1SPLAT!(1) KD2BD Software SPLAT!(1)
2NNAAMMEE
6 splat ‐ An RF SSignal PPropagation, LLoss, AAnd TTerrain analy‐
7 sis tool
8SSYYNNOOPPSSIISS
10 splat [‐t _t_r_a_n_s_m_i_t_t_e_r___s_i_t_e_._q_t_h] [‐r _r_e_c_e_i_v_e_r___s_i_t_e_._q_t_h]
11 [‐c _r_x _a_n_t_e_n_n_a _h_e_i_g_h_t _f_o_r _L_O_S _c_o_v_e_r_a_g_e _a_n_a_l_y_s_i_s
12 _(_f_e_e_t_/_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [‐L _r_x _a_n_t_e_n_n_a _h_e_i_g_h_t _f_o_r _L_o_n_g_l_e_y_‐
13 _R_i_c_e _c_o_v_e_r_a_g_e _a_n_a_l_y_s_i_s _(_f_e_e_t_/_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [‐p _t_e_r_‐
14 _r_a_i_n___p_r_o_f_i_l_e_._e_x_t] [‐e _e_l_e_v_a_t_i_o_n___p_r_o_f_i_l_e_._e_x_t] [‐h
15 _h_e_i_g_h_t___p_r_o_f_i_l_e_._e_x_t] [‐H _n_o_r_m_a_l_i_z_e_d___h_e_i_g_h_t___p_r_o_f_i_l_e_._e_x_t] [‐l
16 _L_o_n_g_l_e_y_‐_R_i_c_e___p_r_o_f_i_l_e_._e_x_t] [‐o _t_o_p_o_g_r_a_p_h_i_c___m_a_p___f_i_l_e_‐
17 _n_a_m_e_._p_p_m] [‐b _c_a_r_t_o_g_r_a_p_h_i_c___b_o_u_n_d_a_r_y___f_i_l_e_n_a_m_e_._d_a_t] [‐s
18 _s_i_t_e_/_c_i_t_y___d_a_t_a_b_a_s_e_._d_a_t] [‐d _s_d_f___d_i_r_e_c_t_o_r_y___p_a_t_h] [‐m _e_a_r_t_h
19 _r_a_d_i_u_s _m_u_l_t_i_p_l_i_e_r _(_f_l_o_a_t_)] [‐f _f_r_e_q_u_e_n_c_y _(_M_H_z_) _f_o_r _F_r_e_s_n_e_l
20 _z_o_n_e _c_a_l_c_u_l_a_t_i_o_n_s _(_f_l_o_a_t_)] [‐R _m_a_x_i_m_u_m _c_o_v_e_r_a_g_e _r_a_d_i_u_s
21 _(_m_i_l_e_s_/_k_i_l_o_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [‐dB _m_a_x_i_m_u_m _a_t_t_e_n_u_a_t_i_o_n _c_o_n_‐
22 _t_o_u_r _t_o _d_i_s_p_l_a_y _o_n _p_a_t_h _l_o_s_s _m_a_p_s _(_8_0_‐_2_3_0 _d_B_)] [‐fz _F_r_e_s_‐
23 _n_e_l _z_o_n_e _c_l_e_a_r_a_n_c_e _p_e_r_c_e_n_t_a_g_e _(_d_e_f_a_u_l_t _= _6_0_)] [‐plo
24 _p_a_t_h___l_o_s_s___o_u_t_p_u_t___f_i_l_e_._t_x_t] [‐pli _p_a_t_h___l_o_s_s___i_n_p_u_t___f_i_l_e_._t_x_t]
25 [‐udt _u_s_e_r___d_e_f_i_n_e_d___t_e_r_r_a_i_n___f_i_l_e_._d_a_t] [‐n] [‐N] [‐nf]
26 [‐ngs] [‐geo] [‐kml] [‐metric]
27DDEESSCCRRIIPPTTIIOONN
29 SSPPLLAATT!! is a powerful terrestrial RF propagation and ter‐
30 rain analysis tool for the spectrum between 20 MHz and 20
31 GHz. SSPPLLAATT!! is free software, and is designed for opera‐
32 tion on Unix and Linux‐based workstations. Redistribution
33 and/or modification is permitted under the terms of the
34 GNU General Public License, Version 2, as published by the
35 Free Software Foundation. Adoption of SSPPLLAATT!! source code
36 in proprietary or closed‐source applications is a viola‐
37 tion of this license and is ssttrriiccttllyy forbidden.
38 SSPPLLAATT!! is distributed in the hope that it will be useful,
40 but WITHOUT ANY WARRANTY, without even the implied war‐
41 ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR‐
42 POSE. See the GNU General Public License for more
43 details.
44IINNTTRROODDUUCCTTIIOONN
46 Applications of SSPPLLAATT!! include the visualization, design,
47 and link budget analysis of wireless Wide Area Networks
48 (WANs), commercial and amateur radio communication systems
49 above 20 MHz, microwave links, frequency coordination and
50 interference studies, and the prediction of analog and
51 digital terrestrial radio and television contour regions.
52 SSPPLLAATT!! provides RF site engineering data such as great
54 circle distances and bearings between sites, antenna ele‐
55 vation angles (uptilt), depression angles (downtilt),
56 antenna height above mean sea level, antenna height above
57 average terrain, bearings, distances, and elevations to
58 known obstructions, Longley‐Rice path attenuation, and
59 received signal strength. In addition, the minimum
60 antenna height requirements needed to clear terrain, the
61 first Fresnel zone, and any user‐definable percentage of
62 the first Fresnel zone are also provided.
63 SSPPLLAATT!! produces reports, graphs, and high resolution topo‐
65 graphic maps that depict line‐of‐sight paths, and regional
66 path loss and signal strength contours through which
67 expected coverage areas of transmitters and repeater sys‐
68 tems can be obtained. When performing line‐of‐sight and
69 Longley‐Rice analyses in situations where multiple trans‐
70 mitter or repeater sites are employed, SSPPLLAATT!! determines
71 individual and mutual areas of coverage within the network
72 specified.
73 Simply typing splat on the command line will return a sum‐
75 mary of SSPPLLAATT!!’s command line options:
76 ‐‐==[ SPLAT! v1.2.1 Available Options...
79 ]==‐‐
80 ‐t txsite(s).qth (max of 4 with ‐c, max of 30 with
82 ‐L)
83 ‐r rxsite.qth
84 ‐c plot coverage of TX(s) with an RX antenna at X
85 feet/meters AGL
86 ‐L plot path loss map of TX based on an RX at X
87 feet/meters AGL
88 ‐s filename(s) of city/site file(s) to import (5 max)
89 ‐b filename(s) of cartographic boundary file(s) to
90 import (5 max)
91 ‐p filename of terrain profile graph to plot
92 ‐e filename of terrain elevation graph to plot
93 ‐h filename of terrain height graph to plot
94 ‐H filename of normalized terrain height graph to
95 plot
96 ‐l filename of Longley‐Rice graph to plot
97 ‐o filename of topographic map to generate (.ppm)
98 ‐u filename of user‐defined terrain file to import
99 ‐d sdf file directory path (overrides path in
100 ~/.splat_path file)
101 ‐m earth radius multiplier
102 ‐n do not plot LOS paths in .ppm maps
103 ‐N do not produce unnecessary site or obstruction
104 reports
105 ‐f frequency for Fresnel zone calculation (MHz)
106 ‐R modify default range for ‐c or ‐L (miles/kilome‐
107 ters)
108 ‐db maximum loss contour to display on path loss maps
109 (80‐230 dB)
110 ‐nf do not plot Fresnel zones in height plots
111 ‐fz Fresnel zone clearance percentage (default = 60)
112 ‐ngs display greyscale topography as white in .ppm
113 files
114 ‐erp override ERP in .lrp file (Watts)
115 ‐pli filename of path‐loss input file
116 ‐plo filename of path‐loss output file
117 ‐udt filename of user defined terrain input file
118 ‐kml generate Google Earth (.kml) compatible output
119 ‐geo generate an Xastir .geo georeference file (with
120 .ppm output) ‐metric employ metric rather than imperial
121 units for all user I/O
122IINNPPUUTT FFIILLEESS
125 SSPPLLAATT!! is a command‐line driven application and reads
126 input data through a number of data files. Some files are
127 mandatory for successful execution of the program, while
128 others are optional. Mandatory files include 3‐arc second
129 topography models in the form of SPLAT Data Files (SDF
130 files), site location files (QTH files), and Longley‐Rice
131 model parameter files (LRP files). Optional files include
132 city location files, cartographic boundary files, user‐
133 defined terrain files, path‐loss input files, antenna
134 radiation pattern files, and color definition files.
