1 SPLAT!(1) KD2BD Software SPLAT!(1)
6 splat An RF Signal Propagation, Loss, And Terrain analysis tool
9 splat [-t transmitter_site.qth] [-r receiver_site.qth] [-c rx antenna
10 height for LOS coverage analysis (feet/meters) (float)] [-L rx antenna
11 height for Longley-Rice coverage analysis (feet/meters) (float)] [-p
12 terrain_profile.ext] [-e elevation_profile.ext] [-h height_profile.ext]
13 [-H normalized_height_profile.ext] [-l Longley-Rice_profile.ext] [-o
14 topographic_map_filename.ppm] [-b cartographic_boundary_filename.dat]
15 [-s site/city_database.dat] [-d sdf_directory_path] [-m earth radius
16 multiplier (float)] [-f frequency (MHz) for Fresnel zone calculations
17 (float)] [-R maximum coverage radius (miles/kilometers) (float)] [-dB
18 threshold beyond which contours will not be displayed] [-gc ground
19 clutter height (feet/meters) (float)] [-fz Fresnel zone clearance per-
20 centage (default = 60)] [-ano alphanumeric output file name] [-ani
21 alphanumeric input file name] [-udt user_defined_terrain_file.dat] [-n]
22 [-N] [-nf] [-dbm] [-ngs] [-geo] [-kml] [-gpsav] [-metric]
25 SPLAT! is a powerful terrestrial RF propagation and terrain analysis
26 tool for the spectrum between 20 MHz and 20 GHz. SPLAT! is free soft-
27 ware, and is designed for operation on Unix and Linux-based worksta-
28 tions. Redistribution and/or modification is permitted under the terms
29 of the GNU General Public License, Version 2, as published by the Free
30 Software Foundation. Adoption of SPLAT! source code in proprietary or
31 closed-source applications is a violation of this license and is
34 SPLAT! is distributed in the hope that it will be useful, but WITHOUT
35 ANY WARRANTY, without even the implied warranty of MERCHANTABILITY or
36 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
40 Applications of SPLAT! include the visualization, design, and link bud-
41 get analysis of wireless Wide Area Networks (WANs), commercial and ama-
42 teur radio communication systems above 20 MHz, microwave links, fre-
43 quency coordination and interference studies, and the prediction of
44 analog and digital terrestrial radio and television contour regions.
46 SPLAT! provides RF site engineering data such as great circle distances
47 and bearings between sites, antenna elevation angles (uptilt), depres-
48 sion angles (downtilt), antenna height above mean sea level, antenna
49 height above average terrain, bearings, distances, and elevations to
50 known obstructions, Longley-Rice path attenuation, and received signal
51 strength. In addition, the minimum antenna height requirements needed
52 to clear terrain, the first Fresnel zone, and any user-definable per-
53 centage of the first Fresnel zone are also provided.
55 SPLAT! produces reports, graphs, and high resolution topographic maps
56 that depict line-of-sight paths, and regional path loss and signal
57 strength contours through which expected coverage areas of transmitters
58 and repeater systems can be obtained. When performing line-of-sight
59 and Longley-Rice analyses in situations where multiple transmitter or
60 repeater sites are employed, SPLAT! determines individual and mutual
61 areas of coverage within the network specified.
64 SPLAT! is a command-line driven application and reads input data
65 through a number of data files. Some files are mandatory for success-
66 ful execution of the program, while others are optional. Mandatory
67 files include digital elevation topography models in the form of SPLAT
68 Data Files (SDF files), site location files (QTH files), and Longley-
69 Rice model parameter files (LRP files). Optional files include city
70 location files, cartographic boundary files, user-defined terrain
71 files, path loss input files, antenna radiation pattern files, and
72 color definition files.
75 SPLAT! imports topographic data in the form of SPLAT Data Files (SDFs).
76 These files may be generated from a number of information sources. In
77 the United States, SPLAT Data Files can be generated through U.S. Geo-
78 logical Survey Digital Elevation Models (DEMs) using the postdownload
79 and usgs2sdf utilities included with SPLAT!. USGS Digital Elevation
80 Models compatible with these utilities may be downloaded from:
81 http://edcftp.cr.usgs.gov/pub/data/DEM/250/.
83 Significantly better resolution and accuracy can be obtained through
84 the use of SRTM Version 2 digital elevation models, especially when
85 supplemented by USGS-derived SDF data. These one-degree by one-degree
86 models are the product of the Space Shuttle STS-99 Radar Topography
87 Mission, and are available for most populated regions of the Earth.
88 SPLAT Data Files may be generated from 3 arc-second SRTM-3 data using
89 the included srtm2sdf utility. SRTM-3 Version 2 data may be obtained
90 through anonymous FTP from: ftp://e0srp01u.ecs.nasa.gov:21/srtm/ver-
93 Note that SRTM filenames refer to the latitude and longitude of the
94 southwest corner of the topographic dataset contained within the file.
95 Therefore, the region of interest must lie north and east of the lati-
96 tude and longitude provided in the SRTM filename.
98 The srtm2sdf utility may also be used to convert 3-arc second SRTM data
99 in Band Interleaved by Line (.BIL) format for use with SPLAT!. This
100 data is available via the web at: http://seamless.usgs.gov/web-
103 Band Interleaved by Line data must be downloaded in a very specific
104 manner to be compatible with srtm2sdf and SPLAT!. Please consult
105 srtm2sdf's documentation for instructions on downloading .BIL topo-
106 graphic data through the USGS's Seamless Web Site.
108 Even greater resolution and accuracy can be obtained by using 1 arc-
109 second SRTM-1 Version 2 topography data. This data is available for
110 the United States and its territories and possessions, and may be down-
111 loaded from: ftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/SRTM1/
113 High resolution SDF files for use with SPLAT! HD may be generated from
114 data in this format using the srtm2sdf-hd utility.
116 Despite the higher accuracy that SRTM data has to offer, some voids in
117 the data sets exist. When voids are detected, the srtm2sdf and
118 srtm2sdf-hd utilities replace them with corresponding data found in
119 usgs2sdf generated SDF files. If USGS-derived SDF data is not avail-
120 able, voids are handled through adjacent pixel averaging, or direct
123 SPLAT Data Files contain integer value topographic elevations in meters
124 referenced to mean sea level for 1-degree by 1-degree regions of the
125 Earth. SDF files can be read by SPLAT! in either standard format
126 (.sdf) as generated directly by the usgs2sdf, srtm2sdf, and srtm2sdf-hd
127 utilities, or in bzip2 compressed format (.sdf.bz2). Since uncom-
128 pressed files can be read slightly faster than files that have been
129 compressed, SPLAT! searches for needed SDF data in uncompressed format
130 first. If uncompressed data cannot be located, SPLAT! then searches
131 for data in bzip2 compressed format. If no compressed SDF files can be
132 found for the region requested, SPLAT! assumes the region is over
133 water, and will assign an elevation of sea-level to these areas.
