ADC RF Worx, Руководство пользователя

Страница: 8 / 26

ADCP-61-810 • Issue 4 • September 2004
Page 2
© 2004, ADC Telecommunications, Inc.
A typical application would be to protect two optical-to-RF receivers. In this setup, the RDS can
independently protect one or two pairs of receivers/amplifiers. If there are two pairs, individual
thresholds can be established for each pair, and once the RDS detects a signal level falling
below threshold, it will switch from A to B (or B to A) for that particular pair. All status
conditions for each pair of receivers are available locally and remotely via the optional SWatch
switch monitoring software.
1.3 Dual Alarm Monitor Mode
The “dual alarm monitor” mode can be used to monitor RF signals anywhere in the forward
path of the network—such as the output signal from any critical amplifier or receiver. The RDS
can monitor two RF signals independently in this mode. Alarms will be triggered when the RF
signal level of either signal falls below the preset threshold (i.e., no switching will occur).
1.4 Graphical User Interface
—
“SWatch” Switch Monitoring System
The SWatch GUI software for the RDS can be purchased separately from ADC
Telecommunications. The program provides continuous remote monitoring of the RDS and
associated systems. It is designed for Windows 95/98/NT systems with a 90 MHz (or faster)
Pentium Processor.
2 DESCRIPTION
This section provides functional, physical, and technical descriptions of the RDS Redundant
Switch.
2.1 Functional Description
The RDS has several distinct and unique modes of operation, including redundant amplifier
mode, dual A/B switch mode, and dual alarm monitor mode. The following paragraphs describe
these various operational modes.
2.1.1 Redundant Amplifier Mode
Figure 2 is a block diagram showing the redundant switch configured for “redundant amplifier”
mode operation. Both the RF input and output signals are applied to a coupler that routes a
small portion of the signal through an analog level detection circuit and an analog-to-digital
converter to the logic and control circuits. Other inputs to the logic and control circuits include
the front-panel mounted SWITCHING THRESHOLD switch and digital display used for
setting the gain trip level (2 to 7 dB down from the amplifier reference level), the Primary AMP
SELECT switch, and the MODE SELECT (NORMAL/CALIBRATION) switch. When
triggered by a Primary amplifier gain failure, the logic and control circuits switch on input
power to the backup amplifier, then, after a 13 msec delay, the RF In and RF Out signals are
also switched over to the backup amplifier (total elapsed time equals approximately 50 msec).