Front Panel Line Loop-Back Switch - Motorola iDEN Site Controller System Manual

Chapter 6 System Testing
Remotely Looping Back the E1 Site Controller for BER Testing

Front Panel Line Loop-Back Switch

6-24
So that the site controller can recognize the 00001 code word, AMI line
coding must be used. AMI encoding allows a string of four zeros to be
transmitted. After the site controller enters loop-back mode, the BER test
box may be changed back to HDB3 line encoding if desired. In normal
operation, the site controller uses HDB3 line coding.
When the craftsperson is done testing the E1 line, he sends the inband loop-
down code to the site controller. This code is a repeating 001 pattern across
the entire E1 frame. The site controller detects this pattern and quits looping
the E1. Normal operation on the E1 line can now begin. The loop-down code
contains no more than four zeros in a row, so HDB3 or AMI line coding may
be used to loop down the site controller.
The front panel of the site controller includes a Loop-Back Switch.
Depressing the SEL/LOOP button for more than two seconds causes site
controller to enter line loop-back mode. Depressing the SEL/LOOP button
for two seconds again deactivates the line loop-back.
Gen 3 Site Controller System Manual
68P80801E30-A 5/1/2002