Asymmetrical Fiber Paths To A Ats 6511 Input Channel; Tsc-4340A - Symmetricom ATS-6511A User Manual

The Index_of_refraction refers to the velocity of the fiber optic signal as it travels through the
fiber. This information can be obtained from the manufacturer of the fiber. It is typically
specified as the delay value based on a unit of measure. Use the value provided and if needed
convert the fiber optic cable length to the correct unit of measurement and calculate the delay as
shown in Equation 2-1.
Once the ATS-6511 delay has been calculated, it must be entered into the system using the
fiber_delay command. The example below is using a delay value of 118.5 ns for both fibers.
Once the fiber delay value has been properly set use the save command to save the current delay
to ensure the system uses the correct delay value after a reboot or power cycle. Users can verify
the value was set properly by using the settings fiber:delay command and reviewing the settings.
ATS-6511>fiber_delay 1.185E-7 1.185E-7
OK
[OK] 2010-05-27T19:29:58Z
ATS-6511>settings fiber:delay
[channelA] 1.185000000000000e-07
[channelB] 1.185000000000000e-07
[OK] 2013-08-13T18:03:24Z
Note: The new delay value will take effect immediately and could cause an alarm if the delay
value forces the 1 PPS offset to be larger than 100 ns. The system will steer the internal clock to
remove the fiber delay, if the alarm light came on it will go out once the 1 PPS Value returns to
within 100 ns. The ATS-6511 outputs will now be accurate to the fine calibration accuracy
specified in Appendix A.

2.6.4 Asymmetrical Fiber Paths To a ATS 6511 Input Channel

Two way mode can still be used in systems with asymmetrical transmit and receive fiber paths to
a particular ATS 6511 input channel. The difference in delay between the two paths must be
determined and entered into the ATS 6511 settings. The delay difference can be determined by
using an optical TDR, or measuring the 1 PPS offset between the ATS 6501 and ATS 6511 using
each of the fibers in two_way_disabled mode. When using the OTDR subtract the ATS 6511 to
ATS 6501 transmit path delay from the ATS 6501 to ATS 6511 transmit delay path to obtain the
fiber delay differential. Enter this number, including the sign, using the fiber_delay_diff
command.
ATS-6511B> fiber_delay_diff <DELAYDIFFFIBERA DELAYDIFFFIBERB> (in seconds)

2.6.5 TSC-4340A

The 4340A fiber distribution amplifier may be used to distribute one fiber connection from the
4372A or 4372A-T to up to eight ATS 6511A/Bs. The 4340A works in any ATS 6511 fiber
mode. Ensure you match fiber types when designing and installing a system which will include a
4340A. If using single mode 4372A or 4372A-T (default for both) ensure you are using a single
mode 4340A (4340AS-8S for example). All of the systems are also capable of operating using
multi-mode fiber by simply replacing the SM SFPs in the units.
ATS-6511A/B/C Users Guide
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DOC 6511_Release K