ePMP 4600 AFC - Can SM end up with different EIRP from AP?

Can an SM end up with an EIRP different from the AP?

I installed my first 4625 SM Tuesday. It connected fine and the AP is allowed the full 36 EIRP. The SM connected at 30 EIRP at first and then once connected to AFC went to 36 EIRP.

I just noticed this morning that around 2 hours ago the SM dropped to 26 EIRP (TX power of 1db). The spectrum chart on the AP vs the SM is drastically different and on the SM side shows my 80mhz channel overlaps frequencies that are limited to 27db. Yesterday the chart on the SM matched the AP and allowed 36 EIRP across the whole outdoor 6ghz band.

Can that happen where the AP is allowed 36 EIRP but the SM is not? SM is only 1.68 miles from AP?

Also can the allowed channels and power change from day to day?

I rebooted the SM and after it connected is went back to 36 EIRP and the power level chart is different then before the reboot.

SM before reboot

SM after reboot

After SM reboot is now seems to match the what the Cambium AFC tool shows for the SM location.

AP current chart

Here is the system log for the SM after reboot. I forgot to gather it before reboot.

2024.07.03 10:43:48 afc: customer-info ±-----------±---------±--------------------+
2024.07.03 10:43:48 afc: customer-info | 6660-6875 | 23.00 | 36 36 36 36 |
2024.07.03 10:43:48 afc: customer-info | 6650-6660 | 8.40 | 21 24 27 30 |
2024.07.03 10:43:48 afc: customer-info | 6525-6650 | 23.00 | 36 36 36 36 |
2024.07.03 10:43:48 afc: customer-info | 6302-6425 | 23.00 | 36 36 36 36 |
2024.07.03 10:43:48 afc: customer-info | 6242-6302 | 17.40 | 30 33 36 36 |
2024.07.03 10:43:48 afc: customer-info | 6182-6242 | 17.30 | 30 33 36 36 |
2024.07.03 10:43:48 afc: customer-info | 6050-6182 | 23.00 | 36 36 36 36 |
2024.07.03 10:43:48 afc: customer-info | 6020-6050 | 18.10 | 31 34 36 36 |
2024.07.03 10:43:48 afc: customer-info | 5959-6020 | -0.60 | 12 15 18 21 |
2024.07.03 10:43:48 afc: customer-info | 5930-5959 | 18.00 | 31 34 36 36 |
2024.07.03 10:43:48 afc: customer-info | 5925-5930 | 23.00 | 36 36 36 36 |
2024.07.03 10:43:48 afc: customer-info ±-----------±---------±--------------------+
2024.07.03 10:43:48 afc: customer-info | Range, MHz | PSD, dBm | 20 40 80 160 |
2024.07.03 10:43:48 afc: customer-info | | | EIRP, dBm, on chan |
2024.07.03 10:43:48 afc: customer-info ±-----------±---------±--------------------++
2024.07.03 10:43:48 afc: customer-info | Grace period expired: 2024-07-04 23:59:00Z |
2024.07.03 10:43:48 afc: customer-info | Expired: 2024-07-04 15:25:49Z |
2024.07.03 10:43:48 afc: customer-info | Now: 2024-07-03 15:43:48Z |
2024.07.03 10:43:48 afc: customer-info | version: 1.4 |
2024.07.03 10:43:48 afc: customer-info | Response to request_id: 213645803 |
2024.07.03 10:43:48 afc: customer-info ±---------------------------------------------+

Here is the one from the AP. Looking at the time on the AP that is last got spectrum data that would be around the same time the SM dropped its TX power levels. Wish I had grabbed the log from the SM before I rebooted.

