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So what am I missing?

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w7ban
So what am I missing?
I have two Mikrotik hAP ac lites and two Grand stream GXP1620/1625 phones. The two Mikrotiks a will not connect to each other when in the same room I have to move them about halfway across the house from each other before they'll even get about a 50/50 percent data connection quality link. The phone quality is pretty bad and you can barely understand what the other person is saying because it cuts out a lot.
w6bi
w6bi's picture
Bandwidth
The hAP lites have some hardware issues with, I think, 5 MHz bandwidth.  Could that be the issue?

Orv W6BI
nc8q
nc8q's picture
So what am I missing?
Missing are the values for:
Channel
Channel width
TX power
Distance to farthest neighbor.
SSID must be correct, cuz you are getting a connection. ;-)

Chuck

 
w7ban
I'm using the defaults.
I'm using the defaults. -2 channel Width 20MHz Tx Power I have tried 22 and 10dBm 0 for auto
w7ban
LQ and NLQ are below 50%.
LQ and NLQ are below 50%. I also tried the "Device-to-Device Linking (DtDLink)" guide both for direct connect and connection through a non vlan switch. I was unable to get any connection that way.
nc8q
nc8q's picture
-2 channel Width 20MHz!

Sorry, OM, 2397 MHz @ 20 MHz bandwidth is partially outside the Part 97 allocation.
Please try channel '-2' at 10 MHz.
You may run 20 MHz bandwidth on channels -1 to 6, 10 MHz bandwidth on channels -2 to 7, and 5 MHz bandwidth on channels -2 to 8.

On the '/cgi-bin/status' page, note the Signal/Noise/Ratio.
A 'Ratio' value of 15 dB or more is sufficient.
As the 'Ratio' increases above 15 dB...TxMbps speeds increase.

Chuck

KE2N
KE2N's picture
overlap with chan 1?

Do you have any part-15 devices on channel 1?   That seems to be the default for a lot of things and it can use 22 MHz of BW..  Put a conventional wireless device on chan 1 and do a scan to see how many other signals there are and how strong.  You may have some IOT devices, for example. They tend to all use channel 1 unless you configure otherwise.

>> Channel 1 @ 20 MHz occupies 2401 -2423 MHz  (https://en.wikipedia.org/wiki/List_of_WLAN_channels#2.4_GHz_(802.11b/g/n/ax)) 

>> Your operation on ch -1 @ 20 MHz occupies 2392-2412 MHz   (operation on -2 @ 20 MHz puts you outside the ham band).

So there is about 11 MHz of full overlap and near-total QRM between such devices.

In fact, I have even seen some interference with 10 MHz and a next-door neighbor on Channel 1 (AREDN signals were weak).   This was an unfortunate one as the part-15 device was a sort of 3-node mesh network that used chan 1,6 and 11 and there was no way not to use channel 1.  Even if the channels do not have direct overlap, there is still splatter outside the channel that is only about 20-30 dB down.

Ken
KE2N

edit - corrected channel to -1 for 20 MHz.

w7ban
I miss spoke, I finally was
I miss spoke, I finally was able to look at this again. It was channel -2 but with 10 width. I tried both in the same room channel -1 at 20 width 3 power and all looked good with 100 link quality and 75 to 100 megabits per second. so I figured I would move one of them across to the other end of the house, well that led to no connection so I slowly raised the power level on both from 3 to 10 to 15 then 22. But no matter what I did I could not reestablish a connection I even rebooted both devices on each power raise. so I then brought them both back into the same room made sure they were both set to 3 power and still I could not get a connection. So I'm kind of at a loss, these things seem to be really finicky. I even tried dropping down the width to 10 on each power setting without success.
nc8q
nc8q's picture
It was channel -2 but with 10 width.

"-2 channel Width 20MHz
Tx Power I have tried 22 and 10dBm
0 for auto"

I suggest using a fixed (use slider) value for distance to farthest node.
The 'auto' (value=0) choice may be for dynamically optimizing links over 1 kilometer.
Please try the next fixed value above zero. (0.62 maybe)
I assume that your house does not span more than 620 meters. 

Please continue to use channel '-2' at 10 MHz bandwidth.

