Is it possible to disable the "generate sync" feature of PMP 450 3.65 APs?
When the AP looses GPS sync from the timing unit, it begins generating its own sync and causes issue with the network.
The older PMP 100, would stop transmitting which alerted you to a problem.
We currently have the PMP 450 APs set to "Auto Sync"
@Logonix wrote:Is it possible to disable the "generate sync" feature of PMP 450 3.65 APs?
When the AP looses GPS sync from the timing unit, it begins generating its own sync and causes issue with the network.
The older PMP 100, would stop transmitting which alerted you to a problem.
We currently have the PMP 450 APs set to "Auto Sync"
Hello,
What version of SW are you using on your PMP 450s?
Setting the AP to "Auto Sync" will cause the AP to drop its SMs when it loses Sync. The "Auto Sync + Free Run" will cause the AP to generate sync once it loses it.
Please note that if there is no data going over the AP/SM link, it might take a while for the AP GUI to be updated to reflect the true state of the SMs registered to it.
Best,
Cambium Jonathan
Thank you for your reply Jonathan,
We are currently using FW 13.2.1. The APs are set to "Auto Sync".
What you describe is true in PMP 100.Â
However, with our PMP 450 APs, what happens is the AP falls back to generating sync and customers continue to show registered. The problem of course is nearby APs start experiencing interference.
What we are experiencing acts like "auto sync + free run", however the radios are set to Auto Sync.
For reference from page 67 in the user guide
AutoSync: The AP automatically receives sync from one of the following sources:
• GPS Sync over Timing Port (UGPS, co-located AP GPS sync output, or “Remote AP” feed from a registered SM’s GPS sync output)
• GPS Sync over Power Port (CMM)
• On-board GPS (internal GPS)
Upon AP power on, the AP does not transmit until a valid synchronization pulse is received from one of the sources above. When there are synchronization sources on both the timing port and the power port, the power port GPS source will be chosen first.
If there is a loss of GPS synchronization pulse, within two seconds the AP automatically attempts to source GPS signaling from another source. On-board GPS (internal GPS) is the last source checked for GPS signaling if there is no receipt of signaling from the timing port or from the power port (the on-board GPS module must not be used as the primary timing source). If no valid GPS signal is received, the AP ceases transmission and SM registration is lost until a valid GPS signal is received again on the AP.
AutoSync + 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 (from the timing port, power port, or on-board GPS), the AP automatically changes to synchronization mode “Generate Sync”. While SM registration ins maintained, in this mode there is no synchronization of APs that can “hear” each other; the AP will only generate a sync signal for the local AP and its associated SMs. Once a valid GPS signal is obtained again, the AP automatically switches to receiving synchronization via the GPS source and SM registration is maintained.
In mode AutoSync + Free Run, if a GPS signal is never achieved initially, the system will not switch to “Free Run” mode, and SMs will not register to the AP. 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 is operating in “Free Run” mode, over a short time it will no longer be synchronized with co-located or nearby APs (within radio range). Due to this lack of transmit and receive synchronization across APs or across systems, performance while in “Free Run” mode may be degraded until the APs 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 is not receiving GPS synchronization pulses from either a CMM or UGPS module, and there are no other APs active within the link range. Using this option will not synchronize transmission of APs that can “hear” each other; it will only generate a sync signal for the local AP and its associated SMs.
This is the same kind of weird sync issues I see on multiple 3.6 450 APs almost every day. I've seen the sync status showing the timing port pulse flip-flopping on and off every second or two. There's nothing wrong with the GPS receiver. I reboot the AP and it's fixed right away. There's a problem in the code somewhere.
George
What timinig unit are you using? We are currently using the Last Mile Gear Cyclone CTM in our operation and are seeing the issue at multiple sites.
Also on another note, I looked into the AP's command line and found the command "synconboard off" (enable/disable onboard GPS sync). Â I disabled it and am waiting to see if it has any effect.
This issue arrived with the 13.2.1 software. Multiple radio's on my network switch to the on-board GPS even though the sync status is present on the power port. We run six cell clusters and at least three of the AP's in each cluster switch to the on-board GPS. Prior to 13.2.1 all AP's received timing reliably on the power port. A reboot will temporarily "fix" the issue for a few hours.