1 SPLAT!(1) KD2BD Software SPLAT!(1)
6 splat - An RF Signal Propagation, Loss, And Terrain analy-
10 splat [-t transmitter_site.qth] [-r receiver_site.qth]
11 [-c rx antenna height for LOS coverage analysis
12 (feet/meters) (float)] [-L rx antenna height for Longley-
13 Rice coverage analysis (feet/meters) (float)] [-p ter-
14 rain_profile.ext] [-e elevation_profile.ext] [-h
15 height_profile.ext] [-H normalized_height_profile.ext] [-l
16 Longley-Rice_profile.ext] [-o topographic_map_file-
17 name.ppm] [-b cartographic_boundary_filename.dat] [-s
18 site/city_database.dat] [-d sdf_directory_path] [-m earth
19 radius multiplier (float)] [-f frequency (MHz) for Fresnel
20 zone calculations (float)] [-R maximum coverage radius
21 (miles/kilometers) (float)] [-dB maximum attenuation con-
22 tour to display on path loss maps (80-230 dB)] [-nf do not
23 plot Fresnel zones in height plots] [-plo path_loss_out-
24 put_file.txt] [-pli path_loss_input_file.txt] [-udt
25 user_defined_terrain_file.dat] [-n] [-N] [-geo] [-kml]
29 SPLAT! is a powerful terrestrial RF propagation and ter-
30 rain analysis tool covering the spectrum between 20 MHz
31 and 20 GHz. SPLAT! is free software, and is designed for
32 operation on Unix and Linux-based workstations. Redistri-
33 bution and/or modification is permitted under the terms of
34 the GNU General Public License as published by the Free
35 Software Foundation, either version 2 of the License or
36 any later version. Adoption of SPLAT! source code in pro-
37 prietary or closed-source applications is a violation of
38 this license, and is strictly forbidden.
40 SPLAT! is distributed in the hope that it will be useful,
41 but WITHOUT ANY WARRANTY, without even the implied war-
42 ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
43 POSE. See the GNU General Public License for more details.
46 Applications of SPLAT! include the visualization, design,
47 and link budget analysis of wireless Wide Area Networks
48 (WANs), commercial and amateur radio communication systems
49 above 20 MHz, microwave links, frequency coordination and
50 interference studies, and the determination of analog and
51 digital terrestrial radio and television contour regions.
53 SPLAT! provides RF site engineering data such as great
54 circle distances and bearings between sites, antenna ele-
55 vation angles (uptilt), depression angles (downtilt),
56 antenna height above mean sea level, antenna height above
57 average terrain, bearings and distances to known obstruc-
58 tions, and Longley-Rice path attenuation. In addition,
59 the minimum antenna height requirements needed to clear
60 terrain, the first Fresnel zone, and 60% of the first
61 Fresnel zone are also provided.
63 SPLAT! produces reports, graphs, and high resolution topo-
64 graphic maps that depict line-of-sight paths, and regional
65 path loss contours through which expected coverage areas
66 of transmitters and repeater systems can be obtained.
67 When performing line-of-sight analysis in situations where
68 multiple transmitter or repeater sites are employed,
69 SPLAT! determines individual and mutual areas of coverage
70 within the network specified.
72 Simply typing splat on the command line will return a sum-
73 mary of SPLAT!'s command line options:
75 --==[ SPLAT! v1.2.0 Available Options...
78 -t txsite(s).qth (max of 4)
80 -c plot coverage of TX(s) with an RX antenna at X
82 -L plot path loss map of TX based on an RX at X
84 -s filename(s) of city/site file(s) to import (max
86 -b filename(s) of cartographic boundary file(s) to
88 -p filename of terrain profile graph to plot
89 -e filename of terrain elevation graph to plot
90 -h filename of terrain height graph to plot
91 -H filename of normalized terrain height graph to
93 -l filename of Longley-Rice graph to plot
94 -o filename of topographic map to generate (.ppm)
95 -u filename of user-defined terrain file to import
96 -d sdf file directory path (overrides path in
98 -n no analysis, brief report
99 -N no analysis, no report
100 -m earth radius multiplier
101 -f frequency for Fresnel zone calculation (MHz)
102 -R modify default range for -c or -L (miles/kilome-
104 -db maximum loss contour to display on path loss maps
106 -nf do not plot Fresnel zones in height plots
107 -plo filename of path-loss output file
108 -pli filename of path-loss input file
109 -udt filename of user defined terrain input file
110 -geo generate a .geo georeference file (with .ppm out-
112 -kml generate a Google Earth .kml file (for point-to-
114 -metric employ metric rather than imperial units for all
119 SPLAT! is a command-line driven application, and reads
120 input data through a number of data files. Some files are
121 mandatory for successful execution of the program, while
122 others are optional. Mandatory files include 3-arc second
123 topography models in the form of SPLAT Data Files (SDF
124 files), site location files (QTH files), and Longley-Rice
125 model parameter files (LRP files). Optional files include
126 city location files, cartographic boundary files, user-
127 defined terrain files, path-loss input files, and antenna
128 radiation pattern files.
