Patent ID: 6018318
Filing Date: 2000-01-25
Classification: G01D,H03M

Abstract:
A method for determining the phase angle in position transmitters with sinusoidal output signals, wherein a sensor generates the sinusoidal output signal U.sub.0 (.alpha.)=A*sin .alpha. and a cosinusoidal output signal U.sub.1 (.alpha.)=A*cos .alpha. depending on the position or rotational position a with A being the output signal amplitude, wherein linear combinations U.sub.2 =U.sub.0 +U.sub.1 and U.sub.3 =U.sub.1 -U.sub.0 are formed from the output signals, wherein it is determined in which quadrant the position value .alpha. lies by examining the preceding signs of the output signals, wherein a division for forming a tangent function or a cotangent function is carried out in dependence on the determined quadrant, and wherein the result of the division is used as an address for inquiring a stored angle table, the output signal of which represents at least the fine resolution of the position value .alpha., said method comprising:converting the output signals U.sub.0, U.sub.1 from analog signals into digital signals in analog/digital converters so that all additional calculations are carried out in purely digital fashion;examining the preceding sign of the digital output signals and forming a cyclic binary code q.sub.1 q.sub.0 thereof, wherein the cyclic binary code determines in which quadrant the position value .alpha. lies;selecting one of said sinusoidal and cosinusoidal output signals as the divisor depending on the determined quadrant in order to prepare an integral division in which the dividend is one of the linear combinations (U.sub.2, U.sub.3), wherein the amount of the divisor always lies within the range above .sqroot.2 of the maximum value of the respective output signal; andsubsequently carrying out the integral division, whereby the result of the integral division represents the address for reading out the angle table.