Optimum length buffer crystals are used with an amplification section for measuring the noise figure for acoustic amplifiers. Measuring the time required to saturate with noise a signal, which is reflected back and forth in the circuit, gives a direct measurement of the amplifiers noise figure

Johnson, V. R.

Yeager, J. R.

English

NASA Technical Reports Server

July 1968	 Brief 68-10272 
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. 
Noise Figure Measurement Concept for Acoustic Amplifiers 
A concept has been reported for measuring the 
noise figure for acoustic amplifiers in a very direct and 
revealing manner. The report also suggests some of the 
physical conditions necessary for long-term acoustic 
memory devices. 
The method incorporates the design of optimum-
length buffer crystals used in conjunction with an am-
plifier section whose gain is equal to total structure 
loss. A signal can thus be admitted at the input and 
reflected back and forth in the circuit, being amplified 
each time it passes through the amplifier section, until 
it is lost in the increasing system noise. Measuring the 
time required to saturate the signal with noise should 
give a direct measurement of the amplifier noise figure. 
Notes: 
1. This method is intended to give a direct measure of 
the acoustic amplifier alone rather than the sum of 
various circuit noise figures.
The report delves mathematically into the major 
theoretical considerations and should be useful as 
a laboratory aid in the study of acoustic amplifi-
cation. 
3. This development is in conceptual stage only, and, 
as of date of publication of this Tech Brief, neither 
a model nor prototype has been constructed. 
Patent status: 
No patent action is contemplated by NASA. 
Source: V. R. Johnson and J. R. Yeager 
of Microwave Electronics 
under contract to 
Goddard Space Flight Center 
(GSC- 10066) 
Category 01 
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=19680000272 2020-03-12T06:10:29+00:00Z


Noise figure measurement concept for acoustic amplifiers

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