131 SPLAT! imports topographic data in the form of SPLAT Data
132 Files (SDFs). These files may be generated from a number
133 of information sources. In the United States, SPLAT Data
134 Files can be generated through U.S. Geological Survey
135 Digital Elevation Models (DEMs) using the usgs2sdf utility
136 included with SPLAT!. USGS Digital Elevation Models com-
137 patible with this utility may be downloaded from:
138 http://edcftp.cr.usgs.gov/pub/data/DEM/250/.
140 Significantly better resolution and accuracy can be
141 obtained through the use of SRTM-3 Version 2 digital ele-
142 vation models. These models are the product of the STS-99
143 Space Shuttle Radar Topography Mission, and are available
144 for most populated regions of the Earth. SPLAT Data Files
145 may be generated from SRTM data using the included
146 srtm2sdf utility. SRTM-3 Version 2 data may be obtained
147 through anonymous FTP from:
148 ftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/
150 Despite the higher accuracy that SRTM data has to offer,
151 some voids in the data sets exist. When voids are
152 detected, the srtm2sdf utility replaces them with corre-
153 sponding data found in existing SDF files (that were pre-
154 sumably created from earlier USGS data through the
155 usgs2sdf utility). If USGS-derived SDF data is not avail-
156 able, voids are handled through adjacent pixel averaging,
157 or direct replacement.
159 SPLAT Data Files contain integer value topographic eleva-
160 tions (in meters) referenced to mean sea level for
161 1-degree by 1-degree regions of the earth with a resolu-
162 tion of 3-arc seconds. SDF files can be read in either
163 standard format (.sdf) as generated by the usgs2sdf and
164 srtm2sdf utilities, or in bzip2 compressed format
165 (.sdf.bz2). Since uncompressed files can be processed
166 slightly faster than files that have been compressed,
167 SPLAT! searches for needed SDF data in uncompressed format
168 first. If uncompressed data cannot be located, SPLAT!
169 then searches for data in bzip2 compressed format. If no
170 compressed SDF files can be found for the region
171 requested, SPLAT! assumes the region is over water, and
172 will assign an elevation of sea-level to these areas.
174 This feature of SPLAT! makes it possible to perform path
175 analysis not only over land, but also between coastal
176 areas not represented by Digital Elevation Model data.
177 However, this behavior of SPLAT! underscores the impor-
178 tance of having all the SDF files required for the region
179 being analyzed if meaningful results are to be expected.
181 SITE LOCATION (QTH) FILES
182 SPLAT! imports site location information of transmitter
183 and receiver sites analyzed by the program from ASCII
184 files having a .qth extension. QTH files contain the
185 site's name, the site's latitude (positive if North of the
186 equator, negative if South), the site's longitude (in
187 degrees West, 0 to 360 degrees), and the site's antenna
188 height above ground level (AGL), each separated by a sin-
189 gle line-feed character. The antenna height is assumed to
190 be specified in feet unless followed by the letter m or
191 the word meters in either upper or lower case. Latitude
192 and longitude information may be expressed in either deci-
193 mal format (74.6889) or degree, minute, second (DMS) for-
196 For example, a site location file describing television
197 station WNJT, Trenton, NJ (wnjt.qth) might read as fol-
205 Each transmitter and receiver site analyzed by SPLAT! must
206 be represented by its own site location (QTH) file.
208 LONGLEY-RICE PARAMETER (LRP) FILES
209 Longley-Rice parameter data files are required for SPLAT!
210 to determine RF path loss in either point-to-point or area
211 prediction mode. Longley-Rice model parameter data is
212 read from files having the same base name as the transmit-
213 ter site QTH file, but with a format (wnjt.lrp):
215 15.000 ; Earth Dielectric Constant (Relative per-
217 0.005 ; Earth Conductivity (Siemens per meter)
218 301.000 ; Atmospheric Bending Constant (N-units)
219 700.000 ; Frequency in MHz (20 MHz to 20 GHz)
220 5 ; Radio Climate (5 = Continental Temper-
222 0 ; Polarization (0 = Horizontal, 1 = Verti-
224 0.5 ; Fraction of situations (50% of loca-
226 0.5 ; Fraction of time (50% of the time)
228 If an LRP file corresponding to the tx_site QTH file can-
229 not be found, SPLAT! scans the current working directory
230 for the file "splat.lrp". If this file cannot be found,
231 then the default parameters listed above will be assigned
232 by SPLAT! and a corresponding "splat.lrp" file containing
233 this data will be written to the current working direc-
234 tory. "splat.lrp" can then be edited by the user as
237 Typical Earth dielectric constants and conductivity values
240 Dielectric Constant Conductiv-
242 Salt water : 80 5.000
243 Good ground : 25 0.020
244 Fresh water : 80 0.010
245 Marshy land : 12 0.007
246 Farmland, forest : 15 0.005
247 Average ground : 15 0.005
248 Mountain, sand : 13 0.002
250 Poor ground : 4 0.001
252 Radio climate codes used by SPLAT! are as follows:
254 1: Equatorial (Congo)
255 2: Continental Subtropical (Sudan)
256 3: Maritime Subtropical (West coast of Africa)
258 5: Continental Temperate
259 6: Maritime Temperate, over land (UK and west
261 7: Maritime Temperate, over sea
263 The Continental Temperate climate is common to large land
264 masses in the temperate zone, such as the United States.
