1 .TH SPLAT! 1 "02 March 2006" "KD2BD Software" "KD2BD Software"
3 splat \- An RF \fBS\fPignal \fBP\fPropagation, \fBL\fPoss, \fBA\fPnd \fBT\fPerrain analysis tool
5 splat [-t \fItransmitter_site.qth\fP]
6 [-r \fIreceiver_site.qth\fP]
7 [-c \fIrx_antenna_height_for_los_coverage_analysis (feet) (float)\fP]
8 [-L \fIrx_antenna_height_for_Longley-Rice_coverage_analysis (feet) (float)\fP]
9 [-p \fIterrain_profile.ext\fP]
10 [-e \fIelevation_profile.ext\fP]
11 [-h \fIheight_profile.ext\fP]
12 [-l \fILongley-Rice_profile.ext\fP]
13 [-o \fItopographic_map_filename.ppm\fP]
14 [-b \fIcartographic_boundary_filename.dat\fP]
15 [-s \fIsite/city_database.dat\fP]
16 [-d \fIsdf_directory_path\fP]
17 [-m \fIearth_radius_multiplier (float)\fP]
18 [-R \fImaximum_coverage_range (for -c or -L) (miles) (float)\fP]
19 [-dB \fImaximum attenuation contour to display on path loss maps (80-230 dB)\fP]
23 \fBSPLAT!\fP is a powerful terrestrial RF propagation and terrain
24 analysis tool covering the spectrum between 20 MHz and 20 GHz. It
25 is designed for operation on Unix and Linux-based workstations.
26 \fBSPLAT!\fP is free software. Redistribution and/or modification
27 is permitted under the terms of the GNU General Public License as
28 published by the Free Software Foundation, either version 2 of the
29 License or any later version. Adoption of \fBSPLAT!\fP source code
30 in proprietary or closed-source applications is a violation of this
31 license, and is \fBstrictly\fP forbidden.
33 \fBSPLAT!\fP is distributed in the hope that it will be useful, but
34 WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY
35 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
38 Applications of \fBSPLAT!\fP include the visualization, design, and
39 link budget analysis of wireless Wide Area Networks (WANs), commercial
40 and amateur radio communication systems above 20 MHz, microwave links,
41 frequency coordination, and the determination of analog and digital
42 terrestrial radio and television contour regions.
44 \fBSPLAT!\fP provides RF site engineering data such as great circle
45 distances and bearings between sites, antenna elevation angles (uptilt),
46 depression angles (downtilt), antenna height above mean sea level,
47 antenna height above average terrain, bearings and distances to known
48 obstructions, Longley-Rice path attenuation, and minimum antenna height
49 requirements needed to establish line-of-sight communication paths absent
50 of obstructions due to terrain. \fBSPLAT!\fP produces reports, graphs,
51 and highly detailed and carefully annotated topographic maps depicting
52 line-of-sight paths, path loss, and expected coverage areas of
53 transmitters and repeater systems. When performing line-of-sight
54 analysis in situations where multiple transmitter or repeater sites
55 are employed, \fBSPLAT!\fP determines individual and mutual areas
56 of coverage within the network specified.
58 \fBSPLAT!\fP operates in two distinct modes: \fIpoint-to-point mode\fP,
59 and \fIarea prediction mode\fP, and may be invoked using either
60 line-of-sight (LOS) or Irregular Terrain (ITM) propagation models.
61 True Earth, four-thirds Earth, or any other Earth radius may be
62 specified by the user when performing line-of-sight analysis.
64 \fBSPLAT!\fP is a command-line driven application, and reads input
65 data through a number of data files. Some files are mandatory for
66 successful execution of the program, while others are optional.
67 Mandatory files include SPLAT Data Files (SDF files), site location
68 files (QTH files), and Longley-Rice model parameter files (LRP files).
69 Optional files include city/site location files, and cartographic
72 \fBSPLAT!\fP imports topographic data in the form of SPLAT Data Files
73 (SDFs). These files may be generated from a number of information sources.
