My 4G setup/project

This a discussion place for anything.
swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Thu Nov 29, 2018 10:07 am

oh, wow I feel real stupid. Apparently, there's a one gigabit version of this PoE splitter that I was not aware of. Guess I'll be ordering that today!!!

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Sat Dec 08, 2018 4:21 pm

Thought I'd post an update on my antenna situation, as it is very interesting (It can also save you a lot of headaches, so its worth your time to probably read the whole story)

TL;DR: My original antenna was never bad, I was actually experiencing, what must have been, a multi-path fade, that caused the signal on my top highest (connected to my main port on my modem) antenna to have 8-10 less dbm, then the lower antenna. I fixed this issue, by moving my antenna mount up 3-5 inches.

Long Version:

A short recap, before I explain what happened yesterday. A week after I installed my setup permanently outside, it rained for the first time. After it rained, I noticed that the signal strength on the top (main) antenna dropped by 8-10dbm. It seems to fluctuate at that point from about 6-10dbm less than my lower, secondary antenna (that was hooked up to my aux port on my modem). I immediately suspect that i had got some water in my antenna cables. I did some research and learned quickly that I did my waterproofing sub-par (you can read about that in previous posts). I re-did the waterproofing, but the signal strength on the top antenna still did not get much better. I suspect that I had some kind of permanent damage, so I went to test my theory, and while doing so accidentally broke the pigtail on the main (bad) antenna. I had used too much coaxial seal, and had bent it too much while attempting to disconnect it. I still swapped the cable assembly from the main (supposedly bad anntenna) to confirm that it was the antenna and not the cable. I swapped it to the known "good" antenna, and the signal stats stayed the same, so I assumed it was a bad antenna, and got it RMA'd.

Fast forward to yesterday.

I received my replacement antenna, and with all my excitement, and eagerness to fix it, I went to install it. I unpackaged it, and went up on the roof and installed it, and discovered to my dismay that the signal stats were about the same. This time about 8dbm lower than the bottom antenna!!!! what the heck. I was so confused. I thought I had isolated the issue to the antenna itself, but now I was second guessing my self. I started to think, what else could it be? I then proceed to try and re-oriented my antenna from a vertical position (for vertical polarization) to horizontal, like the bottom one. This made the signal a little bit stronger (about 2dbm), but not a major improvement. I also tried aiming the antennas in a different position, to see if aiming them directly at the tower, wasn't having the desired effect. None of that made much of a difference. I did find that the bottom antenna got better signal in some positions, but the top one was still bad. Finally, I decided to raise my "bad" top antenna up a little higher, to see if that made a difference? I was running out of options at this point, and just grasping at straws, to be honest. I had originally separated the antennas by 2 wavelengths for 1.9ghz (band 2), which is about 12 inches. I moved it up about 3-5 inches, and BOOM, I suddenly had a 10dbm stronger signal on that top antenna. In fact it was so strong, it was better than my bottom one, which I had previously viewed as good. I'm 99% sure I was experiencing a destructive multipath fade. What I find most interesting is that it persisted for so long, and at that particular point on the antenna mast. Another interesting fact, unrelated, is today we are experiencing a snow/rain/ice storm, and now my bottom antenna is about 8-10dbm less signal than the top, so weather conditions can have a big impact on your signal strengths (especially at this frequency range). It seems though that this particular location was just a multipath fade, that has lasted for weeks. I didn't have this issue when I first put them up, but all the leaves have fallen since I did that, which likely made a big difference (in a negative way in this case). If you notice a big signal difference between your main and diversity antenna, I recommend playing around with the location to see if that makes a difference. If it just lasts a day or two, its probably just a weather impact, but if it lasts for a long period of time, moving the antenna around can make a big difference (well in my case it made a 10 fold power increase!) Anyways, here's some links I recommend on reading about fading.

https://en.m.wikipedia.org/wiki/Fading

http://www.sharetechnote.com/html/Handb ... ading.html

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Sat Dec 08, 2018 4:22 pm

Oh, and also, I got the PoE gigabit splitter then realized my netgate firewall is still only 100mbps interfaces (its pretty old).

dohhhh, guess I'll have to upgrade my firewall if I'm ever going to get over 100mbps down on my 4G connection.

User avatar
JimHelms
Site Admin
Posts: 893
Joined: Tue Dec 19, 2017 8:59 pm
Location: DFW Texas
Contact:

Re: My 4G setup/project

Post by JimHelms » Tue Dec 11, 2018 7:46 am

It is strange how a few inches can make such a difference. I would have never thought the fix would be that simple.

Here is a chart for Bands and wave lengths for those interested:
WaveLength.pdf
(115.44 KiB) Downloaded 149 times

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Tue Dec 11, 2018 10:33 am

JimHelms wrote:
Tue Dec 11, 2018 7:46 am
It is strange how a few inches can make such a difference. I would have never thought the fix would be that simple.

