I've combed through the forums but still perplexed at my options of sync for these new 450i PTP units we have. Not sure why I overlooked this as I just assumed it would work with our existing CMM4 units but I guess that is not an option. So... First question: Can I somehow use the CMM4 for GPS sync with these units? If so, how? (obviously power is different). Second question: If I have a tower where I'm not trying to sync anything else on the tower with the PTP 450i, then would it be totally fine to use the generate sync option for a PTP link? I *really* do NOT want to run a seperate cable up the tower for uGPS when I already have a CMM4 sitting at the bottom of these towers.
Actually this is a really good question that I my self didn't think of. If I recall correctly the new 450i radios are standard 48V POE. I'd go further to ask is there some kind of clock source we can run over the switch to provide this pulse as well? I bet Eric can speak to this... Eric? :)
Your options are:
- Use uGPS (there's a way to fan out one uGPS for multiple 450i AP's AUX port).
- You can use PacketFlux.
- You can use a CMM4 with a modified pin-out... as per Matt Mangriotis @ Cambium: "450i does support timing using the AUX port (it's now an RJ-45 vs. RJ-11 connection to the radio though). The other current option is using the CMM4 (with a slight tweak to the pin out). This is documented in the User Guide on page 6-40."
So I can re-pin the "blue" cable and keep the "red" cable in normal pinout and the 450i will get sync from the CMM4? In this figure, it shows the "PIDU", which I am assuming means "Powered indoor unit" aka: PoE injector??? The user guide also leds one to believe that you also need a 56volt power adapter for the CMM4 as well? Why would I need to do that if the 450i gets it's power from the PIDU?
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The CMM4 is an option to provide power and SYNC to the new PMP 450i access points (and PTP 450i masters).
There are two things to especially consider:
1. the power supply must be 56V to provide the correct voltage level. The CMM4 does allow the use of both a 56V and 29V supply and a selection of which port should use which voltage level is done via the management interface. This allows the mixture of PMP 450 and PMP 450i for example using the CMM4 and sync source.
2. the pinouts of a standard CMM4 need to be changed to be compatible with the PMP 450i. Cambium sells a cable that does this pin swapping or the installer can create these special cables as they make the terminations. The part number for this cable is N000045L001A Ethernet cable adaptor for CMM4. The swapped pins are documented in the user guide.
Beyond that the configuration of the CMM4 is the same from a cabling and connection of the SYNC signal.
And you can of course use the uGPS at each Access Point to provide SYNC as an alternative to the CMM4.
Regards,
Bruce
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Bruce,
Thank you for the response and your answer makes much more sense than the diagram in the user guide that I posted earlier. I suppose for me personally, I'm kinda bummed about getting these units because now I either have to buy an expensive 56 volt adapter for our CMM4's or buy a slightly less expensive uGPS unit to have them sync along with my CMM4 that I already have for GPS sync. At this point of investment one should just turn in the PTP 450i's and shop for a PTP 650.
If I set the units for "generate sync" and use the PoE injectors, is this going to be reliable way to backhaul? In the training classes we were told to use the "generate sync" option only in temporary situations. Is this true for a PTP setup that does not really need to sync with existing devices on the towers?
@Nathan Dothager wrote:
If I set the units for "generate sync" and use the PoE injectors, is this going to be reliable way to backhaul? In the training classes we were told to use the "generate sync" option only in temporary situations. Is this true for a PTP setup that does not really need to sync with existing devices on the towers?
Yeah, there's no problem running them all the time using 'generate sync', we do this for AP's and links that we don't have any need for GPS sync and don't want to spend the money on sync equipment. They'll work fine.