Pulse counting circuit with an extra chain of flip-flops, delay lines, and gates computes the sum of the squares of the pulse sequences. A pulse train and the sum of the squares of the pulses are simultaneously completed

Schaefer, D. H.

English

NASA Technical Reports Server

September 1965
	 Brief 65-10260 
NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Simple Pulse Counting Circuit Computes Sum of Squares 
Reset 
Input  _J1_	 8 
	
X2	 X4	 X 
r, 1- `1 1	 Clear X 
D4
SYMBOLS 
D8	
—14	 FID Delay 
Triggered Flip- Flop 
And Gate 
22	 2 LU 2 LU X 2
16
	 X2
32
	 2 LJ 2 U 2 Li 2 X 1	 i X2 I I	 I I Xa I I X  I I X  I I X64 I 1X1281 '1X256["1X51 
-A- 
Clear X2
	
Reset 
The problem: To calculate the sum (Z) of the 
squares (X 2) of numbers represented by a series of 
pule trains. Previous circuits designed to calculate 
X2 required the conversion of the pulse trains to 
binary representation and then the performance of 
standard computer squaring and adding processes. 
Where it is desired to display the results instan-
taneously, such as in a digital readout meter, standard 
computer techniques are not adequate. 
The solution: A pulse counting circuit that includes 
an additional chain of flip-flops, delay lines plus
and/gates to instantaneously compute the sum of the 
squares of the pulse sequences. 
How it's done: The circuit configuration shown 
uses 4 flip-flops to count up to 15 and 10 additional 
flip-flops to store the sum of the squares. The four 
primary counting flip-flops are reset by a pulse on the 
clear X line after each sequence of pulses. At the end 
of the summation, the 10 summing flip-flops are 
cleared by a pulse on the clear 	 line. 
In a typical operation, three sequential pulses arrive 
at the input X terminal and the first turns on flip-flop 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000258 2020-03-11T17:19:52+00:00Z
X 1 . The second pulse turns X 1 off, X2 on, and also 
travels through delay line D2 to trigger flip-flop X24. 
The third pulse, in a similar manner, causes X24 to 
turn off and X28 to turn on. Before the primary 
counter is reset, the X 2 counter differs from the 
actual sum of the squares by one if the number of 
input pulses is odd. This is corrected when the clear 
X pulse arrives and triggers the X 2 flip-flop. For an 
even number of input pulses, the clear X pulse is not 
passed by and gate I because flip-flop X 1 is off. 
Notes: 
1. Approximately 1092 N gates and delay lines and 3 
1092 N flip-flops would be required to compute the 
sum of the squares up to N pulses. 
2. The advantage of this system is that, as a pulse 
train is completed, summation of the squares of the 
pulses is simultaneously completed.
3. This invention should be of interest to manufac-
turers of analog-to-digital converters and digital 
voltage and power meters. 
4. Inquires concerning this invention may be directed 
to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland, 20771 
Reference: B65-10260 
Patent status: NASA encourages the immediate 
commercial use of this invention. It is owned by 
NASA and inquiries about obtaining royalty-free 
rights for its commercial use may be made to NASA, 
Code AGP, Washington, D.C., 20546. 
Source: David H. Schaefer 
(GSFC-391) 
Brief 65-10260	 Category 01


Simple pulse counting circuit computes sum of squares

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