Ericsson FSU 995 F, Руководство пользователя, Страница: 35 / 86

33
The parameter INDEX LIMIT can be either a positive
or a negative value. For most cases you will most
probably use a positive value. The arc will then shut
off when the monitored index profile of one or both
fibers, depending on the Threshold type used, has
decreased to the set value.
The only case you will need to use a negative index
limit is when you find that the best match of the index
profiles, the so called MFD matching point, is found
after the two index profiles have diverged (see top
figure). A negative value means that the mode field
matching process will terminate when the difference
between the two index profiles has
increased to the
set index limit value. For the process not to terminate
before the divergence, the RTC procedure must be
initiated when the profiles have converged (see bottom
figure). This you achieve by adjusting the splicing
parameter FUSION TIME 2 (p. 39). Estimate, using
the Threshold type test graph, the time it takes from
that the RTC procedure starts to that the index profiles
converge and then add that time to the FUSION TIME
2 parameter. Note that the RTC procedure used in the
Threshold type test takes approximately 20 seconds
(100 RTC cycles x 0.2 seconds).
Using the index limit parameter
A graph from a Threshold type test where the MFD
matching point is found after the hot core index
match point
MFD matching point
An example of a graph when the RTC procedure is
initiated just after the index profiles have diverged.
ADVANCED OPERATION - Splicing program structure: Splicing process
hot core index
matching point