74 In the United States, SPLAT Data Files can be generated through U.S.
75 Geological Survey Digital Elevation Models (DEMs) using the \fBusgs2sdf\fP
76 utility included with \fBSPLAT!\fP. USGS Digital Elevation Models
77 compatible with this utility may be downloaded from:
78 \fIhttp://edcftp.cr.usgs.gov/pub/data/DEM/250/\fP.
80 Significantly better resolution can be obtained through the use
81 of SRTM-3 Version 2 digital elevation models. These models are the
82 result of the STS-99 Space Shuttle Radar Topography Mission, and are
83 available for most populated regions of the Earth. SPLAT Data Files
84 may be generated from SRTM data using the included \fBsrtm2sdf\fP utility.
85 SRTM-3 Version 2 data may be obtained through anonymous FTP from:
86 \fIftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/\fP
88 Despite the higher accuracy that SRTM data has to offer, some voids
89 in the data sets exist. When voids are detected, the \fBsrtm2sdf\fP
90 utility replaces them with corresponding data found in existing SDF
91 files (that were presumably created from earlier USGS data through the
92 \fBusgs2sdf\fP utility). If USGS-derived SDF data is not available, voids
93 are handled through adjacent pixel averaging, or direct replacement.
95 SPLAT Data Files contain integer value topographic elevations (in meters)
96 referenced to mean sea level for 1-degree by 1-degree regions of the
97 earth with a resolution of 3-arc seconds. SDF files can be read in
98 either standard format (\fI.sdf\fP) as generated by the \fBusgs2sdf\fP
99 and \fBsrtm2sdf\fP utilities, or in bzip2 compressed format
100 (\fI.sdf.bz2\fP). Since uncompressed files can be processed slightly
101 faster than files that have been compressed, \fBSPLAT!\fP searches for
102 the needed SDF data in uncompressed format first. If uncompressed data
103 cannot located, \fBSPLAT!\fP then searches for data in bzip2 compressed
104 format. If no compressed SDF files can be found for the region requested,
105 \fBSPLAT!\fP assumes the region is over water, and will assign an
106 elevation of sea-level to these areas.
108 This feature of \fBSPLAT!\fP makes it possible to perform path analysis
109 not only over land, but also between coastal areas not represented by
110 Digital Elevation Model data. This behavior of \fBSPLAT!\fP underscores
111 the importance of having all the SDF files required for the region being
112 analyzed if meaningful results are to be expected.
113 .SH SITE LOCATION (QTH) FILES
114 \fBSPLAT!\fP imports site location information of transmitter and receiver
115 sites analyzed by the program from ASCII files having a \fI.qth\fP extension.
116 QTH files contain the site's name, the site's latitude (positive if North
117 of the equator, negative if South), the site's longitude (in degrees West,
118 0 to 360 degrees), and the site's antenna height above ground level (AGL).
119 A single line-feed character separates each field. The antenna height is
120 assumed to be specified in feet unless followed by the letter \fIm\fP or
121 the word \fImeters\fP in either upper or lower case. Latitude and
122 longitude information may be expressed in either decimal format (74.6889)
123 or degree, minute, second (DMS) format (74 41 20.0).
125 For example, a site location file describing television station WNJT,
126 Trenton, NJ (\fIwnjt.qth\fP) might read as follows:
133 Each transmitter and receiver site analyzed by \fBSPLAT!\fP must be
134 represented by its own site location (QTH) file.
