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WirelessRudy
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Minimum power settings for Mikrotik radios

Thu Apr 21, 2016 1:35 am

We have some very short links that have high signal levels on both end. Even when output power set to 10dBm we have -35dB signal on the other end.

I am a bit reluctant to go even lower in power because in the past I have been told (by MT) that setting radio's power too low is not good. It would make the radio's unstable and CCQ might go down.

With the integrated units we have nowadays attenuation filters or similar are not possible.
In the old days for CPE units we could just mis align the station to get worse signal to and from AP.
But again, today with all the interfering signals and high noise levels we need to work with high gain (=narrow beam) units to get clear signal, but at the cost of too high a signal?

Anybody has any real proof and experiences and at which levels MT radios become unstable, or not, below certain power levels?
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jarda
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Thu Apr 21, 2016 7:44 am

Other option could be to tilt the antennas slightly upwards.
 
WirelessRudy
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Re:

Thu Apr 21, 2016 12:50 pm

Other option could be to tilt the antennas slightly upwards.
hmm, not such a bad idea...... but no applicable. We have hundreds of SXT's and a lots Sextants out there all are fit with their normal standard fitting bracket to a pole.
To lift these up we need to fit these all with special brackets that can have vertical pane tilt.....

No, I prefer someone to tell me what low power settings of radios implicate on its quality.
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jarda
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Thu Apr 21, 2016 12:54 pm

Just use regulatory domain and set the antenna gain value higher to lower the radiated power.
 
WirelessRudy
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Re:

Thu Apr 21, 2016 1:27 pm

Just use regulatory domain and set the antenna gain value higher to lower the radiated power.
That is not an answer to my question.
1. In regulatory domain I can't put negative number on antenna gain. "0" is the minimum so in that case a dBm of 17 will be set, which in my case is still way too high.
2. Manually you can do the same, or better, than regulatory domain. I need to set radios below regulatory domain setting. Like -10, -8 or even -6dBm.

My question is; Do the radio's become unstable if power settings fall below certain level?
I'd presume they all work fine still with 17dBm because that is not seldom the regulatory domain setting. But any lower? What happens then?
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jarda
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Thu Apr 21, 2016 2:06 pm

You probably don't know how it works. Try it and see what happens if you put there 0, 6, 12, or higher positive value...
I am running links close to 0 dbm in this way without any problems.
 
WirelessRudy
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Re:

Thu Apr 21, 2016 2:57 pm

You probably don't know how it works. Try it and see what happens if you put there 0, 6, 12, or higher positive value...
I am running links close to 0 dbm in this way without any problems.
Maybe you don't understand my question; are radios becoming unstable when their power settings are set very low. In the past is was not recommended but since technology has advanced the answer is unclear to me.

You can put regulatory domain and set an antenna gain of 12dBi so the radio, to stay within the regulatory domain EIRP settings will reduce power on a calculated base to achieve the setting within the limit if such gain antenna really would be fit.
I don't see the difference in the radio making a for instance 4dBm output as the result of such setting or I set 4dBm myself manually.
The object of my question is; does the radio become unstable if set to 4dBm or not? And if yes, where is the tipping point?

We have a couple of short and very short links that run with 10dBm setting but still deliver -30dB at the other end. But I don't seem to be able to get 100% CCQ on these links that run with traffic (2-40Mb on average) to and from clients.
I played with 5Ghz/a-n-ac and 5Ghz ac-only, and 5Ghz-n-only, fixed mcs rates or auto, played with the tdma timing, and played with the power levels and changed frequencies.


We found on longer run links that reducing power from full to much lower to get receive from -30's or 40's to -50 made links more stable. But on these short links its a hell more difficult to get stable link. So I am wondering if reducing power to get less overpowered receiver circuits on the other end has a point of where the advantage of the lower power doesn't cope with any possible increase of instability of power output circuits increase....
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jarda
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Thu Apr 21, 2016 3:20 pm

I do understand. As I said, my links work good nearby the zero. If you have too much selective antenna, you need to attenuate the signal somehow or change the antenna because overheating the input of the receiver makes the link problems.
 
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Re: Re:

Thu Apr 21, 2016 3:57 pm

....................

