Abstract: A synchro to digital converter which has a programmable read only memory (prom) that operates under control of a feed back counter and register. The prom is programmed to generate a digital signal proportional to the converter's inherent systematic error. The data stored in the prom is empirically derived by running an error (input angle vs. output angle) curve on the uncompensated converter. The corrected error signal from the prom is converted to analog form by conventional digital to analog converter means and subtracted from the closed loop steering signal which is derived from an approximating network thereby increasing the converter output accuracy to within better than 2 arc minutes.

Abstract: A digital to analog resolver converter uses a digital to analog converter to convert a part of the digital input to a corresponding analog angle value. This analog angle value is applied to sine and cosine function generators which use bits of the digital input signal to select slope and intercept values for approximating the sine and cosine of the analog angle value. The outputs of these function generators are applied to an octant select circuit, which chooses the values to be used as the sine and cosine of the angle in a particular octant. Two circuits then assign the proper sign to the cosine and sine function values.

Abstract: A high accuracy digital to analog resolver converter uses a read only memory device (PROM) programmed to generate a digital signal proportional to the inherent systematic error of a digital to analog resolver converter. This signal is then converted to analog form by conventional means and combined with the primary signal in analog form thereby substantially increasing the accuracy of a digital to analog resolver converter.