2 custom internal clock rates (group 4), Standard internal clock rates (groups 1, 2 and 3), Custom internal clock rates (group 4) – CANOGA PERKINS 2240 Fiber Optic Modem User Manual
Page 35: Nd section 3.3.2 for
Chapter 3 Mode and Rate Selection
Internal Clock Modes - Modes 1, 2, 3, 4
35
3.3.1 Standard Internal Clock Rates (Groups 1, 2 and 3)
If the data rate appears in Table 3-3 on page 33, select the corresponding internal clock group
with the mode switches (refer to Table 3-1 on page 32). Then set the Rate Switches to complete
the rate selection process.
3.3.2 Custom Internal Clock Rates (Group 4)
The Group 4 Internal Clock Mode can be used if an oscillator has been specified or installed in
the custom oscillator socket (refer to section 2.2.5). The available oscillators and their respective
clock frequencies are given in Table 3-5. If the rate appears in table, choose the appropriate
oscillator option for the modem.
Obtaining the desired divide ratio may require changing the position of the TBL/NORM DIP
switch as shown in Table 3-4. The TBL/NORM switch is shown in Figure 2-1 and Figure 3-4.
6
C
O
O
C
192
3072
7
O
O
O
C
384
6144
8
C
C
C
O
64
256
9
O
C
C
O
128
512
* Factory setting
Table 3-4. Group 4 Internal Clock Rate Divide Ratio (Continued)
Rate
DIP Switches
(C) Closed (O) Open
Rate Switches
Group 4 Divide Ratios
Normal and Alternate
Table
1
2
3
4
NORM (ON)*
TBL (OFF)