So I replied to part of your comment in my last email... I had another phone call with the customer and Cambium together. In deference to Cambium and the customer, as we work through these issues I won't go into a lot of details, but this definitely seems to me like there's a good chance that this is going to result in an improvement to a lot of the things which we're whining about in the thread. If my suspicions are true about the mechanism at work here, I could see where many of described misbehaviors of DFS would neatly be described by this. And no, thankfully, this doesn't seem to be a PacketFlux-specific issue, although I can see how questionable sync out of any device might trigger this...
On Mon, Jul 13, 2020 at 8:37 AM Eric Muehleisen <ericm...@gmail.com> wrote: > DFS has been a major pain since 15.x. Setting the configuration parameters > correctly does not make any difference in DFS false positives. We have a > site that once DFS triggers, it will continue to trigger over and over > again until you power cycle it. Even then, that is only a temporary fix > until another DFS event happens. I understand that Cambium must conform to > FCC standards but their DFS algorithm is overly sensitive for sure. I don't > believe it matters what sync device you have, DFS will trigger regardless. > We've had DFS troubles with CTM's, RackInjectors, CMM4's and uGPS. > > Forest, we also have GPS issues similar to Mark's. RackInjector with > junior syncbox. AP's will randomly switch sync sources. This doesn't happen > on AP's with CTM2's on the same site. I would really like to see the > RackInjector provide a temporarily generated sync pulse on the event that > GPS actually does fail. This would prevent SM's from re-registering. > > On Mon, Jul 13, 2020 at 8:44 AM dave <dmilho...@wletc.com> wrote: > >> >> DFS can occur with reflections as well as self interference. Weather >> conditions can adverserly affect this. >> All things RF for radio config must be set for correct operation IE TX >> pwer and Antenna Gains all must be entered to >> reflect correct operating levels before a Reflection or interference >> issue can be determined. >> >> >> On 7/13/20 6:56 AM, Mark Radabaugh wrote: >> >> Forrest, >> >> As usual there are probably multiple issues going on. We have seen an >> increase in the number of DFS hits recently, and we also have a lot of >> Packetflux timing equipment on the network. I have noticed that DFS hits >> tend to be worse in ‘unusual’ hot weather conditions. And we have >> certainly seen a pretty unusual heat wave over the last few weeks. I’m not >> sure if this is just heat changing sensitivity of the DFS detections >> (temperature is involved in the RF calibration), if there is more >> reflection off the ionosphere in these weather conditions, or if the >> weather radar systems are just really jacking up power looking for storms. >> >> >> As far as timing - I do think there is some timing instability going on >> but I can’t pin it down to anything specific. We continue to struggle >> with RackInjectors losing the GPS timing signal from the Syncbox Basic >> during or after storm events. Typical symptom in the RackInjector fails >> to see sync from the syncbox and the AP’s go into freerun. Sat’s in view, >> etc. all look normal, just no pulses. Sometimes a power cycle from the >> RackInjector will fix it, sometimes physically unplugging it will fix it, >> and sometimes you just have to wait. I have instructed the field crews >> multiple times to make absolutely sure they screw in every screw tight on >> the syncbox but I’m not 100% sure they are doing that. I have seen at >> least one come back to the shop with evidence of water damage to the GPS >> board at the top. I would really like to see the extra step of conformal >> coating on the boards if there isn’t a reliable way of keeping water off of >> them. >> >> We have also been seeing an unusual number of LBT issues with the 3.65 >> gear which I believe are related to other AP’s drifting or briefly going >> off timing. >> >> Due to the number of times we were seeing loss of sync we had to enable >> sync + freerun in order to avoid session resets. I’m not convinced that >> we are not still seeing timing jumps due to the sequence of loss of sync, >> into freerun, then an abrupt change in framing when sync comes back. Any >> time something like that happens it tends to cause a wave of DFS and LBT >> events across the network. I can’t necessarily show anything specific at >> this point though. We do get a lot of archived and searchable logging >> from our Sumologic syslog server. I’m going to ask the NOC to put >> together a report of AP’s reporting timing recovery and any correlation >> with DFS or LBT events within a 60 second window and see what we get. >> >> Mark >> >> On Jul 13, 2020, at 3:19 AM, Forrest Christian (List Account) < >> li...@packetflux.com> wrote: >> >> I need to be a bit clearer in that I'm not really sure what version this >> customer is running. The question about 15.x /16.x came from a couple of >> oldish threads which indicated that something broke early in 15, and that >> it still wasn't fixed in 16. But I found that unlikely to still be the >> case another year or two on. In these year-and-a-bit old threads, the >> report was that one had to go back to very early in 15.x to "fix" this >> issue. But like I've said before in this paragraph - I find this unlikely >> to still be the case - I just was hoping to verify that this wasn't a >> common knowledge issue that DFS was broken on 16.x. >> >> I know this customer has been in contact with Cambium. Based on our >> conversations with the customer so far, I get the impression that for some >> reason they've decided this is a sync issue. I don't know if this is a >> customer determination or if Cambium has told them this. I like your word >> dubious as