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Radar detected on XXX

Posted: Wed Dec 26, 2018 12:59 pm
by ognjen
Hello everyone,

I have problem after change some options in wireless card. Change is maked in section Channel Width (from 20/40/80MHz eeeC to 20/40MHz eC), Frequency (from 5825 to 5680), Country (from no_country_set to Serbia).

Problem what I see is:
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Configure on AP & Virtual AP & Station:

AP (just bridge becouse we have virtual ap)
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Virtual AP
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Station
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Does someone have solutions to this problem?

Re: Radar detected on XXX

Posted: Wed Dec 26, 2018 1:55 pm
by mistry7
On DFS Channels you have to deal with this
You choose a frequency and when the AP detect radar on this one, the AP select new channel

Re: Radar detected on XXX

Posted: Wed Dec 26, 2018 1:56 pm
by mkx
Solution is simple: switch off all radars (air control, military and weather ones) around your AP (radius of 100km would probably be enough) ...

Or a more complex solution: change to a channel with no radar interference. Oh, wait, your RB did it already.

Re: Radar detected on XXX

Posted: Wed Dec 26, 2018 6:10 pm
by ognjen
On DFS Channels you have to deal with this
You choose a frequency and when the AP detect radar on this one, the AP select new channel
I change Frequency on station to auto and after re registration on AP, status Channel is changed to 5280.
So, that will resolve my problem? (This problem is show once per day, I need to wait to be sure)

Re: Radar detected on XXX

Posted: Thu Dec 27, 2018 7:26 am
by ognjen
My problem is not resolved :(

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Re: Radar detected on XXX

Posted: Thu Dec 27, 2018 11:19 am
by erlinden
It is not a problem, it is unexpected behaviour (for you). Switching channels is de Dynamic part in DFS. The Wiki: https://en.wikipedia.org/wiki/List_of_WLAN_channels gives you an overview on all allowed channels you can select. Perhaps you can do a WiFi scan with a client to find out the best channel?

Re: Radar detected on XXX

Posted: Thu Dec 27, 2018 11:20 am
by muetzekoeln
There are only four 5GHz channels without enforced DFS by most regulatories:
36 (5180MHz)
40 (5200MHz)
44 (5220MHz)
48 (5240MHz)

Re: Radar detected on XXX

Posted: Thu Dec 27, 2018 11:24 am
by pe1chl
There are only four 5GHz channels without enforced DFS by most regulatories:
Usually those channels are only allowed for indoor use and/or with lower power (100mW instead of 1W).

Re: Radar detected on XXX

Posted: Fri Dec 28, 2018 7:56 am
by ognjen
After disable WPS Mode in wireless card, problem didn't manifest (for now, 23h+)
I hope this problem will not be repeated.

Thanks to everyone!

Re: Radar detected on XXX

Posted: Fri Dec 28, 2018 11:48 am
by pe1chl
After disable WPS Mode in wireless card, problem didn't manifest (for now, 23h+)
I hope this problem will not be repeated.
WPS is totally unrelated to this issue (DFS).
Radar problems can sometimes be temporary due to tropospheric propagation conditions (inversion layer).
So it can be coincidence that you were affected for some time and later it disappeared.
E.g. over western Europe (France/Belgium/Netherlands/UK) there has been good tropospheric propagation the last two days,
but now that is back to normal. Don't know about Serbia.

Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 9:38 am
by ognjen
After disable WPS Mode in wireless card, problem didn't manifest (for now, 23h+)
I hope this problem will not be repeated.
WPS is totally unrelated to this issue (DFS).
Radar problems can sometimes be temporary due to tropospheric propagation conditions (inversion layer).
So it can be coincidence that you were affected for some time and later it disappeared.
E.g. over western Europe (France/Belgium/Netherlands/UK) there has been good tropospheric propagation the last two days,
but now that is back to normal. Don't know about Serbia.
This is matifest after upgrade for 6.43.7 to 6.43.8 and change Frequency mode, country and installation..
My problem is not resolved.

Can I disable radar detection?
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Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 12:03 pm
by pe1chl
Can I disable radar detection?
It is a legal requirement to use radar detection when you want to use certain channels on 5 GHz.
This is because the "primary user" of this band is RADAR and you are only allowed to use those channels where RADAR is not present.
When you run a WiFi link on a RADAR frequency you disturb their operation. E.g. on a weather rain map you will see streaks of
fake rain areas in the direction from the RADAR site to your link site.

When weather institutes become sufficiently fed up with this, they will send out the telecom authority to locate the offenders
and isssue them a ticket.

So you should not operate your links/access points on frequencies where there is RADAR, and the DFS is taking care of that.
It only becomes a problem when the DFS software makes false decisions, but we have not seen proof of that in your case.

Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 1:01 pm
by mkx
When weather institutes become sufficiently fed up with this, they will send out the telecom authority to locate the offenders
and isssue them a ticket.
As an ex MNO radio engineer and current weather service employee I'd ...
[joke-mode=yes]... find rogue wireless operators and execute them on the spot.[joke-mode=no]

Seriously: I can't understand certain wireless operators complaining about recent restrictions regarding use of free radio spectrum. I'd understand if somebody was complaining about new restrictions when using paid spectrum chunk which originally came with less restrictions.