265 For paths shorter than 100 km, there is little difference
266 between Continental and Maritime Temperate climates.
268 The final two parameters in the .lrp file correspond to
269 the statistical analysis provided by the Longley-Rice
270 model. In this example, SPLAT! will return the maximum
271 path loss occurring 50% of the time (fraction of time) in
272 50% of situations (fraction of situations). In the United
273 States, use a fraction of time parameter of 0.97 for digi-
274 tal television (8VSB modulation), or 0.50 for analog (VSB-
275 AM+NTSC) transmissions.
277 For further information on these parameters, see:
278 http://flattop.its.bldrdoc.gov/itm.html and
279 http://www.softwright.com/faq/engineering/prop_long-
283 The names and locations of cities, tower sites, or other
284 points of interest may be imported and plotted on topo-
285 graphic maps generated by SPLAT!. SPLAT! imports the
286 names of cities and locations from ASCII files containing
287 the location of interest's name, latitude, and longitude.
288 Each field is separated by a comma. Each record is sepa-
289 rated by a single line feed character. As was the case
290 with the .qth files, latitude and longitude information
291 may be entered in either decimal or degree, minute, second
294 For example (cities.dat):
296 Teaneck, 40.891973, 74.014506
297 Tenafly, 40.919212, 73.955892
298 Teterboro, 40.859511, 74.058908
299 Tinton Falls, 40.279966, 74.093924
300 Toms River, 39.977777, 74.183580
301 Totowa, 40.906160, 74.223310
302 Trenton, 40.219922, 74.754665
304 A total of five separate city data files may be imported
305 at a time, and there is no limit to the size of these
306 files. SPLAT! reads city data on a "first come/first
307 served" basis, and plots only those locations whose anno-
308 tations do not conflict with annotations of locations read
309 earlier in the current city data file, or in previous
310 files. This behavior minimizes clutter in SPLAT! gener-
311 ated topographic maps, but also mandates that important
312 locations be placed toward the beginning of the first city
313 data file, and locations less important be positioned fur-
314 ther down the list or in subsequent data files.
316 City data files may be generated manually using any text
317 editor, imported from other sources, or derived from data
318 available from the U.S. Census Bureau using the cityde-
319 coder utility included with SPLAT!. Such data is avail-
320 able free of charge via the Internet at: http://www.cen-
321 sus.gov/geo/www/cob/bdy_files.html, and must be in ASCII
324 CARTOGRAPHIC BOUNDARY DATA FILES
325 Cartographic boundary data may also be imported to plot
326 the boundaries of cities, counties, or states on topo-
327 graphic maps generated by SPLAT!. Such data must be of
328 the form of ARC/INFO Ungenerate (ASCII Format) Metadata
329 Cartographic Boundary Files, and are available from the
330 U.S. Census Bureau via the Internet at:
331 http://www.census.gov/geo/www/cob/co2000.html#ascii and
332 http://www.census.gov/geo/www/cob/pl2000.html#ascii. A
333 total of five separate cartographic boundary files may be
334 imported at a time. It is not necessary to import state
335 boundaries if county boundaries have already been
339 SPLAT! is invoked via the command-line using a series of
340 switches and arguments. Since SPLAT! is a CPU and memory
341 intensive application, this type of interface minimizes
342 overhead and lends itself well to scripted (batch) opera-
343 tions. SPLAT!'s CPU and memory scheduling priority may be
344 modified through the use of the Unix nice command.
346 The number and type of switches passed to SPLAT! determine
347 its mode of operation and method of output data genera-
348 tion. Nearly all of SPLAT!'s switches may be cascaded in
349 any order on the command line when invoking the program.
351 SPLAT! operates in two distinct modes: point-to-point
352 mode, and area prediction mode. Either a line-of-sight
353 (LOS) or Longley-Rice Irregular Terrain (ITM) propagation
354 model may be invoked by the user. True Earth, four-thirds
355 Earth, or any other user-defined Earth radius may be spec-
356 ified when performing line-of-sight analysis.
358 POINT-TO-POINT ANALYSIS
359 SPLAT! may be used to perform line-of-sight terrain analy-
360 sis between two specified site locations. For example:
362 splat -t tx_site.qth -r rx_site.qth
364 invokes a line-of-sight terrain analysis between the
365 transmitter specified in tx_site.qth and receiver speci-
366 fied in rx_site.qth using a True Earth radius model, and
367 writes a SPLAT! Obstruction Report to the current working
368 directory. The report contains details of the transmitter
369 and receiver sites, and identifies the location of any
370 obstructions detected along the line-of-sight path. If an
371 obstruction can be cleared by raising the receive antenna
372 to a greater altitude, SPLAT! will indicate the minimum
373 antenna height required for a line-of-sight path to exist
374 between the transmitter and receiver locations specified.
