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<body><div>Greg,</div><div><br></div><div>Did you get my email expressing interest in helping you?</div><div><br></div><div>regards</div><div>Simon</div><div>On Fri, 25 May 2012 18:59:21 +1000, Greg Evans <ggpevans@yahoo.com.au> wrote:<br></div><br><blockquote style="margin: 0 0 0.80ex; border-left: #0000FF 2px solid; padding-left: 1ex"><table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td valign="top" style="font: inherit;"><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">MAny thanks to those who can help. I have attached a word based doc to ease the reading. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Hello, my name is Greg and in years past I use to work as a Radio Communication Engineer. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">My background is in Electrical and Electronic engineering, not computer science and I am a little stuck. I was wondering if someone can help answer my Comsci questions. The problem is described below. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">As an engineer doing Radio Communications the task is to determine coverage and other Radio Communication attributes such as intermods and other things such as harmonic interference. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">In the process of doing the job, you start with a transmitter located at an x-y point. </font>
</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Then you give that x-y point a transmitting height and power level. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font size="3"><font face="Times New Roman">This Tx power level and height, enables distinct points in a closed geographical rectangle or circle, to have its field/strength (F/S) determined at each point.<span style="mso-spacerun: yes"> </span></font></font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">To determine field strength (F/S), you use different power levels, along with different Tx heights and different computer propagation models to find the F/S. These F/S results are graphically displayed (over maps) </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Once the field strength is determined, the second step is called Carrier-To-interference (C/I). If you have two sites close to each other, if they are on the same frequency, the two signals can interfere, degrading either or both of the signals. But sometimes they don’t. eg. Place your new TX site behind a mountain. The mountain shields the two systems from interfering with each other. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Anyway, for C/I calculations, you can pick an x-y point (in a region) and subtract the field strength (from each TX source). Eg. At an x-y point between the two Tx’s, you subtract F/S1 – F/S2. or Vice Versa. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Again computer propagation models are needed to determine F/S, which then allows for the determination of C/I. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">If the C/I is bad, you have to re-site the new Tx site location and start again. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">It has been a while since doing radio communications but I remember that the maps had DEM’s associated with it. Ie. Different maps for different DEM’s. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I am not the expert when it comes to GIS systems and geographic systems. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">From memory you site a TX point, then the program took the DEM (value) across each point (in a region specified by a map) and then for each point, use it as a distance parameter into Radio propagation models, which determines the field strength (F/S) at each point. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I cant remember whether the smaller DEM gives different field strength results compared to a larger DEM being used. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">From memory I think you get different field strengths for different DEM Maps. I am not sure if this is correct. What I do know is that a smaller DEM (for a given area) takes longer to compute than using a larger DEM. The smaller DEM might give the same F/S results but takes ages to compute. I am not sure if this is correct. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Ie. The smaller the DEM, the smaller the “distance parameter” between two points, which takes longer to compute all the F/S at each point. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Further, for a smaller DEM, this means over a given area, there is more Field strength points to calculate. But either model yields good results, only if the propagation model is correct. The size of the DEM determines time to compute. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">The larger the DEM model, the less points there are in a given area, meaning it takes less time to compute compared to smaller DEM’s, but the results at a large DEM, may give false information. The resolution of parameters is poor.</font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">This is the crux of the problem. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I have been reading about the GRASS GIS systems and PostGIS. I believe I can create a better computerised model than that being used at regulators based on GIS concepts.</font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Unfortunately I cant test these systems (on a computer) at the moment. But to save time I am asking some questions. If you can help, I would really appreciate it. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I don’t understand Vectors and Rasters w.r.t GIS systems at the moment, I will learn it later. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">What I intend to do is create a new Radio Communications Tool that is web based. