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SNR dropped from 25 to 13dB

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SNR dropped from 25 to 13dB

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SNR dropped from 25 to 13dB
SNR dropped from 25 to 13dB
2020-05-04 08:14:36 - last edited 2020-05-07 08:27:20
Model: CPE610  
Hardware Version: V2
Firmware Version: 2.2.1 Build 20190812 Rel. 33034 (0000)

I hesitate to share this to this forum because I know it would be difficult to fix as I did everything I know to fix the problem. But everything is no use and I'm thinking that the problem is from my device itself and not with configuration, alignment, obstacles.

 

For you to adapt my case, I will give you all details and background regarding to CPE. I have 8 pieces of CPE, 4pcs of 610 and 4 pieces of 510. I'm using 60 feet pole, anchored. I'm receiving 22-27dB SNR from 4 pairs. I manually configured channel based on what gives me the best ouput. In some settings, I worked on 40MHz, Maxtream:off, N only, and. auto distance. I learned it from R2D2 of this forum and it worked really great. 

 

Everything is fine, I check all CPEs using pharos system everyday. until one day, this CPE610 with 7kms distance dropped the SNR from 25 to 13dB. The major obstacles in our place are trees so I don't consider that in overnight that were trees grew in between. 

 

At first, I thought the two CPEs disallign, so I adjust it, first the client and then AP but still no help. I also adjust the elevation angle through anchor and still no help. We adjust little by little left and right, up and down elevelation and still no help. We worked on alignment for days. We didn't give that easy that we carefully make changes in alignment from time to time. It's almost 1 month now since we encounter the problem. 

 

I'm thinking if there is a big house that has been constructed in between the  signal, but then we are living in province and I don't see such things as obstacles plus the changes happened overnight. 

 

I'm losing hope and the only thing I can do is to add more pole. So we did it yesterday, we add another 12 feet to reach 72 ft high. There was an improvent of 13db to 17db but still not enough thinking that I have 25dB before with only 60 feet pole. 

 

so the last thing in my mind is my CPE is actually defective. if that is really the problem, now that I don't know which one is broken. it is not easy to change antenna from 60 and 70 ft pole. I tried to exchange the function of the two from client and AP and still the same 17dB. I also upgraded and downgraded firmware and still the same output. 

 

thank you in advance for someone who is willing to share some concern. 

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Re:SNR dropped from 25 to 13dB-Solution
2020-05-05 22:11:25 - last edited 2020-05-07 08:27:28

 

NAJIV wrote


that I have read one of your post here in TP link and you used two CPE510, do you placed it in one pole or two poles? 

 

Yes, I used the same pole (you cartainly are referring to this story, there is a photograph of the pole). But on the remote site, I placed the CPEs in about 7 meters distance of each other, since there had been interferences. We found out this distance by trial and error, which is easier for CPE510 than for a CPE610 I guess.

 

What you probably can do to avoid a foreign AP in the line between the two CPE610 is to find another place to mount the CPE610 (some meters apart can make a difference, that also might help with two CPEs at the same pole as noted above).

 

If I remember correctly, MikroTik produced a shield to be placed between two neighboring APs to reduce interference. Maybe this is an additional measure which could help you to reach the former SNR.

 

 

 

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Re:SNR dropped from 25 to 13dB-Solution
2020-05-07 07:39:05 - last edited 2020-05-07 08:27:20

 

NAJIV wrote

I did everything, including turning off the other AP and still nothing. I should be satisfied with with 17 SNR. on my next project I will consider other brands. can I have a recommendation with almost the same price as TP links product?  

 

No, I didn't search for other brands of similar devices since we changed to the 24 (twenty-four) GHz band for long range directional links anyway. This band is almost unpopulated right now and even requires no DFS/TPC, albeit in my country one must register with the regulatory authority to deploy such a link permanently. But devices operating in this band are pretty expensive b/c of the advanced technology they use (full-duplex, near-zero latency, wireless Gigabit bandwidth using special antenna arrays).

 

Our second use case with small-range directional links (up to a few hundred meters) is now handled with EAP225-Outdoor mesh systems, which offer AC1200 in the same price class as Pharos N300 devices.

 

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Re:SNR dropped from 25 to 13dB
2020-05-04 17:39:07 - last edited 2020-05-04 17:39:58

@NAJIV, trees in between the CPEs can affect the SNR greatly by reducing the WiFi signal. If you measure SNR in winter, SNR it's often much better than in spring or summer when trees have many leaves. Generally, you should have a free fresnel zone clearance on such a distcance.

 

But noise can also affect the SNR. If there are more APs or other RF sources in the line, then the noise level can increase.

 

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Re:SNR dropped from 25 to 13dB
2020-05-05 01:32:56

@R1D2 , we don't have winter here. I'm thinking of noise too  but it could be possible to decrease such big number with 1 or 2 devices in overnight? i understood that signal may change over time but not in overnight with almost 10dB changes. 

