Method and device relating to supervision and control of an oscillator signal

A device for generation of an of an oscillator signal (cos(.phi. (t))) having a predetermined frequency variation (f.sub.D (t)), whereby the frequency variation (f.sub.D (t)) comprises at least one time period (.tau.) during which the frequency (f(t)) is intended to vary linearly with time corresponding to one for the time period (.tau.) predetermined frequency slope (.mu..sub.0), comprising:

• a controllable oscillator (71), having a control signal input (75) and an oscillator signal output (73), whereby the controllable oscillator (71) is arranged to emit, via the oscillator signal output(73), an oscillator signal (cos(.phi. (t))), the frequency of which (f(t)) depends on a control signal (V(t)) received via the control signal input (75);
• a control signal generator (77), which in turn comprises a control signal output (79) and a correction signal input (81), the control signal output (79) being connected to the control signal input (75) of the controllable oscillator (71), whereby the control signal generator (77) is adapted to emit via the control signal output (79) the control signal (V(t)) which is modified in dependence of a via the correction signal input (81) received correction signal (K(t)), characterised in that:
• the device comprises means (87,89) for quadrature demodulation of the oscillator signal (cos(.phi.(t))) with respect to a constant frequency .omega..sub.0 /2.pi.), the means for quadrature modulation (87,89), comprising a first and a second quadrature signal output (93,95), whereby the means for quadrature modulation (87,89) are adapted to emit a first quadrature signal (I(t)) (an in-phase) having a secondary phase (.theta..sub.n) and a second quadrature signal (Q(t)) (a quadrature phase), having a phase separated .PI./2 from the secondary phase (.nu..sub.n), via the first and a second quadrature signal output (93,95);
• the device comprises means (97,99) for A/D-conversion of the quadrature signals (I(t), Q(t)), whereby the means (97,99) for A/D-conversion are adapted to A/D-conversion at a number of points of time (t.sub.k ;
• k=0,1, . . . , N) during the time period (.tau.) and to thereby generate time discrete quadrature signals (I.sub.k, Q.sub.k ;
• k=0,1, . . . , N);
• the device comprises means (97) for generating a time discrete approximation signal (Z.sub.k ;
• k=0,1, . . . , N) in dependence of the time discrete quadrature signals (I.sub.k, Q.sub.k), such that the signal value (Z.sub.n) of the time discrete approximations signal, corresponding to given point of time (t.sub.n), represents an approximation of the second time derivative (.theta.(t)) of the secondary phase at the given point of time (t.sub.n);
• the device comprises means (97) for generation of a time discrete error indication signal (e.sub.k ;
• k=0,1, . . . , N) in dependence of the time discrete approximation signals (Z.sub.k), such that the signal value (e.sub.n) of the time discrete error indication signal, corresponding to a given point of time (t.sub.n) indicates the deviation of the frequency slope (.mu.(t.sub.n)) of the oscillator signal (cos(.phi. (t))) at the given point of time (t.sub.n) from the predetermined frequency slope (.mu..sub.0);
• and that,
• the device comprises means (97,99) for generation of the correction signal (K(t)) in dependence of the time discrete error indication signal (e.sub.k), whereby the means (97,99) for generation of the correction signal (K(t)), are connected to the correction signal input (81).

A method for establishing of an oscillator signal frequency slope characterized in:

• a) quadrature demodulation of the oscillator signal (cos(.phi. (t))) with respect to a constant frequency (.omega..sub.0 /2.pi.), whereby a first quadrature signal (I(t)) (in-phase) exhibiting a secondary phase (.theta.(t)) and a second quadrature signal (Q(t)) (quadrature phase) exhibiting a phase difference .pi./2 to the secondary phase (.theta.(t)) are generated;
• b) A/D-conversion (31,29) of the quadrature signals (I(t), Q(t)) at a number of points of time (t.sub.k), whereby time discrete quadrature signals (I.sub.k, Q.sub.k) are generated;
• c) generation of a time discrete approximation signal (Z.sub.k), in dependence of the time discrete quadrature signals (I.sub.k, Q.sub.k) , such that the signal value (Z.sub.n) of the time discrete approximation signal, corresponding to a given time position (t.sub.n), represents an approximation of the second time derivative (.theta.(t.sub.n)) of the secondary phase (.theta..sub.n) at the given point of time (t.sub.n);
• whereby the approximation signal (Z.sub.k) establishes the frequency slope (.mu.(t)) of the oscillator signal (cos(.phi. (t))), since-this frequency slope (.mu.(t)) is directly related to the second time derivative .theta.(t)) of the secondary phase (.theta.(t)).