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 (feet)
12 (float)] [-L rx_antenna_height_for_Longley-Rice_cover-
13 age_analysis (feet) (float)] [-p terrain_profile.ext] [-e
14 elevation_profile.ext] [-h height_profile.ext] [-l Long-
15 ley-Rice_profile.ext] [-o topographic_map_filename.ppm]
16 [-b cartographic_boundary_filename.dat] [-s
17 site/city_database.dat] [-d sdf_directory_path] [-m
18 earth_radius_multiplier (float)] [-R maximum_cover-
19 age_range (for -c or -L) (miles) (float)] [-dB maximum
20 attenuation contour to display on path loss maps (80-230
24 SPLAT! is a powerful terrestrial RF propagation and ter-
25 rain analysis tool covering the spectrum between 20 MHz
26 and 20 GHz. It is designed for operation on Unix and
27 Linux-based workstations. SPLAT! is free software.
28 Redistribution and/or modification is permitted under the
29 terms of the GNU General Public License as published by
30 the Free Software Foundation, either version 2 of the
31 License or any later version. Adoption of SPLAT! source
32 code in proprietary or closed-source applications is a
33 violation of this license, and is strictly forbidden.
35 SPLAT! is distributed in the hope that it will be useful,
36 but WITHOUT ANY WARRANTY, without even the implied war-
37 ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
38 POSE. See the GNU General Public License for more details.
41 Applications of SPLAT! include the visualization, design,
42 and link budget analysis of wireless Wide Area Networks
43 (WANs), commercial and amateur radio communication systems
44 above 20 MHz, microwave links, frequency coordination, and
45 the determination of analog and digital terrestrial radio
46 and television contour regions.
48 SPLAT! provides RF site engineering data such as great
49 circle distances and bearings between sites, antenna ele-
50 vation angles (uptilt), depression angles (downtilt),
51 antenna height above mean sea level, antenna height above
52 average terrain, bearings and distances to known obstruc-
53 tions, Longley-Rice path attenuation, and minimum antenna
54 height requirements needed to establish line-of-sight com-
55 munication paths absent of obstructions due to terrain.
56 SPLAT! produces reports, graphs, and highly detailed and
57 carefully annotated topographic maps depicting line-of-
58 sight paths, path loss, and expected coverage areas of
59 transmitters and repeater systems. When performing line-
60 of-sight analysis in situations where multiple transmitter
61 or repeater sites are employed, SPLAT! determines individ-
62 ual and mutual areas of coverage within the network speci-
65 SPLAT! operates in two distinct modes: point-to-point
66 mode, and area prediction mode, and may be invoked using
67 either line-of-sight (LOS) or Irregular Terrain (ITM)
68 propagation models. True Earth, four-thirds Earth, or any
69 other Earth radius may be specified by the user when per-
70 forming line-of-sight analysis.
73 SPLAT! is a command-line driven application, and reads
74 input data through a number of data files. Some files are
75 mandatory for successful execution of the program, while
76 others are optional. Mandatory files include SPLAT Data
77 Files (SDF files), site location files (QTH files), and
78 Longley-Rice model parameter files (LRP files). Optional
79 files include city/site location files, and cartographic
83 SPLAT! imports topographic data in the form of SPLAT Data
84 Files (SDFs). These files may be generated from a number
85 of information sources. In the United States, SPLAT Data
86 Files can be generated through U.S. Geological Survey
87 Digital Elevation Models (DEMs) using the usgs2sdf utility
88 included with SPLAT!. USGS Digital Elevation Models com-
89 patible with this utility may be downloaded from:
90 http://edcftp.cr.usgs.gov/pub/data/DEM/250/.
92 Significantly better resolution can be obtained through
93 the use of SRTM-3 Version 2 digital elevation models.
94 These models are the result of the STS-99 Space Shuttle
95 Radar Topography Mission, and are available for most popu-
96 lated regions of the Earth. SPLAT Data Files may be gen-
97 erated from SRTM data using the included srtm2sdf utility.
