gps timing question

lately i have been getting some random gps failure…just no sync and what not. it seems this problem got worse since i added a few bhs to my network. heres a basic diagram of what i have

internet ---->
orthogon (not timed to anything) ---->
main cluster ---->
all backhauls on the main cluster are set to master—>
then to remote sites with the receiving bh set to slave—>

Is there a CMM in your network with your BHM’s? I am assuming so since you mentioned GPS. What frequency band are your modules using?

I just had a couple of days of CMM No SYNC hell…

Do you have a different number on satellites visible and satellites tracked?
Does it goes to NO SYNC and the suddenly goes back to normal?

If this is the case, make sure that the GPS antena is in a completly straigth position towards the sky. If it is tilted, it will start causing you ptroblems.

Let me know how it goes…

i didnt take a level to it but it appears to be as straight as possible by eye’n it.

my problem is what you described, tracking 8 then no sync then tracking 2 with no lat or long.

i ordered more rj11 type cables to try swaping all those out.

i also found that the icmp storms can cause funky gps information, not sure how or why but maybe that can help someone

Try using a level, and also try moving the antena from one place to another.
In a perfect world, the number of satellites visible should equal the number os Sat{s tracked.

Check the log file in the CMM and see if there is anything indicating GPS overcurrent, no antenna, etc.

Pull apart all of the connections and make sure that there has been no corrosion, water ingress, shorting, etc.

Meter the antenna cable for anything other than an open (less than 10 Megohms)

As mentioned, move the antenna to another location - a couple of feet could make the difference.

did u do any firmware upgrades recently ?

some people complain on that !

no new firmware upgrades

im using the gen 2 cmm can you log into those? i have never even tried. i thought it was just a hub that cost 2k.

I have pulled all the connections, swapped out the gps receiver, the cmm, and the timing cable (had extras so it wasnt a problem)

i will try relocating and leveling the gps receive

thanks for the help

vince wrote:
i thought it was just a hub that cost 2k.


If it's the standard CMM there is no log.