2
6 splat - An RF Signal Propagation, Loss, And Terrain analysis tool
7
10 splat
11 [-t transmitter_site.qth]
12 [-r receiver_site.qth]
13 [-c rx antenna height for LOS coverage analysis (feet/meters)
14 (float)]
15 [-L rx antenna height for ITM coverage analysis (feet/meters)
16 (float)]
17 [-p terrain_profile.ext]
18 [-e elevation_profile.ext]
19 [-h height_profile.ext]
20 [-H normalized_height_profile.ext]
21 [-l ITM_profile.ext]
22 [-o topographic_map_filename.ppm]
23 [-b cartographic_boundary_filename.dat]
24 [-s site/city_database.dat]
25 [-d sdf_directory_path]
26 [-m earth radius multiplier (float)]
27 [-f frequency (MHz) for Fresnel zone calculations (float)]
28 [-R maximum coverage radius (miles/kilometers) (float)]
29 [-dB threshold beyond which contours will not be displayed]
30 [-gc ground clutter height (feet/meters) (float)]
31 [-fz Fresnel zone clearance percentage (default = 60)]
32 [-ano alphanumeric output file name]
33 [-ani alphanumeric input file name]
34 [-udt user_defined_terrain_file.dat]
35 [-log logfile.ext]
36 [-n] [-N] [-nf] [-sc] [-dbm] [-ngs] [-geo] [-kml] [-gpsav] [-metric]
37 [-olditm]
38
40 SPLAT! is a powerful terrestrial RF propagation and terrain analysis
41 tool for the spectrum between 20 MHz and 20 GHz. SPLAT! is free soft‐
42 ware, and is designed for operation on Unix and Linux-based work- sta‐
43 tions. Redistribution and/or modification is permitted under the terms
44 of the GNU General Public License, Version 2, as published by the Free
45 Software Foundation. Adoption of SPLAT! source code in proprietary or
46 closed-source applications is a violation of this license and is
47 strictly forbidden.
48 SPLAT! is distributed in the hope that it will be useful, but WITHOUT
50 ANY WARRANTY, without even the implied warranty of MERCHANTABILITY or
51 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
52 for more details.
53
55 Applications of SPLAT! include the visualization, design, and link bud‐
56 get analysis of wireless Wide Area Networks (WANs), commercial and ama‐
57 teur radio communication systems above 20 MHz, microwave links, fre‐
58 quency coordination and interference studies, and the prediction of
59 analog and digital terrestrial radio and television contour regions.
60 SPLAT! provides RF site engineering data such as great circle distances
62 and bearings between sites, antenna elevation angles (uptilt), depres‐
63 sion angles (downtilt), antenna height above mean sea level, antenna
64 height above average terrain, bearings, distances, and elevations to
65 known obstructions, Irregular Terrain Model path attenuation, and
66 received signal strength. In addition, the minimum antenna height
67 requirements needed to clear terrain, the first Fresnel zone, and any
68 user-definable percentage of the first Fresnel zone are also provided.
69 SPLAT! produces reports, graphs, and high resolution topographic maps
71 that depict line-of-sight paths, and regional path loss and signal
72 strength contours through which expected coverage areas of transmitters
73 and repeater systems can be obtained. When performing line-of-sight and
74 Irregular Terrain Model analyses in situations where multiple transmit‐
75 ter or repeater sites are employed, SPLAT! determines individual and
76 mutual areas of coverage within the network specified.
77
79 SPLAT! is a command-line driven application and reads input data
80 through a number of data files. Some files are mandatory for successful
81 execution of the program, while others are optional. Mandatory files
82 include digital elevation topography models in the form of SPLAT Data
83 Files (SDF files), site location files (QTH files), and Irregular Ter‐
84 rain Model parameter files (LRP files). Optional files include city
85 location files, cartographic boundary files, user-defined terrain
86 files, path loss input files, antenna radiation pattern files, and
87 color definition files.
88
90 SPLAT! imports topographic data in the form of SPLAT Data Files (SDFs).
91 These files may be generated from a number of information sources. In
92 the United States, SPLAT Data Files can be generated through U.S. Geo‐
93 logical Survey Digital Elevation Models (DEMs) using the postdownload
94 and usgs2sdf utilities included with SPLAT!. USGS Digital Elevation
95 Models compatible with these utilities may be down- loaded from:
96 http://edcftp.cr.usgs.gov/pub/data/DEM/250/
98 Significantly better resolution and accuracy can be obtained through
100 the use of SRTM Version 2 digital elevation models, especially when
101 supplemented by USGS-derived SDF data. These one-degree by one- degree
102 models are the product of the Space Shuttle STS-99 Radar Topography
103 Mission, and are available for most populated regions of the Earth.
104 SPLAT Data Files may be generated from 3 arc-second SRTM-3 data using
105 the included srtm2sdf utility. SRTM-3 Version 2.1 data may be obtained
106 through anonymous FTP from:
107 http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/
109 Note that SRTM filenames refer to the latitude and longitude of the
111 southwest corner of the topographic dataset contained within the file.
112 Therefore, the region of interest must lie north and east of the lati‐
113 tude and longitude provided in the SRTM filename. Even greater resolu‐
114 tion and accuracy can be obtained by using 1 arc-second SRTM-1 Version
115 2.1 topography data. This data is available for the United States and
116 its territories and possessions, and may be down- loaded from:
117 http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/
119 High resolution SDF files for use with SPLAT! HD may begenerated from
121 data in this format using the srtm2sdf-hd utility. Despite the higher
122 accuracy that SRTM data has to offer, some voids in the data sets
123 exist. When voids are detected, the srtm2sdf and srtm2sdf-hd utilities
124 replace them with corresponding data found in usgs2sdf generated SDF
125 files. If USGS-derived SDF data is not available, voids are handled
126 through adjacent pixel averaging, or direct replacement.
127 SPLAT! Data Files contain integer value topographic elevations in
129 meters referenced to mean sea level for 1-degree by 1-degree regions of
130 the Earth. SDF files can be read by SPLAT! in either standard format
131 (.sdf) as generated directly by the usgs2sdf, srtm2sdf, and srtm2sdf-hd
132 utilities, or in bzip2 compressed format (.sdf.bz2). Since uncompressed
133 files can be read slightly faster than files that have been compressed,
134 SPLAT! searches for needed SDF data in uncompressed format first. If
135 uncompressed data cannot be located, SPLAT! then searches for data in
136 bzip2 compressed format. If no compressed SDF files can be found for
137 the region requested, SPLAT! assumes the region is over water, and will
138 assign an elevation of sea-level to these areas.
139 This feature of SPLAT! makes it possible to perform path analysis not
141 only over land, but also between coastal areas not represented by Digi‐
142 tal Elevation Model data. However, this behavior of SPLAT! underscores
143 the importance of having all the SDF files required for the region
144 being analyzed if meaningful results are to be expected.