135 This feature of SPLAT! makes it possible to perform path analysis not
136 only over land, but also between coastal areas not represented by Digi-
137 tal Elevation Model data. However, this behavior of SPLAT! under-
138 scores the importance of having all the SDF files required for the
139 region being analyzed if meaningful results are to be expected.
141 SITE LOCATION (QTH) FILES
142 SPLAT! imports site location information of transmitter and receiver
143 sites analyzed by the program from ASCII files having a .qth extension.
144 QTH files contain the site's name, the site's latitude (positive if
145 North of the equator, negative if South), the site's longitude (in
146 degrees West, 0 to 360 degrees, or degrees East 0 to -360 degrees), and
147 the site's antenna height above ground level (AGL), each separated by a
148 single line-feed character. The antenna height is assumed to be speci-
149 fied in feet unless followed by the letter m or the word meters in
150 either upper or lower case. Latitude and longitude information may be
151 expressed in either decimal format (74.6864) or degree, minute, second
152 (DMS) format (74 41 11.0).
154 For example, a site location file describing television station WNJT-
155 DT, Trenton, NJ (wnjt-dt.qth) might read as follows:
162 Each transmitter and receiver site analyzed by SPLAT! must be repre-
163 sented by its own site location (QTH) file.
165 LONGLEY-RICE PARAMETER (LRP) FILES
166 Longley-Rice parameter data files are required for SPLAT! to determine
167 RF path loss, field strength, or received signal power level in either
168 point-to-point or area prediction mode. Longley-Rice model parameter
169 data is read from files having the same base name as the transmitter
170 site QTH file, but with a .lrp extension. SPLAT! LRP files share the
171 following format (wnjt-dt.lrp):
173 15.000 ; Earth Dielectric Constant (Relative permittivity)
174 0.005 ; Earth Conductivity (Siemens per meter)
175 301.000 ; Atmospheric Bending Constant (N-units)
176 647.000 ; Frequency in MHz (20 MHz to 20 GHz)
177 5 ; Radio Climate (5 = Continental Temperate)
178 0 ; Polarization (0 = Horizontal, 1 = Vertical)
179 0.50 ; Fraction of situations (50% of locations)
180 0.90 ; Fraction of time (90% of the time)
181 46000.0 ; ERP in Watts (optional)
183 If an LRP file corresponding to the tx_site QTH file cannot be found,
184 SPLAT! scans the current working directory for the file "splat.lrp".
185 If this file cannot be found, then default parameters will be assigned
186 by SPLAT! and a corresponding "splat.lrp" file containing these default
187 parameters will be written to the current working directory. The gen-
188 erated "splat.lrp" file can then be edited by the user as needed.
190 Typical Earth dielectric constants and conductivity values are as fol-
192 Dielectric Constant Conductivity
193 Salt water : 80 5.000
194 Good ground : 25 0.020
195 Fresh water : 80 0.010
196 Marshy land : 12 0.007
197 Farmland, forest : 15 0.005
198 Average ground : 15 0.005
199 Mountain, sand : 13 0.002
201 Poor ground : 4 0.001
203 Radio climate codes used by SPLAT! are as follows:
205 1: Equatorial (Congo)
206 2: Continental Subtropical (Sudan)
207 3: Maritime Subtropical (West coast of Africa)
209 5: Continental Temperate
210 6: Maritime Temperate, over land (UK and west coasts of US &
212 7: Maritime Temperate, over sea
214 The Continental Temperate climate is common to large land masses in the
215 temperate zone, such as the United States. For paths shorter than 100
216 km, there is little difference between Continental and Maritime Temper-
219 The seventh and eighth parameters in the .lrp file correspond to the
220 statistical analysis provided by the Longley-Rice model. In this exam-
221 ple, SPLAT! will return the maximum path loss occurring 50% of the time
222 (fraction of time) in 90% of situations (fraction of situations). This
223 is often denoted as F(50,90) in Longley-Rice studies. In the United
224 States, an F(50,90) criteria is typically used for digital television
225 (8-level VSB modulation), while F(50,50) is used for analog (VSB-
228 For further information on these parameters, see: http://flat-
229 top.its.bldrdoc.gov/itm.html and http://www.softwright.com/faq/engi-
230 neering/prop_longley_rice.html
232 The final parameter in the .lrp file corresponds to the transmitter's
233 effective radiated power, and is optional. If it is included in the
234 .lrp file, then SPLAT! will compute received signal strength levels and
235 field strength level contours when performing Longley-Rice studies. If
236 the parameter is omitted, path loss is computed instead. The ERP pro-
237 vided in the .lrp file can be overridden by using SPLAT!'s -erp com-
238 mand-line switch. If the .lrp file contains an ERP parameter and the
239 generation of path loss rather than field strength contours is desired,
240 the ERP can be assigned to zero using the -erp switch without having to
241 edit the .lrp file to accomplish the same result.
244 The names and locations of cities, tower sites, or other points of
245 interest may be imported and plotted on topographic maps generated by
246 SPLAT!. SPLAT! imports the names of cities and locations from ASCII
247 files containing the location of interest's name, latitude, and longi-
248 tude. Each field is separated by a comma. Each record is separated by
249 a single line feed character. As was the case with the .qth files,
250 latitude and longitude information may be entered in either decimal or
251 degree, minute, second (DMS) format.
253 For example (cities.dat):
255 Teaneck, 40.891973, 74.014506
256 Tenafly, 40.919212, 73.955892
257 Teterboro, 40.859511, 74.058908
258 Tinton Falls, 40.279966, 74.093924
259 Toms River, 39.977777, 74.183580
260 Totowa, 40.906160, 74.223310
261 Trenton, 40.219922, 74.754665
263 A total of five separate city data files may be imported at a time, and
264 there is no limit to the size of these files. SPLAT! reads city data
265 on a "first come/first served" basis, and plots only those locations
266 whose annotations do not conflict with annotations of locations read
267 earlier in the current city data file, or in previous files. This
268 behavior minimizes clutter in SPLAT! generated topographic maps, but
269 also mandates that important locations be placed toward the beginning
270 of the first city data file, and locations less important be positioned
271 further down the list or in subsequent data files.