Here is a chart for Bands and wave lengths for those interested:

WaveLength.pdf
Yeah, it's really interesting, but in doing more researching on multipath fading I discovered a term called coherence distance. This basically is the space the wave(s) will stay the same. This distance is very short. I'm trying to calculate it for 1.9ghz, but having a hard time figuring out how to do so.

https://en.wikipedia.org/wiki/Coherence_length

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Tue Dec 11, 2018 10:39 am

In other news, this weekend we got about 3 inches of snow and some freezing rain.

The yagis took a beating, but kept working. I was concerned for a while they might get damaged or the connection would go down, but they seem to be okay.

I knew the yagis could be susceptible to snow/ice, but decided to put them up anyways. Be sure to take this into consideration where you live. Flat panels would be much better if you get a lot of snow/ice.

Signal stats while they were covered in some snow/ice (you can compare with signal stats posted in my first post in this thread):
Screen Shot 2018-12-09 at 6.40.47 AM.png
Speed test while covered in snow:
Screen Shot 2018-12-09 at 6.46.27 AM.png
At last but not least, a picture of the yagis while covered in snow/ice (click on the image to get more detail) The nanostation did quite well throughout most of the weather, although the signal stats were effect somewhat, but the link was still very useable. (sorry I don't know why this image preview is sideways, but if you click on the image to expand it, it looks correct).

2018-12-09 07.58.17.jpg

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Tue Dec 11, 2018 6:08 pm

Also, wanted to share a screenshot from my SDR of band 12 from this same tower that I get band 2. You can clearly see in the signal that it is faded towards the lower end of the band.
Screen Shot 2018-12-10 at 9.36.22 AM.png

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Mon Jan 14, 2019 2:17 pm

so it looks like my top antenna is in a deep multi-path fade again. I can still get 65mbps down, but my upload slowed down to 5mbps from about 25-30mbps up.

I might have to get up there and move the antenna again, if it doesn't go away soon. This is a good reason not to lock to one band, as you also get frequency diversity, instead of just antenna diversity on the same frequency (which is helping me right now, but still.)
Screen Shot 2019-01-14 at 10.39.11 AM.png
Screen Shot 2019-01-14 at 10.39.11 AM.png (38.87 KiB) Viewed 2564 times
Top antenna is RxM main one. You can see 15 dbm difference in RSRP which is almost 100 times less than the bottom antenna!

swwifty
Posts: 502
Joined: Thu Aug 30, 2018 8:21 pm
Location: NE GA Mountains

Re: My 4G setup/project

Post by swwifty » Fri Jan 18, 2019 2:31 pm

A follow up to my previous post.

I got up on the roof on Wednesday, in an effort to try to get the top (main) antenna back into an area on the mast that had better signal. Since my antenna mast, is two 5 foot poles connected together, I took the top off that has the yagi antennas on it, and moved it around. At first I didn't notice any difference between the two antennas, but once I let the antennas sit for a few seconds in one spot, the signal stats updated. In a nut shell, the signal varies ALL OVER THE PLACE within a very small area. I saw as low as -102dbm (RSRP) on one antenna, but I did confirm that this is not a water issue on the top antenna. At one point, both antennas had -106 dbm RSRP. I must be getting a lot of reflections and multipath fading going on, through the trees and terrain. If you look at my first post, in this thread, the terrain path makes it seem like this is link is probably a miracle.

In short, I ended up lowering the top antenna about 3 inches (it didn't make any difference, both antennas are about a foot apart now) and I oriented both of the antennas in +/- 45 degrees to try and help with reflections (I previously had them both mounted in horizontal polarization orientation). It does seem that after mounting them in a 45 degree slant (to match the polarization that the cell tower is transmitting at) even though the signal stats aren't stronger, that speeds are much faster. I was able to achieve an upload speed of 20mbps with RSRP at -110dbm, which I don't recall being able to do before. It's clear that the stronger the RSRP is, the faster your download/upload speed will be. Additionally, I swapped the top and bottom antenna on the modem, so the bottom antenna is now the main one (cause right now it has stronger signal) and the top is the secondary. This helps with upload, as it appears that modulation rates are lowered when the main antenna signal is weak for upload (which makes sense).

Logged in this morning, and now the secondary antenna (the top antenna) picked up about 8dbm over night. It's interesting that the fading can change so suddenly, but also be so permanent (this has been an issue on the top antenna for almost a week now).

Current stats:
Screen Shot 2019-01-18 at 2.54.48 PM.png
Screen Shot 2019-01-18 at 2.54.48 PM.png (55.57 KiB) Viewed 2552 times

tonydobbs
Posts: 20
Joined: Sun Feb 10, 2019 12:57 pm

Re: My 4G setup/project

Post by tonydobbs » Sun Feb 10, 2019 1:22 pm

Thank you so much for all the detailed information you've shared! I'm a software developer living in the mountains of CA trying to achieve similar results and am learning a lot from your posts. I currently have a 8dB panel antenna, and am now starting to consider the yagis. Please keep us posted with your latest developments!

Post Reply
  • Similar Topics
    Replies
    Views
    Last post