A5c : No GPS signal was seen for 3 seconds, no other problem

Products A5
#1

2020-10-30 12:07:40 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 12:08:12 (UTC +0000) : GPS signal recovered
2020-10-30 16:29:15 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 16:29:37 (UTC +0000) : GPS signal recovered
2020-10-30 16:40:55 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 16:41:14 (UTC +0000) : GPS signal recovered
2020-10-30 16:50:06 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 16:50:10 (UTC +0000) : GPS signal recovered
2020-10-30 17:48:41 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 17:52:10 (UTC +0000) : GPS signal recovered
2020-10-30 17:52:15 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 17:59:13 (UTC +0000) : GPS signal recovered
2020-10-30 18:00:35 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:02:11 (UTC +0000) : GPS signal recovered
2020-10-30 18:02:15 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:02:38 (UTC +0000) : GPS signal recovered
2020-10-30 18:02:52 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:02:56 (UTC +0000) : GPS signal recovered
2020-10-30 18:03:00 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:04:14 (UTC +0000) : GPS signal recovered
2020-10-30 18:04:59 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:05:17 (UTC +0000) : GPS signal recovered
2020-10-30 18:05:31 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:06:12 (UTC +0000) : GPS signal recovered
2020-10-30 18:07:15 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:07:20 (UTC +0000) : GPS signal recovered
2020-10-30 18:08:33 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:08:37 (UTC +0000) : GPS signal recovered
2020-10-30 18:11:03 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:11:07 (UTC +0000) : GPS signal recovered
2020-10-30 18:12:52 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:32:25 (UTC +0000) : GPS signal recovered
2020-10-30 18:32:43 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:34:52 (UTC +0000) : GPS signal recovered
2020-10-30 18:37:49 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:37:58 (UTC +0000) : GPS signal recovered
2020-10-30 18:46:23 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 18:46:27 (UTC +0000) : GPS signal recovered
2020-10-30 19:20:56 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:26:19 (UTC +0000) : GPS signal recovered
2020-10-30 19:30:16 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:41:51 (UTC +0000) : GPS signal recovered
2020-10-30 19:42:01 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:42:24 (UTC +0000) : GPS signal recovered
2020-10-30 19:42:28 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:48:02 (UTC +0000) : GPS signal recovered
2020-10-30 19:48:33 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:48:43 (UTC +0000) : GPS signal recovered
2020-10-30 19:48:52 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:48:56 (UTC +0000) : GPS signal recovered
2020-10-30 19:49:01 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:49:05 (UTC +0000) : GPS signal recovered
2020-10-30 19:49:10 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:49:19 (UTC +0000) : GPS signal recovered
2020-10-30 19:49:23 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:49:28 (UTC +0000) : GPS signal recovered
2020-10-30 19:50:27 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:50:32 (UTC +0000) : GPS signal recovered
2020-10-30 19:50:41 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:50:45 (UTC +0000) : GPS signal recovered
2020-10-30 19:50:49 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:50:54 (UTC +0000) : GPS signal recovered
2020-10-30 19:50:58 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:51:08 (UTC +0000) : GPS signal recovered
2020-10-30 19:51:26 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 19:52:30 (UTC +0000) : GPS signal recovered
2020-10-30 22:03:30 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 22:03:34 (UTC +0000) : GPS signal recovered
2020-10-30 23:18:53 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 23:19:12 (UTC +0000) : GPS signal recovered
2020-10-30 23:19:21 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-30 23:37:45 (UTC +0000) : GPS signal recovered
2020-10-31 02:50:50 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 02:50:55 (UTC +0000) : GPS signal recovered
2020-10-31 02:56:06 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 02:56:29 (UTC +0000) : GPS signal recovered
2020-10-31 03:01:47 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:06:05 (UTC +0000) : GPS signal recovered
2020-10-31 03:06:46 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:10:48 (UTC +0000) : GPS signal recovered
2020-10-31 03:14:00 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:25:27 (UTC +0000) : GPS signal recovered
2020-10-31 03:27:39 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:28:56 (UTC +0000) : GPS signal recovered
2020-10-31 03:30:33 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:30:55 (UTC +0000) : GPS signal recovered
2020-10-31 03:32:18 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:33:05 (UTC +0000) : GPS signal recovered
2020-10-31 03:33:47 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:34:52 (UTC +0000) : GPS signal recovered
2020-10-31 03:36:09 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:36:38 (UTC +0000) : GPS signal recovered
2020-10-31 03:46:24 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:46:34 (UTC +0000) : GPS signal recovered
2020-10-31 03:47:55 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:49:48 (UTC +0000) : GPS signal recovered
2020-10-31 03:54:45 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:55:35 (UTC +0000) : GPS signal recovered
2020-10-31 03:57:12 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 03:57:44 (UTC +0000) : GPS signal recovered
2020-10-31 04:00:46 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 04:04:55 (UTC +0000) : GPS signal recovered
2020-10-31 04:05:20 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 04:10:10 (UTC +0000) : GPS signal recovered
2020-10-31 04:10:29 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 04:31:05 (UTC +0000) : GPS signal recovered
2020-10-31 09:09:54 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 09:10:02 (UTC +0000) : GPS signal recovered
2020-10-31 09:14:12 (UTC +0000) : No GPS signal was seen for 3 seconds
2020-10-31 09:33:12 (UTC +0000) : GPS signal recovered

