1800MHz-1900MHz Off-Air Repeaters (OR Series)
Page
91 080 0701F – Rel.04
CHAPTER 3
3.5
3.2) OPERATING PRINCIPLE – 1800/1900MHz ADJUSTABLE BANDWIDTH OFF-AIR REPEATERS
The repeaters described in this handbook have been developed to permit cell coverage as set forth by the
DCS (Digital Cellular System) standard for cell phones operating on the 1800MHz band or by the PCS
(Personal Communications Service) standard for cell phones operating on the 1900MHz band. The DC
powered repeater can be power-fed by a 48Vdc power supply source only. The AC powered repeater can be
power-fed from MAINS (230Vac) or from a 48Vdc power supply source or both from MAINS and from a
48Vdc source. The presence of both power supply voltages guarantees the continuity of the coverage
service even in case of failure of one source. The commutation is handled automatically by the repeater.
Off-Air Repeaters are bi-directional amplifiers. The signal to be extended follows two distinct paths: the up-
link path, from the mobiles to the radio base station, and the down-link path, from the radio base station
towards the mobiles.
Figure 7 provides a block-diagram of the 1800/1900MHz adjustable band Off-Air Repeater.
FIGURE 7 – 1800/1900MHz OFF-AIR REPEATERS BLOCK-DIAGRAM
In down-link the RF signal from the donor antenna is filtered and pre-amplified by a low-noise amplifier (LNA,
ref. C1
).
The selection of the band of frequencies to be extended is handled by two band-selective modules,
ref. D1
and
ref. D2
, which make the band-pass and frequency center programmable entities.
The band of frequencies to be extended can be managed by the user by means of the management system.
The signal is then amplified by the High power amplifier (
ref. E1
) filtered by the MS side duplexer,
ref.
B2
,and transmitted by an antenna or a passive distribution system.
A VSWR detector is equipped.
The up-link path is identical to the down-link path described above.
BTS
dB
ALC
dB
ALC
MS
DOWN
UP
DOWN
UP
MANAGEMENT BUS
MANAGEMENT
UNIT
MODEM
NETWORK
RS232
DC/DC
CONVERTER
LNA DOWN
HPA
DOWN
LNA UP
HPA UP
BAND SELECTIVE 1
UP LINK
DOWN LINK
BAND SELECTIVE 2
UP LINK
DOWN LINK
5.5Vdc
48Vdc
48Vdc
IN
AC/DC
CONVERTER
230Vac
IN
5.5Vdc
10.5Vdc
10.5Vdc
5.5Vdc
10.5Vdc
5.5Vdc
10.5Vdc
5.5Vdc
5.5Vdc
5.5Vdc
10.5Vdc
5.5Vdc
A1
B1
C1
D1
E1
B2
C2
E2
A2
D2
L
F
G
