Weird signal problem on one side of a link. Drops over time

Wondering if anyone else has seen anything like this. We have a 1.5 mile link where one sides signal will just drop down 10-20db over time and come back up to normal if we apply a power setting change and last for up to an hour and then drop again.

This is a follow up to my Do we have a bad B24 unit? post. It’s like the radio on one side has a problem.

We are going to go back up and swap the radios from one tower to another soon to see if the problem follows the radio, but haven’t done that yet. We finally just figured out last night that changing the power and applying it caused the signal to get better for a time. It takes like 30 minutes or more time to see it go bad again, so we had already got down off the towers.

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What’s the throughput of the B24, I notice a lot of Mimosa products try to follow Auto Power rules and if they are not pushing much traffic they will drop the power they are transmitting. Then they go to higher power levels when they have more bandwidth being pushed and they start having PER issues.

The PER settings are in the Link portion of your radio’s config.

There is probably less than 5mbit going one way and 20-30Mbit the other.

I’ve tried multiple Rate Adaptation settings and it seems pretty consistent on dropping that one side low after the 30 minutes of time.

Could you post the picture of your link SNR, but include the scale as well?

Here ya go. Looks like the signal is needing a bump again as it has dropped low again…

Here is the other side during the same period…

What’s your PHY TX/Rx Rate look like during the same time period?

Here is that image. It’s extra bad because the upload(TX) from this link stays consistent and the download(RX) drops low and the download(RX) is what this location needs.

Hrm…

Normally I would say try dropping down to a 20 MHz wide channel, but you just came from that… The SNR even when the link is “good” seems low to me… Could you grab the logs from just after a drop and post them?

Station side has nothing new being put in the log file.
The AP side basically has where we change power and re-applied.

Here is that log:
2020-02-05 10:24:41 (UTC +0000) PHP_DBG: logger MIMO_EVENT: Tx Power2 changed - -3
2020-02-05 10:24:42 (UTC +0000) PHP_DBG: logger MIMO_EVENT: AEThroughput - 1000
2020-02-05 10:24:42 (UTC +0000) root: MIMO_EVENT: AEThroughput - 1000
2020-02-05 11:59:20 (UTC +0000) PHP_DBG: logger MIMO_EVENT: Tx Power2 changed - -4
2020-02-05 11:59:21 (UTC +0000) PHP_DBG: logger MIMO_EVENT: AEThroughput - 1000
2020-02-05 11:59:21 (UTC +0000) root: MIMO_EVENT: AEThroughput - 1000
2020-02-05 13:39:46 (UTC +0000) PHP_DBG: logger MIMO_EVENT: Tx Power2 changed - -1
2020-02-05 13:39:46 (UTC +0000) PHP_DBG: logger MIMO_EVENT: AEThroughput - 1000
2020-02-05 13:39:47 (UTC +0000) root: MIMO_EVENT: AEThroughput - 1000
2020-02-05 15:10:10 (UTC +0000) PHP_DBG: logger MIMO_EVENT: AEThroughput - 1000
2020-02-05 15:10:10 (UTC +0000) root: MIMO_EVENT: AEThroughput - 1000
2020-02-05 16:14:43 (UTC +0000) PHP_DBG: logger MIMO_EVENT: Tx Power2 changed - -1
2020-02-05 16:14:44 (UTC +0000) PHP_DBG: logger MIMO_EVENT: AEThroughput - 1000
2020-02-05 16:14:44 (UTC +0000) root: MIMO_EVENT: AEThroughput - 1000

Well, I just checked my B24 link, I am only .3 mile shorter then you and I only have a guesstimate eyeball alignment and my radios are at -51 and -54. So I think there probably is an issue with your alignment or some sort of obstruction in the link. (I am also running 2x40)

You should be US as well so you should have the same output power available to you. So I would check that.

As far as the power drops, I am not seeing that on my radio, and I am on the latest firmware. You might want to have a chat with Mimosa support. Your issue is probably outside of my realm of knowledge for being able to help you. If you wait a couple weeks here sometimes one of the other guys with B24s pop on here and have some good suggestions…

Thanks for the ideas!

We are going to work on a few things, like a 3rd realignment check, and try swapping radios and the like.

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Well, as I figured it probably was, after more testing, it appeared we have a bad B24.

We had both of these B24s on better quality Jirous JDMW-900 Mi mounts, so it was easy to swap them. The swapping moved the problem to the opposite side, so we ended up getting a new B24 to take it’s place and all the problems went away.

We did no other alignment or changes, and after the replacement both sides have now even chains and no longer slowly drop signal over time.

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Did you talk with support for an RMA? If not, you should do so and please reference this post.