Abstract: A position measurement system includes position error circuitry (PEC) that responds to periodically provided actual position information and a computed position to provide correction information, and a position synthesizer which responds to the correction information to provide the computed position. The computed position information is fed back to the PEC. The position synthesizer establishes a rate of change of the computed position based on the correction information in a manner tending to make the computed position track the actual position. The position synthesizer updates the computed position many times for each time that the actual position information is provided to the PEC, and thus provides much more continuous position information.

Abstract: A technique for overcoming the difficulties that arise from the transition between coarse and fine loop control. Coarse and fine phase locked loops, each having a respective latch provide a coarse number in the range 000.0.degree.-359.9.degree. and a fine number in the range of 0.0000.degree.-0.9999.degree.. The coarse number is offset relative to the fine number so that the least significant digit (tenths digit) of the coarse number is always less than the most significant digit (tenths digit) of the fine number over the entire range of motion. The fine number latch is clocked by a reference clock (ZDS) while correlation circuitry provides a clock signal for the coarse number latch. The correlation circuitry generates the clock signal when the tenths digit of the coarse number agrees with the latched fine number. The result is a latched fine number and a coarse number that is latched when it correlates with the fine number (tenths digits agree).

Abstract: A technique for overcoming the difficulties that arise from the transition between coarse and fine loop control. Coarse and fine phase locked loops, each having a respective latch, provide a coarse number in the range 000.0.degree.-359.9.degree. and a fine number in the range of 0.0000.degree.-0.9999.degree.. The coarse number is offset relative to the fine number so that the least significant digit (tenths digit) of the coarse number is always less than the most significant digit (tenths digit) of the fine number over the entire range of motion. The fine number latch is clocked by a reference clock (ZDS) while correlation circuitry provides a clock signal for the coarse number latch. The correlation circuitry generates the clock signal when the tenths digit of the coarse number agrees with the latched fine number. The result is a latched fine number and a coarse number that is latched when it correlates with the fine number (tenths digits agree).

Abstract: In apparatus for measuring the relative position between a fixed member and a movable member, as in a flight simulator, means for electrically offsetting the position measurement to compensate for mechanical offsets and the like. The relative position may be extracted by applying reference oscillator signals to a stator winding, thereby inducing a signal in a rotor winding. The rotor signal is communicated to a digitally closed phase lock loop including a phase detector, an integrator, a loop filter, a voltage controlled oscillator, and a frequency divider having a counter. The invention provides value setting means such as thumbwheel switches, and comparison means coupled between the value setting means and the frequency divider counter, for generating a pulse signal when the counter contents corresponds to the value set in the value setting means.