We found on longer run links that reducing power from full to much lower to get receive from -30's or 40's to -50 made links more stable. But on these short links its a hell more difficult to get stable link. So I am wondering if reducing power to get less overpowered receiver circuits on the other end has a point of where the advantage of the lower power doesn't cope with any possible increase of instability of power output circuits increase....
Stability in a link by reduction in overall gain would confirm to me that this action is not simply preventing input stage from being simply overloaded by high signal levels ( AGC was designed for that - of course to a max i/p signal ) but this reduction in gain also reduces unwanted signals that the antenna will also pickup in its gain bandwidth, in other words a 5.1- 5.9GHz antenna to a radio card will amplify any signal between 5.1- 5.9GHz in receive mode, another part solution long overdue is when when antenna manufacturers design a channelized antennas (that is a very narrow bandwidth)
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n21roadie
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Re:

Thu Apr 21, 2016 4:21 pm

I do understand. As I said, my links work good nearby the zero. If you have too much selective antenna, you need to attenuate the signal somehow or change the antenna because overheating the input of the receiver makes the link problems.
Strange I always thought in reception mode a low-noise amplifier used for amplifying reception RF signals who's gain action generates more heat and attenuation of the signal produces less heat - unless I am totally mistaken
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WirelessRudy
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Re: Re:

Thu Apr 21, 2016 5:30 pm

another part solution long overdue is when when antenna manufacturers design a channelized antennas (that is a very narrow bandwidth)
The tendency is the other way round. Since 5ghz is being stretched up a bit on the upper end antenna manufacturers are looking to cover this range as well in one antenna design.
I think designing antennas just for specific channels (20, 40 or 80MHz wide?) would make them very expensive....and no market.

Maybe one day some chipset/radio board manufacturer might come up with some build-in adjustable bandpass filter so you could tune your radio receiver circuits to only listen to what we'd want it to.
But I understood ubnt already is doing something in that direction (Airprism) and although their documents cry it works nice and in their forum not a lot is to be found on other forums I came across some that said it hardly makes a measurable difference......
But that's all about radio fine tuning in the band.
We are talking radio down tuning in power here....
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WirelessRudy
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Re: Re:

Thu Apr 21, 2016 5:35 pm

I do understand. As I said, my links work good nearby the zero. If you have too much selective antenna, you need to attenuate the signal somehow or change the antenna because overheating the input of the receiver makes the link problems.
Strange I always thought in reception mode a low-noise amplifier used for amplifying reception RF signals who's gain action generates more heat and attenuation of the signal produces less heat - unless I am totally mistaken
Basically jarda would make me believe down tuning a radio to say 4, or 6 dBm, manually or by using high antenna gain in the reg. domain setting (so the OS calculates the setting) is not harming the actually quality of the link.

Attenuation of the signal on the receiver end would also be nice, if there was some software way of doing this.
The only other way for a integrated unit is to put attenuation material in front of the antenna........ well.
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n21roadie
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Re: Minimum power settings for Mikrotik radios

Thu Apr 21, 2016 8:49 pm

Generally what are you using for links?
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WirelessRudy
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Re: Minimum power settings for Mikrotik radios

Fri Apr 22, 2016 12:57 am

Generally what are you using for links?
On the links > 2km I use Jirious 25dBi dishes, > same but 29dBi. Now we also fit some ubnt dishes.
On the short to medium we use either dynadish, QRT (with metal shield), Sextant (with metal shield).
On the real short ones (20mtr to 500mtrs) we use some SXT's (preferably with metal shield) or SXT-HG (both 'n' and now some newer 'ac' models, again preferably with shields)
We also have some units that have a Netmetal or other shielder rb911xxxx on a 17dBi reduced sidelob from ehh, name won't come up that fast....

So in general, we are upgrading many links. I try to get as much high gain (=narrow beam) antennas, preferably dish or at least shielded.

All radios are Mikrotik.
Tendency is to upgrade antennas to the best I can get for reasonable money compared to the amount of clients behind a link. Hence I am about to order 3 60Ghz links to bridge some 300-450mtrs links..... they cost some but the idea is we get better links and as bonus free a lot of spectrum so the AP's will have more spectrum available and the overal noise in our compact region might go down a bit....
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n21roadie
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Re: Minimum power settings for Mikrotik radios

Sat Apr 23, 2016 6:19 pm

Generally what are you using for links?
On the links > 2km I use Jirious 25dBi dishes, > same but 29dBi. Now we also fit some ubnt dishes.
On the short to medium we use either dynadish, QRT (with metal shield), Sextant (with metal shield).
On the real short ones (20mtr to 500mtrs) we use some SXT's (preferably with metal shield) or SXT-HG (both 'n' and now some newer 'ac' models, again preferably with shields)
We also have some units that have a Netmetal or other shielder rb911xxxx on a 17dBi reduced sidelob from ehh, name won't come up that fast....

