Comtech EF Data DMD1050TS - DMD1050 TS Clocking Options; Tx Clock Options; Figure 3-10. Clocking and Polarity Diagram

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DMD1050TS Satellite Modem Board

Revision 1

Theory of Operation 3–20 MN-DMD1050TS

3.10 DMD1050TS Clocking Options

The DMD1050TS supports several clocking options that can be recovered from the satellite or the

terrestrial links. The clocking options allow you to decide which clock best fits the application.

Figure 3-10 shows a diagram on how the modem processes the clocks for the Tx Clock source

and the Rx Buffer Clock source. Tx and Rx Clocks can be locked independently.

Figure 3-10. Clocking and Polarity Diagram

3.10.1 Tx Clock Options

Tx clock options can be recovered from the terrestrial or satellite interface, or generated

internally. You can select the SCTE Clock (Terrestrial), or the SCT internal clock. The modem

also allows you to recover the SCT Clock from the satellite (Serial Clock Receive (SCR)), or from

the modem internally. The modem allows you to select clock polarity. The Tx clock selections

available are:

• SCT (Internal Oscillator)

• SCTE (External Tx Terrestrial Clock)

• Rx Satellite Clock

Tx CLK

SRC

High Stability

Oscillator

CLOCK &

DATA

EXT REF

EXTERNAL

INTERNAL

SCT CLK

SRC

REF FREQ

SRC

SCT

SCTE

TRANSMIT

RECEIVE

CLOCK & DATA

RECOVERY

SCT

SCTE

RX SAT

SCR

BUFFER CLK

SRC

MODULATION

HIGH STABILITY

DEMODULATION

CLK POL

DATA POLARITY

NORMAL

INVERTED

AUTO

INV. TERR&BASE

INVERT NONE

INV. BASEBAND

INV. TERR DATA

DATA POLARITY

BUFFER CLK POL