Harmonic distortion analyzer effects rapid and accurate setup and calibration of magnetic tape instrumentation recorders. The analyzer is portable, requires no warmup period and need not be calibrated for normal usage. Average setup time with this analyzer is approximately 30 seconds per track

Tinari, D. F.

English

NASA Technical Reports Server

Meter	 Meter	 Calibrate 
Switch 
Record t,-^Reprod.ce 
Distortion Record 
July 1968	 Brief 68-10254 
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. 
Harmonic Distortion Analyzer

Speeds Setup of Magnetic Tape Recorders 
I	 Reproduce	 I
RECORDER 
A harmonic distortion analyzer has been devel-
oped to effect rapid and accurate setup and calibra-
tion of magnetic tape instrumentation recorders. 
When setting up and calibrating such recorders, it is 
necessary to establish a proper recording-head current 
to obtain an acceptable signal-to-noise ratio and min-
imize distortion products in the recorded data signal. 
This analyzer conforms to the generally accepted cri-
terion that the proper recording level has been 
achieved when a signal at a selected frequency is 
recorded on a properly functioning recorder at such 
a record level as to cause the reproduced signal to 
have 1 % third-harmonic content. It would be partic-
ularly useful in facilities where a large number of 
instrumentation recorders are in operation and it be-
comes necessary to make frequent checks for proper 
recording level and performance. 
The analyzer is portable (weighs less than 5 
pounds). It requires no warmup period and need not
ANALYZER 
be calibrated for normal usage. No power is con-
sumed by its selective filter components, so that fail-
ures that would require component replacement and 
instrument recalibration are precluded. The analyzer 
has its own precision signal source and indicating 
meter, eliminating the need for accessory test equip-
ment which must be used with much more compli-
cated-to-operate and costly commercially available 
wave analyzers. In contrast to the commercial instru-
ments also, the new analyzer has only one functional 
front panel control and requires no special skill to 
operate. Average setup time with this analyzer is 
approximately 30 seconds per track. When necessary, 
the analyzer can be completely recalibrated in several 
minutes by any technician familiar with a standard 
rms meter and signal generators. 
The harmonic distortion analyzer is connected to 
the magnetic tape recorder as shown in the sketch. 
The recorder is placed in a "record" mode at the 
(continued overleaf) 
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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selected tape speed, and the precision signal from 
the analyzer is simultaneously recorded and repro-
duced. The meter switch on the analyzer panel is 
placed in the "calibrate" position, and the reproduce 
level of the recorder is adjusted for 100 percent in-
dication on the meter. The switch is then placed in 
the "distortion" position, and the record level con-
trol on the recorder is adjusted to obtain an indica-
tion of 1 percent on the meter. This procedure is re-
peated (usually two or three times) until the meter 
consistently reads 100 percent in the "calibrate" posi-
tion and 1 percent in the "distortion" position. This 
procedure is performed for each data track on the 
recorder.
Note: 
Complete technical details may be obtained from: 
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
Reference: B68-10254 
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: D. F. Tinari 
(GSC-10198)
. 
Brief 68-10254
	 Category 01


Harmonic distortion analyzer speeds setup of magnetic tape recorders

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