Approaches for APSK modulation

An apparatus for providing a modulated signal for transmission, the apparatus comprising:

• controlling circuitry;
• memory coupled with the controlling circuitry, wherein the memory includes instructions that when executed by the controlling circuitry cause the apparatus to perform operations comprising:
• setting a reference point in time for a current block of information to be modulated, wherein the reference point in time is related to an end of a pulse of a previous modulation symbol;
• selecting a modulation symbol from a collection of available modulation symbols for representation of the current block of information to be modulated, wherein each available modulation symbol has a symbol duration, comprises a pulse, and indicates the information by a combination of an amplitude of the pulse and a carrier phase of the pulse, wherein a position of the pulse is defined within the symbol duration of the available modulation symbol, and wherein at least two of the available modulation symbols have different symbol durations, wherein the selection of the modulation symbol for representation of the current block of information to be modulated comprises specifying the position of the pulse in relation to the reference point in time for the current block of information;
• and
• operating a signal generator to provide the selected modulation symbol for transmission.