Figure 4-6. Ext Master Clock As Source - Comtech EF Data SLM-7650 Installation And Operation Manual

SLM-7650 Satellite Modem
Theory of Operation
4.4.3.3.2.5 Timing Configuration #5: EXT Master Clock as Source
This example illustrates the buffer using the EXT Master clock source (Figure 4-6).
The External Master clock frequency must be set in the configuration menu.
Modem Reference clock is either INT, 1, 5, 10, or 20 MHz
TX clock Source = TX Terrestrial
RX Buffer = EXT Master Clock
The External Master clock, inputs on pins 16 and 34. Observe the follows rules:
If "Transmit Terrestrial" or "External" is selected as the buffer output reference
source one of the following constraints must be satisfied:
a. Reference frequency is equal to RX data rate.
b. Receive data rate and REF frequency are both integer multiples of 600 Hz.
c. Receive data rate and REF frequency are both integer multiples of 1 kHz.
User recovers
the clock for
TT and SD
from the
Master clock
RT clocks
in the RD
User
Clock
Master
Ext. Master
Clock
External
Master Clock
Modem

Figure 4-6. EXT Master Clock as Source

4–29
Internal
clock
ST
TT
TRANSMIT
RT
Receive
Buffer
Modem
Revision 4
MN/SLM7650.IOM
1, 5, 10,
or 20 MHz
Reference
detect
To TX IF Output
From decoder
User