Exalt Installation and Management Guide
EX-r Series GigE Digital Microwave Radios
15
201872-003
2015-10-23
Figure 8 Synchronized GPS sources using AUTO SYNC
Offset Timing
Manual control of offset timing is also allowed. This provides a means to delay the synchronization
signal using a user-defined offset. This is helpful when Exalt radios are near other devices operating in
the same frequency band that also use a timing source, such as GPS. The timing source to the Exalt
radios can be adjusted to match the other radio system timing source mechanism.
Offset timing can also optimize timing intervals for repeaters and backbones. As the distance of each
link results in a unique factor for speed-of-light transmission of the radio signal, a subsequent radio can
be delayed in timing so that the overall synchronization of radios is precisely maintained.
Offset timing can be adjusted in 1-ms intervals, from zero to the radio’s frame length setting. For
example, if using a 2-ms frame length, the offset timing can be set from zero up to 1999 ms.
When Sync is Lost
If the primary sync source (for example, the sync source radio or GPS source) signal is lost due to
equipment failure, a disconnected sync cable, or other conditions, the first radio in the daisy-chain
configuration set to AUTO SYNC resumes the sync function for the remaining connected radios.
If a radio is configured as SYNC RECIPIENT, transmission ceases if the sync signal does not appear
at the SYNC IN connector.
A radio running in AUTO SYNC (without the sync source) is said to be
flywheeling
. That is, the clock
is free-running off internal clocking and is no longer synchronized to any source.
If the original sync source is restored to the flywheeling radio configuration, the flywheeling radio
attempts to synchronize to this signal without causing transmission interruption. All interconnected
radios receiving sync from the flywheeling radio also continue to operate without interruption.
When the flywheeling radio runs independently for long periods of time, the synchronization signal
can be too far outside of the capture range of the synchronization loop, and portions of transmission
frames can be lost during the re-synchronization process. This condition is temporary and all
interconnected radios re-synchronize to the sync source, as necessary.
For GPS synchronization, the wiring inside the Exalt radio carries the GPS signal to the next radio
cabled in the system, even when power is removed from the SYNC SOURCE radio or during radio
