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Regular Member
Posts: 467
Registered: ‎10-11-2013
Kudos: 125
Solutions: 2

GPS lock on PrismStation

Is the receiver weaker? I had indoor gps-locks with prism gen1 just behind the window. With PrismStation I need to put the puck out of the window and then it needs 2-3 minutes to get a gps lock. So it seems to be much weaker? 

SuperUser
Posts: 11,348
Registered: ‎12-08-2008
Kudos: 8121
Solutions: 508
Contributions: 1

Re: GPS lock on PrismStation

[ Edited ]

All my PrismStations lock up instantly - IIRC when I tested them indoors they also picked up sats OK without the antenna even being near a window - literally sitting on the floor pointing up at the ceiling.   You might have a bad GPS antenna - do you have another you can swap with it?   Also make sure the SMA connector is actually tight - if it's not you can get significant signal loss there - it's not easy to get to in there next to the RJ45...

Jim

" How can anyone trust Scientists? If new evidence comes along, they change their minds! " Politician's joke (sort of...)

"Humans are allergic to change..They love to say, ‘We’ve always done it this way.’ I try to fight that. "Admiral Grace Hopper, USN, Computer Scientist
Ubiquiti Employee
Posts: 1,388
Registered: ‎04-14-2017
Kudos: 385
Solutions: 28

Re: GPS lock on PrismStation

I agree with @eejimm - a difference in GPS locking capability isn't something that we have seen between these products.
SuperUser
Posts: 11,348
Registered: ‎12-08-2008
Kudos: 8121
Solutions: 508
Contributions: 1

Re: GPS lock on PrismStation

[ Edited ]

This can also be caused by RF interference - with an active antenna (the old UBNT GPS antennas were active;  the new ones are passive) high RF can cause compression in the preamp and cause the GPS to work poorly or fail - we saw this with some of the first AF24HDs we put up at several high-RF sites.   Changing to the passive antennas fixed it.   And other things can cause 1.5GHz interference (GPS L1 band) - the older Tranzeo Pizza-Box 5GHz radios were famous for this.

 

Reaching a lock on GPS should happen before the radio finishes booting up, well before you can even log in.   Not like the 15+ minutes the first Magellan GPS units I built things with back in 1991 took...  ;-)

Jim

" How can anyone trust Scientists? If new evidence comes along, they change their minds! " Politician's joke (sort of...)

"Humans are allergic to change..They love to say, ‘We’ve always done it this way.’ I try to fight that. "Admiral Grace Hopper, USN, Computer Scientist
Veteran Member
Posts: 5,286
Registered: ‎08-26-2009
Kudos: 1531
Solutions: 48

Re: GPS lock on PrismStation

The Qualcomm GPS receivers are crappy in my experience. Every AF and AFX product gets almost instant GPS lock, and the "quality" stays high typically all the time. I experience bad or no lock on Prism intermittently, with low quality more frequently. Clearly my sample size of AF to Prism is lower, but since I started relying on GPS timing for Fixed Frame mode, I am paying more attention to Prism's GPS locking and it generally appears to be less reliable than AF in the exact same RF environment. My suggestion to UBNT after these observations was to consider using the AF GPS chipset (whoever makes that, NOT Qualcomm) in the Prism instead of the Qualcomm one.

Ubiquiti Employee
Posts: 1,388
Registered: ‎04-14-2017
Kudos: 385
Solutions: 28

Re: GPS lock on PrismStation

We are looking at how we can improve the capability of the PRISM products to lock to the GPS signal and there are a few options we're looking at. For the majority of cases though we don't see issues with achieving GPS lock.
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