Program eliminates or reduces time-consuming aspects of computation of power spectrum for high-frequency communication system. This program was written in FORTRAN IV for UNIVAC 1230 or 1108 computer

Detchmendy, D. M.

Hayden, W. L.

English

NASA Technical Reports Server

August 1973	 B73-10227 
NASA TECH BRIEF S	 Lyndon B. Johnson Space Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Spectral Analysis Program (SAP) 
The problem: 
Computation of the power spectrum for a high-
frequency communication system is a difficult and 
time-consuming process, even with a high-speed digital 
computer. This is particularly true when the carrier is 
phase or frequency modulated by a complex signal. 
The solution: 
To solve this problem, a Spectral Analysis Program 
(SAP) has been developed that addresses itself to 
eliminate or reduce the time-consuming aspects of the 
• computation. 
How it's done: 
SAP can handle the large number of data samples 
required to represent all of the frequency components 
in a modulating signal. It considers the nonlinearity 
of the angle modulation process as a series represented 
computation, which, theoretically, generates an infinite 
quantity of new frequency components. By using the 
extended, fast Fourier transform, the power spectrum 
computations are reduced to a manageable quantity. In 
addition angle ,modulation of the system is evaluated 
by low-pass filtering the modulating signal and/or band-
pass filtering the modulated signal.
SAP either accepts an externally supplied modu-
lating signal stored on tape or internally generates a 
sum of sinusoids signal, a periodic square wave, or a 
periodic multilevel signal. After acceptance or genera-
tion, the input modulating signal may be low-pass 
filtered using either a Butterworth, Chebyshev, or user-
defined filter. The signal is then multiplied by the 
modulation process. Next, the modulated signal may 
be bandpass filtered using the same filters. Finally, the 
power spectrum is computed, printed and stored on a 
magnetic tape. 
Notes: 
1. This program is written in FORTRAN IV for the 
IJNIVAC-1230 or 1108 computer. 
2. Inquiriers concerning this program should be 
directed to: 
COSMIC 
112 Barrow Hall 
University of Georgia 
Athens, Georgia 30601 
Reference: MSC-14310 
Source: D. M. Detchmendy and
W. L. Hayden of
TRW, Inc. 
.
under contract to
Johnson Space Center
(MSC-14310) 
Category 09, 02 
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.
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Spectral Analysis Program (SAP)

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