135SSPPLLAATT DDAATTAA FFIILLEESS
137 SSPPLLAATT!! imports topographic data in the form of SPLAT Data
138 Files (SDFs). These files may be generated from a number
139 of information sources. In the United States, SPLAT Data
140 Files can be generated through U.S. Geological Survey
141 Digital Elevation Models (DEMs) using the uussggss22ssddff utility
142 included with SSPPLLAATT!!. USGS Digital Elevation Models com‐
143 patible with this utility may be downloaded from:
144 _h_t_t_p_:_/_/_e_d_c_f_t_p_._c_r_._u_s_g_s_._g_o_v_/_p_u_b_/_d_a_t_a_/_D_E_M_/_2_5_0_/.
145 Significantly better resolution and accuracy can be
147 obtained through the use of SRTM‐3 Version 2 digital ele‐
148 vation models. These models are the product of the STS‐99
149 Space Shuttle Radar Topography Mission, and are available
150 for most populated regions of the Earth. SPLAT Data Files
151 may be generated from SRTM data using the included
152 ssrrttmm22ssddff utility. SRTM‐3 Version 2 data may be obtained
153 through anonymous FTP from:
154 _f_t_p_:_/_/_e_0_s_r_p_0_1_u_._e_c_s_._n_a_s_a_._g_o_v_:_2_1_/_s_r_t_m_/_v_e_r_s_i_o_n_2_/
155 The ssttrrmm22ssddff utility may also be used to convert 3‐arc
157 second SRTM data in Band Interleaved by Line (.BIL) format
158 for use with SSPPLLAATT!!. This data is available via the web
159 at: _h_t_t_p_:_/_/_s_e_a_m_l_e_s_s_._u_s_g_s_._g_o_v_/_w_e_b_s_i_t_e_/_s_e_a_m_l_e_s_s_/
160 Band Interleaved by Line data must be downloaded in a very
162 specific manner to be compatible with ssrrttmm22ssddff and SSPPLLAATT!!.
163 Please consult ssrrttmm22ssddff’s documentation for instructions
164 on downloading .BIL topographic data through the USGS’s
165 Seamless Web Site.
166 Despite the higher accuracy that SRTM data has to offer,
168 some voids in the data sets exist. When voids are
169 detected, the ssrrttmm22ssddff utility replaces them with corre‐
170 sponding data found in existing SDF files (that were pre‐
171 sumably created from earlier USGS data through the
172 uussggss22ssddff utility). If USGS‐derived SDF data is not avail‐
173 able, voids are handled through adjacent pixel averaging,
174 or direct replacement.
175 SPLAT Data Files contain integer value topographic eleva‐
177 tions (in meters) referenced to mean sea level for
178 1‐degree by 1‐degree regions of the earth with a resolu‐
179 tion of 3‐arc seconds. SDF files can be read in either
180 standard format (_._s_d_f) as generated by the uussggss22ssddff and
181 ssrrttmm22ssddff utilities, or in bzip2 compressed format
182 (_._s_d_f_._b_z_2). Since uncompressed files can be read slightly
183 faster than files that have been compressed, SSPPLLAATT!!
184 searches for needed SDF data in uncompressed format first.
185 If uncompressed data cannot be located, SSPPLLAATT!! then
186 searches for data in bzip2 compressed format. If no com‐
187 pressed SDF files can be found for the region requested,
188 SSPPLLAATT!! assumes the region is over water, and will assign
189 an elevation of sea‐level to these areas.
190 This feature of SSPPLLAATT!! makes it possible to perform path
192 analysis not only over land, but also between coastal
193 areas not represented by Digital Elevation Model data.
194 However, this behavior of SSPPLLAATT!! underscores the impor‐
195 tance of having all the SDF files required for the region
196 being analyzed if meaningful results are to be expected.
197SSIITTEE LLOOCCAATTIIOONN ((QQTTHH)) FFIILLEESS
199 SSPPLLAATT!! imports site location information of transmitter
200 and receiver sites analyzed by the program from ASCII
201 files having a _._q_t_h extension. QTH files contain the
202 site’s name, the site’s latitude (positive if North of the
203 equator, negative if South), the site’s longitude (in
204 degrees West, 0 to 360 degrees, or degrees East 0 to ‐360
205 degrees), and the site’s antenna height above ground level
206 (AGL), each separated by a single line‐feed character.
207 The antenna height is assumed to be specified in feet
208 unless followed by the letter _m or the word _m_e_t_e_r_s in
209 either upper or lower case. Latitude and longitude infor‐
210 mation may be expressed in either decimal format (74.6864)
211 or degree, minute, second (DMS) format (74 41 11.0).
212 For example, a site location file describing television
214 station WNJT‐DT, Trenton, NJ (_w_n_j_t_‐_d_t_._q_t_h) might read as
215 follows:
216 WNJT‐DT
218 40.2828
219 74.6864
220 990.00
221 Each transmitter and receiver site analyzed by SSPPLLAATT!! must
223 be represented by its own site location (QTH) file.
224LLOONNGGLLEEYY‐‐RRIICCEE PPAARRAAMMEETTEERR ((LLRRPP)) FFIILLEESS
226 Longley‐Rice parameter data files are required for SSPPLLAATT!!
227 to determine RF path loss in either point‐to‐point or area
228 prediction mode. Longley‐Rice model parameter data is
229 read from files having the same base name as the transmit‐
230 ter site QTH file, but with a format (_w_n_j_t_‐_d_t_._l_r_p):
231 15.000 ; Earth Dielectric Constant (Relative per‐
233 mittivity)
234 0.005 ; Earth Conductivity (Siemens per meter)
235 301.000 ; Atmospheric Bending Constant (N‐units)
236 647.000 ; Frequency in MHz (20 MHz to 20 GHz)
237 5 ; Radio Climate (5 = Continental Temper‐
238 ate)
239 0 ; Polarization (0 = Horizontal, 1 = Verti‐
240 cal)
241 0.50 ; Fraction of situations (50% of loca‐
242 tions)
243 0.90 ; Fraction of time (90% of the time)
244 46000.0 ; ERP in Watts (optional)
245 If an LRP file corresponding to the tx_site QTH file can‐
247 not be found, SSPPLLAATT!! scans the current working directory
248 for the file "splat.lrp". If this file cannot be found,
249 then default parameters will be assigned by SSPPLLAATT!! and a
250 corresponding "splat.lrp" file containing these default
251 parameters will be written to the current working direc‐
252 tory. The generated "splat.lrp" file can then be edited
253 by the user as needed.
254 Typical Earth dielectric constants and conductivity values
256 are as follows:
257 Dielectric Constant Conductiv‐
259 ity
260 Salt water : 80 5.000
261 Good ground : 25 0.020
262 Fresh water : 80 0.010
263 Marshy land : 12 0.007
264 Farmland, forest : 15 0.005
265 Average ground : 15 0.005
266 Mountain, sand : 13 0.002
267 City : 5 0.001
268 Poor ground : 4 0.001
269 Radio climate codes used by SSPPLLAATT!! are as follows:
271 1: Equatorial (Congo)
273 2: Continental Subtropical (Sudan)
274 3: Maritime Subtropical (West coast of Africa)
275 4: Desert (Sahara)
276 5: Continental Temperate
277 6: Maritime Temperate, over land (UK and west
278 coasts of US & EU)
279 7: Maritime Temperate, over sea
280 The Continental Temperate climate is common to large land
282 masses in the temperate zone, such as the United States.
283 For paths shorter than 100 km, there is little difference
284 between Continental and Maritime Temperate climates.
