Patent
1976-08-30
1978-04-18
Griffin, Robert L.
325473, 325368, 325371, H04B 708
Patent
active
040853683
ABSTRACT:
Apparatus for canceling interference suitable for use in conjunction with stationary phased array antennas or transducer arrays designed for satellite or other communication systems employing N-phase PSK (Phase Shift Keying) modulation is disclosed. The techniques used in the apparatus involves processing of signals received by a main array and an auxiliary array of a phased array antenna so that an error signal is derived which is fed back to circuitry which modifies at least one signal received by the auxiliary array. The modified signal or signals are summed with the signal received by the main array so that a sum wave is generated whose interference component is minimal.
The feedback circuitry exponentiates or raises the sum wave to the N.sup.th power to eliminate modulation, since the N.sup.th power of an N-phase PSK signal is a narrowband carrier. Then a term proportional to the desired signal raised to the N.sup.th power is filtered from the exponentiated sum wave and the remainder is utilized for error signal purposes. This technique operates without sacrificing bandwidth or degrading the desired signal and permits reception of signals with frequency spectra substantially overlapping one another.
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Bell Telephone Laboratories Incorporated
Chin Tommy P.
Griffin Robert L.
Hollander James F.
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