I can remember outrage among weather radar crowd when 5GHz spectrum first got allowed for unlicensed use some 20 years ago. First problems soon started to show so current "witch hunt" is only (one of) climax(es) of the whole story.

Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 3:12 pm
by ognjen
@pe1chl Ok, let's say you are right. What now I can to do to resolve this? My AP is set auto freq, my stations is set auto freq. So, what to do in practice to resolve this?

Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 4:03 pm
by pcunite
So, what to do in practice to resolve this?

Use a 5Ghz channel that is not in use in your area, one not under DFS restriction.


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Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 6:02 pm
by pe1chl
@pe1chl Ok, let's say you are right. What now I can to do to resolve this? My AP is set auto freq, my stations is set auto freq. So, what to do in practice to resolve this?
Make a channel list and put those channels in that are not affected by radar.
This requires some manual work, the channel list editor in RouterOS is not very user-friendly, but when you have done it once you
can copy it to other access points via the commandline.

Re: Radar detected on XXX

Posted: Sat Dec 29, 2018 11:15 pm
by ognjen
So, I need to set no_country_set and put frequency like 5825..
Stupid rule, stupid law, stupid country..

Ty @pe1chl and @pcunite.

Re: Radar detected on XXX

Posted: Sun Dec 30, 2018 3:35 pm
by n21roadie
Can I disable radar detection?
It is a legal requirement to use radar detection when you want to use certain channels on 5 GHz.
This is because the "primary user" of this band is RADAR and you are only allowed to use those channels where RADAR is not present.
When you run a WiFi link on a RADAR frequency you disturb their operation. E.g. on a weather rain map you will see streaks of
fake rain areas in the direction from the RADAR site to your link site.

When weather institutes become sufficiently fed up with this, they will send out the telecom authority to locate the offenders
and isssue them a ticket.

So you should not operate your links/access points on frequencies where there is RADAR, and the DFS is taking care of that.
It only becomes a problem when the DFS software makes false decisions, but we have not seen proof of that in your case.
Would it not made more sense that the log would indicate the Radar Identity rather than just "Radar Detected" so that we can trace if we have
(1) Actual Radar present
(2) Co-location interference
(3) Nearby operator on same frequency

Re: Radar detected on XXX

Posted: Sun Dec 30, 2018 3:48 pm
by n21roadie
When weather institutes become sufficiently fed up with this, they will send out the telecom authority to locate the offenders
and isssue them a ticket.
As an ex MNO radio engineer and current weather service employee I'd ...
[joke-mode=yes]... find rogue wireless operators and execute them on the spot.[joke-mode=no]

Seriously: I can't understand certain wireless operators complaining about recent restrictions regarding use of free radio spectrum. I'd understand if somebody was complaining about new restrictions when using paid spectrum chunk which originally came with less restrictions.

I can remember outrage among weather radar crowd when 5GHz spectrum first got allowed for unlicensed use some 20 years ago. First problems soon started to show so current "witch hunt" is only (one of) climax(es) of the whole story.
As a WISP I would question the wisdom of allowing dual usage of frequencies that both Radar and wireless operators use? It would be best to remove these frequencies from the unlicensed band.

Re: Radar detected on XXX

Posted: Sun Dec 30, 2018 7:07 pm
by r00t
Main issue with radar detection is the unreliability. If it only detected WX radars and nothing else, it would be fine. But for that, radars would have to transmit some digitally signed beacon that could be verified to be 100% reliable and avoid the spoofing. Currently entire detection algorithm relies on detecting series of pulses, it's too easy for it to be triggered by noise, non-WIFI signals and non-WX radar devices.
In the end it's a government mandated backdoor that will turn off your WIFI and all you need to trigger it is $2 radar module from China. The idea of protection for WX radars is good, but actual implementation is more than dubious. Getting a lot of radar detection errors on your channels? Maybe your competitor put this small radar module somewhere near your AP and is just having a good laugh...

Re: Radar detected on XXX

Posted: Sun Dec 30, 2018 10:40 pm
by mkx
As a WISP I would question the wisdom of allowing dual usage of frequencies that both Radar and wireless operators use? It would be best to remove these frequencies from the unlicensed band.
Guess what: weather radars were using 5GHz frequencies waaay before this part of RF spectrum was made available as ISM. I don't remember weather guys pushing for that change ...

Re: Radar detected on XXX

Posted: Mon Dec 31, 2018 11:08 am
by pe1chl
As a WISP I would question the wisdom of allowing dual usage of frequencies that both Radar and wireless operators use?
Nobody questions the viability of getting into an unreliable business like WISP where you are fully dependent on what others (including authorities) do?

