1 .TH SPLAT! 1 "20 January 2004" "KD2BD Software" "KD2BD Software"
3 splat \- A \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]
22 \fBSPLAT!\fP is a simple, yet powerful terrain analysis tool written
23 for Unix and Linux-based workstations. \fBSPLAT!\fP is free software.
24 Redistribution and/or modification is permitted under the terms of the
25 GNU General Public License as published by the Free Software Foundation,
26 either version 2 of the License or any later version. Adoption of
27 \fBSPLAT!\fP source code in proprietary or closed-source applications
28 is a violation of this license, and is \fBstrictly\fP forbidden.
30 \fBSPLAT!\fP is distributed in the hope that it will be useful, but
31 WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY
32 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
35 \fBSPLAT!\fP is a terrestrial RF propagation analysis tool for the
36 spectrum between 20 MHz and 20 GHz, and provides information of
37 interest to communication system designers and site engineers.
38 \fBSPLAT!\fP determines great circle distances and bearings between
39 sites, antenna elevation angles (uptilt), depression angles
40 (downtilt), antenna height above mean sea level, antenna height
41 above average terrain, bearings and distances to known obstructions,
42 Longley-Rice path loss, and minimum antenna height requirements
43 needed to establish line-of-sight communication paths absent of
44 obstructions due to terrain. \fBSPLAT!\fP produces reports, graphs,
45 and highly detailed and carefully annotated topographic maps depicting
46 line-of-sight paths, path loss, and expected coverage areas of
47 transmitters and repeater systems. When performing line-of-sight
48 analysis in situations where multiple transmitter or repeater sites
49 are employed, \fBSPLAT!\fP determines individual and mutual areas
50 of coverage within the network specified.
52 \fBSPLAT!\fP operates in two modes: \fIpoint-to-point mode\fP, and
53 \fIarea prediction mode\fP. These modes may be invoked using either
54 line-of-sight (LOS) or Irregular Terrain (ITM) propagation models.
55 True Earth, four-thirds Earth, or any other Earth radius may be
56 specified by the user when performing line-of-sight analysis.
58 \fBSPLAT!\fP is a command-line driven application, and reads input
59 data through a number of data files. Each has its own format. Some
60 files are mandatory for successful execution of the program, while
61 others are optional. Mandatory files include SPLAT Data Files (SDF
62 files), site location files (QTH files), and Longley-Rice model
63 parameter files (LRP files). Optional files include city/site
64 location files, and cartographic boundary files.
66 \fBSPLAT!\fP imports topographic data in the form of SPLAT Data Files
67 (SDFs) that may be generated from a number of information sources. In
68 the United States, SPLAT Data Files are most often derived from U.S.
69 Geological Survey Digital Elevation Models (DEMs) using the \fBusgs2sdf\fP
70 utility included with \fBSPLAT!\fP. USGS Digital Elevation Models
71 compatible with this utility are available at no cost via the Internet at:
72 \fIhttp://edcsgs9.cr.usgs.gov/glis/hyper/guide/1_dgr_demfig/index1m.html\fP.
74 SPLAT Data Files contain topographic elevations to the nearest meter
75 above mean sea level for 1-degree by 1-degree regions of the earth with
76 a resolution of 3-arc seconds. SDF files can be read in either standard
77 format (\fI.sdf\fP) as generated by the \fBusgs2sdf\fP utility, or in
78 bzip2 compressed format (\fI.sdf.bz2\fP). Since uncompressed files can
79 be slightly faster to load than compressed files, \fBSPLAT!\fP searches
80 for the needed SDF data in uncompressed format first. If such data cannot
81 located, then \fBSPLAT!\fP tries to read the data in bzip2 compressed
82 format. If no compressed SDF files can be found for the region requested,
83 \fBSPLAT!\fP assumes the region is over water or outside the United States,
84 and will assign an elevation of sea-level to these areas. This feature
85 of \fBSPLAT!\fP makes it possible to perform path analysis not only over
86 land, but also between coastal areas not represented by USGS Digital
87 Elevation Model Data since they are devoid of any land masses. However,
88 this behavior of \fBSPLAT!\fP underscores the importance of having all
89 the SDF files required for the region being analyzed if meaningful
90 results are to be expected.
