CM
7. END TO END TESTS
Verify communications between Peripheral units (P742 or P743) and Central Unit (P741) -
Advisable for distributed scheme.
The following communication checks confirm that the optical power at the transmit and
receive ports of the Peripheral Units and the Central Unit are within the recommended
operating limits.
Measure and record the optical signal strength received by the Peripheral Unit (P742 or
P743) by disconnecting the optical fibre from the Channel 1 receive port and connecting it to
an optical power meter. The mean level should be in the range − 16.8 dBm to −25.4dBm. If
the mean level is outside of this range check the size and type of fibre being used.
When connecting or disconnecting optical fibres care should be taken not to look
directly into the transmit port or end of the optical fibre.
Measure and record the optical power of the Channel 1 transmit port using the optical power
meter and length of optical fibre. The mean value should be in the range –16.8dBm to –
22.8dBm.
Ensure that all transmit (Tx) and receive (Rx) optical fibres between Peripheral Unit and
Central Unit are reconnected, ensuring correct placement.
Reset any alarm indications and check that no further communications failure alarms are
raised.
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