273 City data files may be generated manually using any text editor,
274 imported from other sources, or derived from data available from the
275 U.S. Census Bureau using the citydecoder utility included with SPLAT!.
276 Such data is available free of charge via the Internet at:
277 http://www.census.gov/geo/www/cob/bdy_files.html, and must be in ASCII
280 CARTOGRAPHIC BOUNDARY DATA FILES
281 Cartographic boundary data may also be imported to plot the boundaries
282 of cities, counties, or states on topographic maps generated by SPLAT!.
283 Such data must be of the form of ARC/INFO Ungenerate (ASCII Format)
284 Metadata Cartographic Boundary Files, and are available from the U.S.
285 Census Bureau via the Internet at: http://www.cen-
286 sus.gov/geo/www/cob/co2000.html#ascii and http://www.cen-
287 sus.gov/geo/www/cob/pl2000.html#ascii. A total of five separate carto-
288 graphic boundary files may be imported at a time. It is not necessary
289 to import state boundaries if county boundaries have already been
293 SPLAT! is invoked via the command-line using a series of switches and
294 arguments. Since SPLAT! is a CPU and memory intensive application,
295 this type of interface minimizes overhead and lends itself well to
296 scripted (batch) operations. SPLAT!'s CPU and memory scheduling prior-
297 ity may be modified through the use of the Unix nice command.
299 The number and type of switches passed to SPLAT! determine its mode of
300 operation and method of output data generation. Nearly all of SPLAT!'s
301 switches may be cascaded in any order on the command line when invoking
304 Simply typing splat on the command line will return a summary of
305 SPLAT!'s command line options:
307 --==[ SPLAT! v1.3.0 Available Options... ]==--
309 -t txsite(s).qth (max of 4 with -c, max of 30 with -L)
311 -c plot coverage of TX(s) with an RX antenna at X feet/meters AGL
312 -L plot path loss map of TX based on an RX at X feet/meters AGL
313 -s filename(s) of city/site file(s) to import (5 max)
314 -b filename(s) of cartographic boundary file(s) to import (5 max)
315 -p filename of terrain profile graph to plot
316 -e filename of terrain elevation graph to plot
317 -h filename of terrain height graph to plot
318 -H filename of normalized terrain height graph to plot
319 -l filename of path loss graph to plot
320 -o filename of topographic map to generate (.ppm)
321 -u filename of user-defined terrain file to import
322 -d sdf file directory path (overrides path in ~/.splat_path file)
323 -m earth radius multiplier
324 -n do not plot LOS paths in .ppm maps
325 -N do not produce unnecessary site or obstruction reports
326 -f frequency for Fresnel zone calculation (MHz)
327 -R modify default range for -c or -L (miles/kilometers)
328 -db threshold beyond which contours will not be displayed
329 -nf do not plot Fresnel zones in height plots
330 -fz Fresnel zone clearance percentage (default = 60)
331 -gc ground clutter height (feet/meters)
332 -ngs display greyscale topography as white in .ppm files
333 -erp override ERP in .lrp file (Watts)
334 -ano name of alphanumeric output file
335 -ani name of alphanumeric input file
336 -udt filename of user defined terrain input file
337 -kml generate Google Earth (.kml) compatible output
338 -geo generate an Xastir .geo georeference file (with .ppm output)
339 -dbm plot signal power level contours rather than field strength
340 -gpsav preserve gnuplot temporary working files after SPLAT! execution
341 -metric employ metric rather than imperial units for all user I/O
343 The command-line options for splat and splat-hd are identical.
345 SPLAT! operates in two distinct modes: point-to-point mode, and area
346 prediction mode. Either a line-of-sight (LOS) or Longley-Rice Irregu-
347 lar Terrain (ITM) propagation model may be invoked by the user. True
348 Earth, four-thirds Earth, or any other user-defined Earth radius may be
349 specified when performing line-of-sight analysis.
351 POINT-TO-POINT ANALYSIS
352 SPLAT! may be used to perform line-of-sight terrain analysis between
353 two specified site locations. For example:
355 splat -t tx_site.qth -r rx_site.qth
357 invokes a line-of-sight terrain analysis between the transmitter speci-
358 fied in tx_site.qth and receiver specified in rx_site.qth using a True
359 Earth radius model, and writes a SPLAT! Path Analysis Report to the
360 current working directory. The report contains details of the trans-
361 mitter and receiver sites, and identifies the location of any obstruc-
362 tions detected along the line-of-sight path. If an obstruction can be
363 cleared by raising the receive antenna to a greater altitude, SPLAT!
364 will indicate the minimum antenna height required for a line-of-sight
365 path to exist between the transmitter and receiver locations specified.
366 Note that imperial units (miles, feet) are specified unless the -metric
367 switch is added to SPLAT!'s command line options:
369 splat -t tx_site.qth -r rx_site.qth -metric
371 If the antenna must be raised a significant amount, this determination
372 may take a few moments. Note that the results provided are the minimum
373 necessary for a line-of-sight path to exist, and in the case of this
374 simple example, do not take Fresnel zone clearance requirements into
377 qth extensions are assumed by SPLAT! for QTH files, and are optional
378 when specifying -t and -r arguments on the command-line. SPLAT! auto-
379 matically reads all SPLAT Data Files necessary to conduct the terrain
380 analysis between the sites specified. SPLAT! searches for the
381 required SDF files in the current working directory first. If the
382 needed files are not found, SPLAT! then searches in the path specified
383 by the -d command-line switch:
385 splat -t tx_site -r rx_site -d /cdrom/sdf/
387 An external directory path may be specified by placing a ".splat_path"
388 file under the user's home directory. This file must contain the full
389 directory path of last resort to all the SDF files. The path in the
390 $HOME/.splat_path file must be of the form of a single line of ASCII
395 and can be generated using any text editor.
397 A graph of the terrain profile between the receiver and transmitter
398 locations as a function of distance from the receiver can be generated
399 by adding the -p switch:
401 splat -t tx_site -r rx_site -p terrain_profile.png
403 SPLAT! invokes gnuplot when generating graphs. The filename extension
404 specified to SPLAT! determines the format of the graph produced. .png
405 will produce a 640x480 color PNG graphic file, while .ps or .postscript
406 will produce postscript output. Output in formats such as GIF, Adobe
407 Illustrator, AutoCAD dxf, LaTeX, and many others are available. Please
408 consult gnuplot, and gnuplot's documentation for details on all the
409 supported output formats.
