System and method for amplitude pre-distortion optimization for GPS signal constant envelope transmission
AssigneeThe Boeing Company
InventorCornel Prunean
Life of this patent
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Abstract
A system and method include a modulator configured to combine satellite codes with carrier signals on an in-phase channel and a quadrature-phase channel to produce I-channel and Q-channel signal components. The powers of the combined satellite codes are selected according to desired code power fractions. A processor pre-distorts the signal components such that they can be transmitted as a unit-amplitude constant envelope transmission that preserves the desired code power fractions. The pre-distortion may also account for data filtering effects that tend to distort the code power fractions.
Claims19
A system comprising:
- a signal waveform generator combiner/modulator (WGCM) configured to:
- multiplex, on an in-phase channel (I-channel), a first set of two or more satellite codes of a plurality of satellite codes to create a base-band in-phase signal component,
- multiplex, on a quadrature-phase channel (Q-channel), a second set of two or more satellite codes of the plurality of satellite codes to create a base-band quadrature-phase signal component, and
- modulate the base-band in-phase signal component and the base-band quadrature-phase signal component onto an RF carrier;
- and
- a processor coupled to the WGCM and configured to pre-distort the base-band in-phase signal component and the base-band quadrature-phase signal component based on a respective desired power fraction for each satellite code of the plurality of satellite codes, such that after modulation of the in-phase and quadrature-phase signal components each satellite code has the respective desired power fraction for the satellite code.
A method of transmitting a GPS signal, comprising:
- modulating, on an in-phase channel (I-channel), a first portion of data using a first combination of two or more satellite codes of a plurality of satellite codes;
- modulating, on a quadrature-phase channel (Q-channel), a second portion of the data using a second combination of two or more satellite codes of the plurality of satellite codes;
- combining each of the modulated first and second portions of the data with a respective carrier signal to produce an in-phase signal component and a quadrature-phase signal component;
- before modulating the data, pre-distorting the data based on a respective desired power fraction for each satellite code of the plurality of satellite codes, such that each satellite code has the respective desired power fraction for the satellite code after modulating the data;
- and
- transmitting the in-phase signal component and the quadrature-phase signal component as a constant envelope signal.
A GPS satellite, comprising:
- a satellite body;
- a GPS signal payload including a modulator and a processor coupled to the modulator;
- and
- a power source configured to provide power to the GPS signal payload;
- wherein the modulator is configured to:
- modulate, on an in-phase channel (I-channel), a first portion of data using a first combination of two or more satellite codes of a plurality of satellite codes,
- modulate, on a quadrature-phase channel (Q-channel), a second portion of the data using a second combination of two or more satellite codes of the plurality of satellite codes, and
- combine each of the modulated first and second portions of the data with a respective carrier signal to produce an in-phase signal component and a quadrature-phase signal component;
- and
- wherein the processor is configured to pre-distort the data, before modulation of the data, based on a respective desired power fraction for each satellite code of the plurality of satellite codes, such that each satellite code has the respective desired power fraction for the satellite code after modulation of the data.
Dependencies are inferred from the claim text.