285 The seventh and eighth parameters in the _._l_r_p file corre‐
287 spond to the statistical analysis provided by the Longley‐
288 Rice model. In this example, SSPPLLAATT!! will return the maxi‐
289 mum path loss occurring 50% of the time (fraction of time)
290 in 90% of situations (fraction of situations). This is
291 often denoted as F(50,90) in Longley‐Rice studies. In the
292 United States, an F(50,90) criteria is typically used for
293 digital television (8‐level VSB modulation), while
294 F(50,50) is used for analog (VSB‐AM+NTSC) broadcasts.
295 For further information on these parameters, see:
297 _h_t_t_p_:_/_/_f_l_a_t_t_o_p_._i_t_s_._b_l_d_r_d_o_c_._g_o_v_/_i_t_m_._h_t_m_l and
298 _h_t_t_p_:_/_/_w_w_w_._s_o_f_t_w_r_i_g_h_t_._c_o_m_/_f_a_q_/_e_n_g_i_n_e_e_r_i_n_g_/_p_r_o_p___l_o_n_g_‐
299 _l_e_y___r_i_c_e_._h_t_m_l
300 The final parameter in the _._l_r_p file corresponds to the
302 transmitter’s effective radiated power, and is optional.
303 If it is included in the levels and field strength level
304 contours when performing Longley‐Rice studies. If the
305 parameter is omitted, path loss is computed instead. The
306 ERP provided in the _._l_r_p file can be overridden by using
307 SSPPLLAATT!!’s _‐_e_r_p command‐line switch. If the _._l_r_p file con‐
308 tains an ERP parameter and the generation of path‐loss
309 rather than signal strength contours is desired, the ERP
310 can be assigned to zero using the _‐_e_r_p switch without hav‐
311 ing to edit the _._l_r_p file to accomplish the same result.
312CCIITTYY LLOOCCAATTIIOONN FFIILLEESS
314 The names and locations of cities, tower sites, or other
315 points of interest may be imported and plotted on topo‐
316 graphic maps generated by SSPPLLAATT!!. SSPPLLAATT!! imports the
317 names of cities and locations from ASCII files containing
318 the location of interest’s name, latitude, and longitude.
319 Each field is separated by a comma. Each record is sepa‐
320 rated by a single line feed character. As was the case
321 with the _._q_t_h files, latitude and longitude information
322 may be entered in either decimal or degree, minute, second
323 (DMS) format.
324 For example (_c_i_t_i_e_s_._d_a_t):
326 Teaneck, 40.891973, 74.014506
328 Tenafly, 40.919212, 73.955892
329 Teterboro, 40.859511, 74.058908
330 Tinton Falls, 40.279966, 74.093924
331 Toms River, 39.977777, 74.183580
332 Totowa, 40.906160, 74.223310
333 Trenton, 40.219922, 74.754665
334 A total of five separate city data files may be imported
336 at a time, and there is no limit to the size of these
337 files. SSPPLLAATT!! reads city data on a "first come/first
338 served" basis, and plots only those locations whose anno‐
339 tations do not conflict with annotations of locations read
340 earlier in the current city data file, or in previous
341 files. This behavior minimizes clutter in SSPPLLAATT!! gener‐
342 ated topographic maps, but also mandates that important
343 locations be placed toward the beginning of the first city
344 data file, and locations less important be positioned fur‐
345 ther down the list or in subsequent data files.
346 City data files may be generated manually using any text
348 editor, imported from other sources, or derived from data
349 available from the U.S. Census Bureau using the cciittyyddee‐‐
350 ccooddeerr utility included with SSPPLLAATT!!. Such data is avail‐
351 able free of charge via the Internet at: _h_t_t_p_:_/_/_w_w_w_._c_e_n_‐
352 _s_u_s_._g_o_v_/_g_e_o_/_w_w_w_/_c_o_b_/_b_d_y___f_i_l_e_s_._h_t_m_l, and must be in ASCII
353 format.
354CCAARRTTOOGGRRAAPPHHIICC BBOOUUNNDDAARRYY DDAATTAA FFIILLEESS
356 Cartographic boundary data may also be imported to plot
357 the boundaries of cities, counties, or states on topo‐
358 graphic maps generated by SSPPLLAATT!!. Such data must be of
359 the form of ARC/INFO Ungenerate (ASCII Format) Metadata
360 Cartographic Boundary Files, and are available from the
361 U.S. Census Bureau via the Internet at: _h_t_t_p_:_/_/_w_w_w_._c_e_n_‐
362 _s_u_s_._g_o_v_/_g_e_o_/_w_w_w_/_c_o_b_/_c_o_2_0_0_0_._h_t_m_l_#_a_s_c_i_i and _h_t_t_p_:_/_/_w_w_w_._c_e_n_‐
363 _s_u_s_._g_o_v_/_g_e_o_/_w_w_w_/_c_o_b_/_p_l_2_0_0_0_._h_t_m_l_#_a_s_c_i_i. A total of five
364 separate cartographic boundary files may be imported at a
365 time. It is not necessary to import state boundaries if
366 county boundaries have already been imported.
367PPRROOGGRRAAMM OOPPEERRAATTIIOONN
369 SSPPLLAATT!! is invoked via the command‐line using a series of
370 switches and arguments. Since SSPPLLAATT!! is a CPU and memory
371 intensive application, this type of interface minimizes
372 overhead and lends itself well to scripted (batch) opera‐
373 tions. SSPPLLAATT!!’s CPU and memory scheduling priority may be
374 modified through the use of the Unix nniiccee command.
375 The number and type of switches passed to SSPPLLAATT!! determine
377 its mode of operation and method of output data genera‐
378 tion. Nearly all of SSPPLLAATT!!’s switches may be cascaded in
379 any order on the command line when invoking the program.
380 SSPPLLAATT!! operates in two distinct modes: _p_o_i_n_t_‐_t_o_‐_p_o_i_n_t
382 _m_o_d_e, and _a_r_e_a _p_r_e_d_i_c_t_i_o_n _m_o_d_e. Either a line‐of‐sight
383 (LOS) or Longley‐Rice Irregular Terrain (ITM) propagation
384 model may be invoked by the user. True Earth, four‐thirds
385 Earth, or any other user‐defined Earth radius may be spec‐
386 ified when performing line‐of‐sight analysis.
387PPOOIINNTT‐‐TTOO‐‐PPOOIINNTT AANNAALLYYSSIISS
389 SSPPLLAATT!! may be used to perform line‐of‐sight terrain analy‐
390 sis between two specified site locations. For example:
391 splat ‐t tx_site.qth ‐r rx_site.qth
393 invokes a line‐of‐sight terrain analysis between the
395 transmitter specified in _t_x___s_i_t_e_._q_t_h and receiver speci‐
396 fied in _r_x___s_i_t_e_._q_t_h using a True Earth radius model, and
397 writes a SSPPLLAATT!! Path Analysis Report to the current work‐
398 ing directory. The report contains details of the trans‐
399 mitter and receiver sites, and identifies the location of
400 any obstructions detected along the line‐of‐sight path.
401 If an obstruction can be cleared by raising the receive
402 antenna to a greater altitude, SSPPLLAATT!! will indicate the
403 minimum antenna height required for a line‐of‐sight path
404 to exist between the transmitter and receiver locations
405 specified. Note that imperial units (miles, feet) are
406 specified unless the _‐_m_e_t_r_i_c switch is added to SSPPLLAATT!!’s
407 command line options:
408 splat ‐t tx_site.qth ‐r rx_site.qth ‐metric
410 If the antenna must be raised a significant amount, this
412 determination may take a few moments. Note that the
413 results provided are the _m_i_n_i_m_u_m necessary for a line‐of‐
414 sight path to exist, and in the case of this simple exam‐
415 ple, do not take Fresnel zone clearance requirements into
416 consideration.