98 SRTM-3 Version 2 data may be obtained through anonymous
99 FTP from: ftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/
101 Despite the higher accuracy that SRTM data has to offer,
102 some voids in the data sets exist. When voids are
103 detected, the srtm2sdf utility replaces them with corre-
104 sponding data found in existing SDF files (that were pre-
105 sumably created from earlier USGS data through the
106 usgs2sdf utility). If USGS-derived SDF data is not avail-
107 able, voids are handled through adjacent pixel averaging,
108 or direct replacement.
110 SPLAT Data Files contain integer value topographic eleva-
111 tions (in meters) referenced to mean sea level for
112 1-degree by 1-degree regions of the earth with a resolu-
113 tion of 3-arc seconds. SDF files can be read in either
114 standard format (.sdf) as generated by the usgs2sdf and
115 srtm2sdf utilities, or in bzip2 compressed format
116 (.sdf.bz2). Since uncompressed files can be processed
117 slightly faster than files that have been compressed,
118 SPLAT! searches for the needed SDF data in uncompressed
119 format first. If uncompressed data cannot located, SPLAT!
120 then searches for data in bzip2 compressed format. If no
121 compressed SDF files can be found for the region
122 requested, SPLAT! assumes the region is over water, and
123 will assign an elevation of sea-level to these areas.
125 This feature of SPLAT! makes it possible to perform path
126 analysis not only over land, but also between coastal
127 areas not represented by Digital Elevation Model data.
128 This behavior of SPLAT! underscores the importance of hav-
129 ing all the SDF files required for the region being ana-
130 lyzed if meaningful results are to be expected.
132 SITE LOCATION (QTH) FILES
133 SPLAT! imports site location information of transmitter
134 and receiver sites analyzed by the program from ASCII
135 files having a .qth extension. QTH files contain the
136 site's name, the site's latitude (positive if North of the
137 equator, negative if South), the site's longitude (in
138 degrees West, 0 to 360 degrees), and the site's antenna
139 height above ground level (AGL). A single line-feed char-
140 acter separates each field. The antenna height is assumed
141 to be specified in feet unless followed by the letter m or
142 the word meters in either upper or lower case. Latitude
143 and longitude information may be expressed in either deci-
144 mal format (74.6889) or degree, minute, second (DMS) for-
147 For example, a site location file describing television
148 station WNJT, Trenton, NJ (wnjt.qth) might read as fol-
156 Each transmitter and receiver site analyzed by SPLAT! must
157 be represented by its own site location (QTH) file.
159 LONGLEY-RICE PARAMETER (LRP) FILES
160 SPLAT! imports Longley-Rice model parameter data from
161 files having the same base name as the transmitter site
162 QTH file, but with a .lrp extension, thus providing simple
163 and accurate correlation between these associated data
164 sets. The format for the Longley-Rice model parameter
165 files is as follows (wnjt.lrp):
167 15.000 ; Earth Dielectric Constant (Relative per-
169 0.005 ; Earth Conductivity (Siemens per meter)
170 301.000 ; Atmospheric Bending Constant (N-units)
171 700.000 ; Frequency in MHz (20 MHz to 20 GHz)
172 5 ; Radio Climate (5 = Continental Temper-
174 0 ; Polarization (0 = Horizontal, 1 = Verti-
176 0.5 ; Fraction of situations (50% of loca-
178 0.5 ; Fraction of time (50% of the time)
180 If an LRP file corresponding to the tx_site QTH file can-
181 not be found, SPLAT! scans the current working directory
182 for the file "splat.lrp". If this file cannot be found,
183 then the default parameters listed above will be assigned
184 by SPLAT! and a corresponding "splat.lrp" file containing
185 this data will be written to the current working direc-
186 tory. "splat.lrp" can then be edited by the user as
189 Typical Earth dielectric constants and conductivity values
192 Dielectric Constant Conductiv-
194 Salt water : 80 5.000
195 Good ground : 25 0.020
196 Fresh water : 80 0.010
197 Marshy land : 12 0.007
198 Farmland, forest : 15 0.005
199 Average ground : 15 0.005
200 Mountain, sand : 13 0.002
202 Poor ground : 4 0.001
204 Radio climate codes used by SPLAT! are as follows:
206 1: Equatorial (Congo)
207 2: Continental Subtropical (Sudan)
208 3: Maritime Subtropical (West coast of Africa)
210 5: Continental Temperate
211 6: Maritime Temperate, over land (UK and west
213 7: Maritime Temperate, over sea
215 The Continental Temperate climate is common to large land
216 masses in the temperate zone, such as the United States.
