1-20. SYSTEM FUNCTIONAL DESCRIPTION (cont)
(9) Analog to Digital Converter Assembly 2A2A13.
The analog to digital conver-
ter assembly 2A2A13 is a data acquisition and distribution system used to process
analog signals to digital data. -
(a) Input signals from the motor control driver
measurement CCA in the electronics drawer assembly 2A2A7,
2A2A3, and multiprogrammer extender 2A2A11 are scanned by
techniques under program control.
CCA and temperature
optical signal generator
(b) Each of four input signals from 488 controller power supply assembly
1A2 are isolated and multiplexed to the analog bus under program control.
(c) Simultaneous sample and hold signals and a trigger signal from matrix
switch assembly 2A2A1O are interrogated and put on the analog bus.
(d) Digital output is applied to the multiprogrammer assembly 2A2A6 and to
the bus multiplexer CCA in the electronics drawer assembly 2A2A7.
e . NIGHTSIDE TEST BENCH 2A3
(1) Nightside Optical Assembly 2A3A1.
The nightside optical assembly provides
program controlled infrared (IR) signals to the TADS nightside assembly and PNVS
The nightside assembly contains three heat sources, designated A, B, and C,
which are controlled by the control unit assembly 1A1. Heat sources A and B are in
the heat source target assembly and heat source C (secondary heat source) is inside
the nightside test bench optical assembly, directly behind the shutter assembly.
The nightside optical assembly contains the following assemblies:
Heat source target assembly 2A3A1A1
Shutter assembly 2A3A1A2
Sensor mount assembly 2A3A1A3
Secondary heat source 2A3A1A17
(a) The heat source target assembly 2A3A1A1 contains heat
which are mounted above an aperture wheel and target assembly. The
sources A and B
and target wheel are used in-conjunction with the-heat sources to provide the
stimulus pattern for performing various IR tests. Five mirrors are used to
collimate the energy and route it to the shutter assembly aperture.
(b) The target wheel and aperture wheel are driven to different positions
depending upon the test requirement. The target wheel, mounted below the aperture
wheel, has 10 positions, and the aperture wheel has four. A single four-phase
stepper motor, which drives both wheels through two magnetic clutches (one for each
wheel), is activated by the motor control CCAs in the electronics drawer assembly
2A2A7. Each clutch rotates a coupling to a gear train which drives a belt on a
sprocket, which in turn moves the target wheel and aperture wheel.