Patent ID: 7777661

Claim:
Interpolation method with an interpolation number of I to be carried out in a high-resolution encoder with the input states of said method being defined by a first input analogue signal A+(α), a second input analogue signal B+(α), a third input analogue signal A−(α)and a fourth input analogue signal B−(α), which signals as cited here one after another are mutually in quadrature, whereat the functional dependence of the first input analogue signal A+(α) on the observed argument α is sinα, and which method comprises an interpolation step, in which intermediate digital signals Fi(α) and inverted intermediate digital signals Gi(α), i=1, . . . I, are generated in that each intermediate digital signal Fi(α)results from a comparison of a potential Pi(α) of the first input analogue signal A+(α) at the value α+αi of its observed argument α within a first half-period to a potential Ni(α) of the third input analogue signal A−(α) at the same value α+αi of the observed argument α, the values αi being uniformly distributed within the first half-period of the observed argument α and the potential P(I/2)(α) being equal to the signal B−(α), the potential P(I)(α) being equal to the signal A−(α), the potential N(I)2)(α) being equal to the signal B+(α) and the potential N(I)(α) being equal to the signal A+(α), and a step of logically combining the intermediate digital signals Fi(α) and Gi(α) in a way that a first output digital signal and a second output digital signal in quadrature thereto are generated, characterized in that a value U of the voltage with respect to zero level of said potentials Pi(α) and Ni(α) is measured at any value of the observed argument α, which voltage at that time is the highest one of the voltages at terminals with said potentials Pi(α) and Ni(α)belonging to a family (I,m) of the potentials with values of the index i=m,I/2−m,I/2+m,I−m where m is equal to a positive integer in the range from 1 to I/2−1, and that an actual peak amplitude A of the input analogue signals A+(α), B+(α), A−(α)and B−(α) is determined as A=k I,m U where the factor k I,m is determined as k I , m = A o U env max + U env min 2 and U env max and U env min are a previously determined highest and lowest value, respectively, of the voltage U env (α) of a waveform envelope of the potentials Pi(α) and Ni(α)from said selected family (I,m) of the potentials at the known value A o of the peak amplitude of said input analogue signals.