411 A graph of elevations subtended by the terrain between the receiver and
412 transmitter as a function of distance from the receiver can be gener-
413 ated by using the -e switch:
415 splat -t tx_site -r rx_site -e elevation_profile.png
417 The graph produced using this switch illustrates the elevation and
418 depression angles resulting from the terrain between the receiver's
419 location and the transmitter site from the perspective of the
420 receiver's location. A second trace is plotted between the left side
421 of the graph (receiver's location) and the location of the transmitting
422 antenna on the right. This trace illustrates the elevation angle
423 required for a line-of-sight path to exist between the receiver and
424 transmitter locations. If the trace intersects the elevation profile
425 at any point on the graph, then this is an indication that a line-of-
426 sight path does not exist under the conditions given, and the obstruc-
427 tions can be clearly identified on the graph at the point(s) of inter-
430 A graph illustrating terrain height referenced to a line-of-sight path
431 between the transmitter and receiver may be generated using the -h
434 splat -t tx_site -r rx_site -h height_profile.png
436 A terrain height plot normalized to the transmitter and receiver
437 antenna heights can be obtained using the -H switch:
439 splat -t tx_site -r rx_site -H normalized_height_profile.png
441 A contour of the Earth's curvature is also plotted in this mode.
443 The first Fresnel Zone, and 60% of the first Fresnel Zone can be added
444 to height profile graphs by adding the -f switch, and specifying a fre-
445 quency (in MHz) at which the Fresnel Zone should be modeled:
447 splat -t tx_site -r rx_site -f 439.250 -H normalized_height_profile.png
449 Fresnel Zone clearances other 60% can be specified using the -fz switch
452 splat -t tx_site -r rx_site -f 439.250 -fz 75 -H height_profile2.png
454 A graph showing Longley-Rice path loss may be plotted using the -l
457 splat -t tx_site -r rx_site -l path_loss_profile.png
459 As before, adding the -metric switch forces the graphs to be plotted
460 using metric units of measure. The -gpsav switch instructs SPLAT! to
461 preserve (rather than delete) the gnuplot working files generated dur-
462 ing SPLAT! execution, allowing the user to edit these files and re-run
465 When performing a point-to-point analysis, a SPLAT! Path Analysis
466 Report is generated in the form of a text file with a .txt filename
467 extension. The report contains bearings and distances between the
468 transmitter and receiver, as well as the free-space and Longley-Rice
469 path loss for the path being analyzed. The mode of propagation for the
470 path is given as Line-of-Sight, Single Horizon, Double Horizon,
471 Diffraction Dominant, or Troposcatter Dominant.
473 Distances and locations to known obstructions along the path between
474 transmitter and receiver are also provided. If the transmitter's
475 effective radiated power is specified in the transmitter's correspond-
476 ing .lrp file, then predicted signal strength and antenna voltage at
477 the receiving location is also provided in the Path Analysis Report.
479 To determine the signal-to-noise (SNR) ratio at remote location where
480 random Johnson (thermal) noise is the primary limiting factor in recep-
485 where T is the ERP of the transmitter in dBW in the direction of the
486 receiver, NJ is Johnson Noise in dBW (-136 dBW for a 6 MHz television
487 channel), L is the path loss provided by SPLAT! in dB (as a positive
488 number), G is the receive antenna gain in dB over isotropic, and NF is
489 the receiver noise figure in dB.
491 T may be computed as follows:
495 where TI is actual amount of RF power delivered to the transmitting
496 antenna in dBW, GT is the transmitting antenna gain (over isotropic) in
497 the direction of the receiver (or the horizon if the receiver is over
500 To compute how much more signal is available over the minimum to neces-
501 sary to achieve a specific signal-to-noise ratio:
505 where S is the minimum required SNR ratio (15.5 dB for ATSC (8-level
506 VSB) DTV, 42 dB for analog NTSC television).
508 A topographic map may be generated by SPLAT! to visualize the path
509 between the transmitter and receiver sites from yet another perspec-
510 tive. Topographic maps generated by SPLAT! display elevations using a
511 logarithmic grayscale, with higher elevations represented through
512 brighter shades of gray. The dynamic range of the image is scaled
513 between the highest and lowest elevations present in the map. The only
514 exception to this is sea-level, which is represented using the color
517 Topographic output is invoked using the -o switch:
519 splat -t tx_site -r rx_site -o topo_map.ppm
521 The .ppm extension on the output filename is assumed by SPLAT!, and is
524 In this example, topo_map.ppm will illustrate the locations of the
525 transmitter and receiver sites specified. In addition, the great cir-
526 cle path between the two sites will be drawn over locations for which
527 an unobstructed path exists to the transmitter at a receiving antenna
528 height equal to that of the receiver site (specified in rx_site.qth).
530 It may desirable to populate the topographic map with names and loca-
531 tions of cities, tower sites, or other important locations. A city
532 file may be passed to SPLAT! using the -s switch:
534 splat -t tx_site -r rx_site -s cities.dat -o topo_map
536 Up to five separate city files may be passed to SPLAT! at a time fol-
537 lowing the -s switch.
539 County and state boundaries may be added to the map by specifying up to
540 five U.S. Census Bureau cartographic boundary files using the -b
543 splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map
545 In situations where multiple transmitter sites are in use, as many as
546 four site locations may be passed to SPLAT! at a time for analysis:
548 splat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p profile.png
550 In this example, four separate terrain profiles and obstruction reports
551 will be generated by SPLAT!. A single topographic map can be specified
552 using the -o switch, and line-of-sight paths between each transmitter
553 and the receiver site indicated will be produced on the map, each in
554 its own color. The path between the first transmitter specified to the
555 receiver will be in green, the path between the second transmitter and
556 the receiver will be in cyan, the path between the third transmitter
557 and the receiver will be in violet, and the path between the fourth
558 transmitter and the receiver will be in sienna.
