Issue with multiband 18Ghz+80Ghz links

Products PTP
1

We are seeing some strange occurrences on our 18Ghz + 80Ghz multi band links.

Using the latest software 11.7 and the 18Ghz+80Ghz multi band dishes, the 18Ghz is sitting around -47 to -50dBm. No matter what we do, it never gets better than this. Yet the 80Ghz is sitting at -30dBm. So it can’t be alignment … these are on a 2 foot dish so if anything the 18Ghz should be better. Distance is only a few km. Link planner says we should be getting way better - and indeed these radios were previously linked up using a 1 foot standard 18Ghz Commscope dish with no issues (on version 10 software).

We are getting no problems throughput wise for the 80Ghz so traffic is ok - until we get heavy rain … then the issue is having the 18Ghz hold up … they drop as well due to lower than expected dbm

There is something weird going on as both these were 820S links and had no issues previously… and only an issue on the Multiband dish where the 850E seems to be fine and expected dbm on alignment.

Has anybody here been using the 18Ghz-80Ghz multiband arrangement and seen any issues / something similar?

2

Hi,

those numbers doesn’t seem right.
I think it could be a problem with alignemet, maybe 80GHz is on a sidelobe.

Please, post your data with tx/rx power and modulation.

In similar scenario I got -39 (80Ghz) and -41 (18GHz).

3

Hi, yeh I thought that too… except we have got -30dBm on the 80Ghz and -47-50dBm on the 18Ghz though. 80Ghz at 128 QAM.

4

We did try to align these things for a while - guess we will give it another go :slight_smile:

5

As another question - does anyone suggest am alignment tool / scope that can be used? (Hint - would be great of Cambium made one to mount on the back of the 850E product :slight_smile: )

6

Hello Arobo,

did you check on the polarization of the 18 GHz radios?

Sincerely yours,

Niragira Olympe

7

Hi, yes polarization is correct on the 18Ghz. These were working linked radios on an existing Commscope 18Ghz dish - just moved to the multiband dish. Also tested on ground (only 20m apart though) and seemed ok (connection was ok but power turned right down on both radios to check working and config).

8

Hello Arobo,

share the link range/LINKPLanner file installation report if you have it. If not, do share the link GPS end points to connect.

Sincerely yours,

Niragira Olympe

9

What was the purpose of a multiband dish over individual dishes for each link? If tower-space isn’t a concern, could you simply switch back to the original antenna as a direct comparison, and even use it permanently? I feel like that would be the simplest/quickest course of repair…

10

Hi, yes tower space and rental was the reason for the multiband arrangement.

1 Like
11

I understand…
That’s frustrating, but perhaps you can try two dishes as a temporary arrangement. Upon reaching out and having a conversation with the Manager of the site, I was allowed a grace period for troubleshooting without any fees or penalties. Could be worth a try!