The block diagram of Scarab-E. Main traffic is passed between 10/100BaseT and SHDSL via Ethernet SW CKT, SHDSL DSP, AFE, Line Driver and Filter CKT, Line Protection and Transformer CKT and Line connector. DC to DC Power Supply CKT can be either remote power feeding or external power adapter as power input source, and generate relative voltage to the relative chipset.

The major functional block diagram of Scarab-E. They are:

• DC to DC Power Supply CKT: It provides power filter functions which make sure inrush current after power on and voltage noise do not effect DC/DC converter which convert  power source from external power adapter or Remote Power Feeding CKT (an optional function) to other voltage (such as 5V, 3.3V, 2.5V, 2.0V) for chips. Power monitor function is an option for better system reliability.

• Ethernet to HDLC Converter and Ethernet PHY CKT: It provides 10BASE-T / 100BASE-TX Ethernet interface which is specified in IEEE 802.3 standard. It provides data conversion between Ethernet and HDLC and connects to SHDSL DSP via HDLC interface.

• SHDSL DSP CKT: It provides SHDSL relative DSL frame, line coding, management and start-up process.

• AFE, Line driver and Filter CKT: Convert digital signal to analogue and vice versa. It provides filter and drive function also.

• Line Protection and Transformer CKT: This block is including protection circuit from abnormal conditions, such as surge, power contact … and so on. Transformer is used to hybrid signal between two wire and four wire system. SiDAtor and Polyswitch are used for secondary protection and GasTube is used for primary protection.

• Line Connector: It provides connection to DSL line, which connect to existed cpooer wires.

• Remote Power Feeding CKT: This is a reserved function. It will use feeding power which is fed from line card as a power source, and convert the voltage to fit the input range of DC to DC Power Supply CKT, extra external power supply is not required.

• CPU (8051) and Serial EEPROM: For the sake of OAM&P, some DSP initialization, management and relative functions, CPU are needed. Serial EEPROM is used for store SHDSL firmware and configuration information. Firmware upgrade and download functions will be considered.

• LEDs:Display Scarab-E working status and SHDSL line interface status. Detail LED color and operating method please refer to 4.1 Interface – LED.

• Setting and Debug Interface CKT: It will be used for operation mode setting and debugging of Scarab-E.

• RS-232:A Local Craft Terminal (LCT) is used for configuration and monitoring of Scarab-E.