CSI CSI-DSP85-PS7, Product Manual

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Functional Block Diagram
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Inadequate isolation between the outside and inside antennas may cause regenerative feedback in the system. This
feedback can cause the amplifier to emit a continuous signal at maximum amplitude and, in some cases, interfere with normal
operation of the dispatch site. Careful consideration of the layout and placement of the system is imperative.
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The installer should refer to the Safety Guidelines section on page 4 and the Important Safety Information section on page 5 for
proper antenna selection and installation. To avoid serious injury or death and damage to the repeater, do not install donor or server
antennas near overhead power lines or high power components. Allow enough distance so that if antennas should fall they will
not come in contact with those components.
•••••
Close proximity to the donor or server antennas with the repeater in operation may expose the user or installer to RF fields
that exceed FCC limits for human exposure.
WARNING!
AMPLIFIER OR HANDSET DAMAGE MAY OCCUR IF A HANDSET IS CONNECTED DIRECTLY TO THE REPEATER OR THE
COAX THAT LEADS TO THE REPEATER.
Important Installation Notes
The repeater uses a single down-conversion/up-conversion scheme. There are multiple RF amplifier stages prior to each down-
converting mixer. The down-converting mixers are followed by a single IF amplifier. A Digital Signal Processor block then processes
the resultant digitized IF signal that was previously generated by an Analog-to-Digital Converter. The processed (filtered) digital signal
is fed to a Digital-to-Analog converter and then up-converted to RF. A driver amplifier and a final power amplifier make up the final gain
stages before application to the diplexer. The maximum total system gain (diplexer input to diplexer output) is nominally 85 dB for either
the downlink or the uplink paths with both links having independent manual and automatic gain controls (AGC).
AGC reacts to analog power detection on both the input and output of the uplink and downlink RF chains. A control algorithm
continuously monitors these detected values and dynamically adjusts various gain stages such that the net system gain
value, entered manually, is maintained without either exceeding FCC parameters or overdriving the A/D converters.
LEDs on the front panel display provide immediate visual indications of the unit’s primary power and major or minor alarm
status. The repeater features automatic shutdown protection, as a safety measure, should excessive drive be applied to the
input or an oscillation condition occur. When in a protected mode, a control algorithm determines the appropriate method of
recovery to a normal, previously defined state, or maintains the protection until manually reset. If recovery has been estab-
lished, the associated LED(s) will either be extinguished or available to be reset. The events
that trigger the error will be saved in the event log.
Circuit Operational Description