gr-cbmc

A Cumulant-Based Modulation Classification module for GNU Radio

Features

• Classification of the modulation of a signal
  • Detection of BPSK, QPSK, 16-QAM and 8-PSK possible
  • Classification and phase correction is done by one block
• The necessary synchronisation is perfomed by custom-built blocks
  • Frequency and Symbolrate estimation
  • Time synchronization (modified version of pfb_clock_sync)
• The result is a stream of symbols (with 1 sample per symbol) without phase-/frequency-/timing-offset, which includes the current modulation as stream tags

Usage

There is a flowgraph in examples/ which demonstrates the classification receiver chain. The receiver of the flowgraph is displayed here:

Further information is available in this bachelor thesis (german). This module was built as part of the thesis. An additional interesting source is the doctoral thesis by Michael Sebastian Mühlhaus: Automatische Modulationsartenerkennung in MIMO-Systemen.

Installation

To install this module, run these commands:

$ mkdir build
$ cd build
$ cmake ../
$ make
$ sudo make install
$ sudo ldconfig

The build process has been tested with

• cppunit, version 1.14.0
• gnuradio, version 3.7.10
• doxygen, version 1.8.13

Current Constraints

• Just setting stream tags, no actual demodulation of the signal
• If there is only noise, always 8PSK will be classified