Cambium Networks PMP 450 AP, Configuration Manual

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Chapter 1: Configuration Configuring synchronization
Page
1-107
In case of PMP, when there are synchronization sources on both the timing port and the power port, the
power port GPS source is chosen first.
If no valid GPS signal is received, the AP/BHM ceases transmission and SM/BHS registration is lost until a
valid GPS signal is received again on the AP or BHM.
Note
After a reboot of 450m AP, the sync acquisition takes a little longer than it had on 450i
(anywhere from 40 seconds to 120 seconds difference).
When the Sync Input field is set to Autosync or Au Free Run, other options become available to
be set e.g. UGPS Power and other fields. This is true on APs and BHMs.
Au Free Run
This mode operates similarly to mode “AutoSync”, but if a previously received synchronization signal is
lost and no GPS signaling alternative is achieved, the AP/BHM automatically changes to synchronization
mode “Generate Sync”. While BHS/SM registration is maintained, in this mode there is no synchronization
of APs/BHMs that can “hear” each other; the AP/BHM will only generate a sync signal for the local
AP/BHM and its associated SMs/BHS. Once a valid GPS signal is obtained again, the AP/BHM
automatically switches to receiving synchronization via the GPS source and SM/BHS registration is
maintained.
Note
In mode Au Free Run
with the Free Run Before GPS Sync parameter set to
disabled
, if a GPS signal is never achieved initially, the system will not switch to “Free Run”
mode, and SMs/BHS will not register to the AP/BHM. A valid GPS signal must be present
initially for the AP to switch into “Free Run” mode (and to begin self-generating a
synchronization pulse).
Also, when an AP/BHM is operating in “Free Run” mode, over a short time it will no longer
be synchronized with co-located or nearby APs/BHMs (within radio range). Due to this lack
of transmit and receive synchronization across APs/BHMs or across systems, performance
while in “Free Run” mode may be degraded until the APs/BHMs operating in “Free Run”
mode regain a external GPS synchronization source. Careful attention is required to ensure
that all systems are properly receiving an external GPS synchronization pulse, and please
consider “Free Run” mode as an emergency option.
Generate Sync (Factory default)
This option may be used when the AP/BHM is not receiving GPS synchronization pulses from either a
CMM4/CMM5 or UGPS/cnPulse module, and there are no other APs/BHMs active within the link range.
Using this option will not synchronize transmission of APs/BHMs that can “hear” each other; it will only
generate a sync signal for the local AP/BHM and its associated SMs/BHS.
Note