2024.07.03 10:43:30 kernel: [680251.194981] SM[bc:e6:7c:90:88:8d] aid=1 peer=5 associated with AP
2024.07.03 10:40:09 kernel: [680050.331270] SM[bc:e6:7c:90:88:8d] aid=1 peer=4 disassociated. Reason: 48 (COMMUNICATION LOST)
2024.07.03 09:59:35 afc: customer-info ±-----------±---------±--------------------+
2024.07.03 09:59:35 afc: customer-info | 6660-6875 | 23.00 | 36 36 36 36 |
2024.07.03 09:59:35 afc: customer-info | 6650-6660 | 22.20 | 35 36 36 36 |
2024.07.03 09:59:35 afc: customer-info | 6525-6650 | 23.00 | 36 36 36 36 |
2024.07.03 09:59:35 afc: customer-info | 5925-6425 | 23.00 | 36 36 36 36 |
2024.07.03 09:59:35 afc: customer-info ±-----------±---------±--------------------+
2024.07.03 09:59:35 afc: customer-info | Range, MHz | PSD, dBm | 20 40 80 160 |
2024.07.03 09:59:35 afc: customer-info | | | EIRP, dBm, on chan |
2024.07.03 09:59:35 afc: customer-info ±-----------±---------±--------------------++
2024.07.03 09:59:35 afc: customer-info | Grace period expired: 2024-07-04 23:59:00Z |
2024.07.03 09:59:35 afc: customer-info | Expired: 2024-07-04 14:57:35Z |
2024.07.03 09:59:35 afc: customer-info | Now: 2024-07-03 14:59:35Z |
2024.07.03 09:59:35 afc: customer-info | version: 1.4 |
2024.07.03 09:59:35 afc: customer-info | Response to request_id: 3304304488 |

Two things… please update to the newest 5.7.1 stable firmware released today. Second, pay close attention to the GPS height when you first start up the radio and when you notice AFC availability changes. My theory is that you might be seeing swings in the reported height that are causing the AFC to change/restrict availability.

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I was originally on 5.7.1RC9 but support had me go back to 5.7.0 on a ticket unrelated to this issue.

Also I had problems with the SMs on 5.7.1RC9 as there is no button to set the SM to fixed-client mode and my SM kept reverting back and getting stuck on standard client mode and only allowing 30 EIRP.

I had to modify the config file manually and upload it to get the SM to do 36 EIRP when I was on 5.7.1RC9.

Just to clarify… I’m only asking you to track the SM’s GPS height, and there’s no need to post your GPS coordinates to the group here. These measurements are for your own troubleshooting purposes. Again, the reason to track the height at various times (like on radio first start, when the AFC is established, and again when you notice that the AFC availability is poor) is to try to determine if the reported height is playing a possible roll in the AFC availability issues.

Height plays a huge roll in how the AFC determines availability. ALSO, GPS accuracy plays a large roll as well. Having radios with low GPS accuracy can cause these issues as well.

Lastly, the problems with standard vs fixed power are typically related to GPS issues. If the radio has no or low GPS on radio start it will default to standard power mode and then the AFC will wait until it gets a better lock in order to bump up to fixed power mode. Lastly, it will only bump up to fixed power mode if there’s a benefit over standard power mode.

5.7.1-RC9 (and 5.7.1 stable, that we released today sometime ago), has this feature of SM chooses between Fixed Client (FC) and Standard Client (SC) based on the one that gets higher EIRP.
So, reason you are seeing SC should be - On FC mode, maximum allowable EIRP is lower than SC.
So, it makes sense to do as follows:
1.
When SM is on SC mode, grab Technical Support Files from SM.

2.a.
At this time (when SM is still in SC mode), grab screenshot from “6GHz Spectrum Availability Tool” (https://afc.cmbn.cloud/afc-ui) by configuring true height (AGL) of the SM on spectrum availability tool.

2.b.
At this time (when SM is still in SC mode), grab one screenshot from “6GHz Spectrum Availability Tool” (https://afc.cmbn.cloud/afc-ui) by configuring on spectrum availability tool the height of the SM as seen in Config > System > Location Services > On-board GPS Height.

And send us technical support files and both screenshots. I’ve also just reached out to you via email.

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What height is the correct one? GPS on the SM and AP both report over 300 meters, but AP is only around 38 meters high and SM is only around 7.6 meters AGL.

Follow @Chinmay_K’s instructions to find out.

@Eric_Ozrelic His instructions do not say what height is correct. When GPS reports height on the SM is it using AGL or MSL?

GPS is using MSL. And I’m making this post longer.

As a test I used the Cambium AFC tool and set the SM location and height to the actual AGL height and got a spectrum chart that matches the SM after I rebooted it.