135 .SH LONGLEY-RICE PARAMETER (LRP) FILES
136 \fBSPLAT!\fP imports Longley-Rice model parameter data from files having
137 the same base name as the transmitter site QTH file, but with a \fI.lrp\fP
138 extension, thus providing simple and accurate correlation between these
139 associated data sets. The format for the Longley-Rice model parameter
140 files is as follows (\fIwnjt.lrp\fP):
142 15.000 ; Earth Dielectric Constant (Relative permittivity)
143 0.005 ; Earth Conductivity (Siemens per meter)
144 301.000 ; Atmospheric Bending Constant (N-units)
145 700.000 ; Frequency in MHz (20 MHz to 20 GHz)
146 5 ; Radio Climate (5 = Continental Temperate)
147 0 ; Polarization (0 = Horizontal, 1 = Vertical)
148 0.5 ; Fraction of situations (50% of locations)
149 0.5 ; Fraction of time (50% of the time)
151 If an LRP file corresponding to the tx_site QTH file cannot
152 be found, \fBSPLAT!\fP scans the current working directory for
153 the file "splat.lrp". If this file cannot be found, then the default
154 parameters listed above will be assigned by \fBSPLAT!\fP and a
155 corresponding "splat.lrp" file containing this data will be written
156 to the current working directory. "splat.lrp" can then be edited
157 by the user as needed.
159 Typical Earth dielectric constants and conductivity values are as
162 Dielectric Constant Conductivity
163 Salt water : 80 5.000
164 Good ground : 25 0.020
165 Fresh water : 80 0.010
166 Marshy land : 12 0.007
167 Farmland, forest : 15 0.005
168 Average ground : 15 0.005
169 Mountain, sand : 13 0.002
171 Poor ground : 4 0.001
173 Radio climate codes used by \fBSPLAT!\fP are as follows:
175 1: Equatorial (Congo)
176 2: Continental Subtropical (Sudan)
177 3: Maritime Subtropical (West coast of Africa)
179 5: Continental Temperate
180 6: Maritime Temperate, over land (UK and west coasts of US & EU)
181 7: Maritime Temperate, over sea
183 The Continental Temperate climate is common to large land masses in
184 the temperate zone, such as the United States. For paths shorter than
185 100 km, there is little difference between Continental and Maritime
188 The final two parameters in the \fI.lrp\fP file correspond to the statistical
189 analysis provided by the Longley-Rice model. In this example, \fBSPLAT!\fP
190 will return the maximum path loss occurring 50% of the time (fraction
191 of time) in 50% of situations (fraction of situations). Use a fraction
192 of time parameter of 0.97 for digital television, 0.50 for analog in the
193 United States. Isotropic antennas are assumed.
195 For further information on these parameters, see:
196 \fIhttp://flattop.its.bldrdoc.gov/itm.html\fP and
197 \fIhttp://www.softwright.com/faq/engineering/prop_longley_rice.html\fP
198 .SH CITY LOCATION FILES
199 The names and locations of cities, tower sites, or other points of interest
200 may be imported and plotted on topographic maps generated by \fBSPLAT!\fP.
201 \fBSPLAT!\fP imports the names of cities and locations from ASCII files
202 containing the location's name, the location's latitude, and the location's
203 longitude. Each field is separated by a comma. Each record is separated
204 by a single line feed character. As was the case with the \fI.qth\fP
205 files, latitude and longitude information may be entered in either
206 decimal or degree, minute, second (DMS) format.
208 For example (\fIcities.dat\fP):
210 Teaneck, 40.891973, 74.014506
211 Tenafly, 40.919212, 73.955892
212 Teterboro, 40.859511, 74.058908
213 Tinton Falls, 40.279966, 74.093924
214 Toms River, 39.977777, 74.183580
215 Totowa, 40.906160, 74.223310
216 Trenton, 40.219922, 74.754665
218 A total of five separate city data files may be imported at a time,
219 and there is no limit to the size of these files. \fBSPLAT!\fP reads
220 city data on a "first come/first served" basis, and plots only those
221 locations whose annotations do not conflict with annotations of
222 locations plotted earlier during \fBSPLAT\fP's execution. This behavior
223 minimizes clutter in \fBSPLAT!\fP generated topographic maps, but also
224 mandates that important locations be placed toward the beginning of
225 the first city data file, and disposable locations be positioned
226 further down the list or in subsequent data files.
228 City data files may be generated manually using any text editor,
229 imported from other sources, or derived from data available from the
230 U.S. Census Bureau using the \fBcitydecoder\fP utility included with
231 \fBSPLAT!\fP. Such data is available free of charge via the Internet
232 at: \fIhttp://www.census.gov/geo/www/cob/bdy_files.html\fP, and must
234 .SH CARTOGRAPHIC BOUNDARY DATA FILES
235 Cartographic boundary data may also be imported to plot the boundaries of
236 cities, counties, or states on topographic maps generated by \fBSPLAT!\fP.