560 SPLAT! generated topographic maps are 24-bit TrueColor Portable PixMap
561 (PPM) images. They may be viewed, edited, or converted to other
562 graphic formats by popular image viewing applications such as xv, The
563 GIMP, ImageMagick, and XPaint. PNG format is highly recommended for
564 lossless compressed storage of SPLAT! generated topographic output
565 files. ImageMagick's command-line utility easily converts SPLAT!'s PPM
568 convert splat_map.ppm splat_map.png
570 Another excellent PPM to PNG command-line utility is available at:
571 http://www.libpng.org/pub/png/book/sources.html. As a last resort, PPM
572 files may be compressed using the bzip2 utility, and read directly by
573 The GIMP in this format.
575 The -ngs option assigns all terrain to the color white, and can be used
576 when it is desirable to generate a map that is devoid of terrain:
578 splat -t tx_site -r rx_site -b co34_d00.dat -ngs -o white_map
580 The resulting .ppm image file can be converted to .png format with a
581 transparent background using ImageMagick's convert utility:
583 convert -transparent "#FFFFFF" white_map.ppm transparent_map.png
585 REGIONAL COVERAGE ANALYSIS
586 SPLAT! can analyze a transmitter or repeater site, or network of sites,
587 and predict the regional coverage for each site specified. In this
588 mode, SPLAT! can generate a topographic map displaying the geometric
589 line-of-sight coverage area of the sites based on the location of each
590 site and the height of receive antenna wishing to communicate with the
591 site in question. A regional analysis may be performed by SPLAT! using
592 the -c switch as follows:
594 splat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o tx_coverage
596 In this example, SPLAT! generates a topographic map called tx_cover-
597 age.ppm that illustrates the predicted line-of-sight regional coverage
598 of tx_site to receiving locations having antennas 30.0 feet above
599 ground level (AGL). If the -metric switch is used, the argument fol-
600 lowing the -c switch is interpreted as being in meters rather than in
601 feet. The contents of cities.dat are plotted on the map, as are the
602 cartographic boundaries contained in the file co34_d00.dat.
604 When plotting line-of-sight paths and areas of regional coverage,
605 SPLAT! by default does not account for the effects of atmospheric bend-
606 ing. However, this behavior may be modified by using the Earth radius
607 multiplier (-m) switch:
609 splat -t wnjt-dt -c 30.0 -m 1.333 -s cities.dat -b counties.dat -o
612 An earth radius multiplier of 1.333 instructs SPLAT! to use the "four-
613 thirds earth" model for line-of-sight propagation analysis. Any appro-
614 priate earth radius multiplier may be selected by the user.
616 When performing a regional analysis, SPLAT! generates a site report for
617 each station analyzed. SPLAT! site reports contain details of the
618 site's geographic location, its height above mean sea level, the
619 antenna's height above mean sea level, the antenna's height above aver-
620 age terrain, and the height of the average terrain calculated toward
621 the bearings of 0, 45, 90, 135, 180, 225, 270, and 315 degrees azimuth.
623 DETERMINING MULTIPLE REGIONS OF LOS COVERAGE
624 SPLAT! can also display line-of-sight coverage areas for as many as
625 four separate transmitter sites on a common topographic map. For exam-
628 splat -t site1 site2 site3 site4 -c 10.0 -metric -o network.ppm
630 plots the regional line-of-sight coverage of site1, site2, site3, and
631 site4 based on a receive antenna located 10.0 meters above ground
632 level. A topographic map is then written to the file network.ppm. The
633 line-of-sight coverage area of the transmitters are plotted as follows
634 in the colors indicated (along with their corresponding RGB values in
637 site1: Green (0,255,0)
638 site2: Cyan (0,255,255)
639 site3: Medium Violet (147,112,219)
640 site4: Sienna 1 (255,130,71)
642 site1 + site2: Yellow (255,255,0)
643 site1 + site3: Pink (255,192,203)
644 site1 + site4: Green Yellow (173,255,47)
645 site2 + site3: Orange (255,165,0)
646 site2 + site4: Dark Sea Green 1 (193,255,193)
647 site3 + site4: Dark Turquoise (0,206,209)
649 site1 + site2 + site3: Dark Green (0,100,0)
650 site1 + site2 + site4: Blanched Almond (255,235,205)
651 site1 + site3 + site4: Medium Spring Green (0,250,154)
652 site2 + site3 + site4: Tan (210,180,140)
654 site1 + site2 + site3 + site4: Gold2 (238,201,0)
656 If separate .qth files are generated, each representing a common site
657 location but a different antenna height, a single topographic map
658 illustrating the regional coverage from as many as four separate loca-
659 tions on a single tower may be generated by SPLAT!.
662 If the -c switch is replaced by a -L switch, a Longley-Rice path loss
663 map for a transmitter site may be generated:
665 splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -o path_loss_map
667 In this mode, SPLAT! generates a multi-color map illustrating expected
668 signal levels in areas surrounding the transmitter site. A legend at
669 the bottom of the map correlates each color with a specific path loss
672 The -db switch allows a threshold to be set beyond which contours will
673 not be plotted on the map. For example, if a path loss beyond -140 dB
674 is irrelevant to the survey being conducted, SPLAT!'s path loss plot
675 can be constrained to the region bounded by the 140 dB attenuation con-
678 splat -t wnjt-dt -L 30.0 -s cities.dat -b co34_d00.dat -db 140 -o
681 The path loss contour threshold may be expressed as either a positive
682 or negative quantity.
684 The path loss analysis range may be modified to a user-specific dis-
685 tance using the -R switch. The argument must be given in miles (or
686 kilometers if the -metric switch is used). If a range wider than the
687 generated topographic map is specified, SPLAT! will perform Longley-
688 Rice path loss calculations between all four corners of the area pre-
691 The colors used to illustrate contour regions in SPLAT! generated cov-
692 erage maps may be tailored by the user by creating or modifying
693 SPLAT!'s color definition files. SPLAT! color definition files have
694 the same base name as the transmitter's .qth file, but carry .lcf,
695 .scf, and .dcf extensions. If the necessary file does not exist in the
696 current working when SPLAT! is run, a file containing default color
697 definition parameters that is suitable for manual editing by the user
698 is written into the current directory.
700 When a regional Longley-Rice analysis is performed and the transmit-
701 ter's ERP is not specified or is zero, a .lcf path loss color defini-
702 tion file corresponding to the transmitter site (.qth) is read by
703 SPLAT! from the current working directory. If a .lcf file correspond-
704 ing to the transmitter site is not found, then a default file suitable
705 for manual editing by the user is automatically generated by SPLAT!.
707 A path loss color definition file possesses the following structure
710 ; SPLAT! Auto-generated Path-Loss Color Definition ("wnjt-dt.lcf")
713 ; Format for the parameters held in this file is as follows:
715 ; dB: red, green, blue
717 ; ...where "dB" is the path loss (in dB) and
718 ; "red", "green", and "blue" are the corresponding RGB color
719 ; definitions ranging from 0 to 255 for the region specified.
721 ; The following parameters may be edited and/or expanded
722 ; for future runs of SPLAT! A total of 32 contour regions
723 ; may be defined in this file.
