As pointed out in Recommendation K.15, § 4.1, it is advisable
that the test conditions simulate real conditions as closely as
possible. As certain Administrations may be exposed to different
environments, or have different service objectives or economic
constraints, these tests may be modified to adapt them to
If the environment is not known, the text given in this
Recommendation should be applied.
None of the tests given in this Recommendation should cause any
significant change in the in the characteristics concerning the
repeaters under test.
In particular, this applies for:
a) current and voltage in the feeding circuit,
b) gain-frequency characteristic,
c) total noise,
d) bit error rate.
The tests consist of:
- prototype tests,
- acceptance tests.
Tests are intended to check the effectiveness of all the various
arrangements made to protect repeaters using solid-state devices.
These arrangements include protective devices incorporated as an
integral part of the repeater or installed externally at the
Prototype tests are carried out to check the effectiveness of
the repeater design and protective elements in a severe
In deciding what protective measures should be adopted,
allowance should be made for the most dangerous e.m.f.s that may be
produced at the inputs and outputs of repeaters using solid-state
devices, even where the occurrence of such e.m.f.s is very
When a repeater using solid-state devices with lightning
protectors at its input (or output) terminals is subjected to an
impulse voltage, the (residual) energy capable of reaching
components within the time-interval from zero to an impulse
voltage, the (residual) energy capable of reaching components
within the time-interval from zero to the striking-time of the
lightning protectors depends, among other things, on the steepness
of the impulse wave-front.
During the prototype test this residual energy should be as
large as in the worst case that may be expected in practice.
This is ensured by choosing an impulse wave of suitable
steepness and amplitude. It is, however, additional to the test
described previously, which recommends that the repeater be
subjected to an impulse having an amplitude less than the striking
voltage of the lightning protectors, in order to find out how it
responds over the whole of the impulse wave.
These tests are carried out on equipment after assembly, to
check that the protection is working properly. The test is in
general less severe than the prototype test in order to avoid
exposing certain components to a degradation that might remain
undetected by any measuring process. However, users are at liberty
to stipulate more stringent tests (adapted to special, real
The user may decide whether the tests are to be carried out on
each equipment or by sampling.
Note – In certain circumstances, users may consider it
worthwhile to carry out additional tests adapted to their own
special requirements. Such tests are not given below.