I'm skeptical as well, but I'm also not one to dismiss a >> possible cause until I fully rule it out, as they could be 100% correct. >> >> I could see where if you have an AP with sync broken intermittently >> (especially if you have freerun on), you might end up with a DFS event as a >> result of things just not being in sync. But I have reason to believe >> this isn't the case with any of their AP's - at least not the ones I have >> seen the GPS status screen on the RackInjector for. >> >> I could also see where a stray pulse or two may be misinterpreted by the >> AP to be the correct alignment and have the same effect with causing AP to >> transmit out of sync as well. But generally, the radios should ignore >> these as they're very rare (and exist in both the PacketFlux and official >> Cambium gear, so if it's a problem with mine, it should be a problem with >> the official gear as well). >> >> And I agree with you 100% about a dislike for DFS. I have a feeling that >> this customer isn't going to help me change my opinion. >> >> >> On Sun, Jul 12, 2020 at 8:23 PM Ken Hohhof <af...@kwisp.com> wrote: >> >>> I am unaware of any correlation between DFS events and either Packetflux >>> or 15.x FW. >>> >>> >>> >>> I don’t use a lot of DFS because honestly it seems fussy no matter >>> what. But I have a tower with 10 sectors in 5 GHz (8 x 450i and 2 x >>> 450m). They are all synced from a Packetflux Rackinjector using Cambium >>> Sync. 4 of the 450i sectors are in 5.4 DFS, and I’m embarrassed to find >>> they are still on 15.2 FW. Uptime of about 6 months and no DFS events. So >>> I’m dubious about all of this. >>> >>> >>> >>> The latest production FW is 16.2.1 and it also has a lot of fixes so I’m >>> not sure why you would be running something so far behind. As I said, I’m >>> embarrassed to find I still have radios on 15.2. >>> >>> >>> >>> Has he opened a case with Cambium support? There are some best >>> practices with DFS. For sure you don’t want to configure the AP to think >>> the antenna gain is lower than it is (not possible with 450m or integrated >>> 450i). You don’t want to set the SM Receive Target Level higher than >>> necessary on other sectors. Then there’s choosing the alternate >>> frequencies. And I suppose a poor sync configuration could cause false DFS >>> detections, where an AP sees the signal from an adjacent AP. >>> >>> >>> >>> But who knows what causes these events? Somebody’s Linksys reflected >>> off a bird? A competitor aiming a new radio? I used to have a 5.4 GHz >>> PTP500 backhaul and the end pointed in the general direction of Chicago >>> would have DFS events when there were storms. I thought ducting was >>> causing it to see distant signals, but it could also have been tripped by >>> lightning. DFS is fussy. I don’t like it. If I could swap out all the >>> SMs on those DFS sectors for 450b, I would probably move them to U-NII-1. >>> >>> >>> >>> >>> >>> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Forrest Christian >>> (List Account) >>> *Sent:* Sunday, July 12, 2020 7:56 PM >>> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >>> *Subject:* Re: [AFMUG] 450i/450m DFS false detect problem solved in >>> later firmware? >>> >>> >>> >>> I read the 16.0.1 release notes, nothing really specific about DFS other >>> than it being on when it shouldn't be. However, I agree there is lots of >>> stuff fixed in there, some of which could have repercussions for DFS. >>> >>> >>> >>> Are you saying that mid to late 15.x was generally broken for DFS and >>> this is largely fixed in 16.x? I guess my real question should have been >>> 'What is the state of DFS in the 450 platform and how fussy is it'? >>> >>> >>> >>> I'm still gathering information from this customer but it sounds like >>> they're still trying to track down the root cause. Sometime in the past >>> week or so they figured out that there was some correlation between the DFS >>> events adding a fair bit of PacketFlux gear, so this correlation is now the >>> leading root cause in their minds. So now I get to try to resolve their >>> problem for them. >>> >>> >>> >>> >>> >>> >>> >>> On Sun, Jul 12, 2020 at 3:00 PM Dave <dmilho...@wletc.com> wrote: >>> >>> If they are not running 16.0.1 nuthing can help them from some weird >>> issues with the DFS bands. >>> >>> Lots of things corrected in 15.2 and later for EIRP and SNR related >>> calculations the help with H/V misreads and A/B channel alignments. >>> >>> Read the release notes in 16.0.1 for further info. >>> >>> >>> >>> On 7/11/2020 3:12 AM, Forrest Christian (List Account) wrote: >>> >>> I'm working with a customer that is having problems with DFS false hits >>> who is convinced this is a PacketFlux sync issue. I'm never one to say it >>> definitively isn't my problem, but I'm skeptical in this case. >>> >>> >>> >>> I know that at some point in the past that anything beyond 15.0.2 was >>> known to have fairly common DFS issues by some customers. I thought this >>> was resolved in later releases, but I also don't see any mention of said >>> issue being resolved in any release notes post 15.0.02. >>> >>> >>> >>> I was wondering if anyone knew the current status? I.E. if they had >>> been seeing the problem previously, and then discovered it was fixed. Or >>> have tried recent releases and discovered the problem still exists, etc... >>> >>> >>> >>> -- >>> >>> - Forrest >>> >>> >>> >>> -- >>> AF mailing list >>> AF@af.afmug.com >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>> >>> >>> >>> >>> -- >>> >>> - Forrest >>> -- >>> AF mailing list >>> AF@af.afmug.com >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>> >> >> >> -- >> - Forrest >> -- >> AF mailing list >> 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 >> > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > -- - Forrest
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