Re: Radar detected on XXX

Posted: Mon Dec 31, 2018 1:34 pm
by n21roadie
As a WISP I would question the wisdom of allowing dual usage of frequencies that both Radar and wireless operators use?
Nobody questions the viability of getting into an unreliable business like WISP where you are fully dependent on what others (including authorities) do?
Just curious what business gives you total immunity to what "others (including authorities) do?"

Re: Radar detected on XXX

Posted: Mon Dec 31, 2018 1:47 pm
by n21roadie
Main issue with radar detection is the unreliability. If it only detected WX radars and nothing else, it would be fine. But for that, radars would have to transmit some digitally signed beacon that could be verified to be 100% reliable and avoid the spoofing. Currently entire detection algorithm relies on detecting series of pulses, it's too easy for it to be triggered by noise, non-WIFI signals and non-WX radar devices.
In the end it's a government mandated backdoor that will turn off your WIFI and all you need to trigger it is $2 radar module from China. The idea of protection for WX radars is good, but actual implementation is more than dubious. Getting a lot of radar detection errors on your channels? Maybe your competitor put this small radar module somewhere near your AP and is just having a good laugh...
I totally agree that radar detection is unreliable also in wireless setting for a given country the radar frequencies in use should be included so that the scan is not starting at say 5180 when radar frequencies used are 56XX.. or a option for us to exclude these frequencies.

Re: Radar detected on XXX

Posted: Mon Dec 31, 2018 7:22 pm
by mkx
I totally agree that radar detection is unreliable also in wireless setting for a given country the radar frequencies in use should be included so that the scan is not starting at say 5180 when radar frequencies used are 56XX.. or a option for us to exclude these frequencies.
Your proposal is totaly unrealistic.

So when weather guys decide to build a new radar, operating od frequency different than the rest of radars, who is going to find all those milions of APs operating in the area?
So when there's a ground control short-range aviation radar, operating in a border area of two large countries, use of that frequency should be banned in whole of the two countries? What if there are enough short-range radars, all operating on different frequencies, should the whole 5GHz band be banned from ISM use?
What if somebody decides that radar signal is not there (for real or "just interferes") and that she doesn't have to use country specific rules? Isn't this the reason for this discussion?

You should be aware that it's us who are guests on 5GHz band and we should follow certain rules not to interfere primary users of this part of RF spectrum.

Re: Radar detected on XXX

Posted: Tue Jan 01, 2019 3:24 pm
by n21roadie
I totally agree that radar detection is unreliable also in wireless setting for a given country the radar frequencies in use should be included so that the scan is not starting at say 5180 when radar frequencies used are 56XX.. or a option for us to exclude these frequencies.
Your proposal is totaly unrealistic.

So when weather guys decide to build a new radar, operating od frequency different than the rest of radars, who is going to find all those milions of APs operating in the area?
So when there's a ground control short-range aviation radar, operating in a border area of two large countries, use of that frequency should be banned in whole of the two countries? What if there are enough short-range radars, all operating on different frequencies, should the whole 5GHz band be banned from ISM use?
What if somebody decides that radar signal is not there (for real or "just interferes") and that she doesn't have to use country specific rules? Isn't this the reason for this discussion?

You should be aware that it's us who are guests on 5GHz band and we should follow certain rules not to interfere primary users of this part of RF spectrum.
I won't suggest a ban on frequencies but a option to deselect available frequencies but the real question is how do we identify radar false positives?

Re: Radar detected on XXX

Posted: Tue Jan 01, 2019 3:45 pm
by BartoszP
@n21roadie ... could you please stop full quoting all posts you are commenting. Use "Post replay" instead of "quoting" post.

Re: Radar detected on XXX

Posted: Tue Jan 01, 2019 8:39 pm
by mkx
I won't suggest a ban on frequencies but a option to deselect available frequencies...

There's option scan-list. I've never played with it, but (brief) description in manual hints it might be step in right direction.

... but the real question is how do we identify radar false positives?

I'm pretty sure everybody would like to get rid of false positives while not missing any due detection. So when you find a way of detecting false positives (and missed positives as well) with 99.9% success rate, you can sell it to MT (and many other AP vendors), get rich and we all live happily ever after.

Re: Radar detected on XXX

Posted: Tue Jan 01, 2019 9:41 pm
by nichky
ognjen did you check country-list for your country?

PozZ iz Makedonie :)

Re: Radar detected on XXX

Posted: Thu Jan 03, 2019 11:12 am
by normis
So, I need to set no_country_set and put frequency like 5825..
Stupid rule, stupid law, stupid country..

Ty @pe1chl and @pcunite.
No, that would be breaking the law (since you are no longer conforming to Serbian frequency list).
Just set manually the frequency, don't use "auto".

Re: Radar detected on XXX

Posted: Thu Jan 03, 2019 12:33 pm
by mkx
Stupid rule, stupid law, stupid country..
No, that would be breaking the law (since you are no longer conforming to Serbian frequency list).

On Balkans, we have this specific attitude towards own states ...

Re: Radar detected on XXX

Posted: Thu Jan 03, 2019 12:41 pm
by normis
Fine, but here are many readers from other places, better show them the correct way :)