Is the metal of the patch exposed. Even if it is exposed, a thin layer will not lower the frequency that much. If it was .100” thick then you may see a significant change,
Sent from my iPhone > On Jul 22, 2020, at 6:50 PM, Forrest Christian (List Account) > <li...@packetflux.com> wrote: > > > Actually it is a bare ceramic patch antenna. Look at the top, you're seeing > the side view. > > When I got the response last time from the vendor they said they don't > recommend it, and stated several reasons including if I remember correctly > something about changing the dielectric constant in some odd way, detuning > the antenna. We didn't get much farther than that since they didn't have a > good answer about whether this was confined to certain types of coating or > what... > > I haven't heard back from them on whether or not the latest modules or not > have the same issues, but I suspect they likely do. > > On the other hand, it wouldn't surprise me to find that what they're > concerned about isn't going to change the tuning enough to actually make a > difference, and they're just being overly cautious. > > > On Wed, Jul 22, 2020 at 7:02 AM Chuck McCown <ch...@wbmfg.com> wrote: >> I would not expect a thin layer of conformal to bother the antenna in a >> significant way. It might if you were putting it on a bare patch but that >> is not the case here. >> >> Sent from my iPhone >> >>> On Jul 22, 2020, at 6:53 AM, Mark Radabaugh <m...@amplex.net> wrote: >>> >>> >>> >>> I decided to try a conformal coating on the Syncbox to see if it would >>> cause any problems with the GPS and avoid the corrosion issues we have >>> seen. We tested before and after the conformal coating with no detectable >>> impairment to the GPS SNR and signal level. >>> >>> Only about 16 hours so far but throwing a pitcher of water on it and >>> leaving the cover off all night in a rainstorm hasn’t seemed to bother it. >>> The picture didn’t catch the sync light but it’s happily blinking away. >>> There is a lot of silicon grease on/around the RJ45 which looks a bit funny >>> but I can’t conformal coat the jack itself for obvious reasons and I was >>> intending to douse this one with water. I’m sure SNR is bad right now with >>> a blob of water on top of the antenna but it’s picking up enough to stay in >>> lock. >>> >>> Going to leave it like this and give it a couple weeks to see how it holds >>> up, but so far so good. >>> >>> Regarding loss of sync on 450 equipment - on further examination of the >>> logs we are seeing issues with 450 equipment randomly losing sync or >>> switching to free-run and back to sync-over-power across a number of >>> injectors - CMM5, CTM-2, and Rackinjectors. These issues started about >>> the time we started deploying SyncInjectors but it’s really looking like >>> that is coincidental. Data is pointing toward something that changed with >>> the firmware rather than the injector. I have not had time yet to see if >>> it included the older 450 versus 450i yet. >>> >>> Mark >>> >>> <IMG_3364.jpeg> >>> >>>> On Jul 13, 2020, at 10:28 PM, Forrest Christian (List Account) >>>> <li...@packetflux.com> wrote: >>>> >>>> You bring up a few fair, and known, points. I'll respond to at least a >>>> few of them: >>>> >>>> In relation to the water ingress, we've seen enough of these to know it's >>>> at least an occasional issue. Especially in hotter climates, one thing >>>> we've seen is the gasket cracking in the enclosure. I'm also not >>>> completely convinced this isn't a water condensation/surface moisture >>>> issue in damper climates. Our enclosure manufacture just switched the >>>> gasketing material, perhaps as a result of our whining, to something >>>> different. I've also looked at various alternatives for enclosures but >>>> haven't found the right one yet. I thought I had one which would have >>>> been perfect, until I got the $50 per unit quote in quantity. Some days I >>>> miss the pipes, but it was time for them to go from a mostly marketing >>>> perspective. >>>> >>>> I've also looked at the conformal coating in the past, and the challenge >>>> has been that the GPS module manufacture has told us this is a no-no since >>>> it apparently changes the tuning of the GPS patch antenna. I probably >>>> need to re-evaluate this now that there's a different patch antenna on the >>>> new modules - but I expect a similar answer. >>>> >>>> For the past couple of years, I've been trying to move to a module flat on >>>> the board and then either using a PCB antenna like is used in devices like >>>> cell phones, where the antenna's pattern is such that mounting it flat on >>>> vertically oriented PCB results in a vertical pattern like the patch has. >>>> This should solve the water getting on the antenna issue, as there won't >>>> be