When I set the SM height to the MSL height in the AFC tool I got a spectrum chart that matched the one the SM was showing when it only allowed 1db TX power (26 EIRP)

So again… make note on the SM of any changes in the reported height between start up and when the AFC reports full or limited availability… then compare the change in height using Cambium’s AFC tool.

e.g. on start up if your radio is saying that the MSL is 300m but after time you notice that the AFC is showing limited availability, check the MSL again, and see if now reads something like 350m (a 50m increase in height). Then go to the Cambium AFC tool and put the radio’s actual height in AGL, and then play around with it, and add 50m to the actual AGL, and see if the AFC tool report matches the limited AFC availability that’s on that SM. OH, and you’ve probably realized that the radio reports measurements in meters, and the Cambium AFC tool is in feet, so you’ll need to make those conversions.

Just happened again this morning. Difference in MSL GPS height from when it worked at full power was only 4 meters.

I checked the customer location with the AFC tool and put in the actual height + 4 meters (13ft) and the AFC tool chart does not match the chart shown on the SM that is causing the TX power of the SM to drop to 1db (27EIRP) which is below the 30EIRP that would be allowed if I set the SM to Standard Client instead of fixed-client.

Somehow the SM it reporting to the AFC or the AFC is providing back to the SM wrong data causing the TX power drop.

AP is still working at full power.

Here are the two charts from the SM logs. One for 24 hours ago and the one from just recently.

2024.07.05 10:24:57 afc: customer-info ±-----------±---------±--------------------+
2024.07.05 10:24:57 afc: customer-info | 6660-6875 | 23.00 | 36 36 36 36 |
2024.07.05 10:24:57 afc: customer-info | 6650-6660 | 8.30 | 21 24 27 30 |
2024.07.05 10:24:57 afc: customer-info | 6525-6650 | 23.00 | 36 36 36 36 |
2024.07.05 10:24:57 afc: customer-info | 6302-6425 | 23.00 | 36 36 36 36 |
2024.07.05 10:24:57 afc: customer-info | 6213-6302 | 17.40 | 30 33 36 36 |
2024.07.05 10:24:57 afc: customer-info | 6182-6213 | 17.30 | 30 33 36 36 |
2024.07.05 10:24:57 afc: customer-info | 6139-6182 | 23.00 | 36 36 36 36 |
2024.07.05 10:24:57 afc: customer-info | 6109-6139 | 16.30 | 29 32 35 36 |
2024.07.05 10:24:57 afc: customer-info | 6079-6109 | 9.00 | 22 25 28 31 |
2024.07.05 10:24:57 afc: customer-info | 6048-6079 | 8.90 | 21 24 27 30 |
2024.07.05 10:24:57 afc: customer-info | 6020-6048 | 18.10 | 31 34 36 36 |
2024.07.05 10:24:57 afc: customer-info | 5959-6020 | -0.60 | 12 15 18 21 |
2024.07.05 10:24:57 afc: customer-info | 5930-5959 | 18.00 | 31 34 36 36 |
2024.07.05 10:24:57 afc: customer-info | 5925-5930 | 23.00 | 36 36 36 36 |
2024.07.05 10:24:57 afc: customer-info ±-----------±---------±--------------------+
2024.07.05 10:24:57 afc: customer-info | Range, MHz | PSD, dBm | 20 40 80 160 |
2024.07.05 10:24:57 afc: customer-info | | | EIRP, dBm, on chan |
2024.07.05 10:24:57 afc: customer-info ±-----------±---------±--------------------++
2024.07.05 10:24:57 afc: customer-info | Grace period expired: 2024-07-06 23:59:00Z |
2024.07.05 10:24:57 afc: customer-info | Expired: 2024-07-06 14:30:57Z |
2024.07.05 10:24:57 afc: customer-info | Now: 2024-07-05 15:24:57Z |
2024.07.05 10:24:57 afc: customer-info | version: 1.4 |
2024.07.05 10:24:57 afc: customer-info | Response to request_id: 88533032 |
2024.07.05 10:24:57 afc: customer-info ±---------------------------------------------+
2024.07.05 10:24:54 afc: customer-info requestId: 88533032
2024.07.04 10:25:53 afc: customer-info ±-----------±---------±--------------------+
2024.07.04 10:25:53 afc: customer-info | 6525-6875 | 23.00 | 36 36 36 36 |
2024.07.04 10:25:53 afc: customer-info | 6020-6425 | 23.00 | 36 36 36 36 |
2024.07.04 10:25:53 afc: customer-info | 5959-6020 | 12.00 | 25 28 31 34 |
2024.07.04 10:25:53 afc: customer-info | 5925-5959 | 23.00 | 36 36 36 36 |
2024.07.04 10:25:53 afc: customer-info ±-----------±---------±--------------------+
2024.07.04 10:25:53 afc: customer-info | Range, MHz | PSD, dBm | 20 40 80 160 |
2024.07.04 10:25:53 afc: customer-info | | | EIRP, dBm, on chan |
2024.07.04 10:25:53 afc: customer-info ±-----------±---------±--------------------++
2024.07.04 10:25:53 afc: customer-info | Grace period expired: 2024-07-05 23:59:00Z |
2024.07.04 10:25:53 afc: customer-info | Expired: 2024-07-05 15:24:53Z |
2024.07.04 10:25:53 afc: customer-info | Now: 2024-07-04 15:25:53Z |
2024.07.04 10:25:53 afc: customer-info | version: 1.4 |
2024.07.04 10:25:53 afc: customer-info | Response to request_id: 3939645400 |
2024.07.04 10:25:53 afc: customer-info ±---------------------------------------------+