237 Such data must be of the form of ARC/INFO Ungenerate (ASCII Format)
238 Metadata Cartographic Boundary Files, and are available from the U.S.
239 Census Bureau via the Internet at:
240 \fIhttp://www.census.gov/geo/www/cob/co2000.html#ascii\fP and
241 \fIhttp://www.census.gov/geo/www/cob/pl2000.html#ascii\fP. A total of
242 five separate cartographic boundary files may be imported at a time.
243 It is not necessary to import state boundaries if county boundaries
244 have already been imported.
245 .SH PROGRAM OPERATION
246 \fBSPLAT!\fP is invoked via the command-line using a series of switches
247 and arguments. Since \fBSPLAT!\fP is a CPU and memory intensive application,
248 this type of interface minimizes overhead and lends itself well to
249 scripted (batch) operations. \fBSPLAT!\fP's CPU and memory scheduling
250 priority may be modified through the use of the Unix \fBnice\fP command.
252 The number and type of switches passed to \fBSPLAT!\fP determine its
253 mode of operation and method of output data generation. Nearly all
254 of \fBSPLAT!\fP's switches may be cascaded in any order on the command
255 line when invoking the program.
256 .SH POINT-TO-POINT ANALYSIS
257 \fBSPLAT!\fP may be used to perform line-of-sight terrain analysis
258 between two specified site locations. For example:
260 \fCsplat -t tx_site.qth -r rx_site.qth\fR
262 invokes a terrain analysis between the transmitter specified
263 in \fItx_site.qth\fP and receiver specified in \fIrx_site.qth\fP,
264 and writes a \fBSPLAT!\fP Obstruction Report to the current working
265 directory. The report contains details of the transmitter and
266 receiver sites, and identifies the location of any obstructions
267 detected during the analysis. If an obstruction can be cleared
268 by raising the receive antenna to a greater altitude, \fBSPLAT!\fP
269 will indicate the minimum antenna height required for a line-of-sight
270 path to exist between the transmitter and receiver locations specified.
271 If the antenna must be raised a significant amount, this determination
272 may take some time. Note that the results provided are the \fIminimum\fP
273 necessary for a line-of-sight path to exist, and do not take Fresnel
274 zone clearance requirements into consideration.
276 \fIqth\fP extensions are assumed by \fBSPLAT!\fP for QTH files, and
277 are optional when invoking the program. \fBSPLAT!\fP automatically
278 reads all SPLAT Data Files necessary to conduct the terrain analysis
279 between the sites specified. \fBSPLAT!\fP searches for the needed
280 SDF files in the current working directory first. If the needed
281 files are not found, \fBSPLAT!\fP then searches in the path specified
282 by the \fI-d\fP command-line switch:
284 \fCsplat -t tx_site -r rx_site -d /cdrom/sdf/\fR
286 An external directory path may be specified by placing a ".splat_path"
287 file under the user's home directory. This file must contain the full
288 directory path to the last resort location of all the SDF files. The
289 path in the \fI$HOME/.splat_path\fP file must be of the form of a
290 single line of ASCII text:
292 \fC/opt/splat/sdf/\fR
294 and can be generated using any text editor.
296 A graph of the terrain profile between the receiver and transmitter
297 locations as a function of distance from the receiver can be generated
298 by adding the \fI-p\fP switch:
300 \fCsplat -t tx_site -r rx_site -p terrain_profile.gif\fR
302 \fBSPLAT!\fP invokes \fBgnuplot\fP when generating graphs. The filename
303 extension specified to \fBSPLAT!\fP determines the format of the graph
304 produced. \fI.gif\fP will produce a 640x480 color GIF graphic file,
305 while \fI.ps\fP or \fI.postscript\fP will produce postscript output.
