User's Guide Part 1

User Guide: PTP 600 Series Wireless operation
phn-0896_009v003
Feb 2010
UNDER DEVELOPMENT
1-29
3. The PTP-SYNC unit measures the difference between the TDD frame timing and
the 1 Hz time reference,
4. The PTP-SYNC signals this time difference to the ODU,
5. The ODU uses the measured time difference as an input to a control loop that
synchronizes TDD timing with the timing reference and thus indirectly with the
network-wide master.
Timing reference
PTP-SYNC requires a 1 Hz timing reference signal. One timing reference signal is
required at each site that contains PTP-SYNC units.
NOTE
One timing reference signal can be used to synchronize up to ten PTP-SYNC.
If more than ten PTP-SYNC must be synchronized on a single site, then
additional timing reference signals are required.
The timing source may be one of the following:
• A separate timing source (typically a GPS receiver) connected directly to the PTP-
SYNC, or through another PTP-SYNC in a daisy-chain arrangement (as shown in
Figure 1-14).
• In
networks where all master ODUs are collocated (for example a network
consisting of a single hub), it is possible to use PTP-SYNCs in the standard
scheme but omitting the external timing source. In this case, one ODU must be
configured as the local timing master.
Advantages of PTP-SYNC over UltraSync
PTP-SYNC has several advantages over the UltraSync solution:
• PTP-SYNC does not require individual GPS receivers located close to the ODUs,
and this reduces the complexity and the cost of the installation on the mast,
• The GPS receiver can be located anywhere with a clear view of the sky, offering
additional flexibility in the installation,
• The PTP-SYNC solution is compatible with standard 1 Hz interfaces, allowing an
operator to take advantage of alternative timing references that may be already
present at the site,