Rx Sat Clock; Cte: Serial Clock Transmit External; Sct: Serial Clock Transmit; Ext Clk/Ext Bnc: External Clock, J16 - Radyne DMD20 Installation And Operation Manual

DMD20/20LBST Universal Satellite Modem
The modem handles RX Buffer clock selections based on source priority levels. The user
assigns priorities to the clock sources based on source selections. Source 1 has the highest
priority and Source 5 being the last resort or lowest priority. If a fallback clock is selected and
activity is lost at the highest priority source, the modem will fall back to the next highest priority
clock with activity. When activity resumes on a higher priority source, the modem resumes using
the higher priority source
Clock Source
RX SAT
SCTE
SCT
EXC BNC
EXT IDI
Refer to Front panel setup menus or Web Browser manual MN-DMDREMOTEOP.
3.7.2.1

RX SAT Clock

The RX Sat clock is recovered from the satellite that is received from the distant end. If selected
the Buffer Clock is lock to the RX sat clock.
3.7.2.2

CTE: Serial Clock Transmit External

When SCTE is selected as the Rx Buffer clock, the modem receives the clock from the Transmit
Terrestrial interface.
3.7.2.3

SCT: Serial Clock Transmit

If SCT clock is selected as the RX Buffer clock source, then it should be configured for internal.
SCT is sometimes referred to as Internal Timing or Send Timing (ST).
3.7.2.4

EXT CLK/EXT BNC: External Clock, J16

The External Clock that can be selected as the RX Buffer clock source. This is a 75ohm
unbalanced BNC connector. This clock source is also identified as EXT BNC. The External
Clock is often used as the station master clock. The RX Clock selection can be accessed in the
INTERFACE/RX SETUP menu. The clock frequency, EXT FREQ can be selected, in the
Interface/General Menu.
Clock specification:
Frequency:
Level:
3.7.2.5

EXT IDI: Insert Data In

External IDI is used only for E1/T1 Drop and Insert applications. The available T1/E1 Frame
Source selections are External, Internal, and IDI/DDO Loopback. The T1/E1 Frame Source
selections can be accessed in the INTERFACE/RX SETUP menus. If Ext IDI is selected as the
RX Buffer clock, then user must first specify T1/E1 Frame Source.
External (RX Buffer Clock recovered from the data)

Internal (RX Buffer Clock recovered from the internal clock)

IDI/DDO Loopback (RX Buffer Clock recovered from the data and looped back)

MN-DMD20-20LBST Revision 14
Priority
1 of 5
2 of 5
3 of 5
4 of 5
5 of 5
1 MHz to 20 MHz
0.5 Vp-p to 5 Vp-p
Theory of Operation
3–13