91 .SH SITE LOCATION (QTH) FILES
92 \fBSPLAT!\fP imports site location information of transmitter and receiver
93 sites analyzed by the program from ASCII files having a \fI.qth\fP extension.
94 QTH files contain the site's name, the site's latitude (in degrees North),
95 the site's longitude (in degrees West), and the site's antenna height
96 above ground level (AGL). A single line-feed character separates each
97 field. The antenna height is assumed to be specified in feet unless
98 followed by the letter \fIm\fP or the word \fImeters\fP in either upper
99 or lower case. Latitude and longitude information may be expressed in
100 either decimal format (74.6889) or degree, minute, second (DMS)
103 For example, a site location file describing television station WNJT,
104 Trenton, NJ (\fIwnjt.qth\fP) might read as follows:
111 Each transmitter and receiver site analyzed by \fBSPLAT!\fP must be
112 represented by its own site location (QTH) file.
113 .SH LONGLEY-RICE PARAMETER (LRP) FILES
114 \fBSPLAT!\fP imports Longley-Rice model parameter data from files having
115 the same base name as the transmitter site QTH file, but carrying a \fI.lrp\fP
116 extension, thus providing simple and accurate correlation between these
117 associated data sets. The format for the Longley-Rice model parameter
118 files is as follows (\fIwnjt.lrp\fP):
120 15.000 ; Earth Dielectric Constant (Relative permittivity)
121 0.005 ; Earth Conductivity (Siemens per meter)
122 301.000 ; Atmospheric Bending Constant (N-units)
123 700.000 ; Frequency in MHz (20 MHz to 20 GHz)
124 5 ; Radio Climate (5 = Continental Temperate)
125 0 ; Polarization (0 = Horizontal, 1 = Vertical)
126 0.5 ; Fraction of situations (50% of locations)
127 0.5 ; Fraction of time (50% of the time)
129 If an LRP file corresponding to the tx_site QTH file cannot
130 be found, \fBSPLAT!\fP scans the current working directory for
131 the file "splat.lrp". If this file cannot be found, then the default
132 parameters listed above will be assigned by \fBSPLAT!\fP and a
133 corresponding "splat.lrp" file containing this data will be written
134 to the current working directory.
136 Typical Earth dielectric constants and conductivity values are as
139 Dielectric Constant Conductivity
140 Salt water : 80 5.000
141 Good ground : 25 0.020
142 Fresh water : 80 0.010
143 Marshy land : 12 0.007
144 Farmland, forest : 15 0.005
145 Average ground : 15 0.005
146 Mountain, sand : 13 0.002
148 Poor ground : 4 0.001
150 Radio climate codes used by \fBSPLAT!\fP are as follows:
152 1: Equatorial (Congo)
153 2: Continental Subtropical (Sudan)
154 3: Maritime Subtropical (West coast of Africa)
156 5: Continental Temperate
157 6: Maritime Temperate, over land (UK and west coasts of US & EU)
158 7: Maritime Temperate, over sea
160 The Continental Temperate climate is common to large land masses in
161 the temperate zone, such as the United States. For paths shorter than
162 100 km, there is little difference between Continental and Maritime
165 The final two parameters in the \fI.lrp\fP file correspond to the statistical
166 analysis provided by the Longley-Rice model. In this example, \fBSPLAT!\fP
167 will return the maximum path loss occurring 50% of the time (fraction
168 of time) in 50% of situations (fraction of situations). Use a fraction
169 of time parameter of 0.97 for digital television, 0.50 for analog in the
170 United States. Isotropic antennas are assumed.
172 For further information on these parameters, see:
173 \fIhttp://elbert.its.bldrdoc.gov/itm.html\fP and
174 \fIhttp://www.softwright.com/faq/engineering/prop_longley_rice.html\fP
175 .SH CITY LOCATION FILES
176 The names and locations of cities, tower sites, or other points of interest
177 may imported and be plotted on topographic maps generated by \fBSPLAT!\fP.