743 If the path loss is less than 80 dB, the color Red (RGB = 255, 0, 0) is
744 assigned to the region. If the path loss is greater than or equal to
745 80 dB, but less than 90 db, then Dark Orange (255, 128, 0) is assigned
746 to the region. Orange (255, 165, 0) is assigned to regions having a
747 path loss greater than or equal to 90 dB, but less than 100 dB, and so
748 on. Greyscale terrain is displayed beyond the 230 dB path loss con-
751 FIELD STRENGTH ANALYSIS
752 If the transmitter's effective radiated power (ERP) is specified in the
753 transmitter's .lrp file, or expressed on the command-line using the
754 -erp switch, field strength contours referenced to decibels over one
755 microvolt per meter (dBuV/m) rather than path loss are produced:
757 splat -t wnjt-dt -L 30.0 -erp 46000 -db 30 -o plot.ppm
759 The -db switch can be used in this mode as before to limit the extent
760 to which field strength contours are plotted. When plotting field
761 strength contours, however, the argument given is interpreted as being
764 SPLAT! field strength color definition files share a very similar
765 structure to .lcf files used for plotting path loss:
767 ; SPLAT! Auto-generated Signal Color Definition ("wnjt-dt.scf") File
769 ; Format for the parameters held in this file is as follows:
771 ; dBuV/m: red, green, blue
773 ; ...where "dBuV/m" is the signal strength (in dBuV/m) and
774 ; "red", "green", and "blue" are the corresponding RGB color
775 ; definitions ranging from 0 to 255 for the region specified.
777 ; The following parameters may be edited and/or expanded
778 ; for future runs of SPLAT! A total of 32 contour regions
779 ; may be defined in this file.
796 If the signal strength is greater than or equal to 128 dB over 1 micro-
797 volt per meter (dBuV/m), the color Red (255, 0, 0) is displayed for the
798 region. If the signal strength is greater than or equal to 118 dBuV/m,
799 but less than 128 dBuV/m, then the color Orange (255, 165, 0) is dis-
800 played, and so on. Greyscale terrain is displayed for regions with
801 signal strengths less than 8 dBuV/m.
803 Signal strength contours for some common VHF and UHF broadcasting ser-
804 vices in the United States are as follows:
809 Analog Television Broadcasting
810 ------------------------------
811 Channels 2-6: City Grade: >= 74 dBuV/m
812 Grade A: >= 68 dBuV/m
813 Grade B: >= 47 dBuV/m
814 --------------------------------------------
815 Channels 7-13: City Grade: >= 77 dBuV/m
816 Grade A: >= 71 dBuV/m
817 Grade B: >= 56 dBuV/m
818 --------------------------------------------
819 Channels 14-69: Indoor Grade: >= 94 dBuV/m
820 City Grade: >= 80 dBuV/m
821 Grade A: >= 74 dBuV/m
822 Grade B: >= 64 dBuV/m
824 Digital Television Broadcasting
825 -------------------------------
826 Channels 2-6: City Grade: >= 35 dBuV/m
827 Service Threshold: >= 28 dBuV/m
828 --------------------------------------------
829 Channels 7-13: City Grade: >= 43 dBuV/m
830 Service Threshold: >= 36 dBuV/m
831 --------------------------------------------
832 Channels 14-69: City Grade: >= 48 dBuV/m
833 Service Threshold: >= 41 dBuV/m
835 NOAA Weather Radio (162.400 - 162.550 MHz)
836 ------------------------------------------
837 Reliable: >= 18 dBuV/m
838 Not reliable: < 18 dBuV/m
839 Unlikely to receive: < 0 dBuV/m
841 FM Radio Broadcasting (88.1 - 107.9 MHz)
842 ----------------------------------------
843 Analog Service Contour: 60 dBuV/m
844 Digital Service Contour: 65 dBuV/m
847 RECEIVED POWER LEVEL ANALYSIS
848 If the transmitter's effective radiated power (ERP) is specified in the
849 transmitter's .lrp file, or expressed on the command-line using the
850 -erp switch, and the -dbm switch is invoked, received power level con-
851 tours referenced to decibels over one milliwatt (dBm) are produced:
853 splat -t wnjt-dt -L 30.0 -erp 46000 -dbm -db -100 -o plot.ppm
855 The -db switch can be used to limit the extent to which received power
856 level contours are plotted. When plotting power level contours, the
857 argument given is interpreted as being expressed in dBm.
859 SPLAT! received power level color definition files share a very similar
860 structure to the color definition files described earlier, except that
861 the power levels in dBm may be either positive or negative, and are
862 limited to a range between +40 dBm and -200 dBm:
864 ; SPLAT! Auto-generated DBM Signal Level Color Definition ("wnjt-
867 ; Format for the parameters held in this file is as follows:
869 ; dBm: red, green, blue
871 ; ...where "dBm" is the received signal power level between +40 dBm
872 ; and -200 dBm, and "red", "green", and "blue" are the corresponding
873 ; RGB color definitions ranging from 0 to 255 for the region speci-
876 ; The following parameters may be edited and/or expanded
877 ; for future runs of SPLAT! A total of 32 contour regions
878 ; may be defined in this file.
899 ANTENNA RADIATION PATTERN PARAMETERS
900 Normalized field voltage patterns for a transmitting antenna's horizon-
901 tal and vertical planes are imported automatically into SPLAT! when a
902 path loss, field strength, or received power level coverage analysis is
903 performed. Antenna pattern data is read from a pair of files having
904 the same base name as the transmitter and LRP files, but with .az and
905 .el extensions for azimuth and elevation pattern files, respectively.
906 Specifications regarding pattern rotation (if any) and mechanical beam
907 tilt and tilt direction (if any) are also contained within SPLAT!
908 antenna pattern files.
910 For example, the first few lines of a SPLAT! azimuth pattern file might
911 appear as follows (kvea.az):
924 The first line of the .az file specifies the amount of azimuthal pat-
925 tern rotation (measured clockwise in degrees from True North) to be
926 applied by SPLAT! to the data contained in the .az file. This is fol-
927 lowed by azimuth headings (0 to 360 degrees) and their associated nor-
928 malized field patterns (0.000 to 1.000) separated by whitespace.
930 The structure of SPLAT! elevation pattern files is slightly different.
931 The first line of the .el file specifies the amount of mechanical beam
932 tilt applied to the antenna. Note that a downward tilt (below the
933 horizon) is expressed as a positive angle, while an upward tilt (above
934 the horizon) is expressed as a negative angle. This data is followed
935 by the azimuthal direction of the tilt, separated by whitespace.
937 The remainder of the file consists of elevation angles and their corre-
938 sponding normalized voltage radiation pattern (0.000 to 1.000) values
939 separated by whitespace. Elevation angles must be specified over a
940 -10.0 to +90.0 degree range. As was the convention with mechanical
941 beamtilt, negative elevation angles are used to represent elevations
942 above the horizon, while positive angles represents elevations below
945 For example, the first few lines a SPLAT! elevation pattern file might
946 appear as follows (kvea.el):
959 In this example, the antenna is mechanically tilted downward 1.1
960 degrees towards an azimuth of 130.0 degrees.
