ADC Digivance Installation And Operation Manual page 25

The LIU is rack or wall mountable and is powered by 120–240 Vac (50–60 Hz) power. Refer
to the Digivance Local Interface Unit User Manual (ADCP-75-113) for a complete description
of the LIU.
2.1.2 Remote BTS (Cell Site Base Station) Interface
A remote interface between the DHU and the BTS (cell site base station) via a donor antenna
requires specific RF input and output signal levels at the DHU and antenna. The correct levels
at the DHU and antenna can be provided using the Remote Interface Unit (RIU). The RIU is
an accessory item that provides adjustable gain or attenuation in both the RF forward and
reverse paths. The RIU connects to a directional antenna through a duplexer which provides
separate forward and reverse path connections for the DHU. In the forward path (downlink),
the RIU provides the DHU with the recommended composite maximum RF input signal level
of –20 dBm. When the level of the RF input signal at the DHU is –20 dBm, the level of the
RF output signal at the DRU is +13 dBm which is the maximum allowed.
In the reverse path, the required RF output signal level to the donor antenna will vary
depending on the distance from the BTS. When the level of the reverse path (uplink) signal at
the DRU is at the recommended composite maximum level of –40 dBm, the level of the RF
output signal from the DHU is –30 dBm. Therefore, it may be necessary to add gain or
attenuation to the reverse path signal in order to achieve the required output signal level at the
RIU antenna port. A block diagram showing a typical remote DHU to BTS interface is
provided in Figure 9.
The RIU is rack or wall mountable and is powered by 120–240 Vac (50–60 Hz) power. Refer
to the Digivance Remote Interface Unit User Manual (ADCP-75-114) for a complete
description of the RIU.
DIRECTIONAL
ANTENNA TO/FROM
CELL SITE BTS
FORWARD
REVERSE
(DOWNLINK)
(UPLINK)
REMOTE
INTERFACE
UNIT
-20 dBm
(COMPOSITE
MAX)
DIGITAL
HOST
UNIT
-30 dBm
(COMPOSITE
MAX)
Figure 9. Remote BTS Interface Block Diagram
ADCP-75-110 • Issue 2B • July 2001
DIRECTIONAL ANTENNA
TO/FROM HANDSETS
-40 dBm
+13 dBm
(COMPOSITE
(COMPOSITE
MAX)
MAX)
OPTICAL LINK
DIGITAL
REMOTE
UNIT
OPTICAL LINK
16425-A
© 2001, ADC Telecommunications, Inc.
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