Remotely Looping Back The E1 Site Controller For Ber Testing; Two Different Ways To Start And Stop A E1 Line Loop-Back On The Site Controller - Motorola iDEN Site Controller System Manual

Gen 3 Site Controller System Manual
Remotely Looping Back the E1 Site Controller
for BER Testing
Two Different Ways to Start and Stop a E1 Line
Loop-Back on the Site Controller
68P80801E30-A 5/1/2002

Remotely Looping Back the E1 Site Controller for BER Testing

SR7.0 or later boot ROM software provides E1 loop-back features not
available in previous releases of software. System operators should be aware
that previous system releases did not support loop-back when the site
controller was operating from boot ROMs. With the SR7.0 or later boot
ROM flash load, the site controller no longer resets after it enters loop-back.
The system operator must send a loop-down command to end the loopback.
Loop-back capability has always existed for the site controller when it
operates under software downloaded from the OMC. Performing a
loop-back test breaks the data links between the MSO and the EBTS.
The site controller downloaded software includes a timer. The default value
of this timer is one hour. When the links have been broken for one hour, this
timer initiates a site controller reset and clears the loop-back. The value of
this timer can be changed to run a longer loop-back test. This timer does not
effect loop-backs when site controller operates under boot ROM software.
Line loop-back connects the received data from the network to the line driver
in the site controller. The data passes through the site controller unchanged.
All framing errors, CRC errors, Bipolar Violations, and Data errors pass
back to the network as they were received.
In-band Line Loop-Back
A craftsperson inserts a E1 test set into the line going to the site controller.
The test box then sends a loop-up code consisting of a repeating 00001
pattern across the entire E1 frame. All 32 DS0s have the data pattern across
them. The site controller detects this pattern and enters loop-back mode.
The site controller will not recognize the 00001 pattern if HDB3
(High-Density Bipolar of Order 3) encoding is used. HDB3 encoding
replaces an occurrence of four zeros in a row with a bipolar violation
substitution word. The loopback decoder in the site controller does not
recognize this bipolar violation substitution word.
Chapter 6 System Testing
6-23