178 \fBSPLAT!\fP imports the names of cities and locations from ASCII files
179 containing the location's name, the location's latitude, and the location's
180 longitude. Each field is separated by a comma. Each record is separated
181 by a single line feed character. As was the case with the \fI.qth\fP
182 files, latitude and longitude information may be entered in either
183 decimal or degree, minute, second (DMS) format.
185 For example (\fIcities.dat\fP):
187 Teaneck, 40.891973, 74.014506
188 Tenafly, 40.919212, 73.955892
189 Teterboro, 40.859511, 74.058908
190 Tinton Falls, 40.279966, 74.093924
191 Toms River, 39.977777, 74.183580
192 Totowa, 40.906160, 74.223310
193 Trenton, 40.219922, 74.754665
195 A total of five separate city data files may be imported at a time.
196 There is no limit to the size of these files. \fBSPLAT!\fP reads city
197 data sequentially, and plots only those locations whose positions do
198 not conflict with previously plotted locations when generating
201 City data files may be generated manually using any text editor,
202 imported from other sources, or derived from data available from the
203 U.S. Census Bureau using the \fBcitydecoder\fP utility included with
204 \fBSPLAT!\fP. Such data is available free of charge via the Internet
205 at: \fIhttp://www.census.gov/geo/www/cob/bdy_files.html\fP, and must
207 .SH CARTOGRAPHIC BOUNDARY DATA FILES
208 Cartographic boundary data may also be imported to plot the boundaries of
209 cities, counties, or states on topographic maps generated by \fBSPLAT!\fP.
210 Such data must be of the form of ARC/INFO Ungenerate (ASCII Format)
211 Metadata Cartographic Boundary Files, and are available from the U.S.
212 Census Bureau via the Internet at:
213 \fIhttp://www.census.gov/geo/www/cob/co2000.html#ascii\fP and
214 \fIhttp://www.census.gov/geo/www/cob/pl2000.html#ascii\fP. A total of
215 five separate cartographic boundary files may be imported at a time.
216 It is not necessary to import state boundaries if county boundaries
217 have already been imported.
218 .SH PROGRAM OPERATION
219 \fBSPLAT!\fP is invoked via the command-line using a series of switches
220 and arguments. Since \fBSPLAT!\fP is a CPU and memory intensive application,
221 this type of interface minimizes overhead, and also lends itself well to
222 scripted operations. \fBSPLAT!\fP's CPU and memory scheduling priority
223 may be adjusted through the use of the Unix \fBnice\fP command.
225 The number and type of switches passed to \fBSPLAT!\fP determine its
226 mode of operation and method of output data generation. Nearly all
227 of \fBSPLAT!\fP's switches may be cascaded in any order on the command
228 line when invoking the program to include all the features described
229 by those switches when performing an analysis.
230 .SH POINT-TO-POINT ANALYSIS
231 \fBSPLAT!\fP may be used to perform line-of-sight terrain analysis
232 between two specified site locations. For example:
234 \fCsplat -t tx_site.qth -r rx_site.qth\fR
236 invokes a terrain analysis between the transmitter specified
237 in \fItx_site.qth\fP and receiver specified in \fIrx_site.qth\fP,
238 and writes a \fBSPLAT!\fP Obstruction Report to the current working
239 directory. The report contains details of the transmitter and
240 receiver sites, and identifies the location of any obstructions
241 detected during the analysis. If an obstruction can be cleared
242 by raising the receive antenna to a greater altitude, \fBSPLAT!\fP
243 will indicate the minimum antenna height required for a line-of-sight
244 path to exist between the transmitter and receiver locations specified.
245 If the antenna must be raised a significant amount, this determination
248 \fI.qth\fP extensions are assumed by \fBSPLAT!\fP for QTH files, and
249 are optional when invoking the program. \fBSPLAT!\fP automatically
250 reads all SPLAT Data Files necessary to conduct the terrain analysis
251 between the sites specified. By default, the location of SDF files
252 is assumed to be in the current working directory unless a
253 ".splat_path" file is present under the user's home directory.
