The TL5120 T-3 Automatic Protection Switches are used to back up one or two T-3 (DS3) lines with a back up T-3 line (see Figures 1 and 2). They are used in pairs, one at each end of the T-3 facilities. The TL5120s may be used on T-3 lines provided by one or more TELCOs or T-3 digital microwave radio facilities.

Figure 1.

Two TL5120s used to back up a T-3 application. The T-3 TX data at each end is sent down both T-3 paths. The TL5120 chooses the best RX signal to pass to the Customer Equipment. The T-3 paths could both be TELCO or digital radio facilities.

Figure 2.

Two TL5120s used to back up two T-3 links with a back up T-3 link. In this application the two TELCO facilities are connected to Customer Equipment 1 and 2 while the back up radio link is being tested. In the event of a failure on either TELCO link, the digital radio will automatically replace the TELCO facility that failed. All the paths could be TELCO or radio facilities.