417 _q_t_h extensions are assumed by SSPPLLAATT!! for QTH files, and
419 are optional when specifying ‐t and ‐r arguments on the
420 command‐line. SSPPLLAATT!! automatically reads all SPLAT Data
421 Files necessary to conduct the terrain analysis between
422 the sites specified. SSPPLLAATT!! searches for the required
423 SDF files in the current working directory first. If the
424 needed files are not found, SSPPLLAATT!! then searches in the
425 path specified by the _‐_d command‐line switch:
426 splat ‐t tx_site ‐r rx_site ‐d /cdrom/sdf/
428 An external directory path may be specified by placing a
430 ".splat_path" file under the user’s home directory. This
431 file must contain the full directory path of last resort
432 to all the SDF files. The path in the _$_H_O_M_E_/_._s_p_l_a_t___p_a_t_h
433 file must be of the form of a single line of ASCII text:
434 /opt/splat/sdf/
436 and can be generated using any text editor.
438 A graph of the terrain profile between the receiver and
440 transmitter locations as a function of distance from the
441 receiver can be generated by adding the _‐_p switch:
442 splat ‐t tx_site ‐r rx_site ‐p terrain_profile.png
444 SSPPLLAATT!! invokes ggnnuupplloott when generating graphs. The file‐
446 name extension specified to SSPPLLAATT!! determines the format
447 of the graph produced. _._p_n_g will produce a 640x480 color
448 PNG graphic file, while _._p_s or _._p_o_s_t_s_c_r_i_p_t will produce
449 postscript output. Output in formats such as GIF, Adobe
450 Illustrator, AutoCAD dxf, LaTeX, and many others are
451 available. Please consult ggnnuupplloott, and ggnnuupplloott’s documen‐
452 tation for details on all the supported output formats.
453 A graph of elevations subtended by the terrain between the
455 receiver and transmitter as a function of distance from
456 the receiver can be generated by using the _‐_e switch:
457 splat ‐t tx_site ‐r rx_site ‐e elevation_profile.png
459 The graph produced using this switch illustrates the ele‐
461 vation and depression angles resulting from the terrain
462 between the receiver’s location and the transmitter site
463 from the perspective of the receiver’s location. A second
464 trace is plotted between the left side of the graph
465 (receiver’s location) and the location of the transmitting
466 antenna on the right. This trace illustrates the eleva‐
467 tion angle required for a line‐of‐sight path to exist
468 between the receiver and transmitter locations. If the
469 trace intersects the elevation profile at any point on the
470 graph, then this is an indication that a line‐of‐sight
471 path does not exist under the conditions given, and the
472 obstructions can be clearly identified on the graph at the
473 point(s) of intersection.
474 A graph illustrating terrain height referenced to a line‐
476 of‐sight path between the transmitter and receiver may be
477 generated using the _‐_h switch:
478 splat ‐t tx_site ‐r rx_site ‐h height_profile.png
480 A terrain height plot normalized to the transmitter and
482 receiver antenna heights can be obtained using the _‐_H
483 switch:
484 splat ‐t tx_site ‐r rx_site ‐H normalized_height_pro‐
486 file.png
487 A contour of the Earth’s curvature is also plotted in this
489 mode.
490 The first Fresnel Zone, and 60% of the first Fresnel Zone
492 can be added to height profile graphs by adding the _‐_f
493 switch, and specifying a frequency (in MHz) at which the
494 Fresnel Zone should be modeled:
495 splat ‐t tx_site ‐r rx_site ‐f 439.250 ‐H normal‐
497 ized_height_profile.png
498 Fresnel Zone clearances other 60% can be specified using
500 the _‐_f_z switch as follows:
501 splat ‐t tx_site ‐r rx_site ‐f 439.250 ‐fz 75 ‐H
503 height_profile2.png
504 A graph showing Longley‐Rice path loss may be plotted
506 using the _‐_l switch:
507 splat ‐t tx_site ‐r rx_site ‐l path_loss_profile.png
509 As before, adding the _‐_m_e_t_r_i_c switch forces the graphs to
511 be plotted using metric units of measure.
512 When performing a point‐to‐point analysis, a SSPPLLAATT!! Path
514 Analysis Report is generated in the form of a text file
515 with a _._t_x_t filename extension. The report contains bear‐
516 ings and distances between the transmitter and receiver,
517 as well as the free‐space and Longley‐Rice path loss for
518 the path being analyzed. The mode of propagation for the
519 path is given as _L_i_n_e_‐_o_f_‐_S_i_g_h_t, _S_i_n_g_l_e _H_o_r_i_z_o_n, _D_o_u_b_l_e
520 _H_o_r_i_z_o_n, _D_i_f_f_r_a_c_t_i_o_n _D_o_m_i_n_a_n_t, or _T_r_o_p_o_s_c_a_t_t_e_r _D_o_m_i_n_a_n_t.
521 Distances and locations to known obstructions along the
523 path between transmitter and receiver are also provided.
524 If the transmitter’s effective radiated power is specified
525 in the transmitter’s corresponding _._l_r_p file, then pre‐
526 dicted signal strength and antenna voltage at the receiv‐
527 ing location is also provided in the Path Analysis Report.
528 To determine the signal‐to‐noise (SNR) ratio at remote
530 location where random Johnson (thermal) noise is the pri‐
531 mary limiting factor in reception:
532 _S_N_R=_T‐_N_J‐_L+_G‐_N_F
534 where TT is the ERP of the transmitter in dBW in the direc‐
536 tion of the receiver, NNJJ is Johnson Noise in dBW (‐136 dBW
537 for a 6 MHz television channel), LL is the path loss pro‐
538 vided by SSPPLLAATT!! in dB (as a _p_o_s_i_t_i_v_e number), GG is the
539 receive antenna gain in dB over isotropic, and NNFF is the
540 receiver noise figure in dB.
541 TT may be computed as follows:
543 _T=_T_I+_G_T
545 where TTII is actual amount of RF power delivered to the
547 transmitting antenna in dBW, GGTT is the transmitting
548 antenna gain (over isotropic) in the direction of the
549 receiver (or the horizon if the receiver is over the hori‐
550 zon).
551 To compute how much more signal is available over the min‐
553 imum to necessary to achieve a specific signal‐to‐noise
554 ratio:
555 _S_i_g_n_a_l__M_a_r_g_i_n=_S_N_R‐_S
557 where SS is the minimum required SNR ratio (15.5 dB for
559 ATSC (8‐level VSB) DTV, 42 dB for analog NTSC television).
560 A topographic map may be generated by SSPPLLAATT!! to visualize
562 the path between the transmitter and receiver sites from
563 yet another perspective. Topographic maps generated by
564 SSPPLLAATT!! display elevations using a logarithmic grayscale,
565 with higher elevations represented through brighter shades
566 of gray. The dynamic range of the image is scaled between
567 the highest and lowest elevations present in the map. The
568 only exception to this is sea‐level, which is represented
569 using the color blue.
570 Topographic output is invoked using the _‐_o switch:
572 splat ‐t tx_site ‐r rx_site ‐o topo_map.ppm
574 The _._p_p_m extension on the output filename is assumed by
576 SSPPLLAATT!!, and is optional.
577 In this example, _t_o_p_o___m_a_p_._p_p_m will illustrate the loca‐
579 tions of the transmitter and receiver sites specified. In
580 addition, the great circle path between the two sites will
581 be drawn over locations for which an unobstructed path
582 exists to the transmitter at a receiving antenna height
583 equal to that of the receiver site (specified in
584 _r_x___s_i_t_e_._q_t_h).
585 It may desirable to populate the topographic map with
587 names and locations of cities, tower sites, or other
588 important locations. A city file may be passed to SSPPLLAATT!!
589 using the _‐_s switch:
590 splat ‐t tx_site ‐r rx_site ‐s cities.dat ‐o topo_map
592 Up to five separate city files may be passed to SSPPLLAATT!! at
594 a time following the _‐_s switch.