254 If this file is present, it must contain the full directory path to
255 the location of all the SDF files required by \fBSPLAT!\fP to perform
256 its analysis for the region containing the transmitter and receiver
257 sites specified. The path in this file must be of the form of a
258 single line of ASCII text:
260 \fC/opt/splat/sdf/\fR
262 and may be generated with any text editor. The default path specified
263 in the \fI$HOME/.splat_path\fP file may be overridden at any time using
266 \fCsplat -t tx_site -r rx_site -d /cdrom/sdf/\fR
268 A graph of the terrain profile between the receiver and transmitter
269 locations as a function of distance from the receiver can be generated
270 by adding the \fI-p\fP switch:
272 \fCsplat -t tx_site -r rx_site -p terrain_profile.gif\fR
274 \fBSPLAT!\fP invokes \fBgnuplot\fP when generating graphs. The filename
275 extension specified to \fBSPLAT!\fP determines the format of the graph
276 produced. \fI.gif\fP will produce a 640x480 color GIF graphic file,
277 while \fI.ps\fP or \fI.postscript\fP will produce postscript output.
278 Output in formats such as PNG, Adobe Illustrator, AutoCAD dxf, LaTeX,
279 and many others are available. Please consult \fBgnuplot\fP, and
280 \fBgnuplot\fP's documentation for details on all the supported
283 A graph of elevations subtended by the terrain between the receiver and
284 transmitter as a function of distance from the receiver can be generated
285 by using the \fI-e\fP switch:
287 \fCsplat -t tx_site -r rx_site -e elevation_profile.gif\fR
289 The graph produced using this switch illustrates the elevation and
290 depression angles resulting from the terrain between the receiver's
291 location and the transmitter site from the perspective of the receiver's
292 location. A second trace is plotted between the left side of the graph
293 (receiver's location) and the location of the transmitting antenna on
294 the right. This trace illustrates the elevation angle required for a
295 line-of-sight path to exist between the receiver and transmitter
296 locations. If the trace intersects the elevation profile at any point
297 on the graph, then this is an indication that a line-of-sight path
298 does not exist under the conditions given, and the obstructions can
299 be clearly identified on the graph at the point(s) of intersection.
301 A graph illustrating terrain height referenced to a line-of-sight
302 path between the transmitter and receiver may be generated using
305 \fCsplat -t tx_site -r rx_site -h height_profile.gif\fR
307 The Earth's curvature is clearly evident when plotting height profiles.
309 A graph showing Longley-Rice path loss may be plotted using the
312 \fCsplat -t tx_site -r rx_site -l path_loss_profile.gif\fR
314 When performing path loss profiles, a Longley-Rice Model Path Loss
315 Report is generated by \fBSPLAT!\fP in the form of a text file with
316 a \fI.lro\fP filename extension. The report contains bearings and
317 distances between the transmitter and receiver, as well as the
318 Longley-Rice path loss for various distances between the transmitter
319 and receiver locations. The mode of propagation for points along the
320 path are given as \fILine-of-Sight\fP, \fISingle Horizon\fP, \fIDouble
321 Horizon\fP, \fIDiffraction Dominant\fP, and \fITroposcatter Dominant\fP.
323 To determine the signal-to-noise (SNR) ratio at remote location
324 where random Johnson (thermal) noise is the primary limiting
328 SNR = T - NJ - L + G - NF
331 where \fBT\fP is the ERP of the transmitter in dBW, \fBNJ\fP is
332 Johnson Noise in dBW (-136 dBW for a 6 MHz TV channel), \fBL\fP
333 is the path loss provided by \fBSPLAT!\fP in dB (as a \fIpositive\fP
334 number), \fBG\fP is the receive antenna gain in dB over isotropic,
335 and \fBNF\fP is the receiver noise figure in dB.
