Phase angle mapping for phase modulation
AssigneeExelis, Inc.
InventorWilliam J. Taft
Life of this patent
Estimating the term…
Abstract
In determining an angle for a phase modulation scheme, a key is generated from a prescribed set of bits contained in a symbol. The symbols have an in-phase (I) data word and a quadrature phase (Q) data word that identify coordinates of the symbols in a complex number plane. An angle is retrieved from a memory table from a storage location identified by the key. Each angle in the memory table is established in accordance with constraints under which the memory table was populated so as to be mapped to a phase angle identifying other coordinates in the complex number plane that are within a specified neighborhood about the coordinates of each of the symbols. A signal is generated to convey the symbols as phase differentials at each sample time between a reference phase and the phase angle.
Claims23
A method, performed by an apparatus, comprising:
- generating a key at each of a plurality of sample times from a prescribed set of bits in respective symbols obtained at each of the sample times, each of the symbols comprising an in-phase (I) digital data word and a quadrature phase (Q) digital data word identifying coordinates of the corresponding symbols in a complex number plane;
- retrieving an indication of an angle from a memory table at each of the sample times at a storage location therein identified by the key generated at the corresponding one of the sample times, each angle in the memory table being established in accordance with constraints under which the memory table was populated so as to be mapped to a phase angle identifying other coordinates in the complex number plane that are within a specified neighborhood about the coordinates of each of the symbols;
- and
- generating a signal to convey the symbols as phase differentials at each of the sample times between a reference phase and the phase angle.
An apparatus comprising:
- a memory to store a memory table having stored therein a plurality of angles in respective storage locations identified by respective keys, each angle in the memory table being established in accordance with constraints under which the memory table was populated so as to be mapped to a phase angle that is within a specified neighborhood about coordinates of a symbol in a complex number plane;
- and
- a processor configured to:
- generate a key at each of a plurality of sample times from a prescribed set of bits in respective symbols obtained at each of the sample times, each of the symbols comprising an in-phase (I) digital data word and a quadrature phase (Q) digital data word identifying the coordinates thereof in the complex number plane;
- retrieve an angle from the memory table at each of the sample times at the storage location therein identified by the generated key;
- and
- generate a signal to convey the symbols as phase differentials at each of the sample times between a reference phase and the phase angle.
A tangible non-transitory computer readable medium having encoded thereon instructions that, when executed by a processor, configure the processor to:
- store a memory table in memory having a plurality of angles in respective storage locations identified by respective keys, each angle in the memory table being established in accordance with constraints under which the memory table was populated so as to be mapped to a phase angle that is within a specified neighborhood about coordinates of a symbol in a complex number plane;
- generate a key at each of a plurality of sample times from a prescribed set of bits in respective symbols obtained at each of the sample times, each of the symbols comprising an in-phase (I) digital data word and a quadrature phase (Q) digital data word identifying the coordinates thereof in the complex number plane;
- retrieve an angle from the memory table at each of the sample times at the storage location therein identified by the generated key;
- and
- generate a signal to convey the symbols as phase differentials at each of the sample times between a reference phase and the phase angle.
Dependencies are inferred from the claim text.