Data Reduction

Overview & Synopsis

A large volume of data were generated both during the development program and the flight lifetime of the Explorer XIII Micrometeoroid Satellite. These data, in the form of payload telemeter signals, were recorded on magnetic tape. To facilitate the reduction of these data, the development of an automatic data read out system, suited both to the special characteristics of the data signals and to the requirements of high-speed digital computing equipment, was initiated at the start of the satellite development program. As indicated earlier in this report, the telemeter signal is a nonsynchronous time-division multiplex containing information coded in three independent forms: Duration of subcarrier oscillation bursts, frequency of the oscillations, and the time (spacing) between the bursts. The data readout system decommutates and digitizes this information and records the digitized data on magnetic tape in computer format. The readout of data coded in all three forms is simultaneous and is done at a rate of up to 25 channels per second. A major design criterion of the data readout system was that the performance should be satisfactory when there was a significant amount of noise in the telemeter signal. The design concept of the data readout system included the shared use of digital formatting and tape recording equipment that was a part of other data readout systems in existence at the NASA Langley Research Center.