337 \fBT\fP may be computed as follows:
343 where \fBTI\fP is actual amount of RF power delivered to the transmitting
344 antenna in dBW, \fBGT\fP is the transmitting antenna gain (over isotropic)
345 in the direction of the receiver (or the horizon if the receiver is over
348 To compute how much more signal is available over the minimum to
349 necessary to achieve a specific signal-to-noise ratio:
352 Signal_Margin = SNR - S
355 where \fBS\fP is the minimum desired SNR ratio (15.5 dB for
356 ATSC DTV, 42 dB for analog NTSC television).
358 A topographic map may be generated by \fBSPLAT!\fP to visualize the
359 path between the transmitter and receiver sites from yet another
360 perspective. Topographic maps generated by \fBSPLAT!\fP display
361 elevations using a logarithmic grayscale, with higher elevations
362 represented through brighter shades of gray. The dynamic range of
363 the image is scaled between the highest and lowest elevations present
364 in the map. The only exception to this is sea-level, which is
367 \fBSPLAT!\fP generated topographic maps are 24-bit TrueColor Portable
368 PixMap (PPM) images, and may be viewed, edited, or converted to other
369 graphic formats by popular image viewing applications such as \fBxv\fP,
370 \fBThe GIMP\fP, \fBImageMagick\fP, and \fBXPaint\fP. PNG format is
371 highly recommended for lossless compressed storage of \fBSPLAT!\fP
372 generated topographic output files. An excellent command-line utility
373 capable of converting \fBSPLAT!\fP PPM graphic files to PNG files is
374 \fBwpng\fP, and is available
375 at: \fIhttp://www.libpng.org/pub/png/book/sources.html\fP. As a last
376 resort, PPM files may be compressed using the bzip2 utility, and read
377 directly by \fBThe GIMP\fP in this format. Topographic output
378 is specified using the \fI-o\fP switch:
380 \fCsplat -t tx_site -r rx_site -o topo_map.ppm\fR
382 The \fI.ppm\fP extension on the output filename is assumed by
383 \fBSPLAT!\fP, and is optional.
385 In this example, \fItopo_map.ppm\fP will illustrate the locations of the
386 transmitter and receiver sites specified. In addition, the great circle
387 path between the two sites will be drawn over locations for which an
388 unobstructed path exists to the transmitter at a receiving antenna
389 height equal to that of the receiver site (specified in \fIrx_site.qth\fP).
391 It may desirable to populate the topographic map with names and locations
392 of cities, tower sites, or other important locations. A city file may be
393 passed to \fBSPLAT!\fP using the \fI-s\fP switch:
395 \fCsplat -t tx_site -r rx_site -s cities.dat -o topo_map\fR
397 Up to five separate city files may be passed to \fBSPLAT!\fP at a time
398 following the \fI-s\fP switch.
400 County and state boundaries may be added to the map by specifying up
401 to five U.S. Census Bureau cartographic boundary files using the \fI-b\fP
404 \fCsplat -t tx_site -r rx_site -b co34_d00.dat -o topo_map\fR
406 In situations where multiple transmitter sites are in use, as many as
407 four site locations may be passed to \fBSPLAT!\fP at a time for analysis:
409 \fCsplat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p profile.gif\fR
411 In this example, four separate terrain profiles and obstruction reports
412 will be generated by \fBSPLAT!\fP. A single topographic map can be
413 specified using the \fI-o\fP switch, and line-of-sight paths between
414 each transmitter and the receiver site indicated will be produced on
415 the map, each in its own color. The path between the first transmitter
416 specified to the receiver will be in green, the path between the
417 second transmitter and the receiver will be in cyan, the path between
418 the third transmitter and the receiver will be in violet, and the
419 path between the fourth transmitter and the receiver will be in sienna.
420 .SH DETERMINING REGIONAL COVERAGE
421 \fBSPLAT!\fP can analyze a transmitter or repeater site, or network
422 of sites, and predict the regional coverage for each site specified.
423 In this mode, \fBSPLAT!\fP can generate a topographic map displaying
424 the geometric line-of-sight coverage area of the sites based on the
425 location of each site, and the height of receive antenna wishing to
426 communicate with the site in question. \fBSPLAT!\fP switches from
427 point-to-point analysis mode to area prediction mode when the \fI-c\fP
428 switch is invoked as follows:
430 \fCsplat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o tx_coverage\fR
432 In this example, \fBSPLAT!\fP generates a topographic map called
433 \fItx_coverage.ppm\fP that illustrates the predicted line-of-sight
434 regional coverage of \fItx_site\fP to receiving locations having
435 antennas 30.0 feet above ground level (AGL). The contents of
436 \fIcities.dat\fP are plotted on the map, as are the cartographic
437 boundaries contained in the file \fIco34_d00.dat\fP.
