Inserting and extracting control data using frequency components

A modulator for inserting control data, the modulator comprising:

• a plurality of frequency component inputs;
• a modulator output;
• a processor;
• and
• a memory storing instructions that, when executed by the processor, cause the modulator to:
• receive primary data subcarriers on respective frequency component inputs which are assigned for receiving primary data;
• receive at least one control data subcarrier on a respective frequency component input which is not assigned to primary data;
• combine all frequency component inputs to one output signal;
• and
• provide the output signal on the output for transmission to a demodulator over a point-to-point medium.

A method for extracting control data in a demodulator comprising a plurality of frequency component outputs and a demodulator input, the method being performed in the demodulator and comprising the steps of:

• receiving one input signal on the input, the input signal having been transferred from a modulator over a point-to-point medium;
• separating frequency components of the input signal to the plurality of subcarriers for respective frequency component outputs;
• providing primary data subcarriers on respective frequency component outputs which are assigned for providing primary data;
• and
• providing at least one control data subcarrier on a respective frequency component output which is not assigned to primary data.