Installation
150-512-100-03, Revision 03
28
September 25, 1998
HRU-512 List 1
When T1 loopback tests are made on the system with external
metallic loopback connections across the HRU-512 List DS1
XMT and RCV ports, the DS1 code that exists at these ports
may be different from the one being sent at the distant end
when the DS1 code option is set to AUTO. If the
HRU-512 List 1 has a metallic loopback and it is in its
AUTO/AMI mode, and then the distant end switches from an
AMI pattern to an all zero B8ZS pattern, the HRU-512 List 1 will
remain in its AMI mode causing it to transmit all 0’s. This
causes the HRU-512 List 1 to indicate a LOC LOS alarm
condition. This will force the HLU to output all ones on all
provisioned DS0 time slots for the user selected bandwidth.
Non-provisioned DS0 channels are not affected.