145
147 SPLAT! imports site location information of transmitter and receiver
148 sites analyzed by the program from ASCII files having a .qth extension.
149 QTH files contain the site’s name, the site’s latitude (positive if
150 North of the equator, negative if South), the site’s longitude (in
151 degrees West, 0 to 360 degrees, or degrees East 0 to -360 degrees), and
152 the site’s antenna height above ground level (AGL), each separated by a
153 single line- feed character. The antenna height is assumed to be speci‐
154 fied in feet unless followed by the letter m or the word meters in
155 either upper or lower case. Latitude and longitude information may be
156 expressed in either decimal format (74.6864) or degree, minute, second
157 (DMS) format (74 41 11.0).
158 For example, aread as follows: site locationfile describing television
160 station WNJT-DT, Trenton, NJ (wnjt-dt.qth) might read as follows:
161 WNJT-DT
163 40.2828
164 74.6864
165 990.00
166 Each transmitter and receiver site analyzed by SPLAT! must be repre‐
168 sented by its own site location (QTH) file.
169
171 Irregular Terrain Model Parameter data files are required for SPLAT! to
172 determine RF path loss, field strength, or received signal power level
173 in either point-to-point or area prediction mode. Irregular Terrain
174 Model parameter data is read from files having the same base name as
175 the transmitter site QTH file, but with a .lrp extension. SPLAT! LRP
176 files share the following format (wnjt-dt.lrp):
177 15.000 ; Earth Dielectric Constant (Relative permittivity)
179 0.005 ; Earth Conductivity (Siemens per meter)
180 301.000 ; Atmospheric Bending Constant (N-units)
181 647.000 ; Frequency in MHz (20 MHz to 20 GHz)
182 5 ; Radio Climate (5 = Continental Temperate)
183 0 ; Polarization (0 = Horizontal, 1 = Vertical)
184 0.50 ; Fraction of situations (50% of locations)
185 0.90 ; Fraction of time (90% of the time)
186 46000.0 ; Effective Radiated Power (ERP) in Watts (optional)
187 If an LRP file corresponding to the tx_site QTH file cannot be found,
189 SPLAT! scans the current working directory for the file "splat.lrp". If
190 this file cannot be found, then default parameters will be assigned by
191 SPLAT! and a corresponding "splat.lrp" file containing these default
192 parameters will be written to the cur- rent working directory. The gen‐
193 erated "splat.lrp" file can then be edited by the user as needed. Typ‐
194 ical Earth dielectric constants and conductivity values are as follows:
195 Dielectric Constant Conductivity
197 Salt water : 80 5.000
198 Good ground : 25 0.020
199 Fresh water : 80 0.010
200 Marshy land : 12 0.007
201 Farmland, forest : 15 0.005
202 Average ground : 15 0.005
203 Mountain, sand : 13 0.002
204 City : 5 0.001
205 Poor ground : 4 0.001
206 Radio climate codes used by SPLAT! are as follows:
208 1: Equatorial (Congo)
210 2: Continental Subtropical (Sudan)
211 3: Maritime Subtropical (West coast of Africa)
212 4: Desert (Sahara)
213 5: Continental Temperate
214 6: Maritime Temperate, over land (UK and west coasts of US & EU)
215 7: Maritime Temperate, over sea
216 The Continental Temperate climate is common to large land masses in the
218 temperate zone, such as the United States. For paths shorter than 100
219 km, there is little difference between Continental and Maritime Temper‐
220 ate climates.
221 The seventh and eighth parameters in the .lrp file correspond to the
223 statistical analysis provided by the ITM model. In this example, SPLAT!
224 will return the maximum path loss occurring 50% of the time (fraction
225 of time, or Time Variability) in 90% of situations (fraction of situa‐
226 tions, or Location Variability). This is often denoted as F(50,90) in
227 Longley-Rice studies. In the United States, an F(50,90) criteria is
228 typically used for digital television (8-level VSB modulation), while
229 F(50,50) is used for analog (VSB-AM+NTSC) broadcasts.
230 For further information on ITM propagation model parameters, please
232 refer to:
233 http://www.its.bldrdoc.gov/resources/radio-propagation-soft‐
235 ware/itm/itm.aspx
236 http://www.softwright.com/faq/engineering/prop_longley_rice.html
237 The last parameter in the .lrp file corresponds to the transmitter’s
239 Effective Radiated Power (ERP), and is optional. If it is included in
240 the .lrp file, then SPLAT! will compute received signal strength levels
241 and field strength level contours when performing ITM studies. If the
242 parameter is omitted, path loss is com- puted instead. The ERP provided
243 in the .lrp file can be overridden by using SPLAT!’s -erp command-line
244 switch. If the .lrp file contains an ERP parameter and the generation
245 of path loss rather than field strength contours is desired, the ERP
246 can be assigned to zero using the -erp switch without having to edit
247 the .lrp file to accomplish the same result.
248
250 The names and locations of cities, tower sites, or other points of
251 interest may be imported and plotted on topographic maps generated by
252 SPLAT!. SPLAT! imports the names of cities and locations from ASCII
253 files containing the location of interest’s name, latitude, and longi‐
254 tude. Each field is separated by a comma. Each record is separated by
255 a single line feed character. As was the case with the .qth files, lat‐
256 itude and longitude information may be entered in either decimal or
257 degree, minute, second (DMS) format.
258 For example (cities.dat):
260 Teaneck, 40.891973, 74.014506
262 Tenafly, 40.919212, 73.955892
263 Teterboro, 40.859511, 74.058908
264 Tinton Falls, 40.279966, 74.093924
265 Toms River, 39.977777, 74.183580
266 Totowa, 40.906160, 74.223310
267 Trenton, 40.219922, 74.754665
268 A total of five separate city data files may be imported at a time, and
270 there is no limit to the size of these files. SPLAT! reads city data on
271 a "first come/first served" basis, and plots only those locations whose
272 annotations do not conflict with annotations of locations read earlier
273 in the current city data file, or in previ- ous files. This behavior
274 minimizes clutter in SPLAT! generated topographic maps, but also man‐
275 dates that important locations be placed toward the beginning of the
276 first city data file, and locations less important be positioned fur‐
277 ther down the list or in subsequent data files.
278 City data files may be generated manually using any text editor,
280 imported from other sources, or derived from data available from the
281 U.S. Census Bureau using the itydecoder utility included with SPLAT!.
282 Such data is available free of charge via the Internet at:
283 http://web.archive.org/web/20130331172800/http://www.cen‐
284 sus.gov/geo/www/cob/bdy_files.html, and must be in ASCII format.
285
287 Cartographic boundary data may also be imported to plot the boundaries
288 of cities, counties, or states on topographic maps generated by SPLAT!.
