Continuous Phase Modulation

Generic CPM modulator.

The input of this block are symbols from an M-ary alphabet +/-1, +/-3, ..., +/-(M-1). Usually, M = 2 and therefore, the valid inputs are +/-1. The modulator will silently accept any other inputs, though. The output is the phase-modulated signal.

Parameters

CPM Type

The modulation type. Can be one of LREC, LRC, LSRC, TFM or GAUSSIAN. See gr_cpm::phase_response() for a detailed description.

Modulation Index

Maximum phase change that can occur between two symbols, i.e., if you only send ones, the phase will increase by every samples. Set this to 0.5 for Minimum Shift Keying variants.

Samples per Symbol

Self explanatory

Pulse Duration (symbols)

The length of the phase duration in symbols. For L=1, this yields full- response CPM symbols, for L > 1, partial-response.

Phase Response Parameter (BT or beta)

For LSRC, this is the rolloff factor. For Gaussian pulses, this is the 3 dB time-bandwidth product.

Example Flowgraph

Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.

Source Files

C++ files

cpmmod_bc_impl.cc

Header files

cpmmod_bc_impl.h

Public header files

cpmmod_bc.h

Block definition

digital_cpmmod_bc.block.yml