SP-100 Position Multiplexer and Analog Input Processor

Paper #:
  • 929233

  • 1992-08-03
Syed, A., Gilliland, K., and Shukla, J., "SP-100 Position Multiplexer and Analog Input Processor," SAE Technical Paper 929233, 1992, https://doi.org/10.4271/929233.
This paper describes the design, implementation, and performance test results of an engineering model of the Position Multiplexer (MUX)-Analog Input Processor (AIP) System for the transmission and continuous measurements of Reflector Control Drive position in SP-100. The specially tailored MUX-AIP combination multiplexes the sensor signals and provides an increase in immunity from low frequency interference by translating the signals up to a higher frequency band. The modulated multiplexed signals are transmitted over a single twisted shielded cable pair from the reflector drives located near reactor to the AIP located at the power conditioning/system controller end of the space craft boom. There the signals are demultiplexed and processed by the AIP, eliminating the need for individual cables for each of the twelve position sensors across the boom. This paper describes the work performed to determine the practical circuit limitations, investigate the circuit/component degradation of the multiplexer due to radiation, develop an interference cancellation technique, and evaluate the measurement accuracy as a function of resolver angle, temperature, radiation, and interference.The system developed performs a complex cross-correlation between the resolver excitation and the resolver sine cosine outputs, from which the precise resolver amplitude and phase can be determined while simultaneously eliminating virtually all uncorrelated interference. Following the correlation, a lookup-table (map) is used to correct for the resolver angular nonlinearities and temperature effects. The system also includes an automatic calibration technique. The calibration data and a lookup-table (map) are also used to correct for the radiation degradation of the resolver Mux components. This system utilizes a simple yet robust signal processing scheme which can also be employed for many of the other signals used for SP-100 control.
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