289 Such data must be of the form of ARC/INFO Ungenerate (ASCII Format)
290 Metadata Cartographic Boundary Files, and are available from the U.S.
291 Census Bureau via the Internet at these sites:
292 http://web.archive.org/web/20130331144934/http://www.cen‐
294 sus.gov/geo/www/cob/co2000.html#ascii
295 http://web.archive.org/web/20130507075658/http://www.cen‐
296 sus.gov/geo/www/cob/pl2000.html#ascii
297 A total of five separate cartographic boundary files may be imported at
299 a time. It is not necessary to import state boundaries if county bound‐
300 aries have already been imported.
301
303 SPLAT! is invoked via the command-line using a series of switches and
304 arguments. Since SPLAT! is a CPU and memory intensive application, this
305 type of interface minimizes overhead and lends itself well to scripted
306 (batch) operations. SPLAT!’s CPU and memory scheduling priority may be
307 modified through the use of the Unix nice command.
308 The number and type of switches passed to SPLAT! determine its mode of
310 operation and method of output data generation. Nearly all of SPLAT!’s
311 switches may be cascaded in any order on the command line when invoking
312 the program. Simply typing splat on the command line will return a sum‐
313 mary of SPLAT!’s command line options:
314 BSPLAT! v1.4.1 Available Options... ]
316 -t txsite(s).qth (max of 4 with -c, max of 30 with -L)
317 -r rxsite.qth
318 -c plot coverage of TX(s) with an RX antenna at X feet/meters
319 AGL
320 -L plot path loss map of TX based on an RX at X feet/meters AGL
321 -s filename(s) of city/site file(s) to import (5 max)
322 -b filename(s) of cartographic boundary file(s) to import (5
323 max)
324 -p filename of terrain profile graph to plot
325 -e filename of terrain elevation graph to plot
326 -h filename of terrain height graph to plot
327 -H filename of normalized terrain height graph to plot
328 -l filename of path loss graph to plot
329 -o filename of topographic map to generate (.ppm)
330 -u filename of user-defined terrain file to import
331 -d sdf file directory path (overrides path in ̃/.splat_path
332 file)
333 -m earth radius multiplier
334 -n do not plot LOS paths in .ppm maps
335 -N do not produce unnecessary site or obstruction reports
336 -f frequency for Fresnel zone calculation (MHz)
337 -R modify default range for -c or -L (miles/kilometers)
338 -sc display smooth rather than quantized contour levels
339 -db threshold beyond which contours will not be displayed
340 -nf do not plot Fresnel zones in height plots
341 -fz Fresnel zone clearance percentage (default = 60)
342 -gc ground clutter height (feet/meters)
343 -ngs display greyscale topography as white in .ppm files
344 -erp override ERP in .lrp file (Watts)
345 -ano name of alphanumeric output file
346 -ani name of alphanumeric input file
347 -udt name of user defined terrain input file
348 -kml generate Google Earth (.kml) compatible output
349 -geo generate an Xastir .geo georeference file (with .ppm out‐
350 put)
351 -dbm plot signal power level contours rather than field strength
352 -log copy command line string to this output file
353 -gpsav preserve gnuplot temporary working files after SPLAT!
354 execution
355 -metric employ metric rather than imperial units for all user
356 I/O
357 -olditm invoke older ITM propagation model rather than the newer
358 ITWOM
359 The command-line options for splat and splat-hd are identical. The -log
361 command line switch causes all invoked command line options to be
362 logged to a file of your choosing (logfile.txt):
363 splat -t tx_site -r rx_site -s nj_cities -o topo_map -log log‐
365 file.txt
366 SPLAT! operates in two distinct modes: point-to-point mode, and area
368 prediction mode. Either a line-of- sight (LOS) or Irregular Terrain
369 (ITM) propagation model may be invoked by the user. True Earth,
370 fourthirds Earth, or any other user-defined Earth radius may be speci‐
371 fied when performing line-of-sight analysis.
372
374 SPLAT! may be used to perform line-of-sight terrain analysis between
375 two specified site locations. For example:
376 splat -t tx_site.qth -r rx_site.qth
378 invokes a line-of-sight terrain analysis between the transmitter speci‐
380 fied in tx_site.qth and receiver specified in rx_site.qth using a True
381 Earth radius model, and writes a SPLAT! Path Analysis Report to the
382 current working directory. The report contains details of the transmit‐
383 ter and receiver sites, and identifies the loca- tion of any obstruc‐
384 tions detected along the line-of-sight path. If an obstruction can be
385 cleared by raising the receive antenna to a greater altitude, SPLAT!
386 will indicate the minimum antenna height required for a line- of-sight
387 path to exist between the transmitter and receiver locations specified.
388 Note that imperial units (miles, feet) are specified unless the -metric
389 switch is added to SPLAT!’s command line options:
390 splat -t tx_site.qth -r rx_site.qth -metric
392 If the antenna must be raised a significant amount, this determination
394 may take a few moments. Note that the results provided are the minimum
395 necessary for a line-of-sight path to exist, and in the case of this
396 sim- ple example, do not take Fresnel zone clearance requirements into
397 consideration. qth extensions are assumed by SPLAT! for QTH files, and
398 are optional when specifying -t and -r arguments on the command-line.
399 SPLAT! automatically reads all SPLAT Data Files necessary to conduct
400 the terrain analysis between the sites specified. SPLAT! searches for
401 the required SDF files in the current working directory first. If the
402 needed files are not found, SPLAT! then searches in the path specified
403 by the -d com- mand-line switch:
404 splat -t tx_site -r rx_site -d /cdrom/sdf/
406 An external directory path may be specified by placing a ".splat_path"
408 file under the user’s home directory. This file must contain the full
409 directory path of last resort to all the SDF files. The path in the
410 $HOME/.splat_path file must be of the form of a single line of ASCII
411 text:
412 /opt/splat/sdf/
414 and can be generated using any text editor.
416 A graph of the terrain profile between the receiver and transmitter
418 locations as a function of distance from the receiver can be generated
419 by adding the -p switch:
420 splat -t tx_site -r rx_site -p terrain_profile.png
422 SPLAT! invokes gnuplot when generating graphs. The filename extension
424 specified to SPLAT! deter- mines the format of the graph produced. .png
425 will produce a 640x480 color PNG graphic file, while .ps or .postscript
426 will produce postscript output. Output in formats such as GIF, Adobe
427 Illustrator, AutoCAD dxf, LaTeX, and many others are available. Please
428 consult gnuplot, and gnuplot’s documentation for details on all the
429 supported output formats.
430 A graph of elevations subtended by the terrain between the receiver and
432 transmitter as a function of distance from the receiver can be gener‐
433 ated by using the -e switch:
434 splat -t tx_site -r rx_site -e elevation_profile.png
436 The graph produced using this switch illustrates the elevation and
438 depression angles resulting from the terrain between the receiver’s
439 location and the transmitter site from the perspective of the
440 receiver’s location. A second trace is plotted between the left side
441 of the graph (receiver’s location) and the location of the transmitting
442 antenna on the right. This trace illustrates the elevation angle
443 required for a line-of-sight path to exist between the receiver and
444 transmitter locations. If the trace intersects the elevation profile at
445 any point on the graph, then this is an indication that a line-of-sight
446 path does not exist under the conditions given, and the obstructions
447 can be clearly identified on the graph at the point(s) of intersection.