962 For best results, the resolution of azimuth pattern data should be
963 specified to the nearest degree azimuth, and elevation pattern data
964 resolution should be specified to the nearest 0.01 degrees. If the
965 pattern data specified does not reach this level of resolution, SPLAT!
966 will interpolate the values provided to determine the data at the
967 required resolution, although this may result in a loss in accuracy.
969 EXPORTING AND IMPORTING REGIONAL CONTOUR DATA
970 Performing a regional coverage analysis based on a Longley-Rice path
971 analysis can be a very time consuming process, especially if the analy-
972 sis is performed repeatedly to discover what effects changes to a
973 transmitter's antenna radiation pattern make to the predicted coverage
976 This process can be expedited by exporting the contour data produced by
977 SPLAT! to an alphanumeric output (.ano) file. The data contained in
978 this file can then be modified to incorporate antenna pattern effects,
979 and imported back into SPLAT! to quickly produce a revised contour map.
980 Depending on the way in which SPLAT! is invoked, alphanumeric output
981 files can describe regional path loss, signal strength, or received
984 For example, an alphanumeric output file containing path loss informa-
985 tion can be generated by SPLAT! for a receive site 30 feet above ground
986 level over a 50 mile radius surrounding a transmitter site to a maximum
987 path loss of 140 dB (assuming ERP is not specified in the transmitter's
988 .lrp file) using the following syntax:
990 splat -t kvea -L 30.0 -R 50.0 -db 140 -ano pathloss.dat
992 If ERP is specified in the .lrp file or on the command line through the
993 -erp switch, the alphanumeric output file will instead contain pre-
994 dicted field values in dBuV/m. If the -dBm command line switch is
995 used, then the alphanumeric output file will contain receive signal
998 SPLAT! alphanumeric output files can exceed many hundreds of megabytes
999 in size. They contain information relating to the boundaries of the
1000 region they describe followed by latitudes (degrees North), longitudes
1001 (degrees West), azimuths (referenced to True North), elevations (to the
1002 first obstruction), followed by either path loss (in dB), received
1003 field strength (in dBuV/m), or received signal power level (in dBm)
1004 without regard to the transmitting antenna's radiation pattern.
1006 The first few lines of a SPLAT! alphanumeric output file could take on
1007 the following appearance (pathloss.dat):
1009 119, 117 ; max_west, min_west
1010 35, 34 ; max_north, min_north
1011 34.2265424, 118.0631096, 48.199, -32.747, 67.70
1012 34.2270358, 118.0624421, 48.199, -19.161, 73.72
1013 34.2275292, 118.0617747, 48.199, -13.714, 77.24
1014 34.2280226, 118.0611072, 48.199, -10.508, 79.74
1015 34.2290094, 118.0597723, 48.199, -11.806, 83.26 *
1016 34.2295028, 118.0591048, 48.199, -11.806, 135.47 *
1017 34.2299962, 118.0584373, 48.199, -15.358, 137.06 *
1018 34.2304896, 118.0577698, 48.199, -15.358, 149.87 *
1019 34.2314763, 118.0564348, 48.199, -15.358, 154.16 *
1020 34.2319697, 118.0557673, 48.199, -11.806, 153.42 *
1021 34.2324631, 118.0550997, 48.199, -11.806, 137.63 *
1022 34.2329564, 118.0544322, 48.199, -11.806, 139.23 *
1023 34.2339432, 118.0530971, 48.199, -11.806, 139.75 *
1024 34.2344365, 118.0524295, 48.199, -11.806, 151.01 *
1025 34.2349299, 118.0517620, 48.199, -11.806, 147.71 *
1026 34.2354232, 118.0510944, 48.199, -15.358, 159.49 *
1027 34.2364099, 118.0497592, 48.199, -15.358, 151.67 *
1029 Comments can be placed in the file if they are proceeded by a semicolon
1030 character. The vim text editor has proven capable of editing files of
1033 Note as was the case in the antenna pattern files, negative elevation
1034 angles refer to upward tilt (above the horizon), while positive angles
1035 refer to downward tilt (below the horizon). These angles refer to the
1036 elevation to the receiving antenna at the height above ground level
1037 specified using the -L switch if the path between transmitter and
1038 receiver is unobstructed. If the path between the transmitter and
1039 receiver is obstructed, an asterisk (*) is placed on the end of the
1040 line, and the elevation angle returned by SPLAT! refers the elevation
1041 angle to the first obstruction rather than the geographic location
1042 specified on the line. This is done in response to the fact that the
1043 Longley-Rice model considers the energy reaching a distant point over
1044 an obstructed path to be the result of the energy scattered over the
1045 top of the first obstruction along the path. Since energy cannot reach
1046 the obstructed location directly, the actual elevation angle to the
1047 destination over such a path becomes irrelevant.
1049 When modifying SPLAT! path loss files to reflect antenna pattern data,
1050 only the last numeric column should be amended to reflect the antenna's
1051 normalized gain at the azimuth and elevation angles specified in the
1052 file. Programs and scripts capable of performing this task are left as
1053 an exercise for the user.
1055 Modified alphanumeric output files can be imported back into SPLAT!
1056 for generating revised coverage maps provided that the ERP and -dBm
1057 options are used as they were when the alphanumeric output file was
1058 originally generated:
1060 splat -t kvea -ani pathloss.dat -s city.dat -b county.dat -o map.ppm
1062 Note that alphanumeric output files generated by splat cannot be used
1063 with splat-hd, or vice-versa due to the resolution incompatibility
1064 between the two versions of the program. Also, each of the three types
1065 of alphanumeric output files are incompatible with one another, so a
1066 file containing path loss data cannot be imported into SPLAT! to pro-
1067 duce signal strength or received power level contours, etc.
1069 USER-DEFINED TERRAIN INPUT FILES
1070 A user-defined terrain file is a user-generated text file containing
1071 latitudes, longitudes, and heights above ground level of specific ter-
1072 rain features believed to be of importance to the SPLAT! analysis being
1073 conducted, but noticeably absent from the SDF files being used. A
1074 user-defined terrain file is imported into a SPLAT! analysis using the
1077 splat -t tx_site -r rx_site -udt udt_file.txt -o map.ppm
1079 A user-defined terrain file has the following appearance and structure:
1081 40.32180556, 74.1325, 100.0 meters
1082 40.321805, 74.1315, 300.0
1083 40.3218055, 74.1305, 100.0 meters
1085 Terrain height is interpreted as being described in feet above ground
1086 level unless followed by the word meters, and is added on top of the
1087 terrain specified in the SDF data for the locations specified. Be
1088 aware that each user-defined terrain feature specified will be inter-
1089 preted as being 3-arc seconds in both latitude and longitude in splat
1090 and 1 arc-second in latitude and longitude in splat-hd. Features
1091 described in the user-defined terrain file that overlap previously
1092 defined features in the file are ignored by SPLAT! to avoid ambiguity.