375 Note that imperial units (miles, feet) are specified
376 unless the -metric switch is added to SPLAT!'s command
379 splat -t tx_site.qth -r rx_site.qth -metric
381 If the antenna must be raised a significant amount, this
382 determination may take a few moments. Note that the
383 results provided are the minimum necessary for a line-of-
384 sight path to exist, and in the case of this simple exam-
385 ple, do not take Fresnel zone clearance requirements into
388 qth extensions are assumed by SPLAT! for QTH files, and
389 are optional when specifying -t and -r arguments on the
390 command-line. SPLAT! automatically reads all SPLAT Data
391 Files necessary to conduct the terrain analysis between
392 the sites specified. SPLAT! searches for the required
393 SDF files in the current working directory first. If the
394 needed files are not found, SPLAT! then searches in the
395 path specified by the -d command-line switch:
397 splat -t tx_site -r rx_site -d /cdrom/sdf/
399 An external directory path may be specified by placing a
400 ".splat_path" file under the user's home directory. This
401 file must contain the full directory path of last resort
402 to all the SDF files. The path in the $HOME/.splat_path
403 file must be of the form of a single line of ASCII text:
407 and can be generated using any text editor.
409 A graph of the terrain profile between the receiver and
410 transmitter locations as a function of distance from the
411 receiver can be generated by adding the -p switch:
413 splat -t tx_site -r rx_site -p terrain_profile.png
415 SPLAT! invokes gnuplot when generating graphs. The file-
416 name extension specified to SPLAT! determines the format
417 of the graph produced. .png will produce a 640x480 color
418 PNG graphic file, while .ps or .postscript will produce
419 postscript output. Output in formats such as GIF, Adobe
420 Illustrator, AutoCAD dxf, LaTeX, and many others are
421 available. Please consult gnuplot, and gnuplot's documen-
422 tation for details on all the supported output formats.
424 A graph of elevations subtended by the terrain between the
425 receiver and transmitter as a function of distance from
426 the receiver can be generated by using the -e switch:
428 splat -t tx_site -r rx_site -e elevation_profile.png
430 The graph produced using this switch illustrates the ele-
431 vation and depression angles resulting from the terrain
432 between the receiver's location and the transmitter site
433 from the perspective of the receiver's location. A second
434 trace is plotted between the left side of the graph
435 (receiver's location) and the location of the transmitting
436 antenna on the right. This trace illustrates the eleva-
437 tion angle required for a line-of-sight path to exist
438 between the receiver and transmitter locations. If the
439 trace intersects the elevation profile at any point on the
440 graph, then this is an indication that a line-of-sight
441 path does not exist under the conditions given, and the
442 obstructions can be clearly identified on the graph at the
443 point(s) of intersection.
445 A graph illustrating terrain height referenced to a line-
446 of-sight path between the transmitter and receiver may be
447 generated using the -h switch:
449 splat -t tx_site -r rx_site -h height_profile.png
451 A terrain height plot normalized to the transmitter and
452 receiver antenna heights can be obtained using the -H
455 splat -t tx_site -r rx_site -H normalized_height_pro-
458 A contour of the Earth's curvature is also plotted in this
461 The first Fresnel Zone, and 60% of the first Fresnel Zone
462 can be added to height profile graphs by adding the -f
463 switch, and specifying a frequency (in MHz) at which the
464 Fresnel Zone should be modeled:
466 splat -t tx_site -r rx_site -f 439.250 -H normal-
467 ized_height_profile.png
469 A graph showing Longley-Rice path loss may be plotted
472 splat -t tx_site -r rx_site -l path_loss_profile.png
474 As before, adding the -metric switch forces the graphs to
475 be plotted using metric units of measure.
477 When performing path loss profiles, a Longley-Rice Model
478 Path Loss Report is generated by SPLAT! in the form of a
479 text file with a .lro filename extension. The report con-
480 tains bearings and distances between the transmitter and
481 receiver, as well as the Longley-Rice path loss for vari-
482 ous distances between the transmitter and receiver loca-
483 tions. The mode of propagation for points along the path
484 are given as Line-of-Sight, Single Horizon, Double Hori-
485 zon, Diffraction Dominant, and Troposcatter Dominant.
487 To determine the signal-to-noise (SNR) ratio at remote
488 location where random Johnson (thermal) noise is the pri-
489 mary limiting factor in reception:
493 where T is the ERP of the transmitter in dBW in the direc-
494 tion of the receiver, NJ is Johnson Noise in dBW (-136 dBW
495 for a 6 MHz television channel), L is the path loss pro-
496 vided by SPLAT! in dB (as a positive number), G is the
497 receive antenna gain in dB over isotropic, and NF is the
498 receiver noise figure in dB.
500 T may be computed as follows:
504 where TI is actual amount of RF power delivered to the
505 transmitting antenna in dBW, GT is the transmitting
506 antenna gain (over isotropic) in the direction of the
507 receiver (or the horizon if the receiver is over the hori-
510 To compute how much more signal is available over the min-
511 imum to necessary to achieve a specific signal-to-noise
516 where S is the minimum required SNR ratio (15.5 dB for
517 ATSC (8-VSB) DTV, 42 dB for analog NTSC television).
519 A topographic map may be generated by SPLAT! to visualize
520 the path between the transmitter and receiver sites from
521 yet another perspective. Topographic maps generated by
522 SPLAT! display elevations using a logarithmic grayscale,
523 with higher elevations represented through brighter shades
524 of gray. The dynamic range of the image is scaled between
525 the highest and lowest elevations present in the map. The
526 only exception to this is sea-level, which is represented
527 using the color blue.
