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1. DESCRIPTION
alteration of the characteristics. This number, however, is greatly dependent
on the care exercised in the use of the records. By conserving one side as a
reference, it is possible to check on the service life of each record in use.
Fig. 1.3. Gliding Frequency Recordings Type QR 2007.
The cutting process and the dimension are in accordance with the Recom-
mendation of the International Electrotechnical Commission (IEC 98/98-1)
recognized by most countries.
The detailed specifications are given at the end of this manual.
The reproduction of the label of the QR 2007 (Fig. 1.4) and the photograph
of a section of the
record,
illuminated by a grazing light beam (Fig. 1.5),
show the exact composition of the recordings.
The QR 2008 and QR 2009 are described in the same way by figures 1.6
through 1.9.
The original sinusoidal signal used for recording the disc tracks was obtained
from a B
&
K Beat Frequency Oscillator with especially low distortion. For the
recording of the gliding frequency bands the frequency of the signal was varied
according to a function of time which was purely logarithmic within
.±
2.2
%
±
1.3
Hz.
This tolerance is equal to the tolerance on the determination of the recorded
frequency when using the Gliding Frequency Records at the exact specified
rotation speed ( 45 rpm) and assuming a logarithmic sweep.
5
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