439 When plotting line-of-sight paths and areas of regional coverage,
440 \fBSPLAT!\fP by default does not account for the effects of
441 atmospheric bending. However, this behavior may be modified
442 by using the Earth radius multiplier (\fI-m\fP) switch:
444 \fCsplat -t wnjt -c 30.0 -m 1.333 -s cities.dat -b counties.dat -o map.ppm\fR
446 An earth radius multiplier of 1.333 instructs \fBSPLAT!\fP to use
447 the "four-thirds earth" model for line-of-sight propagation analysis.
448 Any appropriate earth radius multiplier may be selected by the user.
450 When invoked in area prediction mode, \fBSPLAT!\fP generates a
451 site report for each station analyzed. \fBSPLAT!\fP site reports
452 contain details of the site's geographic location, its height above
453 mean sea level, the antenna's height above mean sea level, the
454 antenna's height above average terrain, and the height of the
455 average terrain calculated in the directions of 0, 45, 90, 135,
456 180, 225, 270, and 315 degrees azimuth.
458 If the \fI-c\fP switch is replaced by a \fI-L\fP switch, a
459 Longley-Rice path loss map for a transmitter site may be generated:
461 \fCsplat -t tx_site -L 30.0 -s cities.dat -b co34_d00.dat -o path_loss_map\fR
463 In this mode, \fBSPLAT!\fP generates a multi-color map illustrating
464 expected signal levels (path loss) in areas surrounding the transmitter
465 site. A legend at the bottom of the map correlates each color with a
466 specific path loss level in decibels. Since Longley-Rice area
467 prediction map generation is quite CPU intensive, provision for
468 limiting the analysis range is provided by the \fI-R\fP switch.
469 The argument must be given in miles. If a range wider than the
470 generated topographic map is specified, \fBSPLAT!\fP will perform
471 Longley-Rice path loss calculations between all four corners of
472 the area prediction map.
473 .SH DETERMINING MULTIPLE REGIONS OF COVERAGE
474 \fBSPLAT!\fP can also display line-of-sight coverage areas for as
475 many as four separate transmitter sites on a common topographic map.
478 \fCsplat -t site1 site2 site3 site4 -c 30.0 -o network.ppm\fR
480 plots the regional line-of-sight coverage of site1, site2, site3,
481 and site4 based on a receive antenna located 30.0 feet above ground
482 level. A topographic map is then written to the file \fInetwork.ppm\fP.
483 The line-of-sight coverage area of the transmitters are plotted as
484 follows in the colors indicated (along with their corresponding RGB
487 site1: Green (0,255,0)
488 site2: Cyan (0,255,255)
489 site3: Medium Violet (147,112,219)
490 site4: Sienna 1 (255,130,71)
492 site1 + site2: Yellow (255,255,0)
493 site1 + site3: Pink (255,192,203)
494 site1 + site4: Green Yellow (173,255,47)
495 site2 + site3: Orange (255,165,0)
496 site2 + site4: Dark Sea Green 1 (193,255,193)
497 site3 + site4: Dark Turquoise (0,206,209)
499 site1 + site2 + site3: Dark Green (0,100,0)
500 site1 + site2 + site4: Blanched Almond (255,235,205)
501 site1 + site3 + site4: Medium Spring Green (0,250,154)
502 site2 + site3 + site4: Tan (210,180,140)
504 site1 + site2 + site3 + site4: Gold2 (238,201,0)
506 If separate \fI.qth\fP files are generated, each representing a common
507 site location but a different antenna height, a single topographic map
508 illustrating the regional coverage from as many as four separate locations
509 on a single tower may be generated by \fBSPLAT!\fP.
510 .SH TOPOGRAPHIC MAP GENERATION
511 In certain situations, it may be desirable to generate a topographic map
512 of a region without plotting coverage areas, line-of-sight paths, or
513 generating obstruction reports. There are several ways of doing this.