595 County and state boundaries may be added to the map by
597 specifying up to five U.S. Census Bureau cartographic
598 boundary files using the _‐_b switch:
599 splat ‐t tx_site ‐r rx_site ‐b co34_d00.dat ‐o topo_map
601 In situations where multiple transmitter sites are in use,
603 as many as four site locations may be passed to SSPPLLAATT!! at
604 a time for analysis:
605 splat ‐t tx_site1 tx_site2 tx_site3 tx_site4 ‐r rx_site ‐p
607 profile.png
608 In this example, four separate terrain profiles and
610 obstruction reports will be generated by SSPPLLAATT!!. A single
611 topographic map can be specified using the _‐_o switch, and
612 line‐of‐sight paths between each transmitter and the
613 receiver site indicated will be produced on the map, each
614 in its own color. The path between the first transmitter
615 specified to the receiver will be in green, the path
616 between the second transmitter and the receiver will be in
617 cyan, the path between the third transmitter and the
618 receiver will be in violet, and the path between the
619 fourth transmitter and the receiver will be in sienna.
620 SSPPLLAATT!! generated topographic maps are 24‐bit TrueColor
622 Portable PixMap (PPM) images. They may be viewed, edited,
623 or converted to other graphic formats by popular image
624 viewing applications such as xxvv, TThhee GGIIMMPP, IImmaaggeeMMaaggiicckk,
625 and XXPPaaiinntt. PNG format is highly recommended for lossless
626 compressed storage of SSPPLLAATT!! generated topographic output
627 files. IImmaaggeeMMaaggiicckk’s command‐line utility easily converts
628 SSPPLLAATT!!’s PPM files to PNG format:
629 convert splat_map.ppm splat_map.png
631 Another excellent PPM to PNG command‐line utility is
633 available at:
634 _h_t_t_p_:_/_/_w_w_w_._l_i_b_p_n_g_._o_r_g_/_p_u_b_/_p_n_g_/_b_o_o_k_/_s_o_u_r_c_e_s_._h_t_m_l. As a
635 last resort, PPM files may be compressed using the bzip2
636 utility, and read directly by TThhee GGIIMMPP in this format.
637 The _‐_n_g_s option assigns all terrain to the color white,
639 and can be used when it is desirable to generate a map
640 that is devoid of terrain:
641 splat ‐t tx_site ‐r rx_site ‐b co34_d00.dat ‐ngs ‐o
643 white_map
644 The resulting .ppm image file can be converted to .png
646 format with a transparent background using IImmaaggeeMMaaggiicckk’s
647 ccoonnvveerrtt utility:
648 convert ‐transparent "#FFFFFF" white_map.ppm transpar‐
650 ent_map.png
651RREEGGIIOONNAALL CCOOVVEERRAAGGEE AANNAALLYYSSIISS
653 SSPPLLAATT!! can analyze a transmitter or repeater site, or net‐
654 work of sites, and predict the regional coverage for each
655 site specified. In this mode, SSPPLLAATT!! can generate a topo‐
656 graphic map displaying the geometric line‐of‐sight cover‐
657 age area of the sites based on the location of each site
658 and the height of receive antenna wishing to communicate
659 with the site in question. A regional analysis may be
660 performed by SSPPLLAATT!! using the _‐_c switch as follows:
661 splat ‐t tx_site ‐c 30.0 ‐s cities.dat ‐b co34_d00.dat ‐o
663 tx_coverage
664 In this example, SSPPLLAATT!! generates a topographic map called
666 _t_x___c_o_v_e_r_a_g_e_._p_p_m that illustrates the predicted line‐of‐
667 sight regional coverage of _t_x___s_i_t_e to receiving locations
668 having antennas 30.0 feet above ground level (AGL). If
669 the _‐_m_e_t_r_i_c switch is used, the argument following the _‐_c
670 switch is interpreted as being in meters rather than in
671 feet. The contents of _c_i_t_i_e_s_._d_a_t are plotted on the map,
672 as are the cartographic boundaries contained in the file
673 _c_o_3_4___d_0_0_._d_a_t.
674 When plotting line‐of‐sight paths and areas of regional
676 coverage, SSPPLLAATT!! by default does not account for the
677 effects of atmospheric bending. However, this behavior
678 may be modified by using the Earth radius multiplier (_‐_m)
679 switch:
680 splat ‐t wnjt‐dt ‐c 30.0 ‐m 1.333 ‐s cities.dat ‐b coun‐
682 ties.dat ‐o map.ppm
683 An earth radius multiplier of 1.333 instructs SSPPLLAATT!! to
685 use the "four‐thirds earth" model for line‐of‐sight propa‐
686 gation analysis. Any appropriate earth radius multiplier
687 may be selected by the user.
688 When performing a regional analysis, SSPPLLAATT!! generates a
690 site report for each station analyzed. SSPPLLAATT!! site
691 reports contain details of the site’s geographic location,
692 its height above mean sea level, the antenna’s height
693 above mean sea level, the antenna’s height above average
694 terrain, and the height of the average terrain calculated
695 toward the bearings of 0, 45, 90, 135, 180, 225, 270, and
696 315 degrees azimuth.
697DDEETTEERRMMIINNIINNGG MMUULLTTIIPPLLEE RREEGGIIOONNSS OOFF LLOOSS CCOOVVEERRAAGGEE
699 SSPPLLAATT!! can also display line‐of‐sight coverage areas for
700 as many as four separate transmitter sites on a common
701 topographic map. For example:
702 splat ‐t site1 site2 site3 site4 ‐c 10.0 ‐metric ‐o net‐
704 work.ppm
705 plots the regional line‐of‐sight coverage of site1, site2,
707 site3, and site4 based on a receive antenna located 10.0
708 meters above ground level. A topographic map is then
709 written to the file _n_e_t_w_o_r_k_._p_p_m. The line‐of‐sight cover‐
710 age area of the transmitters are plotted as follows in the
711 colors indicated (along with their corresponding RGB val‐
712 ues in decimal):
713 site1: Green (0,255,0)
715 site2: Cyan (0,255,255)
716 site3: Medium Violet (147,112,219)
717 site4: Sienna 1 (255,130,71)
718 site1 + site2: Yellow (255,255,0)
720 site1 + site3: Pink (255,192,203)
721 site1 + site4: Green Yellow (173,255,47)
722 site2 + site3: Orange (255,165,0)
723 site2 + site4: Dark Sea Green 1 (193,255,193)
724 site3 + site4: Dark Turquoise (0,206,209)
725 site1 + site2 + site3: Dark Green (0,100,0)
727 site1 + site2 + site4: Blanched Almond (255,235,205)
728 site1 + site3 + site4: Medium Spring Green (0,250,154)
729 site2 + site3 + site4: Tan (210,180,140)
730 site1 + site2 + site3 + site4: Gold2 (238,201,0)
732 If separate _._q_t_h files are generated, each representing a
734 common site location but a different antenna height, a
735 single topographic map illustrating the regional coverage
736 from as many as four separate locations on a single tower
737 may be generated by SSPPLLAATT!!.
738LLOONNGGLLEEYY‐‐RRIICCEE PPAATTHH LLOOSSSS AANNAALLYYSSIISS
740 If the _‐_c switch is replaced by a _‐_L switch, a Longley‐
741 Rice path loss map for a transmitter site may be gener‐
742 ated:
743 splat ‐t wnjt ‐L 30.0 ‐s cities.dat ‐b co34_d00.dat ‐o
745 path_loss_map
746 In this mode, SSPPLLAATT!! generates a multi‐color map illus‐
748 trating expected signal levels in areas surrounding the
749 transmitter site. A legend at the bottom of the map cor‐
750 relates each color with a specific path loss range in
751 decibels or signal strength in decibels over one microvolt
752 per meter (dBuV/m).
753 The Longley‐Rice analysis range may be modified to a user‐
755 specific value using the _‐_R switch. The argument must be
756 given in miles (or kilometers if the _‐_m_e_t_r_i_c switch is
757 used). If a range wider than the generated topographic
758 map is specified, SSPPLLAATT!! will perform Longley‐Rice path
759 loss calculations between all four corners of the area
760 prediction map.