306 Output in formats such as PNG, Adobe Illustrator, AutoCAD dxf, LaTeX,
307 and many others are available. Please consult \fBgnuplot\fP, and
308 \fBgnuplot\fP's documentation for details on all the supported
311 A graph of elevations subtended by the terrain between the receiver and
312 transmitter as a function of distance from the receiver can be generated
313 by using the \fI-e\fP switch:
315 \fCsplat -t tx_site -r rx_site -e elevation_profile.gif\fR
317 The graph produced using this switch illustrates the elevation and
318 depression angles resulting from the terrain between the receiver's
319 location and the transmitter site from the perspective of the receiver's
320 location. A second trace is plotted between the left side of the graph
321 (receiver's location) and the location of the transmitting antenna on
322 the right. This trace illustrates the elevation angle required for a
323 line-of-sight path to exist between the receiver and transmitter
324 locations. If the trace intersects the elevation profile at any point
325 on the graph, then this is an indication that a line-of-sight path
326 does not exist under the conditions given, and the obstructions can
327 be clearly identified on the graph at the point(s) of intersection.
329 A graph illustrating terrain height referenced to a line-of-sight
330 path between the transmitter and receiver may be generated using
333 \fCsplat -t tx_site -r rx_site -h height_profile.gif\fR
335 The Earth's curvature is clearly evident when plotting height profiles.
337 A graph showing Longley-Rice path loss may be plotted using the
340 \fCsplat -t tx_site -r rx_site -l path_loss_profile.gif\fR
342 When performing path loss profiles, a Longley-Rice Model Path Loss
343 Report is generated by \fBSPLAT!\fP in the form of a text file with
344 a \fI.lro\fP filename extension. The report contains bearings and
345 distances between the transmitter and receiver, as well as the
346 Longley-Rice path loss for various distances between the transmitter
347 and receiver locations. The mode of propagation for points along the
348 path are given as \fILine-of-Sight\fP, \fISingle Horizon\fP, \fIDouble
349 Horizon\fP, \fIDiffraction Dominant\fP, and \fITroposcatter Dominant\fP.
351 To determine the signal-to-noise (SNR) ratio at remote location
352 where random Johnson (thermal) noise is the primary limiting
356 SNR = T - NJ - L + G - NF
359 where \fBT\fP is the ERP of the transmitter in dBW, \fBNJ\fP is
360 Johnson Noise in dBW (-136 dBW for a 6 MHz TV channel), \fBL\fP
361 is the path loss provided by \fBSPLAT!\fP in dB (as a \fIpositive\fP
362 number), \fBG\fP is the receive antenna gain in dB over isotropic,
363 and \fBNF\fP is the receiver noise figure in dB.
365 \fBT\fP may be computed as follows:
371 where \fBTI\fP is actual amount of RF power delivered to the transmitting
372 antenna in dBW, \fBGT\fP is the transmitting antenna gain (over isotropic)
373 in the direction of the receiver (or the horizon if the receiver is over
376 To compute how much more signal is available over the minimum to
377 necessary to achieve a specific signal-to-noise ratio:
380 Signal_Margin = SNR - S
383 where \fBS\fP is the minimum desired SNR ratio (15.5 dB for
384 ATSC DTV, 42 dB for analog NTSC television).
386 A topographic map may be generated by \fBSPLAT!\fP to visualize the
387 path between the transmitter and receiver sites from yet another
388 perspective. Topographic maps generated by \fBSPLAT!\fP display
389 elevations using a logarithmic grayscale, with higher elevations
390 represented through brighter shades of gray. The dynamic range of
391 the image is scaled between the highest and lowest elevations present
392 in the map. The only exception to this is sea-level, which is
393 represented using the color blue.
