Demodulator with multiple interference cancellers responsive to correlations between undesired signals and error signals.

摘要

Undesired signals detected by a main antenna (1) are cancelled by corresponding interference cancelling signals. The output of the main antenna is frequency converted to IF region and decomposed into first and second main baseband components. Decision circuits are provided for making a decision on whether each of the first and second main baseband components exceeds each of multiple thresholds and produces multibit codes as well as error signals. Auxiliary antennas (3-1...3-m) respectively detect the undesired signals and feed auxiliary frequency converters (5-1) for translating the frequency of the respective outputs of the auxiliary antennas to the intermediate frequency. Auxiliary quadrature demodulators (7-1) are provided for respectively decomposing the output of each auxiliary frequency converter into first and second auxiliary baseband components. Correlations (8-1,9-1) are detected between the first auxiliary baseband components and the first error signal and between the second auxiliary baseband component and the second error signal. Amplitude and phase controllers (6-1) are responsive to the detected correlations to control the outputs of the auxiliary frequency converters to generate the interference cancelling signals. Variable length delay lines (4-1) are associated respectively with the auxiliary antennas for introducing delays so that both cancelling signals and corresponding interfering components are time-coincident at the summing circuit.