761 The _‐_d_b switch allows a constraint to be placed on the
763 maximum path loss region plotted on the map. A maximum
764 path loss between 80 and 230 dB may be specified using
765 this switch. For example, if a path loss beyond ‐140 dB
766 is irrelevant to the survey being conducted, SSPPLLAATT!!’s path
767 loss plot can be constrained to the region bounded by the
768 140 dB attenuation contour as follows:
769 splat ‐t wnjt‐dt ‐L 30.0 ‐s cities.dat ‐b co34_d00.dat ‐db
771 140 ‐o plot.ppm
772SSIIGGNNAALL CCOONNTTOOUURR CCOOLLOORR DDEEFFIINNIITTIIOONN PPAARRAAMMEETTEERRSS
775 The colors used to illustrate signal strength and path
776 loss contours in SSPPLLAATT!! generated coverage maps may be
777 tailored by the user by creating or modifying SSPPLLAATT!!’s
778 color definition files. SSPPLLAATT!! color definition files
779 have the same base name as the transmitter’s _._q_t_h file,
780 but carry _._l_c_f and _._s_c_f extensions.
781 When a regional Longley‐Rice analysis is performed and the
783 transmitter’s ERP is not specified or is zero, a _._l_c_f path
784 loss color definition file corresponding to the transmit‐
785 ter site (_._q_t_h) is read by SSPPLLAATT!! from the current working
786 directory. If a _._l_c_f file corresponding to the transmit‐
787 ter site is not found, then a default file suitable for
788 manual editing by the user is automatically generated by
789 SSPPLLAATT!!. If the transmitter’s ERP is specified, then a
790 signal strength map is generated and a signal strength
791 color definition file (_._s_c_f) is read, or generated if one
792 is not available in the current working directory.
793 A path‐loss color definition file possesses the following
795 structure (_w_n_j_t_‐_d_t_._l_c_f):
796 ; SPLAT! Auto‐generated Path‐Loss Color Definition
798 ("wnjt‐dt.lcf") File
799 ;
800 ; Format for the parameters held in this file is as fol‐
801 lows:
802 ;
803 ; dB: red, green, blue
804 ;
805 ; ...where "dB" is the path loss (in dB) and
806 ; "red", "green", and "blue" are the corresponding RGB
807 color
808 ; definitions ranging from 0 to 255 for the region speci‐
809 fied.
810 ;
811 ; The following parameters may be edited and/or expanded
812 ; for future runs of SPLAT! A total of 32 contour
813 regions
814 ; may be defined in this file.
815 ;
816 ;
817 80: 255, 0, 0
818 90: 255, 128, 0
819 100: 255, 165, 0
820 110: 255, 206, 0
821 120: 255, 255, 0
822 130: 184, 255, 0
823 140: 0, 255, 0
824 150: 0, 208, 0
825 160: 0, 196, 196
826 170: 0, 148, 255
827 180: 80, 80, 255
828 190: 0, 38, 255
829 200: 142, 63, 255
830 210: 196, 54, 255
831 220: 255, 0, 255
832 230: 255, 194, 204
833 If the path loss is less than 80 dB, the color Red (RGB =
836 255, 0, 0) is assigned to the region. If the path‐loss is
837 greater than or equal to 80 dB, but less than 90 db, then
838 Dark Orange (255, 128, 0) is assigned to the region.
839 Orange (255, 165, 0) is assigned to regions having a path
840 loss greater than or equal to 90 dB, but less than 100 dB,
841 and so on. Greyscale terrain is displayed beyond the 230
842 dB path loss contour.
843 SSPPLLAATT!! signal strength color definition files share a very
845 similar structure (_w_n_j_t_‐_d_t_._s_c_f):
846 ; SPLAT! Auto‐generated Signal Color Definition ("wnjt‐
848 dt.scf") File
849 ;
850 ; Format for the parameters held in this file is as fol‐
851 lows:
852 ;
853 ; dBuV/m: red, green, blue
854 ;
855 ; ...where "dBuV/m" is the signal strength (in dBuV/m)
856 and
857 ; "red", "green", and "blue" are the corresponding RGB
858 color
859 ; definitions ranging from 0 to 255 for the region speci‐
860 fied.
861 ;
862 ; The following parameters may be edited and/or expanded
863 ; for future runs of SPLAT! A total of 32 contour
864 regions
865 ; may be defined in this file.
866 ;
867 ;
868 128: 255, 0, 0
869 118: 255, 165, 0
870 108: 255, 206, 0
871 98: 255, 255, 0
872 88: 184, 255, 0
873 78: 0, 255, 0
874 68: 0, 208, 0
875 58: 0, 196, 196
876 48: 0, 148, 255
877 38: 80, 80, 255
878 28: 0, 38, 255
879 18: 142, 63, 255
880 8: 140, 0, 128
881 If the signal strength is greater than or equal to 128 db
884 over 1 microvolt per meter (dBuV/m), the color Red (255,
885 0, 0) is displayed for the region. If the signal strength
886 is greater than or equal to 118 dbuV/m, but less than 128
887 dbuV/m, then the color Orange (255, 165, 0) is displayed,
888 and so on. Greyscale terrain is displayed for regions
889 with signal strengths less than 8 dBuV/m.
890 Signal strength contours for some common VHF and UHF
892 broadcasting services in the United States are as follows:
893 Analog Television Broadcasting
895 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
896 Channels 2‐6: City Grade: >= 74 dBuV/m
897 Grade A: >= 68 dBuV/m
898 Grade B: >= 47 dBuV/m
899 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
900 Channels 7‐13: City Grade: >= 77 dBuV/m
901 Grade A: >= 71 dBuV/m
902 Grade B: >= 56 dBuV/m
903 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
904 Channels 14‐69: Indoor Grade: >= 94 dBuV/m
905 City Grade: >= 80 dBuV/m
906 Grade A: >= 74 dBuV/m
907 Grade B: >= 64 dBuV/m
908 Digital Television Broadcasting
910 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
911 Channels 2‐6: City Grade: >= 35 dBuV/m
912 Service Threshold: >= 28 dBuV/m
913 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
914 Channels 7‐13: City Grade: >= 43 dBuV/m
915 Service Threshold: >= 36 dBuV/m
916 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
917 Channels 14‐69: City Grade: >= 48 dBuV/m
918 Service Threshold: >= 41 dBuV/m
919 NOAA Weather Radio (162.400 ‐ 162.550 MHz)
921 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
922 Reliable: >= 18 dBuV/m
923 Not reliable: < 18 dBuV/m
924 Unlikely to receive: < 0 dBuV/m
925 FM Radio Broadcasting (88.1 ‐ 107.9 MHz)
927 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
928 Analog Service Contour: 60 dBuV/m
929 Digital Service Contour: 65 dBuV/m
930AANNTTEENNNNAA RRAADDIIAATTIIOONN PPAATTTTEERRNN PPAARRAAMMEETTEERRSS
934 Normalized field voltage patterns for a transmitting
935 antenna’s horizontal and vertical planes are imported
936 automatically into SSPPLLAATT!! when a Longley‐Rice coverage
937 analysis is performed. Antenna pattern data is read from
938 a pair of files having the same base name as the transmit‐
939 ter and LRP files, but with _._a_z and _._e_l extensions for
940 azimuth and elevation pattern files, respectively. Speci‐
941 fications regarding pattern rotation (if any) and mechani‐
942 cal beam tilt and tilt direction (if any) are also con‐
943 tained within SSPPLLAATT!! antenna pattern files.
944 For example, the first few lines of a SSPPLLAATT!! azimuth pat‐
946 tern file might appear as follows (_k_v_e_a_._a_z):
947 183.0
949 0 0.8950590
950 1 0.8966406
951 2 0.8981447
952 3 0.8995795
953 4 0.9009535
954 5 0.9022749
955 6 0.9035517
956 7 0.9047923
957 8 0.9060051
958 The first line of the _._a_z file specifies the amount of
960 azimuthal pattern rotation (measured clockwise in degrees
961 from True North) to be applied by SSPPLLAATT!! to the data con‐
962 tained in the _._a_z file. This is followed by azimuth head‐
963 ings (0 to 360 degrees) and their associated normalized
964 field patterns (0.000 to 1.000) separated by whitespace.