448 A graph illustrating terrain height referenced to a line-of-sight path
450 between the transmitter and receiver may be generated using the -h
451 switch:
452 splat -t tx_site -r rx_site -h height_profile.png
454 A terrain height plot normalized to the transmitter and receiver
456 antenna heights can be obtained using the -H switch:
457 splat -t tx_site -r rx_site -H normalized_height_profile.png
459 A contour of the Earth’s curvature is also plotted in this mode. The
461 first Fresnel Zone, and 60% of the first Fresnel Zone can be added to
462 height profile graphs by adding the -f switch, and specifying a fre‐
463 quency (in MHz) at which the Fresnel Zone should be modeled:
464 splat -t tx_site -r rx_site -f 439.250 -H normalized_height_pro‐
466 file.png
467 Fresnel Zone clearances other 60% can be specified using the -fz switch
469 as follows:
470 splat -t tx_site -r rx_site -f 439.250 -fz 75 -H height_pro‐
472 file2.png
473 A graph showing ITM path loss may be plotted using the -l switch:
475 splat -t tx_site -r rx_site -l path_loss_profile.png
477 As before, adding the -metric switch forces the graphs to be plotted
479 using metric units of measure. The -gpsav switch instructs SPLAT! to
480 preserve (rather than delete) the gnuplot working files generated dur‐
481 ing SPLAT! execution, allowing the user to edit these files and re-run
482 gnuplot if desired.
483 When performing a point-to-point analysis, a SPLAT! Path Analysis
485 Report is generated in the form of a text file with a .txt filename
486 extension. The report contains bearings and distances between the
487 transmitter and receiver, as well as the free-space and ITM path loss
488 for the path being analyzed. The mode of propagation for the path is
489 given as Line-of-Sight, Single Horizon, Double Horizon, Diffraction
490 Dominant, or Tr oposcatter Dominant. Additionally, if the receiver is
491 located at the peak of a single obstruction or at the peak of a second
492 obstruction, SPLAT! will report RX at Peak Terrain Along Path when
493 operating under the ITWOM propagation model.
494 Distances and locations to known obstructions along the path between
496 transmitter and receiver are also pro- vided. If the transmitter’s
497 effective radiated power is specified in the transmitter’s correspond‐
498 ing .lrp file, then predicted signal strength and antenna voltage at
499 the receiving location is also provided in the Path Analysis Report.
500 To determine the signal-to-noise (SNR) ratio at remote location where
502 random Johnson (thermal) noise is the primary limiting factor in recep‐
503 tion:
504 SNR = T − NJ − L + G − NF
506 where T is the ERP of the transmitter in dBW in the direction of the
508 receiver, NJ is Johnson Noise in dBW (-136 dBW for a 6 MHz television
509 channel), L is the path loss provided by SPLAT! in dB (as a positive
510 number), G is the receive antenna gain in dB over isotropic, and NF is
511 the receiver noise figure in dB. ,T may be computed as follows:
512 T = TI + GT
514 where TI is actual amount of RF power delivered to the transmitting
516 antenna in dBW, GT is the transmit- ting antenna gain (over isotropic)
517 in the direction of the receiver (or the horizon if the receiver is
518 over the horizon).
519 To compute how much more signal is available over the minimum to neces‐
521 sary to achieve a specific signal-to-noise ratio:
522 Signal_Margin = SNR − S
524 where S is the minimum required SNR ratio (15.5 dB for ATSC (8-level
526 VSB) DTV, 42 dB for analog NTSC television).
527 A topographic map may be generated by SPLAT! to visualize the path
529 between the transmitter and receiver sites from yet another perspec‐
530 tive. Topographic maps generated by SPLAT! display elevations using a
531 log- arithmic grayscale, with higher elevations represented through
532 brighter shades of gray. The dynamic range of the image is scaled
533 between the highest and lowest elevations present in the map. The only
534 exception to this is sea-level, which is represented using the color
535 blue.
536 Topographic output is invoked using the -o switch:
538 splat -t tx_site -r rx_site -o topo_map.ppm
540 The .ppm extension on the output filename is assumed by SPLAT!, and is
542 optional. In this example, topo_map.ppm will illustrate the locations
543 of the transmitter and receiver sites specified. In addition, the great
544 circle path between the two sites will be drawn over locations for
545 which an unobstructed path exists to the transmitter at a receiving
546 antenna height equal to that of the receiver site (specified in
547 rx_site.qth).
548 It may desirable to populate the topographic map with names and loca‐
550 tions of cities, tower sites, or other important locations. A city file
551 may be passed to SPLAT! using the -s switch:
552 splat -t tx_site -r rx_site -s cities.dat -o topo_map
554 Up to five separate city files may be passed to SPLAT! at a time fol‐
556 lowing the -s switch. County and state boundaries may be added to the
557 map by specifying up to five U.S. Census Bureau cartographic boundary
558 files using the -b switch:
559 splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map
561 In situations where multiple transmitter sites are in use, as many as
563 four site locations may be passed to SPLAT! at a time for analysis:
564 splat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p pro‐
566 file.png
567 In this example, four separate terrain profiles and obstruction reports
569 will be generated by SPLAT!. A sin- gle topographic map can be speci‐
570 fied using the -o switch, and line-of-sight paths between each trans‐
571 mitter and the receiver site indicated will be produced on the map,
572 each in its own color. The path between the first transmitter specified
573 to the receiver will be in green, the path between the second transmit‐
574 ter and the receiver will be in cyan, the path between the third trans‐
575 mitter and the receiver will be in violet, and the path between the
576 fourth transmitter and the receiver will be in sienna.
577 SPLAT! generated topographic maps are 24-bit TrueColor Portable PixMap
579 (PPM) images. They may be viewed, edited, or converted to other graphic
580 formats by popular image viewing applications such as xv, The GIMP,
581 ImageMagick, and XPaint. PNG format is highly recommended for lossless
582 compressed storage of SPLAT! generated topographic output files.
583 ImageMagick’s command-line utility easily con- verts SPLAT!’s PPM files
584 to PNG format:
585 convert splat_map.ppm splat_map.png
587 Another excellent PPM to PNG command-line utility is available at:
589 http://www.libpng.org/pub/png/book/sources.html
591 As a last resort, PPM files may be compressed using the bzip2 utility,
593 and read directly by The GIMP in this format. The -ngs option assigns
594 all terrain to the color white, and can be used when it is desirable to
595 generate a map that is devoid of terrain:
596 splat -t tx_site -r rx_site -b co34_d00.dat -ngs -o white_map
598 The resulting .ppm image file can be converted to .png format with a
600 transparent background using ImageMagick’s convert utility:
601 convert -transparent #FFFFFF white_map.ppm transparent_map.png
603
605 SPLAT! can analyze a transmitter or repeater site, or network of sites,
606 and predict the regional coverage for each site specified. In this
607 mode, SPLAT! can generate a topographic map displaying the geometric
608 line- of-sight coverage area of the sites based on the location of each
609 site and the height of receive antenna wish- ing to communicate with
610 the site in question. A regional analysis may be performed by SPLAT!