514 If one wishes to generate a topographic map illustrating the location
515 of a transmitter and receiver site along with a brief text report
516 describing the locations and distances between the sites, the \fI-n\fP
517 switch should be invoked as follows:
519 \fCsplat -t tx_site -r rx_site -n -o topo_map.ppm\fR
521 If no text report is desired, then the \fI-N\fP switch is used:
523 \fCsplat -t tx_site -r rx_site -N -o topo_map.ppm\fR
525 If the \fI-o\fP switch and output filename are omitted when using
526 either the \fI-n\fP or \fI-N\fP switches, output is written to a
527 file named \fImap.ppm\fP in the current working directory by default.
528 .SH DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
529 \fBSPLAT!\fP determines antenna height above average terrain (HAAT)
530 according to the procedure defined by Federal Communications Commission
531 Part 73.313(d). According to this definition, terrain elevations along
532 eight radials between 2 and 10 miles (3 and 16 kilometers) from the site
533 being analyzed are sampled and averaged for each 45 degrees of azimuth
534 starting with True North. If one or more radials lie entirely over water,
535 or over land outside the United States (areas for which no USGS topography
536 data is available), then those radials are omitted from the calculation
537 of average terrain. If part of a radial extends over a body of water or
538 over land outside the United States, then only that part of the radial
539 lying over United States land is used in the determination of average
542 When performing point-to-point terrain analysis, \fBSPLAT!\fP determines
543 the antenna height above average terrain only if enough topographic
544 data has already been loaded by the program to perform the point-to-point
545 analysis. In most cases, this will be true, unless the site in question
546 does not lie within 10 miles of the boundary of the topography data in
549 When performing area prediction analysis, enough topography data is normally
550 loaded by \fBSPLAT!\fP to perform average terrain calculations. Under
551 such conditions, \fBSPLAT!\fP will provide the antenna height above
552 average terrain as well as the average terrain above mean sea level
553 for azimuths of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and
554 include such information in the site report generated. If one or
555 more of the eight radials surveyed fall over water or land outside
556 the United States, \fBSPLAT!\fP reports \fINo Terrain\fP for those
558 .SH SETTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
559 \fBSPLAT!\fP reads SDF files into a series of memory "slots" as required
560 within the structure of the program. Each "slot" holds one SDF file.
561 Each SDF file represents a one degree by one degree region of terrain.
562 A \fI#define MAXSLOTS\fP statement in the first several lines of
563 \fIsplat.cpp\fP sets the maximum number of "slots" available for topography
564 data. It also sets the maximum size of the topographic maps generated by
565 \fBSPLAT!\fP. MAXSLOTS is set to 9 by default. If \fBSPLAT!\fP produces
566 a segmentation fault on start-up with this default, it is an indication
567 that not enough RAM and/or virtual memory (swap space) are available to
568 run \fBSPLAT!\fP with this number of MAXSLOTS. In this case, MAXSLOTS
569 may be reduced to 4, although this will greatly limit the maximum region
570 \fBSPLAT!\fP will be able to analyze. If 118 megabytes or more of total
571 memory (swap space plus RAM) is available, then MAXSLOTS may be increased
572 to 16. This will permit operation over a 4-degree by 4-degree region,
573 which is sufficient for single antenna heights in excess of 10,000 feet
574 above mean sea level, or point-to-point distances of over 1000 miles.
575 .SH ADDITIONAL INFORMATION
576 Invoking \fBSPLAT!\fP without any arguments will display all the
577 command-line options available with the program along with a brief
580 The latest news and information regarding \fBSPLAT!\fP software is
581 available through the official \fBSPLAT!\fP software web page located
582 at: \fIhttp://www.qsl.net/kd2bd/splat.html\fP.
585 \fC$HOME/.splat_path\fR
586 User-generated file containing the default path to the directory
587 containing the SDF data files.
590 Default Longley-Rice model parameters.
593 John A. Magliacane, KD2BD <\fIkd2bd@amsat.org\fP>
594 Creator, Lead Developer
596 Doug McDonald <\fImcdonald@scs.uiuc.edu\fP>
597 Longley-Rice Model integration
projects / debian / splat / blob