraph.
• Hier block
• Hier block used as one of the core blocks

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Refs §

see ASK