611 using the -c switch as follows:
612 splat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o
614 tx_coverage
615 In this example, SPLAT! generates a topographic map called tx_cover‐
617 age.ppm that illustrates the predicted line-of-sight regional coverage
618 of tx_site to receiving locations having antennas 30.0 feet above
619 ground level (AGL). If the -metric switch is used, the argument follow‐
620 ing the -c switch is interpreted as being in meters rather than in
621 feet. The contents of cities.dat are plotted on the map, as are the
622 cartographic bound- aries contained in the file co34_d00.dat.
623 When plotting line-of-sight paths and areas of regional coverage,
625 SPLAT! by default does not account for the effects of atmospheric bend‐
626 ing. However, this behavior may be modified by using the Earth radius
627 mul- tiplier (-m) switch:
628 splat -t wnjt-dt -c 30.0 -m 1.333 -s cities.dat -b counties.dat
630 -o map.ppm
631 An earth radius multiplier of 1.333 instructs SPLAT! to use the "four-
633 thirds earth" model for line-of-sight propagation analysis. Any appro‐
634 priate earth radius multiplier may be selected by the user. When per‐
635 forming a regional analysis, SPLAT! generates a site report for each
636 station analyzed. SPLAT! site reports contain details of the site’s
637 geographic location, its height above mean sea level, the antenna’s
638 height above mean sea level, the antenna’s height above average ter‐
639 rain, and the height of the average ter- rain calculated toward the
640 bearings of 0, 45, 90, 135, 180, 225, 270, and 315 degrees azimuth.
641
643 SPLAT! can also display line-of-sight coverage areas for as many as
644 four separate transmitter sites on a common topographic map. For exam‐
645 ple:
646 splat -t site1 site2 site3 site4 -c 10.0 -metric -o network.ppm
648 plots the regional line-of-sight coverage of site1, site2, site3, and
650 site4 based on a receive antenna located 10.0 meters above ground
651 level. A topographic map is then written to the file network.ppm. The
652 line-of-sight coverage area of the transmitters are plotted as follows
653 in the colors indicated (along with their corre- sponding RGB values in
654 decimal):
655 site1: Green (0,255,0)
657 site2: Cyan (0,255,255)
658 site3: Medium Violet (147,112,219)
659 site4: Sienna 1 (255,130,71)
660 site1 + site2: Yellow (255,255,0)
661 site1 + site3: Pink (255,192,203)
662 site1 + site4: Green Yellow (173,255,47)
663 site2 + site3: Orange (255,165,0)
664 site2 + site4: Dark Sea Green 1 (193,255,193)
665 site3 + site4: Dark Turquoise (0,206,209)
666 site1 + site2 + site3: Dark Green (0,100,0)
667 site1 + site2 + site4: Blanched Almond (255,235,205)
668 site1 + site3 + site4: Medium Spring Green (0,250,154)
669 site2 + site3 + site4: Tan (210,180,140)
670 site1 + site2 + site3 + site4: Gold2 (238,201,0)
671 If separate .qth files are generated, each representing a common site
673 location but a different antenna height, a single topographic map
674 illustrating the regional coverage from as many as four separate loca‐
675 tions on a single tower may be generated by SPLAT!.
676
678 If the -c switch is replaced by a -L switch, an ITM path loss map for a
679 transmitter site may be generated: splat -t wnjt -L 30.0 -s cities.dat
680 -b co34_d00.dat -o path_loss_map In this mode, SPLAT! generates a
681 multi-color map illustrating expected signal levels in areas surround‐
682 ing the transmitter site. A legend at the bottom of the map correlates
683 each color with a specific path loss range in decibels.
684 The -db switch allows a threshold to be set beyond which contours will
686 not be plotted on the map. For example, if a path loss beyond -140 dB
687 is irrelevant to the survey being conducted, SPLAT!’s path loss plot
688 can be constrained to the region bounded by the 140 dB attenuation con‐
689 tour as follows:
690 splat -t wnjt-dt -L 30.0 -s cities.dat -b co34_d00.dat -db 140
692 -o plot.ppm
693 The path loss contour threshold may be expressed as either a positive
695 or negative quantity.
696 The path loss analysis range may be modified to a user-specific dis‐
698 tance using the -R switch. The argument must be given in miles (or
699 kilometers if the -metric switch is used). If a range wider than the
700 generated topographic map is specified, SPLAT! will perform ITM path
701 loss calculations between all four corners of the area prediction map.
702 The colors used to illustrate contour regions in SPLAT! generated cov‐
704 erage maps may be tailored by the user by creating or modifying
705 SPLAT!’s color definition files. SPLAT! color definition files have the
706 same base name as the transmitter’s .qth file, but carry .lcf, .scf,
707 and .dcf extensions. If the necessary file does not exist in the cur‐
708 rent working when SPLAT! is run, a file containing default color defi‐
709 nition parameters that is suitable for manual editing by the user is
710 written into the current directory.
711 When a regional ITM analysis is performed and the transmitter’s ERP is
713 not specified or is zero, a .lcf path loss color definition file corre‐
714 sponding to the transmitter site (.qth) is read by SPLAT! from the cur‐
715 rent working directory. If a .lcf file corresponding to the transmitter
716 site is not found, then a default file suitable for manual editing by
717 the user is automatically generated by SPLAT!.
718 A path loss color definition file possesses the following structure
720 (wnjt-dt.lcf):
721 ; SPLAT! Auto-generated Path-Loss Color Definition ("wnjt-
723 dt.lcf") FIle
724 ; Format for the parameters held in this file is as follows:
725 ;
726 ; dB: red, green, blue
727 ;
728 ; ...where "dB" is the path loss (in dB) and
729 ; "red", "green", and "blue" are the corresponding RGB color
730 ; definitions ranging from 0 to 255 for the region specified.
731 ;
732 ; The following parameters may be edited and/or expanded
733 ; for future runs of SPLAT! A total of 32 contour regions
734 ; may be defined in this file.