965 The structure of SSPPLLAATT!! elevation pattern files is
967 slightly different. The first line of the _._e_l file speci‐
968 fies the amount of mechanical beam tilt applied to the
969 antenna. Note that a _d_o_w_n_w_a_r_d _t_i_l_t (below the horizon) is
970 expressed as a _p_o_s_i_t_i_v_e _a_n_g_l_e, while an _u_p_w_a_r_d _t_i_l_t (above
971 the horizon) is expressed as a _n_e_g_a_t_i_v_e _a_n_g_l_e. This data
972 is followed by the azimuthal direction of the tilt, sepa‐
973 rated by whitespace.
974 The remainder of the file consists of elevation angles and
976 their corresponding normalized voltage radiation pattern
977 (0.000 to 1.000) values separated by whitespace. Eleva‐
978 tion angles must be specified over a ‐10.0 to +90.0 degree
979 range. As was the convention with mechanical beamtilt,
980 _n_e_g_a_t_i_v_e _e_l_e_v_a_t_i_o_n _a_n_g_l_e_s are used to represent elevations
981 _a_b_o_v_e _t_h_e _h_o_r_i_z_o_n, while _p_o_s_i_t_i_v_e _a_n_g_l_e_s represents eleva‐
982 tions _b_e_l_o_w _t_h_e _h_o_r_i_z_o_n.
983 For example, the first few lines a SSPPLLAATT!! elevation pat‐
985 tern file might appear as follows (_k_v_e_a_._e_l):
986 1.1 130.0
988 ‐10.0 0.172
989 ‐9.5 0.109
990 ‐9.0 0.115
991 ‐8.5 0.155
992 ‐8.0 0.157
993 ‐7.5 0.104
994 ‐7.0 0.029
995 ‐6.5 0.109
996 ‐6.0 0.185
997 In this example, the antenna is mechanically tilted down‐
999 ward 1.1 degrees towards an azimuth of 130.0 degrees.
1000 For best results, the resolution of azimuth pattern data
1002 should be specified to the nearest degree azimuth, and
1003 elevation pattern data resolution should be specified to
1004 the nearest 0.01 degrees. If the pattern data specified
1005 does not reach this level of resolution, SSPPLLAATT!! will
1006 interpolate the values provided to determine the data at
1007 the required resolution, although this may result in a
1008 loss in accuracy.
1009IIMMPPOORRTTIINNGG AANNDD EEXXPPOORRTTIINNGG RREEGGIIOONNAALL PPAATTHH LLOOSSSS CCOONNTTOOUURR DDAATTAA
1012 Performing a Longley‐Rice coverage analysis can be a very
1013 time consuming process, especially if the analysis is
1014 repeated repeatedly to discover what effects changes to
1015 the antenna radiation patterns make to the predicted cov‐
1016 erage area.
1017 This process can be expedited by exporting the Longley‐
1019 Rice regional path loss contour data to an output file,
1020 modifying the path loss data externally to incorporate
1021 antenna pattern effects, and then importing the modified
1022 path loss data back into SSPPLLAATT!! to rapidly produce a
1023 revised path loss map.
1024 For example, a path loss output file can be generated by
1026 SSPPLLAATT!! for a receive site 30 feet above ground level over
1027 a 50 mile radius surrounding a transmitter site to a maxi‐
1028 mum path loss of 140 dB using the following syntax:
1029 splat ‐t kvea ‐L 30.0 ‐R 50.0 ‐db 140 ‐plo pathloss.dat
1031 SSPPLLAATT!! path loss output files often exceed 100 megabytes
1033 in size. They contain information relating to the bound‐
1034 aries of region they describe followed by latitudes
1035 (degrees North), longitudes (degrees West), azimuths, ele‐
1036 vations (to the first obstruction), and path loss figures
1037 (dB) for a series of specific points that comprise the
1038 region surrounding the transmitter site. The first few
1039 lines of a SSPPLLAATT!! path loss output file take on the fol‐
1040 lowing appearance (_p_a_t_h_l_o_s_s_._d_a_t):
1041 119, 117 ; max_west, min_west
1043 35, 33 ; max_north, min_north
1044 34.2265434, 118.0631104, 48.171, ‐37.461, 67.70
1045 34.2270355, 118.0624390, 48.262, ‐26.212, 73.72
1046 34.2280197, 118.0611038, 48.269, ‐14.951, 79.74
1047 34.2285156, 118.0604401, 48.207, ‐11.351, 81.68
1048 34.2290077, 118.0597687, 48.240, ‐10.518, 83.26
1049 34.2294998, 118.0591049, 48.225, 23.201, 84.60
1050 34.2304878, 118.0577698, 48.213, 15.769, 137.84
1051 34.2309799, 118.0570984, 48.234, 15.965, 151.54
1052 34.2314720, 118.0564346, 48.224, 16.520, 149.45
1053 34.2319679, 118.0557632, 48.223, 15.588, 151.61
1054 34.2329521, 118.0544281, 48.230, 13.889, 135.45
1055 34.2334442, 118.0537643, 48.223, 11.693, 137.37
1056 34.2339401, 118.0530930, 48.222, 14.050, 126.32
1057 34.2344322, 118.0524292, 48.216, 16.274, 156.28
1058 34.2354164, 118.0510941, 48.222, 15.058, 152.65
1059 34.2359123, 118.0504227, 48.221, 16.215, 158.57
1060 34.2364044, 118.0497589, 48.216, 15.024, 157.30
1061 34.2368965, 118.0490875, 48.225, 17.184, 156.36
1062 It is not uncommon for SSPPLLAATT!! path loss files to contain
1064 as many as 3 million or more lines of data. Comments can
1065 be placed in the file if they are proceeded by a semicolon
1066 character. The vviimm text editor has proven capable of
1067 editing files of this size.
1068 Note as was the case in the antenna pattern files, nega‐
1070 tive elevation angles refer to upward tilt (above the
1071 horizon), while positive angles refer to downward tilt
1072 (below the horizon). These angles refer to the elevation
1073 to the receiving antenna at the height above ground level
1074 specified using the _‐_L switch _i_f the path between trans‐
1075 mitter and receiver is unobstructed. If the path between
1076 the transmitter and receiver is obstructed, then the ele‐
1077 vation angle to the first obstruction is returned by
1078 SSPPLLAATT!!. This is because the Longley‐Rice model considers
1079 the energy reaching a distant point over an obstructed
1080 path as a derivative of the energy scattered from the top
1081 of the first obstruction, only. Since energy cannot reach
1082 the obstructed location directly, the actual elevation
1083 angle to that point is irrelevant.
1084 When modifying SSPPLLAATT!! path loss files to reflect antenna
1086 pattern data, _o_n_l_y _t_h_e _l_a_s_t _c_o_l_u_m_n _(_p_a_t_h _l_o_s_s_) should be
1087 amended to reflect the antenna’s normalized gain at the
1088 azimuth and elevation angles specified in the file. (At
1089 this time, programs and scripts capable of performing this
1090 operation are left as an exercise for the user.)
1091 Modified path loss maps can be imported back into SSPPLLAATT!!
1093 for generating revised coverage maps:
1094 splat ‐t kvea ‐pli pathloss.dat ‐s city.dat ‐b county.dat
1096 ‐o map.ppm
1097 SSPPLLAATT!! path loss files can also be used for conducting
1099 coverage or interference studies outside of SSPPLLAATT!!.
1100UUSSEERR‐‐DDEEFFIINNEEDD TTEERRRRAAIINN IINNPPUUTT FFIILLEESS
1102 A user‐defined terrain file is a user‐generated text file
1103 containing latitudes, longitudes, and heights above ground
1104 level of specific terrain features believed to be of
1105 importance to the SSPPLLAATT!! analysis being conducted, but
1106 noticeably absent from the SDF files being used. A user‐
1107 defined terrain file is imported into a SSPPLLAATT!! analysis
1108 using the _‐_u_d_t switch:
1109 splat ‐t tx_site ‐r rx_site ‐udt udt_file.txt ‐o map.ppm
1111 A user‐defined terrain file has the following appearance
1113 and structure:
1114 40.32180556, 74.1325, 100.0 meters
1116 40.321805, 74.1315, 300.0
1117 40.3218055, 74.1305, 100.0 meters
1118 Terrain height is interpreted as being described in feet
1120 above ground level unless followed by the word _m_e_t_e_r_s, and
1121 is added _o_n _t_o_p _o_f the terrain specified in the SDF data
1122 for the locations specified. Be aware that each user‐
1123 defined terrain feature specified will be interpreted as
1124 being 3‐arc seconds in both latitude and longitude. Fea‐
1125 tures described in the user‐defined terrain file that
1126 overlap previously defined features in the file are
1127 ignored by SSPPLLAATT!!.