395 \fBSPLAT!\fP generated topographic maps are 24-bit TrueColor Portable
396 PixMap (PPM) images. They may be viewed, edited, or converted to other
397 graphic formats by popular image viewing applications such as \fBxv\fP,
398 \fBThe GIMP\fP, \fBImageMagick\fP, and \fBXPaint\fP. PNG format is
399 highly recommended for lossless compressed storage of \fBSPLAT!\fP
400 generated topographic output files. An excellent command-line utility
401 capable of converting \fBSPLAT!\fP PPM graphic files to PNG files is
402 \fBwpng\fP, and is available
403 at: \fIhttp://www.libpng.org/pub/png/book/sources.html\fP. As a last
404 resort, PPM files may be compressed using the bzip2 utility, and read
405 directly by \fBThe GIMP\fP in this format. Topographic output
406 is specified using the \fI-o\fP switch:
408 \fCsplat -t tx_site -r rx_site -o topo_map.ppm\fR
410 The \fI.ppm\fP extension on the output filename is assumed by
411 \fBSPLAT!\fP, and is optional.
413 In this example, \fItopo_map.ppm\fP will illustrate the locations of the
414 transmitter and receiver sites specified. In addition, the great circle
415 path between the two sites will be drawn over locations for which an
416 unobstructed path exists to the transmitter at a receiving antenna
417 height equal to that of the receiver site (specified in \fIrx_site.qth\fP).
419 It may desirable to populate the topographic map with names and locations
420 of cities, tower sites, or other important locations. A city file may be
421 passed to \fBSPLAT!\fP using the \fI-s\fP switch:
423 \fCsplat -t tx_site -r rx_site -s cities.dat -o topo_map\fR
425 Up to five separate city files may be passed to \fBSPLAT!\fP at a time
426 following the \fI-s\fP switch.
428 County and state boundaries may be added to the map by specifying up
429 to five U.S. Census Bureau cartographic boundary files using the \fI-b\fP
432 \fCsplat -t tx_site -r rx_site -b co34_d00.dat -o topo_map\fR
434 In situations where multiple transmitter sites are in use, as many as
435 four site locations may be passed to \fBSPLAT!\fP at a time for analysis:
437 \fCsplat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p profile.gif\fR
439 In this example, four separate terrain profiles and obstruction reports
440 will be generated by \fBSPLAT!\fP. A single topographic map can be
441 specified using the \fI-o\fP switch, and line-of-sight paths between
442 each transmitter and the receiver site indicated will be produced on
443 the map, each in its own color. The path between the first transmitter
444 specified to the receiver will be in green, the path between the
445 second transmitter and the receiver will be in cyan, the path between
446 the third transmitter and the receiver will be in violet, and the
447 path between the fourth transmitter and the receiver will be in sienna.
448 .SH DETERMINING REGIONAL COVERAGE
449 \fBSPLAT!\fP can analyze a transmitter or repeater site, or network
450 of sites, and predict the regional coverage for each site specified.
451 In this mode, \fBSPLAT!\fP can generate a topographic map displaying
452 the geometric line-of-sight coverage area of the sites based on the
453 location of each site and the height of receive antenna wishing to
454 communicate with the site in question. \fBSPLAT!\fP switches from
455 point-to-point analysis mode to area prediction mode when the \fI-c\fP
456 switch is invoked as follows:
458 \fCsplat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o tx_coverage\fR
460 In this example, \fBSPLAT!\fP generates a topographic map called
461 \fItx_coverage.ppm\fP that illustrates the predicted line-of-sight
462 regional coverage of \fItx_site\fP to receiving locations having
463 antennas 30.0 feet above ground level (AGL). The contents of
464 \fIcities.dat\fP are plotted on the map, as are the cartographic
465 boundaries contained in the file \fIco34_d00.dat\fP.
467 When plotting line-of-sight paths and areas of regional coverage,
468 \fBSPLAT!\fP by default does not account for the effects of
469 atmospheric bending. However, this behavior may be modified
470 by using the Earth radius multiplier (\fI-m\fP) switch:
472 \fCsplat -t wnjt -c 30.0 -m 1.333 -s cities.dat -b counties.dat -o map.ppm\fR
474 An earth radius multiplier of 1.333 instructs \fBSPLAT!\fP to use
475 the "four-thirds earth" model for line-of-sight propagation analysis.
