man_digiflex_com_en_02_5.doc 13
2. TECHNICAL DESCRIPTION
2.1 General Description
The Digiflex Com is a compact, light-weight and easy-to-handle digital
time-domain reflectometer for locating faults in balanced
telecommunication and control lines. It can be handled easily and so
enables even an inexperienced user to locate faults precisely and fast.
Experts in testing will find a variety of additional functions at their hands. By
its design the
Digiflex Com is a robust device suitable for field application.
The
Digiflex Com is double-insulated and equipped with safety terminals to
protect the user.
The
Digiflex Com is similar to radar in that it employs the pulse reflection
technique. Suitable test pulses are transmitted into the cable to be tested.
The pulses travel along the cable at a propagation velocity that is
dependent on the connected test object. In every place where the electric
characteristics of the cable have changed, part of the transmission pulse is
reflected and caused to travel back to the
Digiflex Com where it will be
displayed on the screen with a time delay corresponding to its propagation
time.
A change in the electric characteristics of a cable may be caused either by
a possible fault or by local circumstances such as junction boxes,
connectors, or the end of the cable. The time delay between the incoming
reflection and the moment of pulse transmission is the propagation time to
the point of fault and back. The distance from a place of interest can be
calculated by taking into account the specific pulse propagation velocity of
the cable under test. Shape and size of the reflected signal allow
conclusion to be drawn on the nature and size of the fault. Cable
attenuation can be compensated for by applying a distance-dependent
amplitude correction (amplitude correction) in order to display echoes from
different points of reflection with comparable amplitudes irrespective of
their distance. In this way the
Digiflex Com shows a revealing picture of the
connected cable. There is even a mode called IFL to locate any fault that is
inconsistent in its time structure.
The propagation time of the test pulse which is dependent mainly on the
material of cable insulating material is taken into account by specifying a
signal propagation velocity.
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