Motorola PDR 3500, Базовое руководство по обслуживанию

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68P81093C75-O September 27, 2000 4-1
System Applications
4
Local Control
The PDR 3500 is an APCO 25 digital repeater. The station is
identical in operation to the Quantar station, hence there is no local
control capability. There is no digital-to-audio translation within the
station. Local control style operation can be accomplished in several
ways:
a. A portable radio may be used as an RF control station talking to
the repeater.
b. The station may be equipped with the wireline and the modem
options and routed through a DIU to a tone remote console. The
Tone remote console controls the station via wireline through the
DIU. The wireline in this case is a local 4-wire cable.
Two Antenna
Operation
The PDR 3500 Portable Digital Repeater may be operated with the
internal duplexer, using a single antenna. The duplexer provides the
necessary electrical isolation between the transmitter and the
receiver frequencies for repeater operation. The same isolation can
be obtained by physically separating transmit and receive antennas
either horizontally or vertically. The repeater requires approximately
50 dB isolation between the transmit and receive antennas for proper
operation.
The Isolation values shown are for dipole antennas. If gain antennas
are used, additional separation is required. For example, if both
receive and transmit antennas have 3dB gain each, an additional
6 dB isolation is required. At UHF frequencies, an additional 75 feet
separation is required.
Horizontal Antenna Separation:
VHF Band 275 feet
UHF Band 75 feet
800 MHz Band 40 feet
Vertical Antenna Separation
(tip of one antenna to the base of the other):
VHF Band 23 feet
UHF Band 9.5 feet
800 MHz Band 4 feet