Time Response Simulation of the 1975 Viking Orbiter Digital Tape Recorder

Abstract

The objective of this study is to verify and understand in depth the performance of the speed control (frequency loop) servo of the 1975 Viking Orbiter (VO75) digital tape recorder (DTR). The linear frequency-domain methods, such as the Bode Plot and the Root Locus, are inadequate in analyzing the VO75 DTR servo due to such dominant non-linear effects as servo signal limiting and static/dynamic Coulomb friction. The Time Response method employed in this study is written in the Continuous System Simulation Language (CSSL) for the Univac 1108 computer system. In order to demonstrate the power and flexibility of the graphic interactive simulation program, four aspects of system dynamics are interactively adjusted to arrive at a number of stable system configurations which has significantly different tape transport and/or summing amplifier gain, larger static/dynamic Coulomb friction, system lag than envisioned in the nominal design by linear methods.