Eight-Channel Digitar System

Digitar is an NRL-Developed system capable of the simultaneous digital representation and subsequent serial recording of the angular positions of as many as eight one-speed shafts at preset sampling rates of 1, 2, 5, or 10 times per second. Angular increments of 0.01 degree in the position of the one-speed shaft may be resolved by the coded-disc device used in obtaining the digital representation of the angular shaft position. Data from each of the eight channels and from an independent time - counter channel are recorded in a given sequence at the specified sampling rate on a single- channel magnetic tape. The recorded data are later transcribed from the magnetic tape to a punched-paper-tape medium for insertion into the Computer Mk 22, a relay,-type digital computer used for data-reduction purposes. A system of recording the coded data on photographic film is also described. Although Digitar has been developed to aid in the collection of data for the evaluation of gun fire control systems at NRL, it is applicable to the general problem of quantizing and recording angular shaft position at discrete intervals of time. At missile test ranges, a modified Digitar would be useful in recording bearing, elevation, and range, for deter mining the trajectories of missiles tracked by precision radar sets.