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New Member
Posts: 4
Registered: ‎07-11-2017

No GPS Sync

[ Edited ]

Hi

 

We are running a full Rocket AC Prism GPS Synced network and one of our AP's has GPS Sync enabled and the light on the back of the radio indicates that it is turned on although it doesn't seem to be getting sync. I climbed the tower today to replace to GPS module and we still have no GPS Sync on this radio (Other radios on the same tower sync fine) when everything apart from the actual GPS sync says we should. Currently running 8.5.1 on all AP's and GPS Sync is working fine apart from this one AP, does anyone have any ideas what could be the issue here?

 

I just SSH into the unit cat /var/tmp/gps_sat_info and got no satelites for the output.

 

We also have an issue where a lot of the users seems to drop modulation to 4x from 8x for a second and then bounce back, does anyone else have this issue?

Ubiquiti Employee
Posts: 67
Registered: ‎12-21-2017
Kudos: 16

Re: No GPS Sync

Hi @dkzuio - couple of questions:

- How do you know that GPS sync is not working - what behavior are you seeing - is only no GPS satelites or something else?

- Is there anything specific with that particular Rocket Prism where GPS sync is not working?

- Could you test that particular device in a different area where you know GPS signal should be good?

 

Let me know on the results.

New Member
Posts: 4
Registered: ‎07-11-2017

Re: No GPS Sync

Hi @UBNT-Mindas

 

Thanks for the prompt response. 

 

The GPS coordiantes don't appear in the WebUI and I can't see any GPS Satelites appear when I SSH into the rocket and run the appropriate commands where they do on all of the other Rocket Prisms that are on the same tower that are successfully GPS synced. 

 

There is nothing different that I can see between this AP and other's on the same tower that are synced and working, in fact we used the same config file and just changed the IP addresses. 

 

I unfortunately cannot bring the AP down at this stage as it's currently in production with customers connected to it. We are working on getting a replacement to swap this rocket out with one that has GPS sync working and then I will be able to test it in another location although I don't believe this is the issue. FYI we are running the Prism HD Antenna with 3x30 degree sectors and the two other rockets GPS sync on the same antenna are working fine. All rockets were purchased at the same time. In this instance they are Gen 1 Rockets FYI.

 

Please let me know if you need any further information.

Ubiquiti Employee
Posts: 5,930
Registered: ‎04-14-2017
Kudos: 1224
Solutions: 160

Re: No GPS Sync

Can you please post the status screens from the web UI for your AP and one of your problem clients?
New Member
Posts: 4
Registered: ‎07-11-2017

Re: No GPS Sync

@UBNT-SNK

 

Please see images attached as requested.

AP7-Wireless-Screen.png
AP7-Status-Screen.png
Ubiquiti Employee
Posts: 67
Registered: ‎12-21-2017
Kudos: 16

Re: No GPS Sync

@dkzuio Thanks!

- Can you kill the GPS reader process: /usr/bin/ubnt-gps-reader - it should be respawned again;
- Can you check the output of: cat /dev/ttyS1, the output should be similar to the below (when connected or disconnected):

 

XC.v8.5# cat /dev/ttyS1
,4404,05.07E00,.7.3M00,,6
PS,,,,,,,,,*E
GR,5728V55.04N25.07E,01,,*E
GS311,00,0,,90,2,028,0529*1
$GPGGA,075058.266,5454.0542,N,02354.8027,E,0,00,50.0,70.03,M,0.00,M,,*6F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,075058.266,V,5454.0542,N,02354.8027,E,,,170518,,,N*7F
$GPGSV,3,1,12,30,09,103,,28,39,061,,24,40,284,,20,15,279,*71
$GPGSV,3,2,12,19,29,149,,18,09,028,,17,43,123,,15,55,238,*72
$GPGSV,3,3,12,13,47,177,,12,08,231,,11,13,040,,10,14,327,*75

- Can you change the Ubiquiti GPS antenna to a different one that you know works and see if that helps?

 

Let me know on the results.

New Member
Posts: 4
Registered: ‎07-11-2017

Re: No GPS Sync

@UBNT-Mindas

 

I have killed the process as request and I still get no output when I cat /var/tmp/gps_sat_info

 

