User's Manual

Digital Repeater Line

DSP85 Series

WESTELL.COM

1.877.844.4274 Page 16 of 77

1.7 Ethernet

This port is used to provide local or remote access to the GUI.

1.8 Monitoring and Alarms

The DSP85 Series can be monitored via an ethernet connection using SNMP, SSH and/or HTTP protocols. Public

safety DSP models have dry contacts for traditional alarm panel monitoring as well.

1.9 Circuit Operational Description

The repeater uses a single down-conversion/up-conversion scheme. There are multiple RF amplifier stages before

each down-converting mixer. The down-converting mixers are followed by a single IF amplifier. A digital signal

processor block processes the resultant digitized IF signal generated by an analog-to-digital converter. The filtered

digital signal is fed to a digital-to-analog converter and then up-converted to RF. A driver amplifier and 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. The net system

gain value, entered manually, is optimally maintained without exceeding FCC parameters or overdriving the A/D

converters.

The Status or Power/Fault LED provides immediate visual indication of the unit’s primary power alarm status. The

repeater features automatic shutdown protection as a safety measure if excessive drive is applied to the input or an

oscillation condition occurs. 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 it is manually reset. If recovery is

established, the LED is illuminated green or available to be reset. Events that trigger errors are saved in the event log.

1.10 Functional Block Diagrams