RT-AC68U: is the power limit lower on channels 36-48 vs 149-161?

[sirwifi]

I seem to get a lower signal strength on 5GHz channel 36-48 than on 149-161. I thought the FCC raised the power limits on the lower channels. Didn't Asus follow through, is this a bug in the firmware or something else?

The theory is that lower channels have better penetration and range, so they should be preferred but not when their power is lower. Tx power is set to "Performance".

Anyone else seeing the same thing?

 

[ColinTaylor]

I don't know the answer to your question, and unless somebody actually attaches power meters to the router (like @thiggins has done in the past), I doubt anybody knows for sure. What with the wireless code being closed source.

Also, I very much doubt that just because the regulator in a particular country has increased some of the limits that the manufacturer would retrospectively change it on a router. That would require them to take the device through the certification process again which would be lengthy and expensive.

 

[e38BimmerFN]

Have you tried using 3rd party FW like Merlins FW to see if there is any differences between OEM and Merlin?

 

[sirwifi]

I thought the initial scandal was that Asus was not respecting the lower limits on channels 36-48. Not sure whether they fixed it at some point to comply with the regulations and then never fixed again.

My observation is based on running NetSpot on my Mac client and looking at the signal strength on various channels. There's about a 10dB jump from the lower to the upper channels.

Android WiFi Analyzer shows about the same numbers as NetSpot.

This is as scientific as it's going to get for me

 

[sirwifi]

Have you tried using 3rd party FW like Merlins FW to see if there is any differences between OEM and Merlin?

I'm only using Merlin. This is a modified TM-AC1900 router and it never ran anything else (well maybe for an initial couple of hours while it was being converted ...)

 

[e38BimmerFN]

Ok, might load OEM FW and see if Asus has changed anything. Possible that the source code for the wifi drivers hasn't been touched that span across OEM and Merlin.

 

[jim769]

The 3100 has the same output on the lower channels as the high but it was manufactured after the new laws went in to place. That said i am sure firmware could bump the power up on the older models not sure why they have not done it.

 

[skeal]

Just to be clear here the power of the signal is affected by the frequency used. 2.4gig can punch through pretty thick walls on any channel that has no conflicts. 5gig not so much. It has less penetration than 2.4 by far. A good example of this is cellular technology. In Canada we use a lot of LTE coverage. LTE operates on allot of frequencies but the point is that 4g is way more powerful than LTE. LTE can't punch through walls that well where the lower frequency systems can.
This is often confused with a range issue.

 

[sirwifi]

Just to be clear here the power of the signal is affected by the frequency used. 2.4gig can punch through pretty thick walls on any channel that has no conflicts. 5gig not so much. It has less penetration than 2.4 by far. A good example of this is cellular technology. In Canada we use a lot of LTE coverage. LTE operates on allot of frequencies but the point is that 4g is way more powerful than LTE. LTE can't punch through walls that well where the lower frequency systems can.
This is often confused with a range issue.

So lower 5GHz channels should have better penetration hence signal strength. I'm seeing the opposite, the higher channels in the 5Ghz band show better signal strength by about +10dB.

 

[skeal]

So lower 5GHz channels should have better penetration hence signal strength. I'm seeing the opposite, the higher channels in the 5Ghz band show better signal strength by about +10dB.

That is not what I meant. I'm saying for better penetration power use 2.4g wifi.

 

[sirwifi]

That is not what I meant. I'm saying for better penetration power use 2.4g wifi.

OK, but that's not what my original question was about.

 

[skeal]

OK, but that's not what my original question was about.

Your original question was concerning transmission power on lower and upper channels on the 5g frequency. I’m just saying there is a more important underlying problem to contend with. Your 5g problems could be caused by congestion on the lower channels due to overuse in your particular area.

 

[sirwifi]

It's not congestion, another AP only on lower and upper channels. Unless there's some other kind of noise that you can't see with wifi scanner type apps. After all this time 5GHz is still not popular, at least in my area (which I'm happy about) vs 2.4GHz where everyone piles up.

 

[jim769]

Almost all routers put out much less power on the low 5 GHz channels because at one time it was FCC rule. This is no longer the case but some manufactures have not bothered to change the output. To Skeal while we all know the 2.4 GHz band has better range and penetration the band for most is unusable and is loaded with crap. 5 GHz for now is the future.

 

[joegreat]

I seem to get a lower signal strength on 5GHz channel 36-48 than on 149-161. I thought the FCC raised the power limits on the lower channels. Didn't Asus follow through, is this a bug in the firmware or something else?

The theory is that lower channels have better penetration and range, so they should be preferred but not when their power is lower. Tx power is set to "Performance".

You can find the details about the 5 GHz limitations for each country on Wikipedia - so the router vendors try to be compliant to all the regulations and therefore they limit themselves to the least common minimum...

 

[ColinTaylor]

You can find the details about the 5 GHz limitations for each country on Wikipedia - so the router vendors try to be compliant to all the regulations and therefore they limit themselves to the least common minimum...

Unfortunately Wikipedia only gives very limited information about power levels that relate to DFS in some very specific locations. For example, it provides absolutely no power information relating to the US or Canada and no relevant information for Europe as a whole.

 

[sirwifi]

What I'm interested in is what people are seeing in the real world with their RT-AC68U and maybe someone noticed differences when switching between various firmware versions.

 

[joegreat]

Unfortunately Wikipedia only gives very limited information about power levels that relate to DFS in some very specific locations. For example, it provides absolutely no power information relating to the US or Canada and no relevant information for Europe as a whole.

In EU there are harmonized rules:
- 2.4 GHz = 100 mW
- 5 GHz lower channels = 200 mW - upper channels with DFS up to 1000 mW

Unfortunately no router vendor is really following the good EU limits for 5 GHz - they typically limit the power down to 50-100 mW only - but with custom firmware ("teaked") you can influence this values...

For US/CAN I do not know the limits - but there should be also some as DFS is also used there to allow higher transmission power.

 

[jim769]

What I'm interested in is what people are seeing in the real world with their RT-AC68U and maybe someone noticed differences when switching between various firmware versions.

The Asus and Merlin builds have been locked down for quite some time. John's fork may have better results because of a older wifi driver. Also his fork allows for one to add SSH/Telnet commands to open up all channels and power levels. There was a thread here that had the commands someone may have booked marked it buts its around some were here.

 

[RMerlin]

Manufacturers aren't too keen on changing this because I think it would require getting the device re-validated by the FCC, which can be an expensive process.