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AFSK Modulator

This is a GNU Radio hierblock to create (A)FSK based modulation. This block expecting input as a bitstream and outputs FSK modulated complex signal stream.

Tested on GNU Radio v3.7.11 - Ubuntu.

Index

  1. Installation
  2. AFSK Modulator in More Detail
  3. Example
  4. TODO

Installation

You have to have GNU Radio v3.7.10 (or newer) in your computer first.

$ cd
$ cd gr-HDLC-AFSK/hierblocks/afsk-modulator/
$ gnuradio-companion afsk_mod.grc
  • Run the flowgraph (F6).
  • Reload Blocks
  • Finish. Now this hierblock will appear under HDLC AFSK category as AFSK Modulator block.

Detail

  • This AFSK Modulator outputs zero-centered AFSK signal with mark frequency is -0.5 * fsk_dev and space frequency is +0.5 * fsk_dev.

  • Baudrate is adjustable (default: 1200 baud). Real baudrate implementation is through symbol repetition.

  • Symbols are 1 for bit 0 or space and 0 for bit 1 or mark.

  • The output of the modulator is pulse shaped using a root raised cosine filter. This filter ensures only bandwidth-limited modulation signal is produced.

The following is the AFSK Modulator's bigger picture:

Example

Files:

gr-HDLC-AFSK/hierblocks/afsk-modulator/afsk_mod-example.grc
gr-HDLC-AFSK/hierblocks/afsk-modulator/afsk_mod-example-minimum-shift-keying.grc

TODO

// TODO