735 ;
736 ;
737 80: 255, 0, 0
738 90: 255, 128, 0
739 100: 255, 165, 0
740 110: 255, 206, 0
741 120: 255, 255, 0
742 130: 184, 255, 0
743 140: 0, 255, 0
744 150: 0, 208, 0
745 160: 0, 196, 196
746 170: 0, 148, 255
747 180: 80, 80, 255
748 190: 0, 38, 255
749 200: 142, 63, 255
750 210: 196, 54, 255
751 220: 255, 0, 255
752 230: 255, 194, 204
753 If the path loss is less than 80 dB, the color Red (RGB = 255, 0, 0) is
755 assigned to the region. If the path loss is greater than or equal to 80
756 dB, but less than 90 db, then Dark Orange (255, 128, 0) is assigned to
757 the region. Orange (255, 165, 0) is assigned to regions having a path
758 loss greater than or equal to 90 dB, but less than 100 dB, and so on.
759 Greyscale terrain is displayed beyond the 230 dB path loss contour.
760 Adding the -sc switch will smooth the transitions between the specified
761 quantized contour levels.
762
764 If the transmitter’s effective radiated power (ERP) is specified in the
765 transmitter’s .lrp file, or expressed on the command-line using the
766 -erp switch, field strength contours referenced to decibels over one
767 microvolt per meter (dBuV/m) rather than path loss are produced:
768 splat -t wnjt-dt -L 30.0 -erp 46000 -db 30 -o plot.ppm
770 The -db switch can be used in this mode as before to limit the extent
772 to which field strength contours are plotted. When plotting field
773 strength contours, however, the argument given is interpreted as being
774 expressed in dBuV/m. SPLAT! field strength color definition files
775 share avery similar structure to .lcf files used for plotting path
776 loss:
777 ; SPLAT! Auto-generated Signal Color Definition ("wnjt-dt.scf")
779 File
780 ;
781 ; Format for the parameters held in this file is as follows:
782 ;
783 ; dBuV/m: red, green, blue
784 ;
785 ; ...where "dBuV/m" is the signal strength (in dBuV/m) and
786 ; "red", "green", and "blue" are the corresponding RGB color
787 ; definitions ranging from 0 to 255 for the region specified.
788 ;
789 ; The following parameters may be edited and/or expanded
790 ; for future runs of SPLAT! A total of 32 contour regions
791 ; may be defined in this file.
792 ;
793 ;
794 128: 255, 0, 0
795 118: 255, 165, 0
796 108: 255, 206, 0
797 98: 255, 255, 0
798 88: 184, 255, 0
799 78: 0, 255, 0
800 68: 0, 208, 0
801 58: 0, 196, 196
802 48: 0, 148, 255
803 38: 80, 80, 255
804 28: 0, 38, 255
805 18: 142, 63, 255
806 8: 140, 0, 128
807 If the signal strength is greater than or equal to 128 dB over 1 micro‐
809 volt per meter (dBuV/m), the color Red (255, 0, 0) is displayed for the
810 region. If the signal strength is greater than or equal to 118 dBuV/m,
811 but less than 128 dBuV/m, then the color Orange (255, 165, 0) is dis‐
812 played, and so on. Greyscale terrain is dis- played for regions with
813 signal strengths less than 8 dBuV/m. Signal strength contours for some
814 common VHF and UHF broadcasting services in the United States are as
815 follows:
816 Analog Television Broadcasting
818 ------------------------------
819 Channels 2-6: City Grade: >= 74 dBuV/m
820 Grade A: >= 68 dBuV/m
821 Grade B: >= 47 dBuV/m
822 --------------------------------------------
823 Channels 7-13: City Grade: >= 77 dBuV/m
824 Grade A: >= 71 dBuV/m
825 Grade B: >= 56 dBuV/m
826 --------------------------------------------
827 Channels 14-69: Indoor Grade: >= 94 dBuV/m
828 City Grade: >= 80 dBuV/m
829 Grade A: >= 74 dBuV/m
830 Grade B: >= 64 dBuV/m
831 Digital Television Broadcasting
832 -------------------------------
833 Channels 2-6: City Grade: >= 35 dBuV/m
834 Service Threshold: >= 28 dBuV/m
835 --------------------------------------------
836 Channels 7-13: City Grade: >= 43 dBuV/m
837 Service Threshold: >= 36 dBuV/m
838 --------------------------------------------
839 Channels 14-69: City Grade: >= 48 dBuV/m
840 Service Threshold: >= 41 dBuV/m
841 NOAA Weather Radio (162.400 - 162.550 MHz)
842 ------------------------------------------
843 Reliable: >= 18 dBuV/m
844 Not reliable: < 18 dBuV/m
845 Unlikely to receive: < 0 dBuV/m
846 FM Radio Broadcasting (88.1 - 107.9 MHz)
847 ----------------------------------------
848 Analog Service Contour: 60 dBuV/m
849 Digital Service Contour: 65 dBuV/m
850 RECEIVED POWER LEVEL ANALYSIS If the transmitter’s effective radiated
852 power (ERP) is specified in the transmitter’s .lrp file, or expressed
853 on the command-line using the -erp switch, and the -dbm switch is
854 invoked, received power level contours ref- erenced to decibels over
855 one milliwatt (dBm) are produced:
856 splat -t wnjt-dt -L 30.0 -erp 46000 -dbm -db -100 -o plot.ppm
858 The -db switch can be used to limit the extent to which received power
860 level contours are plotted. When plotting power level contours, the
861 argument given is interpreted as being expressed in dBm. SPLAT!
862 received power level color definition files share a very similar struc‐
863 ture to the color definition files described earlier, except that the
864 power levels in dBm may be either positive or neg ative, and are lim‐
865 ited to a range between +40 dBm and -200 dBm:
866 ; SPLAT! Auto-generated DBM Signal Level Color Definition
868 ("wnjt-dt.dcf") File
869 ;
870 ; Format for the parameters held in this file is as follows:
871 ;
872 ; dBm: red, green, blue
873 ;
874 ; ...where "dBm" is the received signal power level between +40
875 dBm
876 ; and -200 dBm, and "red", "green", and "blue" are the corre‐
877 sponding
878 ; RGB color definitions ranging from 0 to 255 for the region
879 specified.
880 ;
881 ; The following parameters may be edited and/or expanded
882 ; for future runs of SPLAT! A total of 32 contour regions
883 ; may be defined in this file.
884 ;
885 ;
886 +0: 255, 0, 0
887 -10: 255, 128, 0
888 -20: 255, 165, 0
889 -30: 255, 206, 0
890 -40: 255, 255, 0
891 -50: 184, 255, 0
892 -60: 0, 255, 0
893 -70: 0, 208, 0
894 -80: 0, 196, 196
895 -90: 0, 148, 255
896 -100: 80, 80, 255
897 -110: 0, 38, 255
898 -120: 142, 63, 255
899 -130: 196, 54, 255
900 -140: 255, 0, 255
901 -150: 255, 194, 204
902
904 Normalized field voltage patterns for a transmitting antenna’s horizon‐
905 tal and vertical planes are imported automatically into SPLAT! when a
906 path loss, field strength, or received power level coverage analysis is
907 performed. Antenna pattern data is read from a pair of files having the
908 same base name as the transmitter and LRP files, but with .az and .el
909 extensions for azimuth and elevation pattern files, respectively.