XC.v8.5.1# cat /dev/ttyS1
E00,004.0,0,,*F
GGS,1,,,,,,,,1
$GPGGA,000409.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*6E
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000409.000,V,2249.9728,N,11410.4312,E,,,,,,N*73
$GPGSV,1,1,00,,,,*79
$GPGGA,000410.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*66
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000410.000,V,224.9728,N,11410.4312,E,,,,,,N*7B
$GPGSV,1,1,00,,,,*79
$GPGGA,000411.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*67
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GM000411.000,V,2249.9728,N,11410.43,E,,,,,,N*7A
$GPGSV,1,1,00,,,,*79
$GPGGA,000412.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*64
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000412.000,V,2249.9728,N,11410.4312,E,,,,,,N*79
$GPGSV,1,1,00,,,,*79
$GPGGA,000413.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*65
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,00041000,V,2249.9728,N,11410.4312,E,,,,,,N*78
$GPGSV,1,100,,,,*79
$GPGGA,000414.000,2249.9728,N,11410.4312,E,,00,50.0,47.00,M,0.00,M,,*62
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000414.000,V,2249.9728,N,11410.4312,E,,,,,,N*7F
$GPGSV,1,1,00,,,,*79
$GPGGA,000415.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*63
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,00415.000,V,2249.9728,N,11410.4312,E,,,N*7E
$GPGSV,1,1,00,,,,*79
$GPGGA,000416.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*60
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000416.000,V,2249.9728,N,11410.4312,E,,,,,,N*7D
$GPGSV,1,1,00,,,,*79
$GPGGA,000417.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*61
$GPGSA,A,1,,,,,,,,,,,,,,*1E
$GPRMC,000417.000,V,2249.9728,N,11410.4312,E,,,,,,N*7C
$GPGSV,1,1,00,,,,*79
$GPGGA,000418.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*6E
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000418.000,V,2249.9728,N,11410.4312,E,,,,,,N*73
$GPGSV,1,1,00,,,,*79
$GPGGA,000419.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*6F
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000419.000,V,2249.9728,N,11410.4312,E,,,,,,N*72
$GPGSV,1,1,00,,,,*79
$GPGGA,000420.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*65
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000420.000,V,2249.9728,N,11410.4312,E,,,,,,N*78
$GPGSV,1,1,00,,,,*79
$GPGGA,000421.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*64
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000421.000,V,2249.9728,N,11410.4312,E,,,,,,N*79
$GPGSV,1,1,00,,,,*79
$GPGGA,000422.000,2249.9728,N,11410.4312,E,0,00,50.0,47.00,M,0.00,M,,*67
$GPGSA,A,1,,,,,,,,,,,,,,,*1E

 

We just replaced the GPS antenna to a brand new anntenna last week hence me contacting Ubiquiti about the issue as it didn't fix the problem when I did the same thing to another Rocket in the same location and it is now working.

 

Do you have any other suggestions?

 

I also have another question. When running a site survey from a rocket that is GPS synced should I be able to see other rockets show up that are also GPS synced?

Ubiquiti Employee
Posts: 67
Registered: ‎12-21-2017
Kudos: 16

Re: No GPS Sync

@dkzuio -the output you pasted from the ttyS1 serial port looks really similar to the one that is printed when the GPS antenna is not connected. Here is the comparison from a working device w/ and w/o the antenna (hence w/ and w/o any satellites being tracked):

 

 

$GPGSV,1,1,00,,,,*79
$GPGGA,000136.000,5454.0338,N,02354.8167,E,0,00,50.0,45.88,M,0.00,M,,*6D
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000136.000,V,5454.0338,N,02354.8167,E,,,,,N*72
$GPGSV,1,1,00,,,,*79
$GPGGA,000137.000,5454.0338,N,02354.8167,E,0,00,50.0,45.88,M,0.00,M,,*6C
$GPGSA,A,1,,,,,,,,,,,,,*1E
$GPRMC,000137.000,V,5454.0338,N,02354.8167,E,,,,,,N*73
$GPGSV,1,1,00,,,,*79
$GPGGA,000138.000,5454.0338,N,02354.8167,E,0,00,50.0,45.88,M,0.00,M,,*63
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,000138.000,V,5454.0338,N,02354.8167,E,,,,,,N*7C

 

$GPGSV,3,3,12,19,28,149,29,40,,,27,18,09,029,,11,14,041,*45
$GPGGA,073124.000,5454.0419,N,02354.8023,E,1,07,1.2,17.12,M,0.00,M,,*5B
$GPGSA,A,3,13,15,17,19,20,24,28,,,,,,2.6,1.2,2.3*32
$GPRMC,073124.000,A,5454.0419,N,02354.8023,E,0.0,346.7,210518,,,A*61
$GPGSV,3,1,12,15,56,240,34,28,40,061,37,17,42,125,37,24,39,283,29*7F
$GPGSV,3,2,12,13,49,177,30,30,10,103,27,20,16,282,22,12,07,231,23*7B
$GPGSV,3,3,12,19,28,149,29,40,,,27,18,09,029,,11,14,041,*45
$GPGGA,073125.000,5454.0419,N,02354.8023,E,1,07,1.2,17.12,M,0.00,M,,*5A
$GPGSA,A,3,13,15,17,19,20,24,28,,,,,,2.6,1.2,2.3*32
$GPRMC,073125.000,A,5454.0419,N,02354.8023,E,0.0,346.7,210518,,,A*60
$GPGSV,3,1,12,15,56,240,34,28,40,061,37,17,42,125,36,24,39,283,30*76

The main peace of data missing is: GPGSA (active satellite information) and GPGSV (satellite in view).

 

The suggested checks are:
- Change the antenna see if it solves the issue;

- Test the device in an area where another device works (preferably where the signal is very good, in order to detect sensitivity problems);

- Restart the device / process handling the GPS (whole device restart is better).

- Check dmesg for any GPS module faults.

 

If this does not give any results, the probability is high that the device is faulty.

 

Regarding the visibility of other stations in the site survey - this depends on how far away the device is and the arrangement (if there aren't any obstacles to hear the beacons of another AP) but the other AP should be visible.

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