217 For paths shorter than 100 km, there is little difference
218 between Continental and Maritime Temperate climates.
220 The final two parameters in the .lrp file correspond to
221 the statistical analysis provided by the Longley-Rice
222 model. In this example, SPLAT! will return the maximum
223 path loss occurring 50% of the time (fraction of time) in
224 50% of situations (fraction of situations). Use a frac-
225 tion of time parameter of 0.97 for digital television,
226 0.50 for analog in the United States. Isotropic antennas
229 For further information on these parameters, see:
230 http://flattop.its.bldrdoc.gov/itm.html and
231 http://www.softwright.com/faq/engineering/prop_long-
235 The names and locations of cities, tower sites, or other
236 points of interest may be imported and plotted on topo-
237 graphic maps generated by SPLAT!. SPLAT! imports the
238 names of cities and locations from ASCII files containing
239 the location's name, the location's latitude, and the
240 location's longitude. Each field is separated by a comma.
241 Each record is separated by a single line feed character.
242 As was the case with the .qth files, latitude and longi-
243 tude information may be entered in either decimal or
244 degree, minute, second (DMS) format.
246 For example (cities.dat):
248 Teaneck, 40.891973, 74.014506
249 Tenafly, 40.919212, 73.955892
250 Teterboro, 40.859511, 74.058908
251 Tinton Falls, 40.279966, 74.093924
252 Toms River, 39.977777, 74.183580
253 Totowa, 40.906160, 74.223310
254 Trenton, 40.219922, 74.754665
256 A total of five separate city data files may be imported
257 at a time, and there is no limit to the size of these
258 files. SPLAT! reads city data on a "first come/first
259 served" basis, and plots only those locations whose anno-
260 tations do not conflict with annotations of locations
261 plotted earlier during SPLAT's execution. This behavior
262 minimizes clutter in SPLAT! generated topographic maps,
263 but also mandates that important locations be placed
264 toward the beginning of the first city data file, and
265 disposable locations be positioned further down the list
266 or in subsequent data files.
268 City data files may be generated manually using any text
269 editor, imported from other sources, or derived from data
270 available from the U.S. Census Bureau using the cityde-
271 coder utility included with SPLAT!. Such data is avail-
272 able free of charge via the Internet at: http://www.cen-
273 sus.gov/geo/www/cob/bdy_files.html, and must be in ASCII
276 CARTOGRAPHIC BOUNDARY DATA FILES
277 Cartographic boundary data may also be imported to plot
278 the boundaries of cities, counties, or states on topo-
279 graphic maps generated by SPLAT!. Such data must be of
280 the form of ARC/INFO Ungenerate (ASCII Format) Metadata
281 Cartographic Boundary Files, and are available from the
282 U.S. Census Bureau via the Internet at: http://www.cen-
283 sus.gov/geo/www/cob/co2000.html#ascii and http://www.cen-
284 sus.gov/geo/www/cob/pl2000.html#ascii. A total of five
285 separate cartographic boundary files may be imported at a
286 time. It is not necessary to import state boundaries if
287 county boundaries have already been imported.
290 SPLAT! is invoked via the command-line using a series of
291 switches and arguments. Since SPLAT! is a CPU and memory
292 intensive application, this type of interface minimizes
293 overhead and lends itself well to scripted (batch) opera-
294 tions. SPLAT!'s CPU and memory scheduling priority may be
295 modified through the use of the Unix nice command.
297 The number and type of switches passed to SPLAT! determine
298 its mode of operation and method of output data genera-
299 tion. Nearly all of SPLAT!'s switches may be cascaded in
300 any order on the command line when invoking the program.
