A High Precision, Remotely Settable Electronic Timer System

摘要

The report summarizes the design description and operation of an electronic timer system. The system includes two basic sections - a ground-based setting unit and a remotely located, high precision, dual-channel timer that can generate a sequence of electrical outputs at fixed intervals from the preset time. Each channel is settable in 1-msec increments from 1.000 to 19,999.999 sec. The frequency source is a crystal-controlled oscillator accurate to within 2.5 parts in 10 to the 7th power over a voltage range of 21 to 31 V dc, a temperature range of 0 to 60 C, and a shock and vibration environment of a typical missile launch. The timer is set and monitored by the setting unit, by transmitting commands over a two- or three-wire link or a two-way radio link. For each command sent to the timer, an acknowledgment must be returned; otherwise, the setting process stops and a visual indicator registers an error in setting. An oversized breadboard version of the dual-channel timer was used in the system described; the projected size and weight per unit, however, are 60 cu in. and 3 lb, respectively. (Author)