FMUX/S-4E1-E2 Multiplexer
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Copyright © 2007 Cronyx
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3.5. Built-in BER tester
The FMUX multiplexer is equipped with a built-in BER tester, which allows to measure
the bit error rate in the link. The measurements are performed using fixed or pseudo-
random code according to the O.151 recommendation (the pattern length if —
2
23
-1=8,388,607 bits). The BER tester is controlled from the console (see the ''Test' menu'
section).
The BER tester calculates the error rate, by comparing the data transmitted to link to the
data received from the link. When the BER tester is enabled on the local device, test data
is transmitted to the link. If during this no test data are received from the link, the 'Test
pattern not detected' message will be displayed on the console. When no multiplexed data
from the transmission links are received from the link, the AIS signal is output to all E1
ports of the multiplexer.
This situation is shown on the diagram below:
Remote multiplexer:
AIS output to all E1 ports
LERR indicator on
Local multiplexer:
BER tester enabled
"Test pattern not detected" state,
TST, LERR, RERR indicators on
BERT
..
.
..
.
AIS
AIS
AIS