302 POINT-TO-POINT ANALYSIS
303 SPLAT! may be used to perform line-of-sight terrain analy-
304 sis between two specified site locations. For example:
306 splat -t tx_site.qth -r rx_site.qth
308 invokes a terrain analysis between the transmitter speci-
309 fied in tx_site.qth and receiver specified in rx_site.qth,
310 and writes a SPLAT! Obstruction Report to the current
311 working directory. The report contains details of the
312 transmitter and receiver sites, and identifies the loca-
313 tion of any obstructions detected during the analysis. If
314 an obstruction can be cleared by raising the receive
315 antenna to a greater altitude, SPLAT! will indicate the
316 minimum antenna height required for a line-of-sight path
317 to exist between the transmitter and receiver locations
318 specified. If the antenna must be raised a significant
319 amount, this determination may take some time. Note that
320 the results provided are the minimum necessary for a line-
321 of-sight path to exist, and do not take Fresnel zone
322 clearance requirements into consideration.
324 qth extensions are assumed by SPLAT! for QTH files, and
325 are optional when invoking the program. SPLAT! automati-
326 cally reads all SPLAT Data Files necessary to conduct the
327 terrain analysis between the sites specified. SPLAT!
328 searches for the needed SDF files in the current working
329 directory first. If the needed files are not found,
330 SPLAT! then searches in the path specified by the -d
333 splat -t tx_site -r rx_site -d /cdrom/sdf/
335 An external directory path may be specified by placing a
336 ".splat_path" file under the user's home directory. This
337 file must contain the full directory path to the last
338 resort location of all the SDF files. The path in the
339 $HOME/.splat_path file must be of the form of a single
344 and can be generated using any text editor.
346 A graph of the terrain profile between the receiver and
347 transmitter locations as a function of distance from the
348 receiver can be generated by adding the -p switch:
350 splat -t tx_site -r rx_site -p terrain_profile.gif
352 SPLAT! invokes gnuplot when generating graphs. The file-
353 name extension specified to SPLAT! determines the format
354 of the graph produced. .gif will produce a 640x480 color
355 GIF graphic file, while .ps or .postscript will produce
356 postscript output. Output in formats such as PNG, Adobe
357 Illustrator, AutoCAD dxf, LaTeX, and many others are
358 available. Please consult gnuplot, and gnuplot's documen-
359 tation for details on all the supported output formats.
361 A graph of elevations subtended by the terrain between the
362 receiver and transmitter as a function of distance from
363 the receiver can be generated by using the -e switch:
365 splat -t tx_site -r rx_site -e elevation_profile.gif
367 The graph produced using this switch illustrates the ele-
368 vation and depression angles resulting from the terrain
369 between the receiver's location and the transmitter site
370 from the perspective of the receiver's location. A second
371 trace is plotted between the left side of the graph
372 (receiver's location) and the location of the transmitting
373 antenna on the right. This trace illustrates the eleva-
374 tion angle required for a line-of-sight path to exist
375 between the receiver and transmitter locations. If the
376 trace intersects the elevation profile at any point on the
377 graph, then this is an indication that a line-of-sight
378 path does not exist under the conditions given, and the
379 obstructions can be clearly identified on the graph at the
380 point(s) of intersection.
382 A graph illustrating terrain height referenced to a line-
383 of-sight path between the transmitter and receiver may be
384 generated using the -h switch:
386 splat -t tx_site -r rx_site -h height_profile.gif
388 The Earth's curvature is clearly evident when plotting
391 A graph showing Longley-Rice path loss may be plotted
394 splat -t tx_site -r rx_site -l path_loss_profile.gif
396 When performing path loss profiles, a Longley-Rice Model
397 Path Loss Report is generated by SPLAT! in the form of a
398 text file with a .lro filename extension. The report con-
399 tains bearings and distances between the transmitter and
400 receiver, as well as the Longley-Rice path loss for vari-
401 ous distances between the transmitter and receiver loca-
402 tions. The mode of propagation for points along the path
403 are given as Line-of-Sight, Single Horizon, Double Hori-
404 zon, Diffraction Dominant, and Troposcatter Dominant.
