Quadrature product subcarrier modulation system
AssigneeThe Aerospace Corporation
InventorsPhilip A. Dafesh, Tien M. Nguyen
Life of this patent
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Abstract
A coherent adaptive subcarrier modulation system applies subcarrier modulation to quadrature modulated signals with constant envelope modulation suitable for efficient sinewave and squarewave subcarrier modulations. The quadrature subcarrier enables the addition of new signals to the in-phase and quadrature phase signals with spectral isolation in the Global Position System while maintaining a constant envelop amplitude.
Claims20
A system for modulating DS data on an I phase communicating DI data and on a Q phase communicating DQ data, the I phase and Q phase are phases of a modulated carrier signal communicating the DI data and the DQ data and the DS data, the carrier signal has a total phase equal to arctangent of the Q phase divided by the I phase, the system comprising,
- an encoder for encoding the DI data and the DQ data respectively into an Io encoded signal and a Qo encoded signal,
- an encoded subcarrier modulation signal generator for receiving one or more of the DS data and the DI data and the DQ data and for generating an encoded subcarrier modulation signal, the encoded subcarrier modulation signal comprises a product of a data partition function and the DS data, the data partition function is a function of one or more of the DI data and the DQ data and the DS data,
- a modulator for modulating a subcarrier signal by the encoded subcarrier modulation signal for providing a modulated subcarrier signal, for modulating the total phase of the carrier signal by the modulated subcarrier signal, for modulating the I phase of the carrier signal by the Io encoded signal and by an I phase subcarrier signal to provide an I phase carrier signal and for modulating the Q phase of the carrier signal by the Qo encoded signal and by a Q phase subcarrier signal to provide a Q phase carrier signal, the modulator combining the Q phase carrier signal and the I phase carrier signal as a composite signal, the I phase subcarrier signal is an I intermodulation product of the encoded subcarrier modulation signal and the Qo encoded signal, the Q phase subcarrier signal is a Q intermodulation product of the encoded subcarrier modulation signal and the Io encoded signal, the ratio of the Q intermodulation product over the I intermodulation product is equal to the ratio of the Io encoded signal over the Qo encoded signal, the composite signal has a constant amplitude envelop.
A system for modulating DS data on an I phase communicating DI data and on a Q phase communicating DQ data, the I phase and Q phase are phases of a modulated carrier signal communicating the DI data and DQ data, the carrier signal has a total phase equal to arctangent of the Q phase divided by the I phase, the DI data is communicated in spread spectrum signals spread by an CI code, the DQ data is communicated in spread spectrum signals spread by an CQ code, the DS data is communicated in spread spectrum signals spread by an CS code, the DS data is subcarrier data and CS code is a subcarrier code, the system comprising,
- an encoder for encoding the DI data spread by the CI code into an Io encoded signal, and for encoding the DQ data spread by the CQ code into a Qo encoded signal,
- an encoded subcarrier modulation signal generator for receiving the DS data and the CS code and the DI data and the CI code and the DQ data and the CQ code and for generating an encoded subcarrier modulation signal, the encoded subcarrier modulation signal comprises a product of a data partition function and a code partition function and the DS data and the CS code, the data partition function is a function of one or more of the DI data and the QI data and the DS data, the code partition function is a function of one or more of the CI code and the CQ code and the CS code, and
- a modulator for modulating a subcarrier signal by the encoded subcarrier modulation signal for providing a modulated subcarrier signal, for modulating the total phase of the carrier signal by the modulated subcarrier signal, for modulating the I phase of the carrier signal by the Io encoded signal and by an I phase subcarrier signal to provide an I phase carrier signal and for modulating the Q phase of the carrier signal by the Qo encoded signal and by an Q phase subcarrier signal to provide a Q phase carrier signal, the carrier modulator combining the Q phase carrier signal and the I phase carrier signal as a composite signal, the Q phase subcarrier signal is a Q intermodulation product of the encoded subcarrier modulation signal and the Io encoded signal, the I phase subcarrier signal is an I intermodulation product of the encoded subcarrier modulation signal and the Qo encoded signal, the ratio of the Q intermodulation product over the I intermodulation product is equal to the ratio of the Io encoded signal over the Qo encoded signal, the composite signal has a constant amplitude envelop.
Dependencies are inferred from the claim text.