529 Topographic output is invoked using the -o switch:
531 splat -t tx_site -r rx_site -o topo_map.ppm
533 The .ppm extension on the output filename is assumed by
534 SPLAT!, and is optional.
536 In this example, topo_map.ppm will illustrate the loca-
537 tions of the transmitter and receiver sites specified. In
538 addition, the great circle path between the two sites will
539 be drawn over locations for which an unobstructed path
540 exists to the transmitter at a receiving antenna height
541 equal to that of the receiver site (specified in
544 It may desirable to populate the topographic map with
545 names and locations of cities, tower sites, or other
546 important locations. A city file may be passed to SPLAT!
549 splat -t tx_site -r rx_site -s cities.dat -o topo_map
551 Up to five separate city files may be passed to SPLAT! at
552 a time following the -s switch.
554 County and state boundaries may be added to the map by
555 specifying up to five U.S. Census Bureau cartographic
556 boundary files using the -b switch:
558 splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map
560 In situations where multiple transmitter sites are in use,
561 as many as four site locations may be passed to SPLAT! at
564 splat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p
567 In this example, four separate terrain profiles and
568 obstruction reports will be generated by SPLAT!. A single
569 topographic map can be specified using the -o switch, and
570 line-of-sight paths between each transmitter and the
571 receiver site indicated will be produced on the map, each
572 in its own color. The path between the first transmitter
573 specified to the receiver will be in green, the path
574 between the second transmitter and the receiver will be in
575 cyan, the path between the third transmitter and the
576 receiver will be in violet, and the path between the
577 fourth transmitter and the receiver will be in sienna.
579 SPLAT! generated topographic maps are 24-bit TrueColor
580 Portable PixMap (PPM) images. They may be viewed, edited,
581 or converted to other graphic formats by popular image
582 viewing applications such as xv, The GIMP, ImageMagick,
583 and XPaint. PNG format is highly recommended for lossless
584 compressed storage of SPLAT! generated topographic output
585 files. ImageMagick's command-line utility easily converts
586 SPLAT!'s PPM files to PNG format:
588 convert splat_map.ppm splat_map.png
590 Another excellent PPM to PNG command-line utility is
592 http://www.libpng.org/pub/png/book/sources.html. As a
593 last resort, PPM files may be compressed using the bzip2
594 utility, and read directly by The GIMP in this format.
596 REGIONAL COVERAGE ANALYSIS
597 SPLAT! can analyze a transmitter or repeater site, or net-
598 work of sites, and predict the regional coverage for each
599 site specified. In this mode, SPLAT! can generate a topo-
600 graphic map displaying the geometric line-of-sight cover-
601 age area of the sites based on the location of each site
602 and the height of receive antenna wishing to communicate
603 with the site in question. SPLAT! switches from point-to-
604 point analysis mode to area prediction mode when the -c
605 switch is invoked as follows:
607 splat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o
610 In this example, SPLAT! generates a topographic map called
611 tx_coverage.ppm that illustrates the predicted line-of-
612 sight regional coverage of tx_site to receiving locations
613 having antennas 30.0 feet above ground level (AGL). If
614 the -metric switch is used, the argument following the -c
615 switch is interpreted as being in meters, rather than in
616 feet. The contents of cities.dat are plotted on the map,
617 as are the cartographic boundaries contained in the file
620 When plotting line-of-sight paths and areas of regional
621 coverage, SPLAT! by default does not account for the
622 effects of atmospheric bending. However, this behavior
623 may be modified by using the Earth radius multiplier (-m)
626 splat -t wnjt -c 30.0 -m 1.333 -s cities.dat -b coun-
629 An earth radius multiplier of 1.333 instructs SPLAT! to
630 use the "four-thirds earth" model for line-of-sight propa-
631 gation analysis. Any appropriate earth radius multiplier
632 may be selected by the user.
634 When invoked in area prediction mode, SPLAT! generates a
635 site report for each station analyzed. SPLAT! site
636 reports contain details of the site's geographic location,
637 its height above mean sea level, the antenna's height
638 above mean sea level, the antenna's height above average
639 terrain, and the height of the average terrain calculated
640 in the directions of 0, 45, 90, 135, 180, 225, 270, and
643 DETERMINING MULTIPLE REGIONS OF LOS COVERAGE
644 SPLAT! can also display line-of-sight coverage areas for
645 as many as four separate transmitter sites on a common
646 topographic map. For example:
648 splat -t site1 site2 site3 site4 -c 10.0 -metric -o net-
651 plots the regional line-of-sight coverage of site1, site2,
652 site3, and site4 based on a receive antenna located 10.0
653 meters above ground level. A topographic map is then
654 written to the file network.ppm. The line-of-sight cover-
655 age area of the transmitters are plotted as follows in the
656 colors indicated (along with their corresponding RGB val-
659 site1: Green (0,255,0)
660 site2: Cyan (0,255,255)
661 site3: Medium Violet (147,112,219)
662 site4: Sienna 1 (255,130,71)
664 site1 + site2: Yellow (255,255,0)
665 site1 + site3: Pink (255,192,203)
666 site1 + site4: Green Yellow (173,255,47)
667 site2 + site3: Orange (255,165,0)
668 site2 + site4: Dark Sea Green 1 (193,255,193)
669 site3 + site4: Dark Turquoise (0,206,209)
671 site1 + site2 + site3: Dark Green (0,100,0)
672 site1 + site2 + site4: Blanched Almond (255,235,205)
673 site1 + site3 + site4: Medium Spring Green (0,250,154)
674 site2 + site3 + site4: Tan (210,180,140)
676 site1 + site2 + site3 + site4: Gold2 (238,201,0)
678 If separate .qth files are generated, each representing a
679 common site location but a different antenna height, a
680 single topographic map illustrating the regional coverage
681 from as many as four separate locations on a single tower
682 may be generated by SPLAT!.
