# 4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 1 Geographic Information Processing Terrain Mapping and Analysis Contour map after Gaussian filtering.

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4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 1 Geographic Information Processing Terrain Mapping and Analysis Contour map after Gaussian filtering Malvern Quadrangle USGS DEM Data

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 2 Topographic Cross-Sections Slice through topography normal to earth Data are typically Gaussian filtered Bearing between endpoints is selected Vertical axis plots the height along the surface-projected path [m] Horizontal axis plots horizontal distance along the path between endpoints [km]

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 3 Problem: Inter-Township Radio Path Determine if Line-of-Site radio transmission is possible between two specified points. –Locate points on topography –Map path between points and check –Make vertical cross-section along path –Determine height of required antennas for clear path

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 4 Example: Radio Beam Path Endpoints [Township buildings]: –Upper Uwclan Twp, Chester County, PA –East Nantmeal Twp, Chester County, PA Path displays [Downingtown Quadrangle]: –Elevation –Topographic –Cross-section

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 5 Elevation Displays Elevation Map with PathTopographic Map with Path [20-meter contours]

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 6 Cross-Section of Path Cross-section along Path [Distance in kilometers, Height in meters]

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 7 Comment Clear transmission will require a 10-meter mast at the low end, so that signal can clear the first hill. There are other (Fresnel) effects that would also indicate the necessity of the mast. Antenna beam angle will be critical, in order for signal pass between the two hills

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 8 Example: Radio Beam Path Endpoints: –Bucktown Mountain, Chester County, PA –Phoenixville, Chester County, PA Path displays: –Pottstown, Phoenixville, Downingtown, and Malvern quadrangles –Elevation –Cross-section

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 9 Endpoint Specifications (* Bucktown antenna tower *) ptBlat = 40.188341; ptBlon = 75.682048; (* Phoenixville School *) ptAlat = 40.118889; ptAlon = 75.510278;

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 10 Radio Beam Path 15 x 15 – minute plot showing desired transmission path on Pottstown, Phoenixville, Downingtown, and Malvern quadrangles

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 11 Path Programming (* Locate, get, and mark heights on path *) For[i = 0, i < aLon + 1, i++, ii = lonptB + i; jj = latptB + Round[i*slope]; height[i] = y[[jj, ii]]; d[jj, ii] = 0; y[[jj, ii]] = 0; ] (* Plot cross-section *) (* Scale x-Axis to kilometers *) xDist = 10.6742*(aLon - 1)/450.0; yDist = 13.8793*(aLat - 1)/450.0; lDist = Sqrt[xDist^2 + yDist^2]; (* Plot Height Data in meters *) ListPlot[Table[height[dst], {dst, aLon}], DataRange -> {0, lDist}, AxesOrigin -> {0.0, 120.0}]

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 12 Radio Path - No Interference Path cross-section - No interfering landscape

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 13 Comments Four quadrangles needed for path plot No interfering landscape features on path Radio transmission should be good This proved correct in field tests

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 14 Example: Emergency Radio Path Determine if Line-of-Site radio transmission is possible between Town Hall of flooded town and Shelter in school. –Locate points on topography –Map path between points and check –Make vertical cross-section along path –Determine height of required antennas for clear path

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 15 Endpoint Specifications (* Locate Yardley Borough Hall: Point A *) ptAlat = 40.241359; ptAlon = 74.837337; (* Locate Wm Penn School: Point B *) ptBlat = 40.21119; ptBlon = 74.834717;

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 16 West Trenton Radio Path Upper point is Yardley, PA Borough Hall (Flood area) Lower Point is WmPenn School (Shelter area) Line is is radio path attempted

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 17 West Trenton Contour Plot Contour path indicates possible interference from hills

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 18 Radio Path with Interference

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 19 Comments Transmission and reception sites will require very elevated antennas for a direct path Possible use of elevated repeater to relay through another site may be preferable. (In fact, this was done.)

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 20 Endpoint Specifications (* Locate Yardley Borough Hall: Point A *) ptAlat = 40.241359; ptAlon = -74.837337; (* Locate Repeater: Point B *) ptBlat = 40.190000; ptBlon = -74.844722;

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 21 Repeater Radio Path Upper point is Yardley, PA Borough Hall (Flood area) Lower Point is Repeater near Shelter area Line is is radio path attempted

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 22 Repeater Path Contour Plot Contour path indicates possible interference from hills

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 23 Radio Path with Antenna

4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 24 Comments Transmission and reception sites will probably be adequate, with some diffraction Use of elevated repeater to relay through another site is feasible. Yardley antenna may need gain and power of at least 5 Watts

Flat Terrain Propagation http://www.agc.army.mil/operations/progra ms/LOS/20040418/5- SRTM%20DTED%202%20brief.ppthttp://www.agc.army.mil/operations/progra ms/LOS/20040418/5- SRTM%20DTED%202%20brief.ppt 4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 25

Questions 4/20/2015© 2009 Raymond P. Jefferis III Lect 08 - 26

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