We are using DFS on PMP450 for customer access and AF5XHD for backhauls. It works surprisingly well. On both the PMP450 and AF5XHD's you can set an alternative freq and a secondary alternative for the radios to immediately jump to if they detect RADAR. Radios will try the first alt freq and if they get a hit on that will then go to the second freq. It should happen instantly without taking the link down. If you do not set the alt freqs the radios will shutdown for 30 minutes and then attempt to use that freq again. I have noticed that the wider the channels you use the more "susceptible" you are yo getting a radar event. Try running on 20mhz channels and you wont get as many hits if any. We have some AP's that have been running for 6 months+ without any radar hits. We are also not anywhere near any airports so that may be helping us as well.
On Thu, Nov 21, 2019 at 12:42 PM Matt Hoppes < mattli...@rivervalleyinternet.net> wrote: > You do. > > On 11/21/19 12:27 PM, Adam Moffett wrote: > > There might be something I don't understand, but I thought you had flat > > EIRP limit of +30dbm whether it's an SM or an AP. > > > > On 11/21/2019 12:11 PM, castarritt . wrote: > >> 6 dBm loss for the AP transmit isn't the end of the world. It's the up > >> to 23 dBm loss on the SM transmit power that destroys the > >> usefulness of DFS for PTMP past a couple miles. The ~16 dBi gain 90° > >> sectors 2-300' up in the air just can't hear those SMs over all the > >> noise they are picking up. What we need is the ability to run > >> downlink on DFS and uplink on 5.2 or 5.8. > >> > >> > >> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett <dmmoff...@gmail.com > >> <mailto:dmmoff...@gmail.com>> wrote: > >> > >> Yeah I think on most equipment you can set alternate channels that > >> are just shifted over 5mhz from where you were. And yeah I think > >> the channel needs to be clear for a few minutes before you can go > >> back to it. > >> > >> Assuming you don't really have a TDWR near you, I don't think DFS > >> events are that big of a deal. My understanding is that DFS > >> events are more likely if you lie to the software about antenna > >> gain to cheat the EIRP limit. False detects happen, but I don't > >> think it's a daily event. Disclaimer: I've mostly used it on > >> Point to point with dishes. I'm not sure if you'd pick up more > >> anomolies on a sector antenna. > >> > >> The biggest bummer is the EIRP limit. When you're trying to get > >> that 32 SNR for the 256QAM then losing 6db kind of hurts. Or when > >> you've already got someone hooked up 10 miles away and lowering > >> the power ruins them. > >> > >> Where you really want to use DFS (In my opinion) is at a site > >> where you have a bunch of customers within 1-2 miles. > >> Unfortunately I don't have sites like that. > >> > >> -Adam > >> > >> > >> > >> On 11/21/2019 11:31 AM, Ken Hohhof wrote: > >>> > >>> We mostly avoid DFS frequencies on APs because of the impact if > >>> we get false radar detects. Also we are mostly a Cambium shop. > >>> So I’m a bit confused about DFS on other vendor equipment like > >>> Ubiquiti as well as home routers. > >>> > >>> Question 1 – what happens when there’s a DFS detection? On the > >>> Cambium gear, we have to select 1 or 2 alternate frequencies. > >>> But on other gear, I don’t see this. When there’s a DFS hit, > >>> does it jump to another random frequency? Does it rescan the > >>> current frequency until it tests clear and only then resume > >>> transmission? Is the answer right in front of me and I’m being > >>> stupid? Maybe in the case of routers they are exempt because of > >>> low EIRP? > >>> > >>> Question 2 – what about 40/80/160 MHz channels? We have a > >>> competitor using Ubiquiti gear and advertising residential > >>> subscriber speed plans up to 100x100. Clearly they must be using > >>> at least 40 MHz channels if not 80 MHz, or else their marketing > >>> people have burning pants and long noses. And I don’t see how a > >>> WISP, especially one surrounded by other WISPs, could use wide > >>> channels other than in DFS bands. We have some PTP links using > >>> 40 MHz but only 10 and 20 MHz channels on our APs. So assuming > >>> you are using 40 or 80 MHz in DFS, what happens when there’s a > >>> DFS detect? Does the whole 40 or 80 MHz have to find a new > >>> home? Can it slide over 2.5 or 5 MHz and substantially overlap > >>> the previous occupied spectrum? DFS bands come with enough > >>> spectrum to use wide channels, but is there enough to jump around > >>> when you take a DFS hit? > >>> > >>> > >> -- > >> AF mailing list > >> AF@af.afmug.com <mailto:AF@af.afmug.com> > >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com > >> > >> > > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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