Comtech EF Data CIC-50 - Manual (Page 15)

CIC-50 T1/E1 G.703 Interface Converter .
Rev. 1 3
3
Chapter 3.
OPERATION
After applying power to the modem, the following configuration changes must be made
to the modem in order for it to operate with the CIC-50.
•
Program the transmit and receive data rates to either 1544 or 2048 kbps. Both
directions must be at the same rate.
•
Set the data interface type to EIA-422. The modem itself operates in this
electrical format while the converter translates between EIA-422 and G.703.
•
Set the transmit clocking to INT. This is required so that the modem’s internal
transmit data rate clock is driven to the converter on the ST lines to provide a
high stability reference for the G.703 clock recovery circuitry. The recovered
clock and data drive into the modem on the TT and SD lines, respectively.
Three switches must be set properly on the CIC-50, depending upon the specific G.703
format in use. They can be accessed with a small screwdriver.
3.1.1 MODE SELECT
0 E1, always used with a 2048 kbps data rate.
1-2 Unused.
3 T1(1), used at 1544 kbps and short cable lengths of 0-133 feet.
4 T1(2), used with 133-266 ft. cable.
5 T1(3), used with 266-399 ft. cable.
6 T1(4), used with 399-533 ft. cable.
7 T1(5), used with 533-655 ft. cable.