Black Box ME760A-R2, User Manual

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CHAPTER 2: Introduction
2.1 Functional Description
This section contains functional descriptions of the LDM-MR19.2’s circuit blocks
(primarily the circuits required for correctly configuring the unit).
2.1.1 E
NCODER
The encoder modulates the input data from the DTE using the “conditional
diphase modulation” technique. You can configure the encoder to operate in
one of five modes:
• 4-wire full-duplex
• 4-wire half-duplex
• 2-wire half-duplex
• 4-wire multipoint
• 2-wire multipoint
2.1.2 M
ODULATION
T
IMING
The modulation-timing circuit supplies the Transmit clock to the encoder. Four
clock sources are available:
• INT.CK (internal clock—from the modem’s internal crystal oscillator)
• EXT.CK (external clock—from DTE, Pin 24)
• RCV.CK (receive clock—recovered from Receive signal)
• ASYNC (asynchronous timing for working with the async-to-sync converter
in an async application)
Setting the XMT TIMING jumpers determines the timing option.