Interference compensation system

An interference compensation system comprising a first input terminal for receiving an interference signal I.sub.A, a second input terminal for receiving a desired signal and an interference signal I.sub.M, an amplitude-phase control circuit (3) for adjusting an amplitude and phase of an interference signal I.sub.A from the first input terminal so that the amplitude and the phase of the output signal I.sub.VM of the amplitude-phase control circuit (3) are the same amplitude and the opposite phase as compared with the interference signal I.sub.M from the second input terminal, and a combiner (4) for combining the output signal I.sub.VM of the amplitude-phase control circuit (3) and the signal I.sub.M from the second input terminal to provide a compensated output signal I.sub.E substantially free from an interference signal to the output terminal (15) CHARACTERIZED IN THAT:

• said interference compensation system comprises;
• (a) an amplitude-phase control circuit (3) comprising a pair of control signal input terminals each receiving the control signals A+a.multidot.cos .omega.t and B+a.multidot.sin .omega.t, respectively, and said amplitude-phase control circuit (3) controlling the input interference signal I.sub.A so that the average length and the average direction of the output vector I.sub.VM is defined by the values A and B, and the head of the output vector I.sub.VM rotates periodically according to the values (a) and (.omega.), where A and B change according to the difference between I.sub.M and I.sub.A, and (a) and (.omega.) are the amplitude and the angular frequency of the low frequency signal superposed on the values A and B,
• (b) a low frequency oscillator (7,12) for providing a pair of outputs a.multidot.cos .omega.t and a.multidot.sin .omega.t having 90.degree. phase difference with each other,
• (c) an envelope detector (10) connected to the output of said combiner (4) to provide the envelope level of the combined signal I.sub.E,
• (d) means (11) connected to the output of said envelope detector to provide the low frequency component of the envelope signal,
• (e) a pair of phase detectors (13a, 13b) each having two inputs, the first input of each phase detector receives the output of said means (11) in the paragraph (d), and the second input of each phase detector receives the signal having the frequency (.omega.) with 90.degree. phase difference with each other from said low frequency oscillator in the paragraph (b),
• (f) a pair of low pass filter means (14a, 14b) each connected to the outputs of the related phase detector (13a, 13b) to prevent double frequency components (2.omega.),
• (g) a pair of voltage integrators (6a, 6b) each connected to the output of the related low pass filter means (14a, 14b) to integrate the output of the low pass filter means to provide the values A and B, respectively,
• (h) a pair of adders (8a, 8b) for adding the outputs A, B of said voltage integrators (6a, 6b), and the outputs a.multidot.cos .omega.t, a.multidot.sin .omega.t of said low frequency oscillator to provide A+a.multidot.cos .omega.t, and B+a.multidot.sin .omega.t, respectively, which are applied to the control input terminals, respectively, of said amplitudephase control circuit (3), and
• (i) a closed control loop for providing the values A+a.multidot.cos .omega.t, and B+a.multidot.sin .omega.t by said combiner (4), said envelope detector (10), said means (11), said phase detectors (13a, 13b), said low pass filter means (14a, 14b), said voltage integrators (6a, 6b), said adders (8a, 8b), and said amplitude-phase control circuit (3).