I did just notice that if I put in the SM MSL height in the AFC tool (324 meters) that the chart matches what the SM is showing. Some type of bug where on 24hr renewal the AFC is taking the MSL height and using it as the AGL height?

Rebooting the SM did not fix it this time. Upon SM reboot it queried the AFC and got the same spectrum information.

SM Currently

Cambium AFC Tool at MSL GPS height of SM. See it matches the SM above

Cambium AFC Tool at AGL height of SM.

Looks to me like somehow the AFC is reading the SM height wrong, or the SM is reporting to AFC the wrong height.

Hopefully Cambium can help find a solution as this is causing me all types of issues. I need to know is this a bug, an AFC service issue, or some type of GPS issue. SM constantly gets data from AFC that does not match the Cambium AFC checker tool unless I put the SM at an unreasonable AGL height hundreds of feet above the actual SM height.

Also in my opinion, Cambium should add an AFC query or refresh button to the AP and SM. Would make troubleshooting this issue a little easier as right now the only way to get the SM to check the AFC again is to wait for the regular 24 hour check or reboot the SM.

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After further observation and testing it seems the issue is related to the SM reported MSL height. I am seeing variations of around 30-40 meters (100-130ft). Altering the height of the SM in the Cambium AFC tool to actual AGL of the SM + 30-40 meters I end up with a spectrum chart that limits my SM power on the chosen channel. Putting in the actual SM height in the chart and I am good.

I decided to then go out to the SM to see if I could improve GPS tracking. Old location of the GPS puck is in the below photo.

I pulled out the puck and tried putting it right on top of the flat part of the SM bracket and got a little better tracking. I then put it back in the GPS holder and moved the GPS holder to the flat part of the SM bracket and my GPS signal got worse. Seems like the GPS holder can interfere with the signal.

Since the puck is magnetic I then tried mouting it to the top back of the dish and this is where I got my best signal. I then took off the label sticker on the back of the puck to expose the magnet so I could get a better magnetic lock on the dish. For now this is where I will keep it to see how the GPS signal stays.

After moving it and rebooting the SM the GPS came up around 35 meters lower than it was reporting before.

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Well apparently that GPS puck location was not a fix. I tried many locations at this home and none of them gave a better signal than where I put it on the dish.

Just checked the SM GPS again and the signal was shown as Low but 11 satellites tracked. That would probably be ok but the SM height jumped around 60 meters higher which will really screw up my AFC allowed power levels for this SM. So most of the time the signal is Good but sometimes it is low and the MSL height jumps up higher. Odd as I always am tracking between 9-12 satellites all the time.

How do we go about fixing this? I know Cambium is not to blame, but this is a dumb system to do SM power levels using the GPS height, which I am not sure on how to solve for an SM whose MSL height keeps changing wildly…

Here is the SM mounting location. SM was replacing a AirmaxAC CPE on the same mount.