Front Panel Features
The RJ-45 jack allows front panel test access for local or downstream loopbacks. The address select knob (SW3) determines which element is being looped back. Table 3 lists the loopback options.
Three LEDs on the front panel of the U-BR1TE III report the synchronization and loopback status. Descriptions of these LEDs are given in Table 4. The SLC Series 5 COT must be externally timed from a suitable composite clock with stratum one traceability.
3. TESTING
The U-BR1TE III responds to embedded operation channel loopbacks, including B1, B2, and 2B+D, when configured for D channel operations.
Table 3. Rotary Switch Legend
Display | Name | Interpretation |
| | |
0 | NT1 | NT1, address of the NT1 |
| | latching OCU in DDS mode. |
| | |
1 | ADR1 | Address #1, address of this unit |
| | |
2* | ADR2 | Address #2, the next downstream |
| | unit away |
| | |
3 | ADR3 | Address #3, the second unit |
| | downstream |
| | |
4 | ADR4 | Address #4, the third unit |
| | downstream |
| | |
5 | ADR5 | Address #5, the fourth unit |
| | downstream |
| | |
6 | ADR6 | Address #6, the fifth unit |
| | downstream |
| | |
7** | LPBK | Loopback, forces this unit to |
| | loopback the selected B1 or B2 |
| | channel. Loopbacks occur in both |
| | the customer and network |
| | directions. |
| | |
8 | CRTX | Carrier transmit, in the carrier |
| | direction |
| | |
9 | LPTX | Loop transmit, in the loop |
| | direction |
| | |
Clockwise rotation selects the B1 channel. |
Counterclockwise rotation selects the B2 channel |
*Factory Default Setting |
** Reserved for special testing |
| | |
When used in B1 configuration (non-D channel modes of operation) the U-BR1TE III will respond to an in- band DS0 DP latching loopback sequence. When remote testing is not available, or during troubleshooting, the U-BR1TE III front panel provides local test capabilities for use with industry standard Digital Logic Test Sets such as the TPI 108/109 or equivalent testers. Available tests include a local loopback, loopback of up to 5 addressable downstream ISDN devices, loopback of the customer’s NT1, and point-to-point testing in both the upstream and downstream directions.
NOTE
When a U-BR1TE III is performing a loopback, the loopback occurs internal to the U-interface transceiver.
Loopback Tests
Loopbacks in the network-to-customer direction can be initiated from either the ISDN switch or the front panel. Front panel initiated loopbacks are non- obtrusive to unused channels, thereby preventing synchronization loss or dropouts on the carrier or loop while testing.
From the RJ-45 jack on the front panel, a DS0 digital test set is used to inject the required 64 kbps test pattern into the B1 or B2 channel. The address select knob determines the downstream element to be looped back, and the direction of rotation of the knob selects which channel is to be looped back. Clockwise (CW) rotation selects the B1 channel, and counterclockwise (CCW) rotation selects the B2 channel. To initiate a loopback, perform the following procedure:
1.Connect the DS0 tester to the RJ-45 jack.
2.Rotate the address select knob in the direction associated with the desired loopback channel until the desired downstream element address is reached (see Table 3). The LEDs indicate successful loopback activation according to Table 4.
3.Data is looped back at the selected address until the jack is disconnected or the address select knob is changed.
Point-To-Point Test (CRTX/LPTX)
Point-to-point testing using a DS0 digital tester can be performed to either the T1 carrier interface (SW3, position 8), or the U-interface (SW3, position 9).
