Coherent detection architecture for remote calibration of cohere

Details Coherent detection architecture for remote calibration of cohere Coherent detection architecture for remote calibration of cohere

1996-10-25

1998-09-15

Pham, Chi H.

Pulse or digital communications

Receivers

Particular pulse demodulator or detector

342165, 342174, 342360, H03D 100, G01S 740, H01Q 300

Patent

active

058090878

ABSTRACT:
An architecture for remote calibration of coherent systems uses coherent reference and calibration signals that contain the relative amplitude and phase information desired in the calibration process. Circuitry extracts the relevant amplitude and phase information needed for the calibration while compensating for non-synchronized clocks and the effects of Doppler shifts due to relative motion of the transmitting and receiver platforms. The coherent detection architectures can be used effectively with any scheme designed to determine the relative amplitudes and phases of the signals emitted from the different elements of the phased array. These architectures are particularly applicable to coherent encoding calibration procedures that enhance the effective SNR by using coherent transmission of orthogonal transform encoded signals from N elements of the phased array. In an example calibration architecture, coherent elemental signals are encoded using controlled switching of the delay phase control circuits themselves to effectively generate a perfect orthogonal transform encoding of the signal vectors, even though the control circuits may be imperfect; no additional encoding hardware is required. The switching is dictated by matrix elements of an N xN invertible binary matrix, with the most preferred embodiment being an orthogonal binary matrix, i.e., a Hadamard matrix. The coherent signals are decoded with the inverse of the same binary matrix used in the control circuit encoding.

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R.L. Pickholtz et al., "Theory of Spread-Spectrum Communications--A Tutorial", IEEE Transactions on Communication, vol. COM-30, No. 5, May 1982.
R.L. Pickholtz et al., "Revisions to Theory of Spread-Spectrum Communications--A Tutorial", IEEE Transactions on Communication, vol. COM-32, No. 2, Feb. 1984.
D.V. Sarwate et al., "Crosscorrelation Properties of Pseudorandom and Related Sequences", Proceedings of the IEEE, vol. 68, No.1 5, May 1980.
W.K. Pratt et al., "Hadamard Transform Image Coding", Proceedings of the IEEE 57, No. 1 (Jan. 1969), pp. 58-68.

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