Table 2.1
RF-2000E/EW Duplex Nominal Power Level
(Power Level 1)
Modulation
Nominal Nominal
Input Output
dBm dBm
FM/FSK/MSK -21 +24
4PSK/QPSK/OQPSK -23 +22
8PSK -25 +20
16 QAM -27 +18
QPR3/9QPRS -26 +19
QPR5/25QPRS -26.5 +18.5
QPR7/49QPRS -27 +18
QPR9 -28 +17
Amplifiers
•
In digital radio applications, in order to maintain linearity
over the entire signaling envelope, the amplifiers operate
at a reduced average power level to meet the output power
level requirement as shown in Table 2.1. Each amplifier is
mounted on the front of the panel to allow easy AGC/ALC
adjustment and amplifier replacement in the field. Necessary
information for ordering spare or replacement amplifiers is
provided in Part 5, Ordering.
Directional Couplers
•
Directional couplers, built into the amplifiers, provide signal
monitor points (Figure 2.3). These allow in-service measure-
ment of transmit output power. The monitor points are
calibrated to indicate actual RF out-put power at the antenna
connector. When measuring transmit power, the power
meter reading obtained, plus the loss (in dB) marked at the
amplifier monitor point, minus the branching loss (in dB)
marked on the panel, equals actual transmit output power.
For example:
(1) Power meter indication
=
+5.0dBm
(2) Loss marked at monitor
=
18.2dB
(3) Branching Loss
=
-2.2dB
(4) Output Power
=
+21.0dBm
RF-2000E/EW Repeater
RF-2000E/EW Repeater
Website
www.peninsulaengineering.com
AGC/ALC and Max.Gain Adjustment
•
There are two field-adjustable potentiometers on the
amplifier (shown in Figure 2.7). The repeater Output level
and Nominal gain is adjusted by AGC/ALC potentiometer.
The other potentiometer is for Maximum Gain adjustment,
which is left at minimum attenuation by the factory. If for
any system requirement, the maximum (linear) gain of the
repeater can be reduced by this potentiometer. However,
any reduction of the maximum gain of the repeater will also
reduce the AGC/ALC range of the repeater by the same
amount. For various options of repeaters, with the same
operation point, input/output power level, they will have the
same AGC dynamic range. However, more complex options
have higher branching loss, hence less maximum available
gain. Therefore they will have less downfade reserve, dB to dB.
Power Supply
•
The only active elements in the RF-2000E /EW assembly
are the amplifiers which operate from a +13.5 Vdc source.
Current requirements are 1.0 Amperes per amplifier for
Power Level 1 frequency channel and 1.4 Amperes per
amplifier for Power Level 2 frequency channel. The repeater
assembly may be powered from solar panels/batteries,
primary cells only, or from an ac/dc supply with standby
battery (shown in Figures 2.8 and 2.9). 3A fuses are used
for Power Level 1 and 4A fuses are used for Power Level 2.
•
Storage batteries and solar cell panels are selected on
the basis of the average insulation and temperature range
at the site. The batteries are engineered to provide the
required reserve capacity across the temperature range and
during periods when the output from the solar panels is low
or not available. Controllers are used with the solar panels
to efficiently charge the batteries without overcharging.
Peninsula Engineering can determine the solar and battery
capacity. The location of the site should be specified when
requesting assistance.
•
In areas where commercial power is available, an ac power
supply can be provided. Although one ac power supply will
provide ample current to power all amplifiers, dual AC power
14