Raisecom Technology Co., Ltd.
http://www.raisecom.com
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Loop-back
OFF
Positive Positive PCM31 Enable
Normal
Remote
Loop-back
Since the relationships between V.35 data and clock phase are different on different brand
Routers, TX CLK and RX CLK phase options are used to solve the problem. When TX CLK
and RX CLK are both set to Positive, the RC801-30B-FV35 modem has passed the test at the
V.35 synchronous WAN interface of CISCO series Routers.
TX CLK positive: TD signal will be sampled at the falling edge of TCK clock signal
TX CLK negative: TD signal will be sampled at the rising edge of TCK clock signal
RX CLK positive: RD signal will be sampled at the falling edge of RCK clock signal
RX CLK negative: RD signal will be sampled at the rising edge of RCK clock signal
PCM30/31 option. When other equipment (i.e. DXC, MUX) in the link requires the frame
format to be PCM30, the modem shall be configured to PCM30 (N
≤
30); when requires the
frame format to be PCM31, the modem shall be configure to PCM31 (N
≤
31). The local and
remote sites shall have the same configuration.
CRC option. Disable/Enable the CRC function according to the link requirement. The local
and remote sites shall have the same configuration.
Loop-back test is the auxiliary function used for users to test and diagnose the equipment and
link.
Local Loop-back is performed at local V.35 interface and used for test and diagnosis the V.35
interface.
The local V.35 interface loop-back can only performed on the ‘Master Clock’ and ‘Terminal
Clock’ equipment. As the above figure, the local equipment is set to Master Clock or Terminal
Clock mode. The 5
th
and 6
th
bits of SW2 are switched to ON, and the 1
st
~ 5
th
bits are set to
configure the customized bandwidth. The loop-back status can be viewed at the port of local
Router.
Remote loop-back is performed at the optical interface on remote equipment to test and diagnose
the optical link. In order to perform the remote loop-back at optical interface, 2 conditions must be
satisfied.
1.
RC801-30B-FV35 modems work point to point, and in pairs (or RC802-30B series E1 fiber
optic modem at the remote site).
2.
The test can only be performed on the ‘Master Clock’ and ‘Terminal Clock’ equipment.
As the above figure, the local equipment is set to Master Clock or Terminal Clock mode. The 5
th
bit is switched to ON, and the 6
th
bit is switched to OFF. If the optical fiber is connected properly,
the loop-back status can be viewed at the port of local Router.