476 Any appropriate earth radius multiplier may be selected by the user.
478 When invoked in area prediction mode, \fBSPLAT!\fP generates a
479 site report for each station analyzed. \fBSPLAT!\fP site reports
480 contain details of the site's geographic location, its height above
481 mean sea level, the antenna's height above mean sea level, the
482 antenna's height above average terrain, and the height of the
483 average terrain calculated in the directions of 0, 45, 90, 135,
484 180, 225, 270, and 315 degrees azimuth.
486 If the \fI-c\fP switch is replaced by a \fI-L\fP switch, a
487 Longley-Rice path loss map for a transmitter site may be generated:
489 \fCsplat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -o path_loss_map\fR
491 In this mode, \fBSPLAT!\fP generates a multi-color map illustrating
492 expected signal levels (path loss) in areas surrounding the transmitter
493 site. A legend at the bottom of the map correlates each color with a
494 specific path loss level in decibels. Since Longley-Rice area
495 prediction map generation is very CPU intensive, provision for
496 limiting the analysis range is provided by the \fI-R\fP switch.
497 The argument must be given in miles. If a range wider than the
498 generated topographic map is specified, \fBSPLAT!\fP will perform
499 Longley-Rice path loss calculations between all four corners of
500 the area prediction map.
502 The \fI-db\fP switch allows a constraint to be placed on the maximum
503 path loss region plotted on the map. A path loss between 80 and
504 230 dB may be specified using this switch. For example, if a path
505 loss beyond -140 dB is irrelevant to the survey being conducted,
506 \fBSPLAT!\fP's path loss plot can be constrained to the region
507 bounded by the 140 dB attenuation contour as follows:
509 \fCsplat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -db 140 -o plot.ppm\fR
511 .SH DETERMINING MULTIPLE REGIONS OF COVERAGE
512 \fBSPLAT!\fP can also display line-of-sight coverage areas for as
513 many as four separate transmitter sites on a common topographic map.
516 \fCsplat -t site1 site2 site3 site4 -c 30.0 -o network.ppm\fR
518 plots the regional line-of-sight coverage of site1, site2, site3,
519 and site4 based on a receive antenna located 30.0 feet above ground
520 level. A topographic map is then written to the file \fInetwork.ppm\fP.
521 The line-of-sight coverage area of the transmitters are plotted as
522 follows in the colors indicated (along with their corresponding RGB
525 site1: Green (0,255,0)
526 site2: Cyan (0,255,255)
527 site3: Medium Violet (147,112,219)
528 site4: Sienna 1 (255,130,71)
530 site1 + site2: Yellow (255,255,0)
531 site1 + site3: Pink (255,192,203)
532 site1 + site4: Green Yellow (173,255,47)
533 site2 + site3: Orange (255,165,0)
534 site2 + site4: Dark Sea Green 1 (193,255,193)
535 site3 + site4: Dark Turquoise (0,206,209)
537 site1 + site2 + site3: Dark Green (0,100,0)
538 site1 + site2 + site4: Blanched Almond (255,235,205)
539 site1 + site3 + site4: Medium Spring Green (0,250,154)
540 site2 + site3 + site4: Tan (210,180,140)
542 site1 + site2 + site3 + site4: Gold2 (238,201,0)
544 If separate \fI.qth\fP files are generated, each representing a common
545 site location but a different antenna height, a single topographic map
546 illustrating the regional coverage from as many as four separate locations
547 on a single tower may be generated by \fBSPLAT!\fP.
548 .SH TOPOGRAPHIC MAP GENERATION
549 In certain situations, it may be desirable to generate a topographic map
550 of a region without plotting coverage areas, line-of-sight paths, or
551 generating obstruction reports. There are several ways of doing this.
552 If one wishes to generate a topographic map illustrating the location
553 of a transmitter and receiver site along with a brief text report
554 describing the locations and distances between the sites, the \fI-n\fP
555 switch should be invoked as follows:
557 \fCsplat -t tx_site -r rx_site -n -o topo_map.ppm\fR
559 If no text report is desired, then the \fI-N\fP switch is used:
561 \fCsplat -t tx_site -r rx_site -N -o topo_map.ppm\fR
563 If the \fI-o\fP switch and output filename are omitted when using
564 either the \fI-n\fP or \fI-N\fP switches, output is written to a
565 file named \fImap.ppm\fP in the current working directory by default.