406 To determine the signal-to-noise (SNR) ratio at remote
407 location where random Johnson (thermal) noise is the pri-
408 mary limiting factor in reception:
412 where T is the ERP of the transmitter in dBW, NJ is John-
413 son Noise in dBW (-136 dBW for a 6 MHz TV channel), L is
414 the path loss provided by SPLAT! in dB (as a positive num-
415 ber), G is the receive antenna gain in dB over isotropic,
416 and NF is the receiver noise figure in dB.
418 T may be computed as follows:
422 where TI is actual amount of RF power delivered to the
423 transmitting antenna in dBW, GT is the transmitting
424 antenna gain (over isotropic) in the direction of the
425 receiver (or the horizon if the receiver is over the hori-
428 To compute how much more signal is available over the min-
429 imum to necessary to achieve a specific signal-to-noise
434 where S is the minimum desired SNR ratio (15.5 dB for ATSC
435 DTV, 42 dB for analog NTSC television).
437 A topographic map may be generated by SPLAT! to visualize
438 the path between the transmitter and receiver sites from
439 yet another perspective. Topographic maps generated by
440 SPLAT! display elevations using a logarithmic grayscale,
441 with higher elevations represented through brighter shades
442 of gray. The dynamic range of the image is scaled between
443 the highest and lowest elevations present in the map. The
444 only exception to this is sea-level, which is represented
445 using the color blue.
447 SPLAT! generated topographic maps are 24-bit TrueColor
448 Portable PixMap (PPM) images. They may be viewed, edited,
449 or converted to other graphic formats by popular image
450 viewing applications such as xv, The GIMP, ImageMagick,
451 and XPaint. PNG format is highly recommended for lossless
452 compressed storage of SPLAT! generated topographic output
453 files. An excellent command-line utility capable of con-
454 verting SPLAT! PPM graphic files to PNG files is wpng, and
456 http://www.libpng.org/pub/png/book/sources.html. As a
457 last resort, PPM files may be compressed using the bzip2
458 utility, and read directly by The GIMP in this format.
459 Topographic output is specified using the -o switch:
461 splat -t tx_site -r rx_site -o topo_map.ppm
463 The .ppm extension on the output filename is assumed by
464 SPLAT!, and is optional.
466 In this example, topo_map.ppm will illustrate the loca-
467 tions of the transmitter and receiver sites specified. In
468 addition, the great circle path between the two sites will
469 be drawn over locations for which an unobstructed path
470 exists to the transmitter at a receiving antenna height
471 equal to that of the receiver site (specified in
474 It may desirable to populate the topographic map with
475 names and locations of cities, tower sites, or other
476 important locations. A city file may be passed to SPLAT!
479 splat -t tx_site -r rx_site -s cities.dat -o topo_map
481 Up to five separate city files may be passed to SPLAT! at
482 a time following the -s switch.
484 County and state boundaries may be added to the map by
485 specifying up to five U.S. Census Bureau cartographic
486 boundary files using the -b switch:
488 splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map
490 In situations where multiple transmitter sites are in use,
491 as many as four site locations may be passed to SPLAT! at
494 splat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p
497 In this example, four separate terrain profiles and
498 obstruction reports will be generated by SPLAT!. A single
499 topographic map can be specified using the -o switch, and
500 line-of-sight paths between each transmitter and the
501 receiver site indicated will be produced on the map, each
502 in its own color. The path between the first transmitter
503 specified to the receiver will be in green, the path
504 between the second transmitter and the receiver will be in
505 cyan, the path between the third transmitter and the
506 receiver will be in violet, and the path between the
507 fourth transmitter and the receiver will be in sienna.
