Nokia 9500 MPR User Manual page 1033

Release 7.0.0 3DB 19286 ACAA Issue 01
WebEML User Manual
71 RF Core Facing Loopback
71.1 Purpose
This chapter provides procedures to perform RF Core Facing Loopback for the
MPT-HL, MPT-HLC, or MPT-HLS Transceiver.
71.2 General
An RF Core Facing loopback is used to help isolate a problem on the RF path.
With the MPT-HL, two methods are available, transmit and receive. The transmit RF
Core Facing loopback is used at the transmit site of the path to isolate the transmitter
from possible path and receiver problems. The receive RF Core Facing loopback is
used at the receive site of the path to isolate the receiver from possible transmitter
and path problems. With the MPT-HLC/HLS, only the receive loopback is available.
A transmit RF Core Facing loopback is enabled by the user configuring the RX
frequency to the same value as the TX frequency, allowing the receiver at the
transmit site to use the TX RF signal of the path.
Transmit RF Core Facing loopback is only supported at TX frequencies that are
within the allowed RX frequency range of the transceiver.
This loopback routes the TX RF signal to the Rx RF.
Receive RF Core Facing loopback is only supported at RX frequencies that are
within the allowed TX frequency range of the transceiver.
It is possible to enable this loopback only on the aggregate traffic. This loopback will
be a Loop and Continue with the MPT-HLC/HLS. It is not a Loop and Continue with
the MPT-HL. With both radios, the loopback will block the normal receive traffic.
A RF Core Facing loopback may require an external connection for some modem
profiles. Without an external connection, the RF loopback is dependent on internal
leakage in the transceiver. This leakage varies between units and also with operating
frequency. The leakage is sufficient that the loopback will work with the lowest
capacity profiles without an external connection. It may be sufficient to work with
other profiles, but this is not guaranteed.
RF Core Facing Loopback
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