Coherent detection architecture for remote calibration of coherent systems using direct sequence spread spectrum transmission of reference and calibration signals
First Claim
1. A transmission/receiving architecture for remote calibration of coherent systems using direct sequence spread spectrum transmission of reference and calibration signals comprising:
- first and second binary antipodal waveform generators for synchronously generating first and second orthogonal signals P1 (t) and P2 (t), respectively;
up converting means for generating first and second up converted signals;
first transmitting means for applying amplitude and phase values to said first up converted signal and transmitting a calibration signal S1 (t);
second transmitting means for receiving the second up converted signal and transmitting a reference signal S2 (t);
a receiving antenna for receiving coherent calibration and reference signals from said first and second transmitting means;
down converting means for generating the in-phase and quadrature components of the received coherent calibration and reference signals;
third and fourth binary antipodal waveform generators for generating orthogonal delayed replica signals P1 (t-τ
) and P2 (t-τ
), respectively;
processing means for generating estimates of the amplitudes and phases of said reference and calibration signals in the form of first and second values B1 and B2, respectively; and
an estimator for receiving said first and second values B1 and B2 and producing amplitude and phase estimates of the received calibration signal for calibration decoding.
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Abstract
An architecture that provides for coherent detection of the relative amplitude and phase of a calibration signal used in the remote calibration of an active transmitting or receiving phased array system employs two coherent signals, one being a reference signal and the other being the calibration signal that contains the relative amplitude and phase information desired in the calibration process. Direct sequence spread spectrum techniques are used to transmit the two coherent signals. Continuous time binary antipodal waveform signals are generated and used to transmit the reference and calibration signals. Relevant amplitude and phase information needed for the calibration can be extracted while compensating for non-synchronized oscillators and the effects of Doppler shifts due to relative motion of the transmitting and receiving platforms. The detection architecture is effective for satellite-based phased array systems, including geostationary, medium and low earth orbit communication satellites, and space-based synthetic aperture radar reconnaissance satellites.
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Citations
11 Claims
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1. A transmission/receiving architecture for remote calibration of coherent systems using direct sequence spread spectrum transmission of reference and calibration signals comprising:
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first and second binary antipodal waveform generators for synchronously generating first and second orthogonal signals P1 (t) and P2 (t), respectively; up converting means for generating first and second up converted signals; first transmitting means for applying amplitude and phase values to said first up converted signal and transmitting a calibration signal S1 (t); second transmitting means for receiving the second up converted signal and transmitting a reference signal S2 (t); a receiving antenna for receiving coherent calibration and reference signals from said first and second transmitting means; down converting means for generating the in-phase and quadrature components of the received coherent calibration and reference signals; third and fourth binary antipodal waveform generators for generating orthogonal delayed replica signals P1 (t-τ
) and P2 (t-τ
), respectively;processing means for generating estimates of the amplitudes and phases of said reference and calibration signals in the form of first and second values B1 and B2, respectively; and an estimator for receiving said first and second values B1 and B2 and producing amplitude and phase estimates of the received calibration signal for calibration decoding. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A coherent detection architecture for remote calibration of coherent systems using direct sequence spread spectrum transmission of reference and calibration signals comprising:
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a generation/transmission subsystem comprising; a first binary antipodal waveform generator for generating a baseband signal P1 (t); a second binary antipodal waveform generator synchronized to the first binary antipodal generator for generating a baseband signal P2 (t) orthogonal to said baseband signal P1 (t); up converting means for generating first and second up converted signals; a first transmitting antenna for accepting a signal from said first mixer and emitting a signal S1 (t) as a calibration signal; means for applying amplitude and phase values to the calibration signal; and a second transmitting antenna for accepting a signal from said second mixer and emitting a signal S2 (t) as a reference signal; and a reception/detection subsystem comprising; an antenna for receiving the transmitted calibration and reference signals S1 (t) and S2 (t); down converting means for generating the in-phase and quadrature components of the received coherent calibration and reference signals; a first binary antipodal waveform generator for generating a baseband delayed replica signal P1 (t-τ
));a second binary antipodal waveform generator synchronized to the first binary antipodal waveform generator for generating a baseband delayed replica signal P2 (t-τ
));a second demodulator for heterodyning the baseband reference and calibration signals from the first synchronous demodulator and low pass filter to produce in-phase and quadrature baseband reference output signals; a third demodulator for heterodyning the baseband reference and calibration signals from the first synchronous demodulator and low pass filter to produce in-phase and quadrature baseband calibration output signals; a first complex integrator for integrating the in-phase and quadrature baseband reference output signals over each of multiple repetitions of the delayed replica signals and producing a complex value B1 ; a second complex integrator for integrating the in-phase and quadrature baseband calibration output signals over each of multiple repetitions of the delayed replica signals and producing a complex value B2 ; and an amplitude and phase estimator operating on the complex values B1 and B2 for producing relative amplitude and phase estimates of the received calibration signal for calibration decoding. - View Dependent Claims (9, 10, 11)
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Specification