Good Morning:
I had an interesting situation as our Inland Empire mesh builds out. Our current hub if you will is a Rocket M2 with a 120 degree sector located atop a water tank at the highest point in town. The majority of nodes looking back at it are NanoStation M2 that are within 2-5 miles of the tank location. One user, approximately 2.5 miles out has a RocketDish M2 pointed back. Until just recently, all were seeing good performance despite a couple spots having less than optimal line of site to the tank.
Last weekend a new node came live, again, a NanoStation M2, located about 7 miles out. We had solid LQ at 100% but junk NLQ dancing anywhere from 0 to 50% completely unusable. Another Nanostation in place confirmed the numbers so we went back to cabling, etc. I adjusted the sector towards the site as I knew it was on the fringe with marginal improvement. Finally the member at this site dropped some cash and put up a RocketDish M2 feeling the distance may have been on the fringe. This made some improvement but only marginal considering the significant increase in gain that the dish provides. This link actually has the best line of site of any existing node so should be the best overall connection, at least in theory. The system is running channel -2 at 10mhz. Any ideas that we might dig into this weekend? An interesting note too is that other links now appear to be suffering a bit as well. I do have a second 120 sector prepared for deployment at the tank providing 240 degree coverage. This should happen within the next two weeks.
Thanks,
Keith
I had an interesting situation as our Inland Empire mesh builds out. Our current hub if you will is a Rocket M2 with a 120 degree sector located atop a water tank at the highest point in town. The majority of nodes looking back at it are NanoStation M2 that are within 2-5 miles of the tank location. One user, approximately 2.5 miles out has a RocketDish M2 pointed back. Until just recently, all were seeing good performance despite a couple spots having less than optimal line of site to the tank.
Last weekend a new node came live, again, a NanoStation M2, located about 7 miles out. We had solid LQ at 100% but junk NLQ dancing anywhere from 0 to 50% completely unusable. Another Nanostation in place confirmed the numbers so we went back to cabling, etc. I adjusted the sector towards the site as I knew it was on the fringe with marginal improvement. Finally the member at this site dropped some cash and put up a RocketDish M2 feeling the distance may have been on the fringe. This made some improvement but only marginal considering the significant increase in gain that the dish provides. This link actually has the best line of site of any existing node so should be the best overall connection, at least in theory. The system is running channel -2 at 10mhz. Any ideas that we might dig into this weekend? An interesting note too is that other links now appear to be suffering a bit as well. I do have a second 120 sector prepared for deployment at the tank providing 240 degree coverage. This should happen within the next two weeks.
Thanks,
Keith
Next item is to check if your overdriving central node with all the signals. A high LQ means the link is good on its own, the low NLQ means the "Central" node is having trouble hearing you, this could be because all the NanoStations at 2-3 miles are drowning out the farther node,or more likely the Rocket Dish at 2.5 miles away is beaming full RF power into the node the node may be backing down its receiver pre-amp to maintain quality of the signal. Make sure this node isn't thrashing the frontend and have it back down its power if needed.
As for "Ubiquiti" being more sensitive to the Distance parameter, the code we use is used across devices, don't expect this to be different for one device over another, the distance parameter does need to be set correctly (its better long vs short, too long and it slows down a bit, too short and you thrash the RF, go for long over short always)
How strong should we liit the signals? Using Charts, we could adjust as needed.
Bob W8ERD
I did change channels to-1 on all but the most near-field rocket dish and saw some gains but do still notice fluctuations from day to night.
you need to separate the channels. You cant have 2 radios on the same ch at the same site, like that. Try placing the the dish on -1 and set the distance properly. technical you should have 20mhz spacing between the channels, that difficult to get on -2 , -1 , 0. you could go to ch 0. There was just a post about how it was done on 5ghz were we have more spectrum.
you will need to DTD link the nodes, you will not need a Vlan switch, just plug them into each other.
[Edited to correct.]
The "O" in "OFDM" modulation was designed so that we can have adjacent channels with really good mitigated interference. Now, this will certainly break down if you have 2 unshielded transmitters 5" apart at the site in near field. However, the San Diego folks just tested on Sunday to show that there was no detectable impact on ch -2 @ 5 Mhz when running a 2nd node on ch -1 @ 5 Mhz on the same tower--it can be done--Rockets with 120 degree unshielded Sectors.
Put this into context that a channel has 64 individual modulated carriers. There's already built in null guard carriers between channels. The design of the symbol timing and spacing of the carriers in the channel has a nulled-out interference pattern between carriers (this is what is expected of 'orthogonal' signals). Cutting the bandwidth in half is still using 64 carriers, but the symbol length is doubled and spacing cut in half to archive Orthogonality. With 2 adjacent signals from different transmitters are received, the power and phases will not be identical between signals to be orthogonal, but the additional digital pass filters and null carriers are a built in gap between channels. This is why OFDM is taking over as the dominate modulate for digital communications. It is the best know efficient use of bandwidth.
The more RF shielding, directionality of the antenna, the closer you can get the nodes on the tower and not have impact with adjacent channels. It's more a question of how close is too close vs. one should never do.
Joe AE6XE
In know it's hard to believe. I'm the one who has been championing guard channels to separate collocated devices. Conrad, KG6JEI, and I conducted the test Joe describes, I wouldn't have believed it, if I hadn't seen it for myself. It's also contrary to advice I've been given by respected WISP technicians and on the UBNT forum.
This is good news though. It means we have more channels available to us at a single site if we remember to keep adjacent channel devices configured to the same bandwidth.
Now I'll need to go back and edit my earlier posts to the contrary.
Andre, K6AH
What type of throughput was achieved with the -1 and -2 operating at 5mhz? would it be acceptable for the last 1-5 mile links?
I did split channels at the repeater site where I have a link node pointing down at my repeater radio building. Ultimately this will become a DTD but have to run some conduit and do some trenching first. I have -2 on the sector at 10mhz with a dtd to a nanostattion running low power pointed at my repeater 100' below. I did notice some improvement after doing this though not what I would have hoped for.
i will provide an update after tweaking other settings as suggested. Keep the thoughts coming and many thanks!
Keith