CSI CSI-DSP95-252-L7, Product Manual, Page: 13 / 40

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The repeater uses a single down-conversion/up-conversion scheme. There are multiple RF amplifi er stages prior to each down-
converting mixer. The down-converting mixers are followed by a single IF amplifi er. A Digital Signal Processor block then processes
the resultant digitized IF signal that was previously generated by an Analog-to-Digital Converter. The processed (fi ltered) digital signal
is fed to a Digital-to-Analog converter and then up-converted to RF. A driver amplifi er and a fi nal power amplifi er make up the fi nal
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 continu-
ously 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.
Circuit Operational Description
Functional Block Diagram
Upon detection of oscillation the unit will shut down. After a “short duration” of 30 seconds the unit will attempt normal operation. If no
continued oscillation is occurring the unit will stay on. However, if oscillation is still occurring, the repeater will remain shut down and retry
1 additional time in the “short duration” loop. If after these two “short duration” retries, the oscillation is still detected, it will turn off again
and wait a “long duration” period of 10 minutes. If after 6 “long duration” retries, oscillation continues, the unit will go into a “disable
duration” of 24 hours. It will continue in the “disable duration” loop and retry every 24 hours.
LED 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
defi ned state, or maintains the protection until manually reset.
Indoor Antennas continued
3. To determine the quantity and locations of indoor antennas, use an appropriate phone’s signal meter to determine areas of
weak signals. These are the approximate areas where indoor antennas may be needed. Also be aware the signal from an
indoor antenna, in most cases, can be expected to penetrate about two standard offi ce sheetrock type walls to reach users.
After two walls or if the walls are made of other materials, it may be necessary to split the available signal and add more
antennas.