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SECTION 4: THEORY OF OPERATION
PARAGRAPH
TITLE
PAGE
4.1
INTRODUCTION ..........................................................................................................12
4.2
POWER SUPPLY AND ALARM CIRCUITRY.............................................................12
4.2.1 Power Supply Circuit........................................................................................................12
4.2.2 Alarm Circuit....................................................................................................................12
4.3
FUNCTIONAL DESCRIPTION ....................................................................................13
4.3.1 Ring Detection..................................................................................................................13
4.3.2 Loop Current Detection Circuit .........................................................................................13
4.3.3 Reverse Battery Detection Circuit .....................................................................................13
4.3.4 Analog-to-Digital Conversion............................................................................................13
4.3.5 CPLD (Mux / Demux)......................................................................................................13
4.3.6 RS-485 / RS-422 Data Transmission Circuit .....................................................................14
4.3.7 Fiber Optic / Copper Transceiver Circuit ..........................................................................14
SECTION 5: MAINTENANCE AND TROUBLESHOOTING
5.1
INTRODUCTION ..........................................................................................................15
5.2
FAULT ISOLATION......................................................................................................15