I'm thinking to point my other CPE (ap) on this 610 and see if there's changes since I'm thinking that the problem is in the device itself. 

 

I'm getting  -91dBm to -92 dBm noise strength from 4 pairs. before the fluctation happened, it gave the same number of -91dbm. 

thank you for answering you are still active in this forum, hope TPlink will give you a cut as after sales support for their product.

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Re:SNR dropped from 25 to 13dB
2020-05-05 11:48:45

Hello @NAJIV

 

NAJIV wrote
I'm thinking to point my other CPE (ap) on this 610 and see if there's changes since I'm thinking that the problem is in the device itself. 

I'm getting  -91dBm to -92 dBm noise strength from 4 pairs. before the fluctation happened, it gave the same number of -91dbm. 

 

So, noise level can't be ruled out if I understand you correctly, yes? Than it must be a change in RSSI.

 

Of course, it could be the device, but a change of 10dBm (factor 10) is possible indeed if someone deployed a foreign AP in the line between the two CPEs. Even rain can affect signal strength by 3dBm (factor 2) in my experience.

 

hope TPlink will give you a cut as after sales support for their product.

 

Hm, that would be a good idea. smiley Unfortunately, they don't.

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Re:SNR dropped from 25 to 13dB
2020-05-05 14:17:15

@R1D2 

 

 

 

 

 

Of course, it could be the device, but a change of 10dBm (factor 10) is possible indeed if someone deployed a foreign AP in the line between the two CPEs.

 

 

 

 

 

this is what I'm also thinking. even signal jammer is in my list but that is illegal here in Philippines.

 

i'm also thinking that someone put up an AP in between and affects my signal. I tried to change different channel but still no help.
 

i remember that I experienced two APs in same pole with the same channel messed up my connection. SNR is still the same of 24dB but i'm receaving poor connection, lots of time out and can't send bandwith higher than 5mbps. I change channel and make it different for two CPEs and that's fix the problem. 

my point is I am aware that that i need to change channel base on situation.

while I'm writing this, I thought of how about turning of the other CPE and let this CPE with issue to be the only one functioning... I will try it tomorrow. although, from the start before the problem happened, the two CPE shared the same pole and still no problem with 24dB SNR as long as set in different channels.while I'm also writing this I thought and remember (too difficult for me to write in english so I thought of many things while writing haha) that I have read one of your post here in TP link and you used two CPE510, do you placed it in one pole or two poles? 

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#5
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Re:SNR dropped from 25 to 13dB-Solution
2020-05-05 22:11:25 - last edited 2020-05-07 08:27:28

 

NAJIV wrote


that I have read one of your post here in TP link and you used two CPE510, do you placed it in one pole or two poles? 

 

Yes, I used the same pole (you cartainly are referring to this story, there is a photograph of the pole). But on the remote site, I placed the CPEs in about 7 meters distance of each other, since there had been interferences. We found out this distance by trial and error, which is easier for CPE510 than for a CPE610 I guess.

 

What you probably can do to avoid a foreign AP in the line between the two CPE610 is to find another place to mount the CPE610 (some meters apart can make a difference, that also might help with two CPEs at the same pole as noted above).

 

If I remember correctly, MikroTik produced a shield to be placed between two neighboring APs to reduce interference. Maybe this is an additional measure which could help you to reach the former SNR.

 

 

 

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
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Re:SNR dropped from 25 to 13dB
2020-05-07 06:29:08 - last edited 2020-05-07 08:27:26

@R1D2 

 

 

thanks for your replies every since.

 

 

I did everything, including turning off the other AP and still nothing. I should be satisfied with with 17 SNR. on my next project I will consider other brands. can I have a recommendation with almost the same price as TP links product?  

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#7
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Re:SNR dropped from 25 to 13dB-Solution
2020-05-07 07:39:05 - last edited 2020-05-07 08:27:20

 

NAJIV wrote

I did everything, including turning off the other AP and still nothing. I should be satisfied with with 17 SNR. on my next project I will consider other brands. can I have a recommendation with almost the same price as TP links product?  

 

No, I didn't search for other brands of similar devices since we changed to the 24 (twenty-four) GHz band for long range directional links anyway. This band is almost unpopulated right now and even requires no DFS/TPC, albeit in my country one must register with the regulatory authority to deploy such a link permanently. But devices operating in this band are pretty expensive b/c of the advanced technology they use (full-duplex, near-zero latency, wireless Gigabit bandwidth using special antenna arrays).

 

Our second use case with small-range directional links (up to a few hundred meters) is now handled with EAP225-Outdoor mesh systems, which offer AC1200 in the same price class as Pharos N300 devices.

 

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
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#8
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Re:SNR dropped from 25 to 13dB
2020-05-07 07:53:40

@R1D2 

 

i have AC1200, and it didn't work for me. I even reviewed that AP in my blog because of my disappointment especially when it comes to price. 

Whoa that's 24.. 

again thank you. for your help. I wouldn't have such knowledge without you sharing tips. 

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