Metrodata FM4900, Руководство пользователя

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TEST & TROUBLESHOOTING
76-02-011F 54
9. 3 Network Interface (NI)
9 . 3. 1 NI Remote Loop
When the REMOTE LOOP is activated, a loop-up code is transmitted to the remote FM4900,
switching it in to LOOP . Therefore a Loop may be performed at the remote end without any
need for maintenance staff to attend the remote site.
Remote Loop-Up is transmitted as repeated '10000' while Remote Loop-Down is transmitted
as repeated '100'. The Loop-Up code is transmitted for 5
⋅
5 seconds with the remote FM4900
going into Loop after 4.5 seconds.
The remote FM4900 stays in this mode until Loop-Down is transmitted from the local unit.
Figure 9. 4 NI remote loop test
The unit receiving the remote Loop-Up signal loops both the E3 and DTE ports adjacent to
each of those ports, therefore removing its own influence. This therefore validates:
a) the remote DTE cable if the remote DTE recognises its own transmissions
b) the local DTE cable, the local FM4900 and the E3 link if the local DTE recognises its own
transmissions.
Tx
Rx
HSSI
HSSI