684 LONGLEY-RICE PATH LOSS ANALYSIS
685 If the -c switch is replaced by a -L switch, a Longley-
686 Rice path loss map for a transmitter site may be gener-
689 splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -o
692 In this mode, SPLAT! generates a multi-color map illus-
693 trating expected signal levels (path loss) in areas sur-
694 rounding the transmitter site. A legend at the bottom of
695 the map correlates each color with a specific path loss
698 The Longley-Rice analysis range may be modified to a user-
699 specific value using the -R switch. The argument must be
700 given in miles (or kilometers if the -metric switch is
701 used). If a range wider than the generated topographic
702 map is specified, SPLAT! will perform Longley-Rice path
703 loss calculations between all four corners of the area
706 The -db switch allows a constraint to be placed on the
707 maximum path loss region plotted on the map. A maximum
708 path loss between 80 and 230 dB may be specified using
709 this switch. For example, if a path loss beyond -140 dB
710 is irrelevant to the survey being conducted, SPLAT!'s path
711 loss plot can be constrained to the region bounded by the
712 140 dB attenuation contour as follows:
714 splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -db
718 ANTENNA RADIATION PATTERN PARAMETERS
719 Normalized field voltage patterns for a transmitting
720 antenna's horizontal and vertical planes are imported
721 automatically into SPLAT! when a Longley-Rice coverage
722 analysis is performed. Antenna pattern data is read from
723 a pair of files having the same base name as the transmit-
724 ter and LRP files, but with .az and .el extensions for
725 azimuth and elevation pattern files, respectively. Speci-
726 fications regarding pattern rotation (if any) and
727 mechanical beam tilt and tilt direction (if any) are also
728 contained within SPLAT! antenna pattern files.
730 For example, the first few lines of a SPLAT! azimuth pat-
731 tern file might appear as follows (kvea.az):
744 The first line of the .az file specifies the amount of
745 azimuthal pattern rotation (measured clockwise in degrees
746 from True North) to be applied by SPLAT! to the data con-
747 tained in the .az file. This is followed by azimuth head-
748 ings (0 to 360 degrees) and their associated normalized
749 field patterns (0.000 to 1.000) separated by whitespace.
751 The structure of SPLAT! elevation pattern files is
752 slightly different. The first line of the .el file speci-
753 fies the amount of mechanical beam tilt applied to the
754 antenna. Note that a downward tilt (below the horizon) is
755 expressed as a positive angle, while an upward tilt (above
756 the horizon) is expressed as a negative angle. This data
757 is followed by the azimuthal direction of the tilt, sepa-
760 The remainder of the file consists of elevation angles and
761 their corresponding normalized voltage radiation pattern
762 (0.000 to 1.000) values separated by whitespace. Eleva-
763 tion angles must be specified over a -10.0 to +90.0 degree
764 range. As was the convention with mechanical beamtilt,
765 negative elevation angles are used to represent elevations
766 above the horizon, while positive angles represents eleva-
767 tions below the horizon.
769 For example, the first few lines a SPLAT! elevation pat-
770 tern file might appear as follows (kvea.el):
783 In this example, the antenna is mechanically tilted down-
784 ward 1.1 degrees towards an azimuth of 130.0 degrees.
786 For best results, the resolution of azimuth pattern data
787 should be specified to the nearest degree azimuth, and
788 elevation pattern data resolution should be specified to
789 the nearest 0.01 degrees. If the pattern data specified
790 does not reach this level of resolution, SPLAT! will
791 interpolate the values provided to determine the data at
792 the required resolution, although this may result in a
796 IMPORTING AND EXPORTING REGIONAL PATH LOSS CONTOUR DATA
797 Performing a Longley-Rice coverage analysis can be a very
798 time consuming process, especially if the analysis is
799 repeated repeatedly to discover what effects changes to
800 the antenna radiation patterns make to the predicted cov-
803 This process can be expedited by exporting the Longley-
804 Rice regional path loss contour data to an output file,
805 modifying the path loss data externally to incorporate
806 antenna pattern effects, and then importing the modified
807 path loss data back into SPLAT! to rapidly produce a
808 revised path loss map.