anything directly below the seam to leak on. The holdup has been me >>>> trying to possibly move to a module with a different GPS chipset at the >>>> same time, hoping that this would be better than our existing module. >>>> With all the warts (some of which will be described below), I'm finding >>>> that the modules/chipset that we're using is actually not that bad in >>>> comparison to some others. I even have had an eval of a 'timing grade' >>>> gps receiver here, which had more failures than the non-timing-grade ones >>>> we're using. I have a few more to qualify, but look for this change in >>>> coming months assuming I can find a suitable module and antenna which >>>> works. >>>> >>>> In relation to the random timing loss of lock, I am not going to disagree >>>> with you at all. I suspect some of this might be leftovers from the >>>> GPS+GLONASS issue from the end of the year which seems to have resolved >>>> itself for the most part, but I know enough about that bug that it >>>> wouldn't shock me to find that there are still lingering issues. The >>>> problem here is that although it 'feels' like there might be more issues, >>>> I don't have quantifiable numbers. With all of that in mind, I'm >>>> currently working on in-field upgrade procedures for upgrading the >>>> firmware for these modules to get them the GLONASS fix. This seems to be >>>> a more troublesome problem than it should be, since it's just an issue of >>>> getting the right firmware - the problem being that the company who built >>>> the firmware for these got gobbled and the successor company tends to be >>>> more difficult to work with. I have firmware which does work on the >>>> modules, it just isn't an official build by the manufacturer. >>>> >>>> Around the end of the year, we did switch our basics to a newer module, >>>> based on the same chipset. The Basics shipped since then default to >>>> GPS+GALILEO. Recently we've been using this module in Aux Port and >>>> Deluxes, but with GPS+GLONASS+Fixed-Glonass firmware since the Cambium >>>> firmware doesn't understand (yet) the Galileo sentences. So anything you >>>> get from us today has this latest chipset in it, and has the GLONASS fix >>>> even if it isn't enabled. I will say that testing and in-field reports >>>> indicates this is even more stable, not sure how much of it is because of >>>> the increased antenna gain, and how much of it is due to the updated >>>> firmware, or how much is just a side effect of having a lot more of the >>>> older units in the field having customers report problems on. I know at >>>> least some of it is measurable on the bench here, so it isn't all based on >>>> field reports. The only downside so far is that we do see an uptick in >>>> DoA's (but still well under 1%). Frustratingly, the DoA's we've gotten >>>> back have somehow resurrected themselves between the field and here, but >>>> thankfully there doesn't seem to be any increased in-field failures that >>>> we can see other than the DoA's. >>>> >>>> To Eric's point about the holdover timer.. I understand the CTM2's had >>>> this functionality built in. Nothing else I'm aware of has had that >>>> except for some our early GPS modules which just produced a pulse no >>>> matter what, and when it could align it it would. This was good in the >>>> early days, not so much nowadays. >>>> >>>> I'm looking at a couple options to implement a holdover. First of all, >>>> assuming the docs are correct, I can tell the GPS modules to produce sync >>>> all the time, or only when they have a 2D lock, or when they have a 3d >>>> lock. Sync all the time can be bad. Especially if you're not >>>> monitoring lock status, since it means that a GPS can be out of lock but >>>> producing sync pulses which are wildly wrong, causing all sorts of issues. >>>> 2d lock can be bad too since it shares similar issues. As a result, >>>> the modules default to '3d lock'. I've been toying with doing something >>>> dynamic in the rackinjector where it is able to dynamically changes the >>>> mode, so it waits until you get 3d lock, and then since it should have a >>>> good position, switches to '2d lock' mode, or maybe even freerun. At the >>>> bare minimum, I probably will allow customers to change the setting >>>> statically if they're willing to deal with the ramifications. >>>> >>>> I have some other ideas I'm cooking up as well, just don't want to say too >>>> much until I'm actually a bit farther down the path. >>>> >>>> >>>> On Mon, Jul 13, 2020 at 5:57 AM Mark Radabaugh <m...@amplex.net> 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 >>>> >>>> >>>> -- >>>> - 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 > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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