910 Specifi- cations regarding pattern rotation (if any) and mechanical
911 beam tilt and tilt direction (if any) are also con- tained within
912 SPLAT! antenna pattern files.
913 For example, the first few lines of a SPLAT! azimuth pattern file might
915 appear as follows (kvea.az):
916 183.0
918 0 0.8950590
919 1 0.8966406
920 2 0.8981447
921 3 0.8995795
922 4 0.9009535
923 5 0.9022749
924 6 0.9035517
925 7 0.9047923
926 8 0.9060051
927 The first line of the .az file specifies the amount of azimuthal pat‐
929 tern rotation (measured clockwise in degrees from True North) to be
930 applied by SPLAT! to the data contained in the .az file. This is fol‐
931 lowed by azimuth headings (0 to 360 degrees) and their associated nor‐
932 malized field patterns (0.000 to 1.000) sepa- rated by whitespace.
933 The structure of SPLAT! elevation pattern files is slightly different.
935 The first line of the .el file specifies the amount of mechanical beam
936 tilt applied to the antenna. Note that a downward tilt (below the hori‐
937 zon) is expressed as a positive angle, while an upward tilt (above the
938 horizon) is expressed as a negative angle. This data is followed by
939 the azimuthal direction of the tilt, separated by whitespace.
940 The remainder of the file consists of elevation angles and their corre‐
942 sponding normalized voltage radiation pattern (0.000 to 1.000) values
943 separated by whitespace. Elevation angles must be specified over a
944 -10.0 to +90.0 degree range. As was the convention with mechanical
945 beamtilt, negative elevation angles are used to represent elevations
946 above the horizon, while positive angles represents elevations below
947 the horizon. For example, the first few lines a SPLAT! elevation pat‐
948 tern file might appear as follows (kvea.el):
949 1.1 130.0
951 -10.0 0.172
952 -9.5 0.109
953 -9.0 0.115
954 -8.5 0.155
955 -8.0 0.157
956 -7.5 0.104
957 -7.0 0.029
958 -6.5 0.109
959 -6.0 0.185
960 In this example, the antenna is mechanically tilted downward 1.1
962 degrees towards an azimuth of 130.0 degrees.
963 For best results, the resolution of azimuth pattern data should be
965 specified to the nearest degree azimuth, and elevation pattern data
966 resolution should be specified to the nearest 0.01 degrees. If the pat‐
967 tern data specified does not reach this level of resolution, SPLAT!
968 will interpolate the values provided to determine the data at the
969 required resolution, although this may result in a loss in accuracy.
970
972 Performing a regional coverage analysis based on an ITM path analysis
973 can be a very time consuming process, especially if the analysis is
974 performed repeatedly to discover what effects changes to a transmit-
975 ter’s antenna radiation pattern make to the predicted coverage area.
976 This process can be expedited by exporting the contour data produced by
978 SPLAT! to an alphanumeric out- put (.ano) file. The data contained in
979 this file can then be modified to incorporate antenna pattern effects,
980 and imported back into SPLAT! to quickly produce a revised contour map.
981 Depending on the way in which SPLAT! is invoked, alphanumeric output
982 files can describe regional path loss, signal strength, or received
983 signal power levels.
984 For example, an alphanumeric output file containing path loss informa‐
986 tion can be generated by SPLAT! for a receive site 30 feet above ground
987 level over a 50 mile radius surrounding a transmitter site to a maximum
988 path loss of 140 dB (assuming ERP is not specified in the transmitter’s
989 .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
994 -erp switch, the alphanumeric output file will instead contain pre‐
995 dicted field values in dBuV/m. If the -dBm command line switch is used,
996 then the alphanumeric output file will contain receive signal power
997 levels in dBm.
998 SPLAT! alphanumeric output files can exceed many hundreds of megabytes
1000 in size. They contain informa- tion relating to the boundaries of the
1001 region they describe followed by latitudes (degrees North), longitudes
1002 (degrees West), azimuths (referenced to True North), elevations (to the
1003 first obstruction), followed by either path loss (in dB), received
1004 field strength (in dBuV/m), or received signal power level (in dBm)
1005 without regard to the transmitting antenna’s radiation pattern.
1006 The first few lines of a SPLAT! alphanumeric output file could take on
1008 the following appearance (pathloss.dat):
1009 119, 117 ; max_west, min_west
1011 35, 34 ; max_north, min_north
1012 34.2265424, 118.0631096, 48.199, -32.747, 67.70
1013 34.2270358, 118.0624421, 48.199, -19.161, 73.72
1014 34.2275292, 118.0617747, 48.199, -13.714, 77.24
1015 34.2280226, 118.0611072, 48.199, -10.508, 79.74
1016 34.2290094, 118.0597723, 48.199, -11.806, 83.26 *
1017 34.2295028, 118.0591048, 48.199, -11.806, 135.47 *
1018 34.2299962, 118.0584373, 48.199, -15.358, 137.06 *
1019 34.2304896, 118.0577698, 48.199, -15.358, 149.87 *
1020 34.2314763, 118.0564348, 48.199, -15.358, 154.16 *
1021 34.2319697, 118.0557673, 48.199, -11.806, 153.42 *
1022 34.2324631, 118.0550997, 48.199, -11.806, 137.63 *
1023 34.2329564, 118.0544322, 48.199, -11.806, 139.23 *
1024 34.2339432, 118.0530971, 48.199, -11.806, 139.75 *
1025 34.2344365, 118.0524295, 48.199, -11.806, 151.01 *
1026 34.2349299, 118.0517620, 48.199, -11.806, 147.71 *
1027 34.2354232, 118.0510944, 48.199, -15.358, 159.49 *
1028 34.2364099, 118.0497592, 48.199, -15.358, 151.67 *
1029 Comments can be placed in the file if they are preceeded by a semi‐
1031 colon. The vim text editor has proven capable of editing files of this
1032 size.
1033 Note as was the case in the antenna pattern files, negative elevation
1035 angles refer to upward tilt (above the horizon), while positive angles
1036 refer to downward tilt (below the horizon). These angles refer to the
1037 eleva- tion to the receiving antenna at the height above ground level
1038 specified using the -L switch if the path between transmitter and
1039 receiver is unobstructed. If the path between the transmitter and
1040 receiver is obstructed, an asterisk (*) is placed on the end of the
1041 line, and the elevation angle returned by SPLAT! refers the elevation
1042 angle to the first obstruction rather than the geographic location
1043 specified on the line. This is done in response to the fact that the
1044 ITM model considers the energy reaching a distant point over an
1045 obstructed path to be the result of the energy scattered over the top
1046 of the first obstruction along the path. Since energy cannot reach the
1047 obstructed location directly, the actual elevation angle to the desti‐
1048 nation over such a path becomes irrelevant.