566 .SH DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
567 \fBSPLAT!\fP determines antenna height above average terrain (HAAT)
568 according to the procedure defined by Federal Communications Commission
569 Part 73.313(d). According to this definition, terrain elevations along
570 eight radials between 2 and 10 miles (3 and 16 kilometers) from the site
571 being analyzed are sampled and averaged for each 45 degrees of azimuth
572 starting with True North. If one or more radials lie entirely over water
573 or over land outside the United States (areas for which no USGS topography
574 data is available), then those radials are omitted from the calculation
575 of average terrain. If part of a radial extends over a body of water or
576 over land outside the United States, then only that part of the radial
577 lying over United States land is used in the determination of average
580 Note that SRTM elevation data, unlike older 3-arc second USGS data,
581 extends beyond the borders of the United States. Therefore, HAAT
582 results may not be in full compliance with FCC Part 73.313(d)
583 in areas along the borders of the United States if the SDF files
584 used by \fBSPLAT!\fP are SRTM-derived.
586 When performing point-to-point terrain analysis, \fBSPLAT!\fP determines
587 the antenna height above average terrain only if enough topographic
588 data has already been loaded by the program to perform the point-to-point
589 analysis. In most cases, this will be true, unless the site in question
590 does not lie within 10 miles of the boundary of the topography data in
593 When performing area prediction analysis, enough topography data is
594 normally loaded by \fBSPLAT!\fP to perform average terrain calculations.
595 Under such conditions, \fBSPLAT!\fP will provide the antenna height
596 above average terrain as well as the average terrain above mean sea
597 level for azimuths of 0, 45, 90, 135, 180, 225, 270, and 315 degrees,
598 and include such information in the site report generated. If one or
599 more of the eight radials surveyed fall over water, or over regions
600 for which no SDF data is available, \fBSPLAT!\fP reports \fINo Terrain\fP
601 for the radial paths affected.
602 .SH RESTRICTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
603 \fBSPLAT!\fP reads SDF files as needed into a series of memory "slots"
604 within the structure of the program. Each "slot" holds one SDF file
605 representing a one degree by one degree region of terrain.
606 A \fI#define MAXSLOTS\fP statement in the first several lines of
607 \fIsplat.cpp\fP sets the maximum number of "slots" available for topography
608 data. It also sets the maximum size of the topographic maps generated by
609 \fBSPLAT!\fP. MAXSLOTS is set to 9 by default. If \fBSPLAT!\fP produces
610 a segmentation fault on start-up with this default, it is an indication
611 that not enough RAM and/or virtual memory (swap space) is available to
612 run \fBSPLAT!\fP with this number of MAXSLOTS. In situations where
613 available memory is low, MAXSLOTS may be reduced to 4 with the understanding
614 that this will greatly limit the maximum region \fBSPLAT!\fP will be able
615 to analyze. If 118 megabytes or more of total memory (swap space plus
616 RAM) is available, then MAXSLOTS may be increased to 16. This will
617 permit operation over a 4-degree by 4-degree region, which is sufficient
618 for single antenna heights in excess of 10,000 feet above mean sea
619 level, or point-to-point distances of over 1000 miles.
620 .SH ADDITIONAL INFORMATION
621 Invoking \fBSPLAT!\fP without any arguments will display all the
622 command-line options available with the program along with a brief
625 The latest news and information regarding \fBSPLAT!\fP software is
626 available through the official \fBSPLAT!\fP software web page located
627 at: \fIhttp://www.qsl.net/kd2bd/splat.html\fP.
630 John A. Magliacane, KD2BD <\fIkd2bd@amsat.org\fP>
631 Creator, Lead Developer
633 Doug McDonald <\fImcdonald@scs.uiuc.edu\fP>
634 Longley-Rice Model integration
projects / debian / splat / blob