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SC720/SC820
Overview
2.2
Data Repeater Communications
A Data Repeater is a well situated automatic re-transmission station used to significantly extend the effective
RADIO communications range of a transceiver. The Data Repeater station consists of a receiver, control
circuitry, interconnect circuitry, a transmitter, power supplies, an optional duplexer and at least one antenna. The
SAFECOM Data Repeater is a FULL DUPLEX FM RADIO repeater. The repeater receives the RADIO signal on
one frequency, demodulates it, processes it, remodulates it, applies it to the input of the repeater transmitter, and
re-transmits it on a second frequency. A Full Duplex system can transmit and receive at the same time
(simultaneously).
2.3
SC720/SC820 Data Repeater Overview
The ability of the SC9000 Receiver to monitor Radio Communicator Panels, which are geographically separated
by great distances, is significantly improved by telemetry range extension through the use of the SAFECOM
SC720/SC820 Data Repeater.
Note:
The SC720/SC820 is intended for single (one) customer operating company service.
The SAFECOM SC720/SC820 Data Repeater is a Full Duplex, real-time, digital data repeater system. It
simultaneously receives (FREQ X) and transmits (FREQ Y) on two separate RADIO frequencies, in the UHF
frequency spectrum. See Figure 1.
SC4000
Base Station
The SC720/SC820 is based on a Kenwood model #TKR-820 platform. The existing repeater signaling unit has
been replaced by the SAFECOM DK1000 Controller Board. The incorporation of the DK1 000 provides the real-
time digital data repeater capability to the system.
Note:
The SC720/SC820 can NOT be used as a transceiver for voice, voice repeater, or store and forward
digipeater communications.
The SC720/SC820 has an enhanced feature to limit identifying-carrier detect (CD) to SAFECOM RADIO signals
transmitted by the RF2000 Radio Modem or Remote comm panels. The DK1000 controller board will look at the
group of message bytes received when it detects a RADIO carrier (Carrier Detect - CD). If the CD message
groups do NOT contain the proper message validation, the RADIO signal will be ignored by the SC720/SC820.
ONLY messages with the proper validation byte messages will be processed by the DK1000 controller board for
data repeater RADIO communications.
The SC720/SC820 power output is adjustable from a minimum of 2 watts to a maximum of 25 watts. The
SC720/SC820 can be configured with a duplexer to allow the transmitter and receiver to connect to the same
antenna. With a duplexer installed, the maximum power output is reduced.
90007-201C
Customer Site
RF2000
AUTOMATION
SC9000
SOFTWARE
RECEIVER
Figure 1: Data Repeater Operations
SC720/SC820 Operation and Installation Guide
FREQ Y
FREQ X
FREQ X
FREQ Y
PRINTER
Page 8
Repeater Site
SC820
© 2004 Bosch Security Systems
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