I hope this helps.
Chuck
 

nc8q
nc8q's picture
Linking two Mikrotik hAPs via RF mesh

"I have two Mikrotik hAP ac lites ... The two Mikrotiks a will not connect to each other when in the same room "

"I miss spoke, I finally was able to look at this again. It was channel -2 but with 10 width."

Please only use channel '-2' at 10 MHz bandwidth for the time period of this testing.

It is odd that 2 devices in the same room with the same settings do not link.

I suggest that you use only channel '-2' at 10 MHz bandwidth.
Any other channel will result in sharing bandwidth with the Part 15 allocation.

"I tried both in the same room channel -1 at 20 width 3 power and all looked good"

"so I figured I would move one of them across to the other end of the house, well
that led to no connection so I slowly raised the power level on both from 3 to 10 to 15 then 22.
But no matter what I did I could not reestablish a connection I even rebooted both devices on each power raise.
so I then brought them
both back into the same room made sure they were both set to 3 power and still I could not get a connection."

I am confused with these 2 posts you entered:

  1. "The two Mikrotiks a will not connect to each other when in the same room..."
  2. "I tried both in the same room channel -1 at 20 width 3 power and all looked good...
    I then brought them both back into the same room made sure they were both set to 3 power and still I could not get a connection."

Channel '-1' shares 50% of its bandwidth with Part 15's channel '1'.

Please use channel '-2' and 10 MHz bandwidth.

Please try a fixed value for 'Distance to FARTHEST Neighbor'.

Max Tx power is a good test setting.

KE2N
KE2N's picture
same question

I have to ask the same question: do you have something in your house running on channel +1?

Ken
 

w7ban
Scan from local area.
Scan from local area.
Image Attachments: 
nc8q
nc8q's picture
Scanner display
Does your scanner cover channel '-2' ?
 
KE2N
KE2N's picture
as they used to say on Mythbusters

There's your problem.

You need the channel +1 interference to be at least 10 dB lower than the AREDN signal, at the receive location, to get some kind of reasonable LQ.
-50 dBm is quite strong. Some of these devices actually saturate at about -40, so it would be hard to get a signal more than 10 dB stronger at the location where you took this scan.

Ken

w7ban
Good to know
This makes testing and deployment kind of hard. I can only guess results will be better when I add directional radios?
KE2N
KE2N's picture
it can help

but there is a limit to how much directionality you can get in the real world.  I was surprised to see that the 2-foot solid dish can pick up signals from "behind".  Adding the full Rock Shield kit did not make all that much difference.  I put it down to reflections of the unwanted signal coming from the direction the dish was aimed at.   This perhaps is one reason why paths with really clear field-of-view work much better than paths with (reflecting) clutter.     I do have one 5 GHz part-15 link where I have aimed the antenna a little high to reduce competition from users below the path. It produce a modest improvement in SNR.

The attached scan shows the receive environment in the shack.where I pick up my Channel -1 signal from up on the tower.  There is actually quite a strong 10 MHz AREDN signal on Ch -1 here, but it is not recognized by the part-15 analyzer. Anyway - you can see I have managed to keep channel +1 clear of anything detectable from this location.

 

Image Attachments: 
nc8q
nc8q's picture
Good to know...

"This makes testing and deployment kind of hard."

This seems to be testing a point-to-point link with indoor desktop devices sharing an active Part 15 channel.
-----

"I can only guess results will be better when I add directional radios?"

 I guess results will be better with commercial outdoor rated devices designed for point-to-point links on unshared channels.

Chuck
 

w7ban
TP-Link 5GHz N300

I plan on using TP-Link 5GHz N300 (CPE510) https://www.amazon.com/dp/B00N2RO63U/ which would be connected to my MikroTik hAP ac lite Dual-concurrent Access Points (RB952Ui-5ac2nD-US).

My goal to to have working VOIP, Video, and a webserver, connected between two sites, once the concept is proven and is reliable, I was going to try and invite others in the local area to join the network.
 

KM6SLF
KM6SLF's picture
I did something similar,
I did something similar, using 2 GXP1625s, one attached to a little GL iNET 150M and another attached to an old Ubiquiti Airrouter. Both on channel -2, 10MHz. We tested them from one room to another and had fantastic voice quality. I wonder what the problem might be.

Are both Mikrotic hAP's powered with their factory supplied 24v power supplies? Both running stable versions of the firmware? 

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