Counter includes one section which counts the first several pulses, and a second section which counts pulses from a clock between the beginning of a sampling interval and the receipt of the first pulse by the circuit. The number of clock pulses indicates receipt time of the first pulse

Baumer, W. E.

Timm, J. D.

English

NASA Technical Reports Server

August 1969	 Brief 69-10313 
.
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. 
Circuit Counts Pulses and Indicates Time of Occurrence of Slow Pulses 
A circuit has been devised to (1) count pulses (such 
as those generated by an ion chamber or sensor in 
response to ionizing particles or radiation) received 
over a wide range of pulse repetition rates and (2) 
to indicate the time of occurrence of the slow pulses, 
i.e., for phenomena in which a pulse may occur at 
infrequent intervals. In the latter case, it is often 
desirable to determine the exact time of occurrence 
of the pulse. For example, if an ionizing particle 
sensor is rotating so that at different times during a 
sampling interval it is pointing in different directions, 
a determination of the instant when a pulse occurred 
also indicates the orientation of the sensor at that 
instant. 
The counter includes one section which counts the 
first several pulses received from the detector or 
sensor and a second section which counts pulses 
from a clock during the period between the beginning 
of a sampling interval and the receipt of the first 
pulse by the circuit. The number of clock pulses 
counted indicates the time of receipt of the first pulse. 
If a larger number of pulses is received during an 
interval than the first section cain contain, two things 
happen: a) the clock pulse count in the second sec-
tion is dumped; i.e., the counter is reset to zero, 
b) that section begins counting the number of times 
the first section overflows. Thus, the second section 
of the circuit has two functions: at low pulse rates 
it counts clock pulses, and at high pulse rates it 
counts the number of times the first section overflows. 
In one form of the circuit, two groups of binary 
memory elements, i.e., flipflops, are included. One 
group of three elements is in the first section of the 
circuit, and the other group, consisting of six ele-
ments, is in the second section of the circuit. With
this combination of nine elements, Ahe circuit can 
count a maximum of 2 11 pulses. The first pulses to 
be received are registered in the first group of three 
elements, which can count up to seven pulses. Be-
fore the first pulse is received, however, the second 
group of six elements counts clock pulses. When the 
seventh pulse is received, the clock pulse count in 
the second group of elements is reset to zero; there-
after arithmetic carries from the overflowing first 
group of elements are delivered to the second group. 
Thus, at high pulse rates, the second group counts 
the most significant digits of the pulse count, while 
at low pulse rates (less than 7 per sampling interval) 
it indicates the time at which the first pulse was re-
ceived since the last sampling. At each sampling, all 
nine elements are reset to zero. The circuit indicates 
the total number of count pulses received during the 
sampling interval in all cases, regardless of the num-
ber of these count pulses. 
Note: 
Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-103 13 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Royalty-free, non-exclu-
sive licenses for its commercial use will be granted 
by NASA. Inquiries concerning license rights should 
(continued overkai( 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000312 2020-03-16T18:09:57+00:00Z
be made to NASA, Code GP, Washington, D.C. 
20546.
Source: J. D. Timm and W. E. Baumer of 
Computr Control Co., Inc.
under contract to 
NASA Pasadena Office
(XNP-06234) 
Brief 69-10313	 Category 01


Circuit counts pulses and indicates time of occurrence of slow pulses

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