So in general, we are upgrading many links. I try to get as much high gain (=narrow beam) antennas, preferably dish or at least shielded.

All radios are Mikrotik.
Tendency is to upgrade antennas to the best I can get for reasonable money compared to the amount of clients behind a link. Hence I am about to order 3 60Ghz links to bridge some 300-450mtrs links..... they cost some but the idea is we get better links and as bonus free a lot of spectrum so the AP's will have more spectrum available and the overal noise in our compact region might go down a bit....
I see, so most of the very short links you cannot do much with however for the links with 25/29dBi dishes maybe you could use a lower power radio card!
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WirelessRudy
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Re: Minimum power settings for Mikrotik radios

Mon Apr 25, 2016 11:52 am

Generally what are you using for links?
On the links > 2km I use Jirious 25dBi dishes, > same but 29dBi. Now we also fit some ubnt dishes.
On the short to medium we use either dynadish, QRT (with metal shield), Sextant (with metal shield).
On the real short ones (20mtr to 500mtrs) we use some SXT's (preferably with metal shield) or SXT-HG (both 'n' and now some newer 'ac' models, again preferably with shields)
We also have some units that have a Netmetal or other shielder rb911xxxx on a 17dBi reduced sidelob from ehh, name won't come up that fast....

So in general, we are upgrading many links. I try to get as much high gain (=narrow beam) antennas, preferably dish or at least shielded.

All radios are Mikrotik.
Tendency is to upgrade antennas to the best I can get for reasonable money compared to the amount of clients behind a link. Hence I am about to order 3 60Ghz links to bridge some 300-450mtrs links..... they cost some but the idea is we get better links and as bonus free a lot of spectrum so the AP's will have more spectrum available and the overal noise in our compact region might go down a bit....
I see, so most of the very short links you cannot do much with however for the links with 25/29dBi dishes maybe you could use a lower power radio card!
A bit hard with Netmetals.... but anyway, on the medium to medium long links I have no issues. The Netmetals can be set to 12 or 14dBm and on the other end we get -40 to -45 so that's no so bad in a high noise environment.
It's the very short links that we are looking for an nice solution.
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Need Help

Mon Apr 25, 2016 11:58 am

Need Help about to connect ,share files and printer between two LAN interfaces in mikrotik (example 192.168.1.0/22 and 192.168.2.0/24)

thanx in advance
 
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Re: Re:

Tue Aug 30, 2016 11:09 am

The object of my question is; does the radio become unstable if set to 4dBm or not? And if yes, where is the tipping point?

We have a couple of short and very short links that run with 10dBm setting but still deliver -30dB at the other end. But I don't seem to be able to get 100% CCQ on these links that run with traffic (2-40Mb on average) to and from clients.
I played with 5Ghz/a-n-ac and 5Ghz ac-only, and 5Ghz-n-only, fixed mcs rates or auto, played with the tdma timing, and played with the power levels and changed frequencies.


We found on longer run links that reducing power from full to much lower to get receive from -30's or 40's to -50 made links more stable. But on these short links its a hell more difficult to get stable link. So I am wondering if reducing power to get less overpowered receiver circuits on the other end has a point of where the advantage of the lower power doesn't cope with any possible increase of instability of power output circuits increase....
Hi, I want to jump in to this discussion.
Rudy, I've experienced the same issues as you have, when lowering the output power to get a stable or adjust the EIRP to the regulatory domain the links gets unstable.
I've wrote about this in the trainers forum in 2014:
The WiFi regulations in Europe limits the 5Ghz EIRP to 30dB, at least most of Europe.
All the boards with built in a 5Ghz radio have the high TX-powered radios (-5HPnD).
When PtP links with high gain antennas are built with those boards we have to lover the TX-power so much that the radios comes out of it's calibration.
The complication with this is that it will lower the CCQ and overall performance of the radio.
So to get a stable and good working long distance PtP link in Europe, we need an other calibration or a low TX-powered radio in those PtP boards.
I had this conversation with Uldis at the MuM in Venice, and he admitted that when the power is reduced to under 6-7dB the radio comes out of it's calibration.
I also wrote:
I've compared the built in radio in the RB912UAG-5HPnD-OUT with an added SR71E radio in the same board and the difference in stability and quality of signal is obvious.
I hope we can have both a EU and a US/global profile for the radio.
So, I hope that Uldis could add some information in this topic

/Paul
Reboot is the last resort, try to find out what's wrong instead.

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