As you can see this happens every so often – but there’s no other problem. What could be the cause? Is there a solution to this ? Thanks

#2

I have a similar issue with one of my towers, doesn’t matter the equipment, manufacturer or what I do around it I get GPS drops like this frequently.

Spent months on the issue, dunno what could be causing the interference. But I have moved APs to other towers and tried Ubiquiti and Mimosa APs and everything looses GPS on that tower… Really annoying.

That said, you can look around for high power radio towers, airports or something else of the sort that might be the cause of your issues.

#3

I have also experienced this on a 4-mile P-P B5C link. Would be interesting to compare notes.

#4

Not sure what notes I can share. I am completely flummoxed, the tower is a grain elevator. No correlation to the motors running. Tower is in the middle of a field with not really anything else around it. 120 ft up and I am the only electronics of note. Everything is brand new on the tower as well, friend of mine built it, we can’t figure anything to be causing the issue.

We have equipment 3 miles away in two different directions, neither of which has the same issue. There is another WISP to our south that runs Cambium, but they have not reported issues. I live in the area and have never noticed an issue with GPS.

Not much else to say. Feel free to ask questions, I spent 6 months on the issue and bugged Mimosa several times about the issue. Can’t get anything. Never tried talking to UBNT support, but I can’t imagine they would be all that much more helpful.

#5

My site has two 10W FM translators and first attempt to install the stock SUB radio resulted in 100% loss of GPS signals. I did a bench analysis and was able to duplicate the GPS carnage using a RF service monitor simulating FM signal using a close coupled +18 dBm whip next to the B5C radio. I did a full write up to Mimosa forum, including a shielding solution which made a vast improvement. Just way surprized to see repeated GPS outages like yours after all that effort.
Curious if you have added any snap on ferrite devices to your POE LAN cables? I have done that on both ends of the my CAT cables. Mostly to protect the Netonix POE managed switch. Do you have a ground cable connected to keep the honest static at bay?

#6

Grounded out the wazoo.

We have never seen ethernet errors that were not related to damaged cables or bad PoE bricks at the location.

We will loose GPS for a couple hours, then it will “magically” come back. I have been present at the tower during GPS down times and not noted anything that would seem to correlate with the issue. No amateur radio guys in the area to correlate issues with or be at fault either.

Didn’t realize you were the one who did that writeup. Thanks for that, I have referenced it to a few other people in the forums who have had similar issues to your own.

Not tried out ferrite, the CAT 5e (Yes, please keep reading) has an aluminum shield as well as is ran inside 2 inch steel conduit to the top of the tower. Everything is grounded both top and bottom and the conduit is grounded to the tower in multiple spots. We also have a B11 on the tower that looses GPS at similar times as other radios and we have tested Ubiquiti radios as well. Really weird problem.

#7

One other option would be to upgrade the GPS antenna from the internal square patch to one that is external filtered.

The B5C GPS internal patch antenna has a tiny connector on the other end of a 10 inch or so coax cable.
If anyone knows that tiny connector type, I would appreciate that info so I could order a bulkhead cable connector to TNC-female or N-female.

Forgot to ask, what does your number of satellites show before/during these outages? Have you ever swapped out the B5C for another?

#8

I have not had any issues with GPS on my B5c link, but that is several miles away from my location that has GPS issues.

We loose all GPS and Glonass. If I recall correctly from my logging, not all of them at once, but the GPS will drop off or GLOSNASS then the other one will drop. If I see it popup in my SMNP logging I will post a pic.