Steve,
Increasing the clutter resolution greatly increases the processing time/power requirements. It’s not much unlike the data and processing requirements when going to a higher resolution picture or video display. The data size exponentially increases (think like the inverse square law). There are ways to improve this. In the case of radio mobile you can run propagations for multiple sites in the command line batch mode and use more than one processor on the computer. Not easy but possible. Personally I use my GIS software as much as possible to do any heavy lifting before I get to the propagation stage. That software uses the GPU’s on my video card as parallel computing cores. For things like processing LIDAR data or resampling clutter to a higher resolution GIS is the key and processing horsepower is king. The terrain data today is publically available at 10 meter resolution. I will try to attach a very crude white paper I put together many years ago that shows terrain data/resolution in pictures to give a person a better understanding of the topic. Better yet I will just put it in a public dropbox folder and link to the papers. These are very old documents (circa 2005-2006) and I made them back when the only clutter data available was 1 km resolution and BEFORE Radio Mobile had any clutter tuning abilities. https://www.dropbox.com/sh/vp1m3x92uhyg96u/AAD85kuOO6j-lJtsKRi9Y594a?dl=0. These papers in the folder were never made in to anything that is publication quality, I just made them to use as a quick explanation guide using images. The capability and quality of Radio Mobile at the time was not as good as it is today either. Back in those days Roger was always having to listen to me whine and requesting new features….lol Clutter data for the most part is really just used to add additional attenuation to your free space loss calculations in addition to any fade margins you add to the plot that account for variations such as weather and changing of the leaves etc. Good radio propagation practice has you design for your worst case situations (summer time with leaves on the trees etc.) with the fade margins also set to deal with fluctuations in noise floor that still leaves enough signal to noise to make sure you can achieve modulation rates to deliver the speed tier you sold. This fact is going to be required now in your new FCC form 477 reporting. It will no longer be good enough to show you can cover an area, but you must also report the speed you can actually deliver to that area. You can’t claim to deliver 50 meg download if you can’t achieve good enough SNR to get your radios to have that modulation rate. To answer your last question. LIDAR is just going to give you the first echo reflections, not the underlying terrain elevation data. The USGS has already gone through the pain to get the good ground elevation separate from clutter and published that in the National Elevation Dataset (NED). 10 meter resolution is pretty darn good even if you have higher resolution clutter data to overlay on top. Unless you have areas where the slope of the terrain changes drastically in more than 10 meters distance horizontally, the interpolation process does not introduce that much error over the reality of the ground truth. You can however go out and manually survey specific locations and integrate that data through GIS processes if required. For critical and expensive microwave paths that just have to work, this is not out of consideration since you just have to gather ground truth data over that path and not a whole geographic area. Thank You, Brian Webster www.wirelessmapping.com www.Broadband-Mapping.com From: AF [mailto:af-boun...@af.afmug.com] On Behalf Of Steve Jones Sent: Friday, December 06, 2019 12:13 PM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] clutter data and drones Brian, Assuming the software allows you to input your own clutter data, at high resolution, what impact on processing the models is there as the clutter data gets higher in resolution? Are we talking massive percentage? I think im maybe overestimating clutter datas usefulness. I would first need to have accurate topo data that knows what is ground, and what is treetop/building roof. And that data really would need to be at the same, or better resolution than my clutter data. (if my topo data is 30 meter, and my clutter data is 3 meter, my output will be best guess on top of the 30 meter average that may or may not have already included the clutter, depending on when the sampling was done?) Am I misunderstanding clutter data? I had thought it was plotted elevations of clutter, but is it more just regionated averages? if that question makes any sense When the topo data was/is collected, are there mechanisms in play to differentiate terrain from structure/clutter? Say chicago was collected, would it show ground elevation or would it show the rooftop elevations as the average ground elevation? Back to the original query, assuming a guy had a drone with the capability of carrying the equipment and the battery life to not have to constantly recharge. Would a person be able to collect both topo and clutter data, that can differentiate it, and at a fine detail. What kind of data size is that information? I know that the data available to radio mobile in the day could be downloaded over dialup given some time, so it didnt seem to be overly massive. On Fri, Dec 6, 2019 at 9:07 AM Brian Webster <i...@wirelessmapping.com> 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] 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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