1049 When modifying SPLAT! path loss files to reflect antenna pattern data,
1051 only the last numeric column should be amended to reflect the antenna’s
1052 normalized gain at the azimuth and elevation angles specified in the
1053 file. Programs and scripts capable of performing this task are left as
1054 an exercise for the user. Modified alphanumeric output files can be
1055 imported back into SPLAT! for generating revised coverage maps provided
1056 that the ERP and -dBm options are used as they were when the alphanu‐
1057 meric output file was originally generated:
1058 splat -t kvea -ani pathloss.dat -s city.dat -b county.dat -o
1060 map.ppm
1061 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.
1068
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 con- ducted, but noticeably absent from the SDF files being used. A
1074 user-defined terrain file is imported into a SPLAT! analysis using the
1075 -udt switch:
1076 splat -t tx_site -r rx_site -udt udt_file.txt -o map.ppm
1078 A user-defined terrain file has the following appearance and structure:
1080 40.32180556, 74.1325, 100.0 meters
1082 40.321805, 74.1315, 300.0
1083 40.3218055, 74.1305, 100.0 meters
1084 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 aware
1088 that each user-defined terrain feature specified will be interpreted as
1089 being 3-arc seconds in both latitude and longitude in splat and 1 arc-
1090 second in latitude and longitude in splat-hd. Features described in the
1091 user-defined terrain file that overlap previously defined features in
1092 the file are ignored by SPLAT! to avoid ambiguity.
1093
1095 The height of ground clutter can be specified using the -gc switch:
1096 splat -t wnjt-dt -r kd2bd -gc 30.0 -H wnjt-dt_path.png
1098 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 loca- tions.
1103
1105 In certain situations it may be desirable to generate a topographic map
1106 of a region without plotting coverage areas, line-of-sight paths, or
1107 generating obstruction reports. There are several ways of doing this.
1108 If one wishes to generate a topographic map illustrating the location
1109 of a transmitter and receiver site along with a brief text report
1110 describing the locations and distances between the sites, the -n switch
1111 should be invoked as follows:
1112 splat -t tx_site -r rx_site -n -o topo_map.ppm
1114 If no text report is desired, then the -N switch is used:
1116 splat -t tx_site -r rx_site -N -o topo_map.ppm
1118 If a topographic map centered about a single site out to a minimum
1120 specified radius is desired instead, a command similar to the following
1121 can be used:
1122 splat -t tx_site -R 50.0 -s NJ_Cities -b NJ_Counties -o
1124 topo_map.ppm
1125 where -R specifies the minimum radius of the map in miles (or kilome‐
1127 ters if the -metric switch is used). Note that the tx_site name and
1128 location are not displayed in this example. If display of this informa‐
1129 tion is desired, simply create a SPLAT! city file (-s option) and
1130 append it to the list of command-line options illustrated above.
1131 If the -o switch and output filename are omitted in these operations,
1133 topographic output is written to a file named tx_site.ppm in the cur‐
1134 rent working directory by default.
1135
1137 Topographic, coverage (-c), and path loss contour (-L) maps generated
1138 by SPLAT! may be imported into Xastir (X Amateur Station Tracking and
1139 Information Reporting) software by generating a georeference file using
1140 SPLAT!’s -geo switch:
1141 splat -t kd2bd -R 50.0 -s NJ_Cities -b NJ_Counties -geo -o
1143 map.ppm
1144 The georeference file generated will have the same base name as the -o
1146 file specified, but have a .geo extension, and permit proper interpre‐
1147 tation and display of SPLAT!’s .ppm graphics in Xastir software.
1148
1150 Keyhole Markup Language files compatible with Google Earth may be gen‐
1151 erated by SPLAT! when per- forming point-to-point or regional coverage
1152 analyses by invoking the -kml switch:
1153 splat -t wnjt-dt -r kd2bd -kml
1155 The KML file generated will have the same filename structure as a Path
1157 Analysis Report for the transmitter and receiver site names given,
1158 except it will carry a .kml extension.
1159 Once loaded into Google Earth (File --> Open), the KML file will anno‐
1161 tate the map display with the names of the transmitter and receiver
1162 site locations. The viewpoint of the image will be from the position of
1163 the transmitter site looking towards the location of the receiver. The
1164 point-to-point path between the sites will be displayed as a white line
1165 while the RF line-of-sight path will be displayed in green. Google
1166 Earth’s navigation tools allow the user to "fly" around the path, iden‐
1167 tify landmarks, roads, and other fea- tured content.
1168 When performing regional coverage analysis, the .kml file generated by
1170 SPLAT! will permit path loss or signal strength contours to be layered
1171 on top of Google Earth’s display along with a corresponding color key
1172 in the upper left-hand corner. The generated .kml file will have the
1173 same basename as that of the .ppm file normally generated.
1174
1176 SPLAT! determines antenna height above average terrain (HAAT) according
1177 to the procedure defined by Federal Communications Commission Part
1178 73.313(d). According to this definition, terrain elevations along eight
1179 radials between 2 and 10 miles (3 and 16 kilometers) from the site
1180 being analyzed are sampled and averaged for each 45 degrees of azimuth
1181 starting with True North. If one or more radials lie entirely over
1182 water or over land outside the United States (areas for which no USGS
1183 topography data is available), then those radials are omitted from the
1184 calculation of average terrain.
1185 Note that SRTM-3 elevation data, unlike older USGS data, extends beyond
1187 the borders of the United States. Therefore, HAAT results may not be
1188 in full compliance with FCC Part 73.313(d) in areas along the borders
1189 of the United States if the SDF files used by SPLAT! are SRTM-derived.
1190 When performing point-to-point terrain analysis, SPLAT! determines the
1192 antenna height above average ter- rain only if enough topographic data
1193 has already been loaded by the program to perform the point-to-point
1194 analysis. In most cases, this will be true, unless the site in question
1195 does not lie within 10 miles of the boundary of the topography data in
1196 memory.
1197 When performing area prediction analysis, enough topography data is
1199 normally loaded by SPLAT! to per- form average terrain calculations.
1200 Under such conditions, SPLAT! will provide the antenna height above
1201 average terrain as well as the average terrain above mean sea level for
1202 azimuths of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and include
1203 such information in the generated site report. If one or more of the
1204 eight radials surveyed fall over water, or over regions for which no
1205 SDF data is available, SPLAT! reports No Terrain for the radial paths
1206 affected.
1207
1209 The latest news and information regarding SPLAT! software is available
1210 through the official SPLAT! soft- ware web page located at:
1211 http://www.qsl.net/kd2bd/splat.html.
1213
1215 John A. Magliacane, KD2BD <kd2bd@amsat.org> Creator, Lead Developer
1216 Doug McDonald <mcdonald@scs.uiuc.edu> Original Longley-Rice ITM
1217 Model integration
1218 Ron Bentley <ronbentley@embarqmail.com> Fresnel Zone plotting and
1219 clearance determination
1220KD2BD Software 25 July 2013 SPLAT![22m(1)