810 For example, a path loss output file can be generated by
811 SPLAT! for a receive site 30 feet above ground level over
812 a 50 mile radius surrounding a transmitter site to a maxi-
813 mum path loss of 140 dB using the following syntax:
815 splat -t kvea -L 30.0 -R 50.0 -db 140 -plo pathloss.dat
817 SPLAT! path loss output files often exceed 100 megabytes
818 in size. They contain information relating to the bound-
819 aries of region they describe followed by latitudes
820 (degrees North), longitudes (degrees West), azimuths, ele-
821 vations (to the first obstruction), and path loss figures
822 (dB) for a series of specific points that comprise the
823 region surrounding the transmitter site. The first few
824 lines of a SPLAT! path loss output file take on the fol-
825 lowing appearance (pathloss.dat):
827 119, 117 ; max_west, min_west
828 35, 33 ; max_north, min_north
829 34.2265434, 118.0631104, 48.171, -37.461, 67.70
830 34.2270355, 118.0624390, 48.262, -26.212, 73.72
831 34.2280197, 118.0611038, 48.269, -14.951, 79.74
832 34.2285156, 118.0604401, 48.207, -11.351, 81.68
833 34.2290077, 118.0597687, 48.240, -10.518, 83.26
834 34.2294998, 118.0591049, 48.225, 23.201, 84.60
835 34.2304878, 118.0577698, 48.213, 15.769, 137.84
836 34.2309799, 118.0570984, 48.234, 15.965, 151.54
837 34.2314720, 118.0564346, 48.224, 16.520, 149.45
838 34.2319679, 118.0557632, 48.223, 15.588, 151.61
839 34.2329521, 118.0544281, 48.230, 13.889, 135.45
840 34.2334442, 118.0537643, 48.223, 11.693, 137.37
841 34.2339401, 118.0530930, 48.222, 14.050, 126.32
842 34.2344322, 118.0524292, 48.216, 16.274, 156.28
843 34.2354164, 118.0510941, 48.222, 15.058, 152.65
844 34.2359123, 118.0504227, 48.221, 16.215, 158.57
845 34.2364044, 118.0497589, 48.216, 15.024, 157.30
846 34.2368965, 118.0490875, 48.225, 17.184, 156.36
848 It is not uncommon for SPLAT! path loss files to contain
849 as many as 3 million or more lines of data. Comments can
850 be placed in the file if they are proceeded by a semicolon
851 character. The vim text editor has proven capable of
852 editing files of this size.
854 Note as was the case in the antenna pattern files, nega-
855 tive elevation angles refer to upward tilt (above the
856 horizon), while positive angles refer to downward tilt
857 (below the horizon). These angles refer to the elevation
858 to the receiving antenna at the height above ground level
859 specified using the -L switch if the path between trans-
860 mitter and receiver is unobstructed. If the path between
861 the transmitter and receiver is obstructed, then the ele-
862 vation angle to the first obstruction is returned by
863 SPLAT!. This is because the Longley-Rice model considers
864 the energy reaching a distant point over an obstructed
865 path as a derivative of the energy scattered from the top
866 of the first obstruction, only. Since energy cannot reach
867 the obstructed location directly, the actual elevation
868 angle to that point is irrelevant.
870 When modifying SPLAT! path loss files to reflect antenna
871 pattern data, only the last column (path loss) should be
872 amended to reflect the antenna's normalized gain at the
873 azimuth and elevation angles specified in the file. (At
874 this time, programs and scripts capable of performing this
875 operation are left as an exercise for the user.)
877 Modified path loss maps can be imported back into SPLAT!
878 for generating revised coverage maps:
880 splat -t kvea -pli pathloss.dat -s city.dat -b county.dat
883 SPLAT! path loss files can also be used for conducting
884 coverage or interference studies outside of SPLAT!.
886 USER-DEFINED TERRAIN INPUT FILES
887 A user-defined terrain file is a user-generated text file
888 containing latitudes, longitudes, and heights above ground
889 level of specific terrain features believed to be of
890 importance to the SPLAT! analysis being conducted, but
891 noticeably absent from the SDF files being used. A user-
892 defined terrain file is imported into a SPLAT! analysis
893 using the -udt switch:
895 splat -t tx_site -r rx_site -udt udt_file.txt -o map.ppm
897 A user-defined terrain file has the following appearance
900 40.32180556, 74.1325, 100.0 meters
901 40.321805, 74.1315, 300.0
902 40.3218055, 74.1305, 100.0 meters
904 Terrain height is interpreted as being described in feet
905 above ground level unless followed by the word meters, and
906 is added on top of the terrain specified in the SDF data
907 for the locations specified. Be aware that each user-
908 defined terrain feature specified will be interpreted as
909 being 3-arc seconds in both latitude and longitude. Fea-
910 tures described in the user-defined terrain file that
911 overlap previously defined features in the file are
914 SIMPLE TOPOGRAPHIC MAP GENERATION
915 In certain situations it may be desirable to generate a
916 topographic map of a region without plotting coverage
917 areas, line-of-sight paths, or generating obstruction
918 reports. There are several ways of doing this. If one
919 wishes to generate a topographic map illustrating the
920 location of a transmitter and receiver site along with a
921 brief text report describing the locations and distances
922 between the sites, the -n switch should be invoked as fol-
925 splat -t tx_site -r rx_site -n -o topo_map.ppm
927 If no text report is desired, then the -N switch is used:
929 splat -t tx_site -r rx_site -N -o topo_map.ppm
931 If a topographic map centered about a single site out to a
932 minimum specified radius is desired instead, a command
933 similar to the following can be used:
935 splat -t tx_site -R 50.0 -s NJ_Cities -b NJ_Counties -o
938 where -R specifies the minimum radius of the map in miles
939 (or kilometers if the -metric switch is used).