509 DETERMINING REGIONAL COVERAGE
510 SPLAT! can analyze a transmitter or repeater site, or net-
511 work of sites, and predict the regional coverage for each
512 site specified. In this mode, SPLAT! can generate a topo-
513 graphic map displaying the geometric line-of-sight cover-
514 age area of the sites based on the location of each site
515 and the height of receive antenna wishing to communicate
516 with the site in question. SPLAT! switches from point-to-
517 point analysis mode to area prediction mode when the -c
518 switch is invoked as follows:
520 splat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o
523 In this example, SPLAT! generates a topographic map called
524 tx_coverage.ppm that illustrates the predicted line-of-
525 sight regional coverage of tx_site to receiving locations
526 having antennas 30.0 feet above ground level (AGL). The
527 contents of cities.dat are plotted on the map, as are the
528 cartographic boundaries contained in the file
531 When plotting line-of-sight paths and areas of regional
532 coverage, SPLAT! by default does not account for the
533 effects of atmospheric bending. However, this behavior
534 may be modified by using the Earth radius multiplier (-m)
537 splat -t wnjt -c 30.0 -m 1.333 -s cities.dat -b coun-
540 An earth radius multiplier of 1.333 instructs SPLAT! to
541 use the "four-thirds earth" model for line-of-sight propa-
542 gation analysis. Any appropriate earth radius multiplier
543 may be selected by the user.
545 When invoked in area prediction mode, SPLAT! generates a
546 site report for each station analyzed. SPLAT! site
547 reports contain details of the site's geographic location,
548 its height above mean sea level, the antenna's height
549 above mean sea level, the antenna's height above average
550 terrain, and the height of the average terrain calculated
551 in the directions of 0, 45, 90, 135, 180, 225, 270, and
554 If the -c switch is replaced by a -L switch, a Longley-
555 Rice path loss map for a transmitter site may be gener-
558 splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -o
561 In this mode, SPLAT! generates a multi-color map illus-
562 trating expected signal levels (path loss) in areas sur-
563 rounding the transmitter site. A legend at the bottom of
564 the map correlates each color with a specific path loss
565 level in decibels. Since Longley-Rice area prediction map
566 generation is very CPU intensive, provision for limiting
567 the analysis range is provided by the -R switch. The
568 argument must be given in miles. If a range wider than
569 the generated topographic map is specified, SPLAT! will
570 perform Longley-Rice path loss calculations between all
571 four corners of the area prediction map.
573 The -db switch allows a constraint to be placed on the
574 maximum path loss region plotted on the map. A path loss
575 between 80 and 230 dB may be specified using this switch.
576 For example, if a path loss beyond -140 dB is irrelevant
577 to the survey being conducted, SPLAT!'s path loss plot can
578 be constrained to the region bounded by the 140 dB attenu-
579 ation contour as follows:
581 splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -db
585 DETERMINING MULTIPLE REGIONS OF COVERAGE
586 SPLAT! can also display line-of-sight coverage areas for
587 as many as four separate transmitter sites on a common
588 topographic map. For example:
590 splat -t site1 site2 site3 site4 -c 30.0 -o network.ppm
592 plots the regional line-of-sight coverage of site1, site2,
593 site3, and site4 based on a receive antenna located 30.0
594 feet above ground level. A topographic map is then
595 written to the file network.ppm. The line-of-sight cover-
596 age area of the transmitters are plotted as follows in the
597 colors indicated (along with their corresponding RGB val-
600 site1: Green (0,255,0)
601 site2: Cyan (0,255,255)
602 site3: Medium Violet (147,112,219)
603 site4: Sienna 1 (255,130,71)
605 site1 + site2: Yellow (255,255,0)
606 site1 + site3: Pink (255,192,203)
607 site1 + site4: Green Yellow (173,255,47)
608 site2 + site3: Orange (255,165,0)
609 site2 + site4: Dark Sea Green 1 (193,255,193)
610 site3 + site4: Dark Turquoise (0,206,209)
612 site1 + site2 + site3: Dark Green (0,100,0)
613 site1 + site2 + site4: Blanched Almond (255,235,205)
614 site1 + site3 + site4: Medium Spring Green (0,250,154)
615 site2 + site3 + site4: Tan (210,180,140)
617 site1 + site2 + site3 + site4: Gold2 (238,201,0)
619 If separate .qth files are generated, each representing a
620 common site location but a different antenna height, a
621 single topographic map illustrating the regional coverage
622 from as many as four separate locations on a single tower
623 may be generated by SPLAT!.
