YOKOGAWA AQ7260 OTDR, User Manual, Page: 435 / 442

Chapter 10 APPENDIX
10-8
10.3 Glossary
This section explains the terms used in this manual.
Attenuation
Gain of the amplifier built into this instrument. The smaller the attenuation displayed on
this instrument, the larger the gain, and the better the S/N ratio of the acquired trace.
However, the trace may be saturated at high reflection levels. So, it is necessary to select
an appropriate gain according to the measurement object.
For the method of changing the attenuation, refer to page 3-20
Attenuation dead zone
Distance width at points where the optical connector’s return loss is 45dB or higher and
the back scatter level is within
±
0.5dB of the normal level.
Back scattering ray
When light travels through an optical fiber, a symptom called “Rayleigh scattering” occurs
due to uneven density or components of substances that are smaller than wavelengths.
Among these scattering rays, those which travel in the opposite direction of incident rays
are called back scattering rays.
± 0.5dB
Attenuation dead zone
Incident ray
Back scattering ray
Refer