941 If the -o switch and output filename are omitted in these
942 operations, topographic output is written to a file named
943 map.ppm in the current working directory by default.
945 GEOREFERENCE FILE GENERATION
946 Topographic, coverage (-c), and path loss contour (-L)
947 maps generated by SPLAT! may be imported into Xastir (X
948 Amateur Station Tracking and Information Reporting) soft-
949 ware by generating a georeference file using SPLAT!'s -geo
952 splat -t kd2bd -R 50.0 -s NJ_Cities -b NJ_Counties -geo -o
955 The georeference file generated will have the same base
956 name as the -o file specified, but have a .geo extension,
957 and permit proper interpretation and display of SPLAT!'s
958 .ppm graphics in Xastir software.
960 GOOGLE MAP KML FILE GENERATION
961 Keyhole Markup Language files compatible with Google Earth
962 may be generated by SPLAT! when performing point-to-point
963 analyses by invoking the -kml switch:
965 splat -t wnjt -r kd2bd -kml
967 The KML file generated will have the same filename struc-
968 ture as an Obstruction Report for the transmitter and
969 receiver site names given, except it will carry a .kml
972 Once loaded into Google Earth (File --> Open), the KML
973 file will annotate the map display with the names of the
974 transmitter and receiver site locations. The viewpoint of
975 the image will be from the position of the transmitter
976 site looking towards the location of the receiver. The
977 point-to-point path between the sites will be displayed as
978 a white line while the RF line-of-sight path will be dis-
979 played in green. Google Earth's navigation tools allow
980 the user to "fly" around the path, identify landmarks,
981 roads, and other featured content.
983 DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
984 SPLAT! determines antenna height above average terrain
985 (HAAT) according to the procedure defined by Federal Com-
986 munications Commission Part 73.313(d). According to this
987 definition, terrain elevations along eight radials between
988 2 and 10 miles (3 and 16 kilometers) from the site being
989 analyzed are sampled and averaged for each 45 degrees of
990 azimuth starting with True North. If one or more radials
991 lie entirely over water or over land outside the United
992 States (areas for which no USGS topography data is avail-
993 able), then those radials are omitted from the calculation
996 Note that SRTM elevation data, unlike older 3-arc second
997 USGS data, extends beyond the borders of the United
998 States. Therefore, HAAT results may not be in full com-
999 pliance with FCC Part 73.313(d) in areas along the borders
1000 of the United States if the SDF files used by SPLAT! are
1003 When performing point-to-point terrain analysis, SPLAT!
1004 determines the antenna height above average terrain only
1005 if enough topographic data has already been loaded by the
1006 program to perform the point-to-point analysis. In most
1007 cases, this will be true, unless the site in question does
1008 not lie within 10 miles of the boundary of the topography
1011 When performing area prediction analysis, enough topogra-
1012 phy data is normally loaded by SPLAT! to perform average
1013 terrain calculations. Under such conditions, SPLAT! will
1014 provide the antenna height above average terrain as well
1015 as the average terrain above mean sea level for azimuths
1016 of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and
1017 include such information in the generated site report. If
1018 one or more of the eight radials surveyed fall over water,
1019 or over regions for which no SDF data is available, SPLAT!
1020 reports No Terrain for the radial paths affected.
1022 RESTRICTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
1023 SPLAT! reads SDF files as needed into a series of memory
1024 pages or "slots" within the structure of the program.
1025 Each "slot" holds one SDF file representing a one degree
1026 by one degree region of terrain. A #define MAXSLOTS
1027 statement in the first several lines of splat.cpp sets the
1028 maximum number of "slots" available for holding topography
1029 data. It also sets the maximum size of the topographic
1030 maps generated by SPLAT!. MAXSLOTS is set to 9 by
1031 default. If SPLAT! produces a segmentation fault on
1032 start-up with this default, it is an indication that not
1033 enough RAM and/or virtual memory (swap space) is available
1034 to run SPLAT! with the number of MAXSLOTS specified. In
1035 situations where available memory is low, MAXSLOTS may be
1036 reduced to 4 with the understanding that this will greatly
1037 limit the maximum region SPLAT! will be able to analyze.
1038 If 118 megabytes or more of total memory (swap space plus
1039 RAM) is available, then MAXSLOTS may be increased to 16.
1040 This will permit operation over a 4-degree by 4-degree
1041 region, which is sufficient for single antenna heights in
1042 excess of 10,000 feet above mean sea level, or point-to-
1043 point distances of over 1000 miles.
1045 ADDITIONAL INFORMATION
1046 The latest news and information regarding SPLAT! software
1047 is available through the official SPLAT! software web page
1048 located at: http://www.qsl.net/kd2bd/splat.html.
1051 John A. Magliacane, KD2BD <kd2bd@amsat.org>
1052 Creator, Lead Developer
1054 Doug McDonald <mcdonald@scs.uiuc.edu>
1055 Longley-Rice Model integration
1057 Ron Bentley <ronbentley@earthlink.net>
1058 Fresnel Zone plotting and clearance determination
1063 KD2BD Software 20 December 2006 SPLAT!(1)
projects / debian / splat / blob