625 TOPOGRAPHIC MAP GENERATION
626 In certain situations, it may be desirable to generate a
627 topographic map of a region without plotting coverage
628 areas, line-of-sight paths, or generating obstruction
629 reports. There are several ways of doing this. If one
630 wishes to generate a topographic map illustrating the
631 location of a transmitter and receiver site along with a
632 brief text report describing the locations and distances
633 between the sites, the -n switch should be invoked as fol-
636 splat -t tx_site -r rx_site -n -o topo_map.ppm
638 If no text report is desired, then the -N switch is used:
640 splat -t tx_site -r rx_site -N -o topo_map.ppm
642 If the -o switch and output filename are omitted when
643 using either the -n or -N switches, output is written to a
644 file named map.ppm in the current working directory by
647 DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
648 SPLAT! determines antenna height above average terrain
649 (HAAT) according to the procedure defined by Federal Com-
650 munications Commission Part 73.313(d). According to this
651 definition, terrain elevations along eight radials between
652 2 and 10 miles (3 and 16 kilometers) from the site being
653 analyzed are sampled and averaged for each 45 degrees of
654 azimuth starting with True North. If one or more radials
655 lie entirely over water or over land outside the United
656 States (areas for which no USGS topography data is avail-
657 able), then those radials are omitted from the calculation
658 of average terrain. If part of a radial extends over a
659 body of water or over land outside the United States, then
660 only that part of the radial lying over United States land
661 is used in the determination of average terrain.
663 Note that SRTM elevation data, unlike older 3-arc second
664 USGS data, extends beyond the borders of the United
665 States. Therefore, HAAT results may not be in full com-
666 pliance with FCC Part 73.313(d) in areas along the borders
667 of the United States if the SDF files used by SPLAT! are
670 When performing point-to-point terrain analysis, SPLAT!
671 determines the antenna height above average terrain only
672 if enough topographic data has already been loaded by the
673 program to perform the point-to-point analysis. In most
674 cases, this will be true, unless the site in question does
675 not lie within 10 miles of the boundary of the topography
678 When performing area prediction analysis, enough topogra-
679 phy data is normally loaded by SPLAT! to perform average
680 terrain calculations. Under such conditions, SPLAT! will
681 provide the antenna height above average terrain as well
682 as the average terrain above mean sea level for azimuths
683 of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and
684 include such information in the site report generated. If
685 one or more of the eight radials surveyed fall over water,
686 or over regions for which no SDF data is available, SPLAT!
687 reports No Terrain for the radial paths affected.
689 RESTRICTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
690 SPLAT! reads SDF files as needed into a series of memory
691 "slots" within the structure of the program. Each "slot"
692 holds one SDF file representing a one degree by one degree
693 region of terrain. A #define MAXSLOTS statement in the
694 first several lines of splat.cpp sets the maximum number
695 of "slots" available for topography data. It also sets
696 the maximum size of the topographic maps generated by
697 SPLAT!. MAXSLOTS is set to 9 by default. If SPLAT! pro-
698 duces a segmentation fault on start-up with this default,
699 it is an indication that not enough RAM and/or virtual
700 memory (swap space) is available to run SPLAT! with this
701 number of MAXSLOTS. In situations where available memory
702 is low, MAXSLOTS may be reduced to 4 with the understand-
703 ing that this will greatly limit the maximum region SPLAT!
704 will be able to analyze. If 118 megabytes or more of
705 total memory (swap space plus RAM) is available, then
706 MAXSLOTS may be increased to 16. This will permit opera-
707 tion over a 4-degree by 4-degree region, which is suffi-
708 cient for single antenna heights in excess of 10,000 feet
709 above mean sea level, or point-to-point distances of over
712 ADDITIONAL INFORMATION
713 Invoking SPLAT! without any arguments will display all the
714 command-line options available with the program along with
715 a brief summary of each.
717 The latest news and information regarding SPLAT! software
718 is available through the official SPLAT! software web page
719 located at: http://www.qsl.net/kd2bd/splat.html.
722 John A. Magliacane, KD2BD <kd2bd@amsat.org>
723 Creator, Lead Developer
725 Doug McDonald <mcdonald@scs.uiuc.edu>
726 Longley-Rice Model integration
projects / debian / splat / blob