Setting The System On Time Point (Otp); Figure 3 Timing System Diagram - Symmetricom ATS-6511A User Manual

NOTE: 4340As shipped after August 2011 will work with two way systems. If you have a
4340A shipped prior to August 2011, contact Symmetricom for information on upgrading the unit
to work in two way systems.
2.7

Setting the System On Time Point (OTP)

The OTP of a system is defined as the point at which the timing signals coincide with
UTC(USNO). Typical systems use distribution amplifiers and cabling to distribute timing signals
from a single source to multiple users. This distribution network will delay the timing signals and
affect their accuracy. For this reason it is important to select an appropriate OTP so that the
desired timing signals are accurate when they reach the user.
Section 2.6 describes calibrating the ATS-6511 in both the two-way and one-way modes
assuming that the OTP of the system is the rear panel of the ATS-6511. This is not generally a
convenient location for the OTP of the system because there will be a delay associated with the
distribution of the signals to the user. Figure 3 illustrates how to move the OTP of the system
from the rear panel of the ATS-6511 to the user inputs. In moving the OTP of the system it is
imperative that the distribution delays from the ATS-6511 to each of the users is equal. This will
ensure that all users receive accurate timing signals.
ATS-6501
Once the delay of the distribution network is known the OTP of the system can be shifted from
the output of the ATS-6511 to the input of the user equipment. Use the dist_delay command to
enter the delay value between the rear panel and desired OTP location as shown in Figure 3-2.
Installing cables and distribution with the same delays will also ensure the 10 MHz signals are in
phase, and the rising edge is aligned with the 1 PPS signals. The example below shows a delay of
50nSec.
ATS-6511>dist_delay 5.0E-8
[OK] 2013-08-13T18:04:40Z
Verify the system settings using the settings pps_adjust command.
ATS-6511A>settings pps_adjust
[distribution_delay] 5.000000000000000e-08
[OK] 2013-08-13T18:04:56Z
ATS-6511
Delay 1 = Delay 2 = Delay 3 = Delay 4 = Distribution_Delay

Figure 3 Timing System Diagram

19
DOC 6511_Release K
ATS-6511A/B/C Users Guide
OLD OTP
NEW OTP
Delay 1
PPS Output 1
Delay 2
PPS Output 2
Delay 3
PPS Output 3
Delay 4
PPS Output 4
User 1
User 2
User 3
User 4