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Ie. get all the Maps and layers and display them in a web-page served by a Web based server. Then write models that will take a specified point eg. A transmitter, along with a DEM to figure out the Field Strength and Carrier-to-Interference all done through a web-browser. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I call this application a Web-RADCOM-GIS tool. (WRG - Web based radio communications)</font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">This would be good for groups of Radio Communications engineers. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Instead of paying $100,000 for software crippled by dongles and other means, the idea is that the radio communications engineers (or anyone else interested in radio communications, eg HAM radio people). can see F/S results, displayed in a browser window, without any money laid down.</font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">The limit of users is limitless. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Instead, the idea is that they can log into a mapserver using a browser, see different layers and do different vector (and raster) operations to determine radio calculations (eg. F/S and C/I). </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">This new webserver GIS system, could even be extended to planning mobile Base Station sites. The better the modelling tool, the better the mobile coverage and interference modelling, meaning less RF spectrum is wasted. The better the Mobile Phone models get done, the less of mobile base stations need to be deployed, meaning less RF energy bumping around near buildings. In other words, making more out of less. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">The less base stations, the less rent paid for building housing the base station antennas. For Example. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Anyway having a web-based GIS system allows for heaps of group-work. Instead of buying the DEM maps and installing them on each PC (in the group), all they have to do is reference different DEM maps through a MAP server, inside a browser. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I have seen this in action. It takes ages to change the Maps on heaps of PC. And similarly if the computer propagation models change, it is effortless to change. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I intent to make this paid for or free for use, this way anyone on the planet can model and investigate different Radio Communication attributes. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Moreover, more everyday people get a chance to see Radio communications. It gives uses who need a frequency allocation (a channel to operate on) a chance to design them using the tool. Then all the FCC has to do is check their results. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Previously in <st1:country-region w:st="on"><st1:place w:st="on">Australia</st1:place></st1:country-region> the regulators do all the calculations and frequency allocation. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Anyway going back to the RADCOM tool. I saw a screen shot showing height profiles (in a GRASS window). This is exactly what is needed to determine Field Strength. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">I am not sure if I am right, I figure for web page based system, one can use PHP to generate SQL statements, which puts data into either a postgreSQL system or postGIS systems. Then similarly, use PHP and SQL to extract data from the PostGRE or PostGIS and display it on a web-page in a browser. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Even better save the results (as a dataset) and print the F/S or C/I results. Going a step further overlay the results over a census collection district, for example. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">The crux of this, leaves me wondering. To make this Radcom tool faster, you should in theory change the way the system computes. Specifically, I am looking at changing either or both, {PostGIS) or (postgre sql) to be re-done in assembly language. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Assembly is orders of magnitude faster. I am unsure whether the performance increase comes from coding PostGIS or PostgreSQL in assembly. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Your advice on whether to code PostGIS or PostGRE in assembly this is keenly sought. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">The second thing is that in theory for a web based app, I would have to redo all the menu (and window forms) in PHP? Could you please advise of any books that are good on these topics. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman" size="3">Thankyou for your time and help on these matters. </font>
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</p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><o:p><font face="Times New Roman" size="3"> </font></o:p></p></td></tr></tbody></table></blockquote><br><br><br><div id="M2Signature"><div>-- </div><div>Holder of "2011 Oracle Spatial Excellence Award for Education and Research."<br>SpatialDB Advice and Design, Solutions Architecture and Programming,<br>Oracle Database 10g Administrator Certified Associate; Oracle Database 10g SQL Certified Professional<br>Oracle Spatial, SQL Server, PostGIS, MySQL, ArcSDE, Manifold GIS, FME, Radius Topology and Studio Specialist.<br>39 Cliff View Drive, Allens Rivulet, 7150, Tasmania, Australia.<br>Website: www.spatialdbadvisor.com<br> Email: simon@spatialdbadvisor.com<br> Voice: +61 362 396397<br>Mobile: +61 418 396391<br>Skype: sggreener<br>Longitude: 147.20515 (147° 12' 18" E)<br>Latitude: -43.01530 (43° 00' 55" S)<br>GeoHash: r22em9r98wg<br>NAC:W80CK 7SWP3</div></div></body></html>