That is essentially what CN Heat is doing. It is an obstruction. But this doesn't help with LTE and TVWS where clutter is really not a hard stop.
On Fri, Dec 6, 2019 at 10:48 AM Adam Moffett <dmmoff...@gmail.com> wrote: > There's a simplified solution to the problem of the LIDAR data not telling > you the type or density of the clutter: > > Treat all clutter as a hard stop. > > Before you tell me I'm crazy, consider that in unlicensed bands we're > trying to get 32+ SNR with a hard EIRP limit of +30dbm or +36dbm. Ergo we > need LOS. LIDAR data can't tell us about the nature of the foliage, but it > can tell us the foliage is present and therefore tell us that we don't even > want to hit this location because even if it works it's going to contribute > to sub-optimal sector performance. > > CBRS changes the math, obviously, because EIRP can go to +47 or some > such. In the here and now and for the foreseeable future, that would be an > imperfect, but IMO valid, solution for Part 15 use. > > -Adam > > > On 12/6/2019 10:06 AM, Brian Webster wrote: > > Clutter data in the public domain is mostly 30 meter square resolution. > Cameron has talked about a lot of the issues with the data. Radio Mobile > (and TowerCoverage since it runs on that) has the ability to tune the > cluster classifications a bit. I worked with Roger in implementing that > clutter model. It is not actually part of the Longley Rice propagation > model, what he did at my begging was allow a user to manually edit the > height and density for each clutter class and then the tool assigns a loss > factor per pixel/30 meter square of clutter and then subtracts the sum > total of the clutter loss for the ray being propagated. This is not perfect > but when the cell companies use their expensive propagation tools, they > tune their clutter models for each market by drive testing a known > transmitter with a roving unit and run those drive test results against > what the software thinks the signals should be. In this process they > compare the know clutter classes that were propagated through and it > self-tweaks the loss factors is applies for each clutter class. In radio > mobile you do basically the same thing but without automation. To get it > right you have to go out and measure a lot of your real world signal levels > and manually run propagations until the two match (minus your fade margins > built in to your plots). > > > > This works well if you spend the time, the bigger issue is that the 30 > meter square is assigned just one clutter class code. In general it works > well for free stuff. The reality of knowing about specific tree lines > alongside a house or in urban environments with tree lined streets or in > back years, those individual trees to not get factored in to your > propagation, just the building losses if that building clutter is set to a > height to show as an obstruction(in WISP cases most are not if you are > mounting your antenna on the roof for average suburban clutter). The answer > to this is to have higher resolution clutter. The terrain data used is 10 > meter resolution, meaning there have been hard data points gathered at > least every 10 meters horizontally and interpolated. Some terrain data is > available at 3 meters but that is not as widely available. So the issue > remains how do you get better resolution clutter data. LIDAR can indeed be > used and the best versions are actually driven on the streets and not flown > from the air. As Cameron mentioned however that data still only gives you > the height/size/area where the clutter is. It does not tell you what type > of class that it is and/or what type of RF losses each pixel of that data > should be assigned, plus you are typically only getting the clutter data > from the street facing side. Think of the old movie sets and only seeing > the building face. > > > > Another method of increasing clutter accuracy is to resample the data from > 30 meter pixels down to smaller sized pixels. This has limited benefit. > Mostly this can allow you to take things like tree clutter and trim out the > highway areas and or possibly cut out the trees with specific building data > footprints and assign a different clutter class by pixel. This is very > tedious to do on a large scale and you first have to have other good data > sources to trim or reclassify these smaller pixels properly to a new > clutter class. While all of this gives you a better physical map of what > and where you have clutter down to a more realistic reality, you would then > have to go back and manually recalibrate the tuning because tuning over > larger pixels is an averaging process using the single clutter class. As > you might guess all of this takes time and money. At some point there will > likely be some cool efforts done by others where we can integrate this. For > instance Microsoft released building outline GIS data for the whole country > that they machine learned from aerial imagery. That could be used over > resampled data although if the buildings had tree cover they didn’t get > captured in the first place because they are not visible in the images. > There are other open source projects for things like spectrum sensing on a > Raspberry Pi and software defined radio that if you put enough sensors out > there they might help tune the clutter loss models. > https://electrosense.org/ > > > > > > This is probably way more than you wanted to read about clutter data and > RF propagations but hey I am a geek like that. > > > > Thank You, > > Brian Webster > > www.wirelessmapping.com > > www.Broadband-Mapping.com > > > > *From:* AF [mailto:af-boun...@af.afmug.com <af-boun...@af.afmug.com>] *On > Behalf Of *castarritt . > *Sent:* Thursday, December 05, 2019 4:47 PM > *To:* AnimalFarm Microwave Users Group > *Subject:* Re: [AFMUG] clutter data and drones > > > > Google maps uses some of the 1M resolution LIDAR data. Check out Austin, > TX (maybe most other metro areas as well?) in google, enable "globe view", > and then turn on 3D. Now use left ctrl and drag with the mouse to move > your view angle. This is the data cnHeat and the Google CBRS SAS solution > supposedly use. OT: I wonder if any of the usual suspects are making PC > flight simulators that use this data. > > > > On Thu, Dec 5, 2019 at 3:30 PM Steve Jones <thatoneguyst...