1095 The height of ground clutter can be specified using the -gc switch:
1097 splat -t wnjt-dt -r kd2bd -gc 30.0 -H wnjt-dt_path.png
1099 The -gc switch as the effect of raising the overall terrain by the
1100 specified amount in feet (or meters if the -metric switch is invoked),
1101 except over areas at sea-level and at the transmitting and receiving
1102 antenna locations. Note that the addition of ground clutter does not
1103 necessarily modify the Longley-Rice path loss results unless the addi-
1104 tional clutter height results in a switch in the propagation mode from
1105 a less obstructed path to a more obstructed path (from Line Of Sight to
1106 Single Horizon Diffraction Dominant, for example). It does, however,
1107 affect Fresnel zone clearances and line of sight determinations.
1109 SIMPLE TOPOGRAPHIC MAP GENERATION
1110 In certain situations it may be desirable to generate a topographic map
1111 of a region without plotting coverage areas, line-of-sight paths, or
1112 generating obstruction reports. There are several ways of doing this.
1113 If one wishes to generate a topographic map illustrating the location
1114 of a transmitter and receiver site along with a brief text report
1115 describing the locations and distances between the sites, the -n switch
1116 should be invoked as follows:
1118 splat -t tx_site -r rx_site -n -o topo_map.ppm
1120 If no text report is desired, then the -N switch is used:
1122 splat -t tx_site -r rx_site -N -o topo_map.ppm
1124 If a topographic map centered about a single site out to a minimum
1125 specified radius is desired instead, a command similar to the following
1128 splat -t tx_site -R 50.0 -s NJ_Cities -b NJ_Counties -o topo_map.ppm
1130 where -R specifies the minimum radius of the map in miles (or kilome-
1131 ters if the -metric switch is used). Note that the tx_site name and
1132 location are not displayed in this example. If display of this infor-
1133 mation is desired, simply create a SPLAT! city file (-s option) and
1134 append it to the list of command-line options illustrated above.
1136 If the -o switch and output filename are omitted in these operations,
1137 topographic output is written to a file named tx_site.ppm in the cur-
1138 rent working directory by default.
1140 GEOREFERENCE FILE GENERATION
1141 Topographic, coverage (-c), and path loss contour (-L) maps generated
1142 by SPLAT! may be imported into Xastir (X Amateur Station Tracking and
1143 Information Reporting) software by generating a georeference file using
1144 SPLAT!'s -geo switch:
1146 splat -t kd2bd -R 50.0 -s NJ_Cities -b NJ_Counties -geo -o map.ppm
1148 The georeference file generated will have the same base name as the -o
1149 file specified, but have a .geo extension, and permit proper interpre-
1150 tation and display of SPLAT!'s .ppm graphics in Xastir software.
1152 GOOGLE MAP KML FILE GENERATION
1153 Keyhole Markup Language files compatible with Google Earth may be gen-
1154 erated by SPLAT! when performing point-to-point or regional coverage
1155 analyses by invoking the -kml switch:
1157 splat -t wnjt-dt -r kd2bd -kml
1159 The KML file generated will have the same filename structure as a Path
1160 Analysis Report for the transmitter and receiver site names given,
1161 except it will carry a .kml extension.
1163 Once loaded into Google Earth (File --> Open), the KML file will anno-
1164 tate the map display with the names of the transmitter and receiver
1165 site locations. The viewpoint of the image will be from the position
1166 of the transmitter site looking towards the location of the receiver.
1167 The point-to-point path between the sites will be displayed as a white
1168 line while the RF line-of-sight path will be displayed in green.
1169 Google Earth's navigation tools allow the user to "fly" around the
1170 path, identify landmarks, roads, and other featured content.
1172 When performing regional coverage analysis, the .kml file generated by
1173 SPLAT! will permit path loss or signal strength contours to be layered
1174 on top of Google Earth's display in a semi-transparent manner. The
1175 generated .kml file will have the same basename as that of the .ppm
1176 file normally generated.
1178 DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
1179 SPLAT! determines antenna height above average terrain (HAAT) according
1180 to the procedure defined by Federal Communications Commission Part
1181 73.313(d). According to this definition, terrain elevations along
1182 eight radials between 2 and 10 miles (3 and 16 kilometers) from the
1183 site being analyzed are sampled and averaged for each 45 degrees of
1184 azimuth starting with True North. If one or more radials lie entirely
1185 over water or over land outside the United States (areas for which no
1186 USGS topography data is available), then those radials are omitted from
1187 the calculation of average terrain.
1189 Note that SRTM-3 elevation data, unlike older USGS data, extends beyond
1190 the borders of the United States. Therefore, HAAT results may not be
1191 in full compliance with FCC Part 73.313(d) in areas along the borders
1192 of the United States if the SDF files used by SPLAT! are SRTM-derived.
1194 When performing point-to-point terrain analysis, SPLAT! determines the
1195 antenna height above average terrain only if enough topographic data
1196 has already been loaded by the program to perform the point-to-point
1197 analysis. In most cases, this will be true, unless the site in ques-
1198 tion does not lie within 10 miles of the boundary of the topography
1201 When performing area prediction analysis, enough topography data is
1202 normally loaded by SPLAT! to perform average terrain calculations.
1203 Under such conditions, SPLAT! will provide the antenna height above
1204 average terrain as well as the average terrain above mean sea level for
1205 azimuths of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and include
1206 such information in the generated site report. If one or more of the
1207 eight radials surveyed fall over water, or over regions for which no
1208 SDF data is available, SPLAT! reports No Terrain for the radial paths
1211 ADDITIONAL INFORMATION
1212 The latest news and information regarding SPLAT! software is available
1213 through the official SPLAT! software web page located at:
1214 http://www.qsl.net/kd2bd/splat.html.
1217 John A. Magliacane, KD2BD <kd2bd@amsat.org>
1218 Creator, Lead Developer
1220 Doug McDonald <mcdonald@scs.uiuc.edu>
1221 Original Longley-Rice Model integration
1223 Ron Bentley <ronbentley@embarqmail.com>
1224 Fresnel Zone plotting and clearance determination
1229 KD2BD Software 15 November 2008 SPLAT!(1)