Pulse width/amplitude- and noise-sensors are updated to integrated circuit design concepts, and rise time/amplitude sensor design is reduced to an operational prototype to make all the sensors compatable for one system operation. Therefore, transients interfering with the design operation of receivers could be individually isolated and identified

Cash, J.

English

NASA Technical Reports Server

November 1967	 Brief 67-10471 
NASA TECH'BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Transient Sensor Development 
An overall analysis has been made of the historical 
development of pulse width/ amplitude-, rise time/ 
amplitude-, and noise-sensors and recommendations 
made for improvements in design, calibration tech-
niques, and techniques to make all the sensors com-
patible for operation in one system. In this way, 
transients interfering with the design operation of 
receivers could be individually isolated and identified. 
The sensors, originally of discrete component design, 
were updated to integrated circuit design concepts 
with one, the rise time/amplitude sensor design being 
reduced to an operational prototype. The integrated 
circuit designs can be expected to be less critical in 
calibration, more stable over the operating tempera-
ture range, require less power, and be much smaller 
than equivalent discrete component designs. 
The pulse width/amplitude sensor design consists 
of a dwell and integrator circuit feeding an opera-
tional amplifier used to trigger an output generator in 
the form of a flip-flop circuit. The dwell circuit sets 
up a dead zone that includes both the positive and 
negative regions about zero potential. The integrator 
determines how much time will elapse before the 
dwell circuit bias is overcome by the input signal 
amplitude. When this occurs, the operational ampli-
fier triggers the flip-flop causing it to reverse state. 
With the integrator circuit removed, the sensor be-
comes a threshold level detector. 
The rise time/amplitude sensor is designed to detect 
positive voltage transients and leave an output with 
both a positiXe and a negative voltage level shift. The 
sensor monitors the leading edge of a pulse and de-
termines the time elapsed between the initial excursion 
(usually at the theoretical 10% point) and some pre-
determined amplitude corresponding to a theoretical 
90% point. When a pulse appears, having an ampli-
tude corresponding to a 90% point and a rise time
window between 50 and 5000 nanoseconds, opera-
tional amplifiers switch an output generator to pro-
duce an output no-go condition. If the output is high, 
a no-go condition exists and the output generator is 
reset to a go condition by an external source. Ampli-
tude and rise time window settings are adjustable; 
however, they are not independent. The prototype. 
sensor exhibits current drain of approximately 50 ma 
total plus an acceptable rise time sensitivity of 26 
nanoseconds (17.3%) changeover a temperature range 
of 50° to 110°F. 
The noise sensor design should detect conducted 
interference on dc power leads of the receivers and 
have a fixed frequency and bandwidth but be adapt-
able to a wide range of other frequencies. Input sensi-
tivity should be adjustable from 10 to 100 m y . Primary 
current drain is less than 50 ma at +12 and -6 vdc 
and the output is by means of a bistable flip-flop 
capable of being reset by an external source. Because 
the circuit bandwidth increases as the noise amplitude 
increases, an amplitude in excess of 100 my could 
cause a no-go output outside the desired bandwidth of 
the sensor and there would be no way to identify what 
triggered the no-go condition. To overcome this, the 
sensor would have to be only amplitude sensitive 
within the desired bandwidth. This would increase 
the complexity of the sensor but the exact frequency 
generating a noise problem could be detected and 
steps taken to eliminate it. 
Note: 
Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10471
(continued overlea) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000471 2020-03-11T20:54:22+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: J. Cash
of Federal Electric Corporation

under contract to

Marshall Space Flight Center

(MFS-13370 and 13371) 
Brief 67-10471	 Category 01


Transient sensor development

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