@gmail.com> > wrote: > > The issue with publicly available clutter data is it seems old, poor > resolution or inaccurate. If heat is using the same data as linkplanner, > its definitely bunk. > > > > On Thu, Dec 5, 2019 at 3:26 PM Adam Moffett <dmmoff...@gmail.com> wrote: > > Have you looked at CnHeat? > > We're about to do some testing with it here. They mentioned USGS LIDAR as > one of the data sources. Presumably that's blended with other imaging > somehow. > > > > > > On 12/5/2019 4:02 PM, Cameron Crum wrote: > > LIDAR is not clutter specific, it just can't penetrate clutter (it's > light) so clutter ends up looking like terrain. The benefit is that you get > an elevation, the drawback is that you don't know the type of clutter or > how high it is above the terrain. I suppose if you compare the lidar data > against a terrain only DEM, you could extract the clutter height. Here is > the thing... some propagation does penetrate vegetation to some degree, so > if you are talking about frequencies that do, then lidar is not necessarily > a good thing to use as everything ends up looking like an obstruction. You > also need a model that can actually account for clutter (vegetation) > density when talking about how much it will affect the signal. Obviously > leaf types and things like that can have other effects, but I'm unaware of > any model that goes to that depth. While some account for clutter heights > to use diffraction losses and some lump-sum type losses for a given clutter > category, none of the models that are in use in the wisp industry account > for clutter density and there are only a few in existence that do. > > > > You can get high res clutter data (types) from thermal satellite imaging > from one of the geospatial data companies like Terrapin Geographic, or > SPOT. It is surprisingly accurate and is what real prop tools like Planet > use. The downside is no elevations, so you still have user input for that. > Unless you are willing to shell out big bucks, don't bother looking. We are > talking about 10's of thousands for a modestly sized area. The cellcos can > afford it. > > > > On Thu, Dec 5, 2019 at 10:41 AM Adam Moffett <dmmoff...@gmail.com> wrote: > > Interesting. And unfortunately I don't know any more about LIDAR than a > Google Search does. > > > > On 12/5/2019 11:27 AM, Steve Jones wrote: > > Just the SAS administrators will be competitive product. So garbage in > garbage out will really apply. Basic SAS functionality is uniform, but > feature sets will differ. More accurate propagation modeling every night > will be something we benefit from and Im thinking that will be one of the > things they compete against each other with. They didnt say that > specifically, but the second iteration of SAS will be more bigger, > potentially even bigly in its scope. I really thought it was all going to > be modeled after cellco, with a bend toward cellcos overtaking CBRS with > shady handshakes and involuntary roaming agreements, but it appears > winnforum isnt just government lackeys, the people involved have actually > put gear in the air or at least listen to those that have. I think > cantgetright may have been a co-chair of a committee somewhere > > > > Where would a guy who doesnt know what LIDAR is go to find out more about > that clutter data? > > > > On Thu, Dec 5, 2019 at 10:12 AM Adam Moffett <dmmoff...@gmail.com> wrote: > > I think the USGS is making 3D clutter maps with LIDAR. CnHeat is supposed > to use that wherever it's available. > > I haven't heard how that relates to the SAS though. Is this something you > learned from the "450 Lady"? Care to share? > > > > > > On 12/5/2019 10:25 AM, Steve Jones wrote: > > first question is if a guy collects accurate clutter data, can he use it > in any of the propagation tools we use? > > > > second, and this is where you braniacs come in, what equipment would it > take on a drone to collect this data? > > > > IIRC drone limit without FAA is something like 300 feet. would that even > be tall enough to sweep a wide enough path that it wouldnt take 300 battery > charges to do a square mile? > > > > I envision a course plotted drone trip that will fly over with a pilot car > trailing to maintain the required operator LOS. > > If you think about how many miles youve put on verifying link paths over > the years, its not really a prohibitive thing. > > > > CBRS and SAS is whats driving this query, but general propagation > anomalies creates quite a pickle that better accuracy/resolution clutter > accuracy would alleviate. > > > > Please tell me there is already a consortium thats built out a clutter > standard with a clutter submission mechanism, that would completely tickle > me silly. > > > > I also dont know the impact to the propagation back ends as you increase > the resolution of the data. Im assuming the SAS administrators are running > something a little beefier than Radio Mobile. > > > > I could see this being a lucrative niche market, if there were a way > around the drone operator licensing requirements (though that cost is > pretty minimal). Basically a company builds up a small fleet of drones, > outfitted with the appropriate gear. You create an account, input your > coverage area (or any region) that you want high resolution data for. they > reprogram the course and ship it to you (after collecting the upfront > payment, deposit, and massive liability release) they provide you with a > road course to drive while the drone does its thing, anticipate points of > retrieval for recharge, etc. when its all done, you stick it in the box and > ship it back. would be cooler if the whole thing was transported back and > forth by amazon drones. > > > > If I had a guarantee that the collected data would be useful to the > company, into radio mobile, link planner, towercoverage, and SAS > administrators, its something i could see a fair price tag of 3-10k on it > for our coverage area, and no farmers blasted it out of the sky. > > > > we use clutter data now thats antiquated so it would come with the > understanding that photosynthesis and bulldozers impact accuracy from the > minute its collected. > > > > maybe this data is already out there and i dont know? > > > > > > > > -- > 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 > > -- > 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 >
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