We have setup a mountaintop node on channel -2(2.397ghz), and it has been working great for the last several weeks. Today all of a sudden the LNQ dropped on all the connected nodes, and I can hardly get a connection good enough to view any status pages. I did manage to get in to the setup, and reboot the node, but the problem still remains the same. When the node first went up, we didnt have this problem. We had several people connecting @ 100%LQ and 100%NLQ. Now every connected node is showing less than 25% LNQ. From my QTH I am also connected to another mountaintop node 20 miles away, and it seems solid with low ping response.
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You did not show what the signal levels are. But if they are OK, then I would look at distance settings. If you added-on a station and his distance setting is too small for his actual RF coverage, it can trash the quality everyone else's connections.
I totally agree that the Distance setting is critical.
Correct me I'm wrong but the Distance value is only viewable after logging into a node via root/password. If the Distance value was viewable by anyone, it may be possible for folks on the network to spot Distance issues and get feedback to the node owner of the likely issue. Right now it is just a guess for nodes that folks do not have login ability. Sounds like this should be a FEATURE REQUEST.
- Mike ab4yy
Did somone back down the TX power of the node?
Its odd that everyone on the ground is having trouble hearing it, as that would (usually) mean a wide area problem which I would think the mountain top would hear as well if it's noise based.
Did someone bring up a node with high TX power aimed at "ground" nodes (aka most RF going towards them jamming where the mountain node might not hear the noise because it's shielded)
As far as the TX Power, it has not been touched... I will have to just watch it. Our plan is to add some backbone links via 5ghz, then tilt the mountaintop nodes down to not pickup faraway nodes(and maybe less noise). We are still in the building phase of our network.
KE2N,
I read your comments which brought up fond memories of times past. Just a few thoughts here...
I used to run a 24/7 link from my home in Woodland Hills to Mt. Wilson, a 28 mile path. This was the control link for the WA6TDD repeater. The transmit dish was a 6-footer with 1.25 watts going into it using a klystron, and the receive dish was a 4-footer.
I was able to watch from home the signal strength in real-time as received at Mt. Wilson. Normally the signal would wander up and down about 2 to 3 dB and all of a sudden take a 6-10 dB drop and come right back up. I had plenty of fade margin so this wasn't a problem. But, every once in a while the signal would momentarily drop about 30 to 40 dB and come right back up and although I rarely lost the link, and if I did, it was only for about a second or less. Rainy or cloudy days was not so much of a problem, but clear warm days with inversion, it could be a problem. The dishes were properly aligned - not on side lobes. This is a pretty long path for 5-6 GHz and is subject to super-refraction and what's called de-coupling. The degree of severity can vary depending on the terrain over which the signal is traveling. This is the same thing that causes distant lights to twinkle; the "ray" of light coming towards you is momentarily deflected, or bent away from you. This same problem is why you will often see two dishes in a diversity system over long hauls in commercial systems. To partially resolve the problem you might try using antennas with a fatter lobe. This will result in lower signal levels, but they may be more reliable.
I finally reversed the dishes and put the 4-foot dish at the transmit end to get a fatter "beam" (lobe) and the 6-foot dish at the receive end. This improved the situation quite a bit, but didn't totally eliminate it.
How much time resolution do you have in the history files of the system?
A buddy of mine has been running a 5 GHz Rocket system using approximately 4-foot dishes on each end over a 31 mile path across desert terrain for a radio station's audio and control for about a year now, and there have been no reports of dropouts or hiccups. I'm totally amazed.
I now live in Glendale, about 14 line of site miles from Mt. Wilson and am thinking of putting up a Ubiquity 5 GHz link between my home and the mountain. This is what led me to the AREDN site about a year ago. I would like to use 4-foot dishes, not so much for gain, but for the sake of beamwidth and as "blinders" from other signals being seen at the mountain which overlooks most of Los Angeles.
Thanks for reading all of this.
Burt, K6OQK
Burt, K6OQK
Just in case, the eastern part of Glendora is covered by 5ghz and connects into the area mesh down to Orange County, check out these 2 links:
Node Settings to connect: http://mesh.w6jpl.ampr.org:8080/jpl-mesh-nodes.html
Coverage Map: https://drive.google.com/open?id=0B2bEy75HhwWhMUZ3bklsZ0ZYcjg
With these 802.11 radios, it can be misleading on tracking SNR. The radios keep getting smarter. At first, everything was fixed with modulation, frequency, antenna count, power, error correction bits, etc. The design necessitated handling the worst possible conditions for the environment (and then new interference from someone would suddenly knock the link out :) ). Today, these radios dynamically test and use every possible combination of all these options--for every neighbor. Consequently, things like SNR can be different by ~10dB just by the radio using different options to adapt to the environment.
Let's say that an inversion layer comes in, the radio might drop link rate a notch and increase SNR to compensation--would be noticed given a max data thoughput drop. As link rate increases, these radios start dropping xmit power to keep linearity in the PA. Although every new generation hardware will make this less and less of an issue.
You are the 3rd person I'm aware of looking to or already putting up mesh equipment on Mt Wilson. There's a live 2.4Ghz Bullet on ch -2 plugged into a 4'+ fixed dish pointing south right now--opportunity and unused dish sort of thing. Don, KE6BXT, and I were connecting to it from a residential street in Pasadena last month. I think we left it on 5Mhz channel width for anyone that wants to stick up a node to see if they can hear it--just need to be on a line of sight between there and long beach (or out in your boat farther out :) ).
We're getting off topic, so let's create another thread if desire to further dialog on this local topic.
Joe AE6XE
NLQ in your case is how well the lower/remote nodes hear the "mountain" so you are looking at the graphs from the wrong side.
(NLQ is always "how well the other side hears me" and LQ is always "how well do I hear my neighbor")