Abstract: A position encoder system is provided, such system including a code wheel, a pair of sensors, a counter, and a processor capable of identifying the correlation between separately identified markings of the code wheel. The identified correlation is indicative of code wheel accuracy, and thus is used to correct error in any angular position determined using the code wheel.

Abstract: A resonant mode energy recovery circuit is disclosed for supplying drive pulses to an electroluminescent (EL) display arranged as a matrix of pixels addressed by a plurality of column and row electrodes. An external inductor is used to alternately store and supply energy from the column electrodes of the EL display which has an impedance equivalent to an array of capacitors and resistors. Switching transistors and diodes are used to start and stop the resonant current flow at 1/4 wavelength intervals of the resonant frequency of the resonant tank formed by the external inductor and the array capacitors coupled to the column electrodes in order to form the pulses required to address the columns of the matrix. Switched current sources are used to start and stop nonresonant current flow to form the refresh and write pulses used to form the pulses required to address the rows of the matrix.

Abstract: An apparatus and method for the frequency modulation and demodulation of a carrier signal by a modulating frequency signal, whereby essentially the same apparatus is used for both functions. During demodulation, the modulating device is switched into a closed loop having a relatively narrow bandwidth, thereby permitting the carrier generated by the modulator to be locked in phase with the signal to be demodulated. During modulation, the loop is opened up and the modulator is used in a normal fashion.

Abstract: Improved circuits for pre-emphasis and de-emphasis of video luminance signals, the improvement comprising the utilization of field effect transistors in a non-linear frequency-discriminating network; and automatic circuitry useful in both recording and reproduction of recorded video information.