Dmd1050 Clocking Options; Tx Clock Options - Comtech EF Data Radyne DMD1050 Installation And Operation Manual

DMD1050 Satellite Modem Board

3.10 DMD1050 Clocking Options

The DMD1050 supports a number of different clocking options that can be recovered from the
satellite or the terrestrial links. The various clocking options allow users to determine which
clock will best fit their applications. Figure 3-9 gives an overview on how the modem processes
the various clocks for the Tx Clock source and the Rx Buffer Clock source. Tx and Rx Clocks
may be independently locked.
SD
TT
ST
High Stability
Oscillator
EXT REF
TRANSMIT
RECEIVE
RT
BUFFER CLK POL
RD
DATA POLARITY

3.10.1 TX Clock Options

TX clock options can be recovered from the terrestrial interface, satellite interface or internally
generated. The allows users to select SCTE Clock (Terrestrial) or the SCT internal clock. The
modem also allows user to recover the SCT Clock from the satellite (SCR) or from the modem
internally. The modem allows users to select clock polarity. The Tx clock selections available
are:
MN-DMD1050
Revision 9
DMD1050 CLOCKING AND POLARITY
SCTE
SCT
HIGH STABILITY
INTERNAL
REF FREQ
SRC
EXTERNAL SCT CLK
SRC
SCR
NORMAL
INVERTED
SCT
BUFFER CLK
SCTE
SRC
RX SAT
INVERT NONE
INV. TERR&BASE
INV. BASEBAND
INV. TERR DATA
Figure 3-9. Clocking and Polarity Diagram
INVERT NONE
INV. TERR&BASE
INV. BASEBAND
INV. TERR DATA
DATA POLARITY
CLOCK &
DATA
Tx CLK
CLK POL
SRC
NORMAL
INVERTED
AUTO
CLOCK & DATA
DEMODULATION
RECOVERY
Theory of Operation
MODULATION
3–17