GE DS-SD4-1, Справочное руководство

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8 SD Series Reference Manual (x710 Mode) MDS 05-4670A01, Rev. E
Continuously-Keyed versus Switched-Carrier Operation
The keying behavior of the master station can be used to describe the
operation of an MAS system.
Continuously-Keyed operation means the master station transmitter is
always keyed and an RF carrier is always present, even when there is no
data to send. The master station is always transmitting and receiving
simultaneously. Different frequencies must be used for transmit and
receive. This is the method used in many MAS systems, as is shown in
Figure 4. This network arrangement is useful for high-speed polling
applications.
NOTE:
The SDx acting as a master does not support full-duplex oper-
ation.
Switched-Carrier operation is a half-duplex mode of operation where
the master station transmitter is keyed to send data and unkeyed to
receive.
Single-Frequency (Simplex) Operation
Single-frequency operation (also known as simplex) is a special case of
switched-carrier operation. Single frequency operation is automatically
selected whenever the transmit and receive frequencies are set to the
same value.
NOTE:
Data turn-around times are increased when inter-working with
an MDS x710 network. This restriction does
not apply to
homogeneous SD networks.
4.0 INSTALLATION PLANNING
Careful planning of the installation site helps achieve optimal performance
from the transceiver. This section discusses pre-installation factors. After
reviewing this section, refer to the step-by-step installation procedures begin-
ning on Page 18.
4.1 Typical Installation
Figure 6 shows a typical station arrangement. Wiring connections and installa-
tion steps for the transceiver are provided in the sections that follow.