Photoelectric detection system

A photoelectric beam system for the detection of the arrival of an object at a discrete station wherein artificial light, natural light, or no light may be present is described. A signal generator turns on and off a signal light at a selected frequency. When the object in question arrives on station, ambient light is blocked by the object, and the light from the signal light is reflected onto a photoelectric sensor which has a delayed electrical output but is of the frequency of the signal light. Outputs from both the signal source and the photoelectric sensor are fed to inputs of an exclusively OR detector which provides as an output the difference between them. The difference signal is a small width pulse occurring at the frequency of the signal source. By filter means, this signal is distinguished from those responsive to sunlight, darkness, or 120 Hz artificial light. In this fashion, the presence of an object is positively established

NSSC-2 operating system design requirements specification

The design requirements and implementation standards for an NSSC-2 operating system are defined. An operating system diagram is presented along with system concepts and terminology

A Checkout Language for Future Space Vehicles

To support an increased emphasis on automated checkout of future space vehicles, a procedureoriented computer language is required. This language needs to be more user-oriented and needs to have a more complete set of capabilities than existing languages. Such a language, named TOTAL, was developed under contract to NASAKSC. This paper presents an overall view of the language in terms of its major characteristics as derived from the basic design objectives