1128SSIIMMPPLLEE TTOOPPOOGGRRAAPPHHIICC MMAAPP GGEENNEERRAATTIIOONN
1130 In certain situations it may be desirable to generate a
1131 topographic map of a region without plotting coverage
1132 areas, line‐of‐sight paths, or generating obstruction
1133 reports. There are several ways of doing this. If one
1134 wishes to generate a topographic map illustrating the
1135 location of a transmitter and receiver site along with a
1136 brief text report describing the locations and distances
1137 between the sites, the _‐_n switch should be invoked as fol‐
1138 lows:
1139 splat ‐t tx_site ‐r rx_site ‐n ‐o topo_map.ppm
1141 If no text report is desired, then the _‐_N switch is used:
1143 splat ‐t tx_site ‐r rx_site ‐N ‐o topo_map.ppm
1145 If a topographic map centered about a single site out to a
1147 minimum specified radius is desired instead, a command
1148 similar to the following can be used:
1149 splat ‐t tx_site ‐R 50.0 ‐s NJ_Cities ‐b NJ_Counties ‐o
1151 topo_map.ppm
1152 where ‐R specifies the minimum radius of the map in miles
1154 (or kilometers if the _‐_m_e_t_r_i_c switch is used). Note that
1155 the tx_site name and location are not displayed in this
1156 example. If display of this information is desired, sim‐
1157 ply create a SSPPLLAATT!! city file (_‐_s option) and append it to
1158 the list of command‐line options illustrated above.
1159 If the _‐_o switch and output filename are omitted in these
1161 operations, topographic output is written to a file named
1162 _t_x___s_i_t_e_._p_p_m in the current working directory by default.
1163GGEEOORREEFFEERREENNCCEE FFIILLEE GGEENNEERRAATTIIOONN
1165 Topographic, coverage (_‐_c), and path loss contour (_‐_L)
1166 maps generated by SSPPLLAATT!! may be imported into XXaassttiirr (X
1167 Amateur Station Tracking and Information Reporting) soft‐
1168 ware by generating a georeference file using SSPPLLAATT!!’s _‐_g_e_o
1169 switch:
1170 splat ‐t kd2bd ‐R 50.0 ‐s NJ_Cities ‐b NJ_Counties ‐geo ‐o
1172 map.ppm
1173 The georeference file generated will have the same base
1175 name as the _‐_o file specified, but have a _._g_e_o extension,
1176 and permit proper interpretation and display of SSPPLLAATT!!’s
1177 .ppm graphics in XXaassttiirr software.
1178GGOOOOGGLLEE MMAAPP KKMMLL FFIILLEE GGEENNEERRAATTIIOONN
1180 Keyhole Markup Language files compatible with GGooooggllee EEaarrtthh
1181 may be generated by SSPPLLAATT!! when performing point‐to‐point
1182 or regional coverage analyses by invoking the _‐_k_m_l switch:
1183 splat ‐t wnjt‐dt ‐r kd2bd ‐kml
1185 The KML file generated will have the same filename struc‐
1187 ture as a Path Analysis Report for the transmitter and
1188 receiver site names given, except it will carry a _._k_m_l
1189 extension.
1190 Once loaded into GGooooggllee EEaarrtthh (File ‐‐> Open), the KML
1192 file will annotate the map display with the names of the
1193 transmitter and receiver site locations. The viewpoint of
1194 the image will be from the position of the transmitter
1195 site looking towards the location of the receiver. The
1196 point‐to‐point path between the sites will be displayed as
1197 a white line while the RF line‐of‐sight path will be dis‐
1198 played in green. GGooooggllee EEaarrtthh’s navigation tools allow
1199 the user to "fly" around the path, identify landmarks,
1200 roads, and other featured content.
1201 When performing regional coverage analysis, the _._k_m_l file
1203 generated by SSPPLLAATT!! will permit path loss or signal
1204 strength contours to be layered on top of GGooooggllee EEaarrtthh’s
1205 display in a semi‐transparent manner. The generated _._k_m_l
1206 file will have the same basename as that of the _._p_p_m file
1207 normally generated.
1208DDEETTEERRMMIINNAATTIIOONN OOFF AANNTTEENNNNAA HHEEIIGGHHTT AABBOOVVEE AAVVEERRAAGGEE TTEERRRRAAIINN
1210 SSPPLLAATT!! determines antenna height above average terrain
1211 (HAAT) according to the procedure defined by Federal Com‐
1212 munications Commission Part 73.313(d). According to this
1213 definition, terrain elevations along eight radials between
1214 2 and 10 miles (3 and 16 kilometers) from the site being
1215 analyzed are sampled and averaged for each 45 degrees of
1216 azimuth starting with True North. If one or more radials
1217 lie entirely over water or over land outside the United
1218 States (areas for which no USGS topography data is avail‐
1219 able), then those radials are omitted from the calculation
1220 of average terrain.
1221 Note that SRTM elevation data, unlike older 3‐arc second
1223 USGS data, extends beyond the borders of the United
1224 States. Therefore, HAAT results may not be in full com‐
1225 pliance with FCC Part 73.313(d) in areas along the borders
1226 of the United States if the SDF files used by SSPPLLAATT!! are
1227 SRTM‐derived.
1228 When performing point‐to‐point terrain analysis, SSPPLLAATT!!
1230 determines the antenna height above average terrain only
1231 if enough topographic data has already been loaded by the
1232 program to perform the point‐to‐point analysis. In most
1233 cases, this will be true, unless the site in question does
1234 not lie within 10 miles of the boundary of the topography
1235 data in memory.
1236 When performing area prediction analysis, enough topogra‐
1238 phy data is normally loaded by SSPPLLAATT!! to perform average
1239 terrain calculations. Under such conditions, SSPPLLAATT!! will
1240 provide the antenna height above average terrain as well
1241 as the average terrain above mean sea level for azimuths
1242 of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and
1243 include such information in the generated site report. If
1244 one or more of the eight radials surveyed fall over water,
1245 or over regions for which no SDF data is available, SSPPLLAATT!!
1246 reports _N_o _T_e_r_r_a_i_n for the radial paths affected.
1247RREESSTTRRIICCTTIINNGG TTHHEE MMAAXXIIMMUUMM SSIIZZEE OOFF AANN AANNAALLYYSSIISS RREEGGIIOONN
1249 SSPPLLAATT!! reads SDF files as needed into a series of memory
1250 "pages" within the structure of the program. Each "page"
1251 holds one SDF file representing a one degree by one degree
1252 region of terrain. A _#_d_e_f_i_n_e _M_A_X_P_A_G_E_S statement in the
1253 first several lines of _s_p_l_a_t_._c_p_p sets the maximum number
1254 of "pages" available for holding topography data. It also
1255 sets the maximum size of the topographic maps generated by
1256 SSPPLLAATT!!. MAXPAGES is set to 9 by default. If SSPPLLAATT!! pro‐
1257 duces a segmentation fault on start‐up with this default,
1258 it is an indication that not enough RAM and/or virtual
1259 memory (swap space) is available to run SSPPLLAATT!! with the
1260 number of MAXPAGES specified. In situations where avail‐
1261 able memory is low, MAXPAGES may be reduced to 4 with the
1262 understanding that this will greatly limit the maximum
1263 region SSPPLLAATT!! will be able to analyze. If 118 megabytes
1264 or more of total memory (swap space plus RAM) is avail‐
1265 able, then MAXPAGES may be increased to 16. This will
1266 permit operation over a 4‐degree by 4‐degree region, which
1267 is sufficient for single antenna heights in excess of
1268 10,000 feet above mean sea level, or point‐to‐point dis‐
1269 tances of over 1000 miles.
1270AADDDDIITTIIOONNAALL IINNFFOORRMMAATTIIOONN
1272 The latest news and information regarding SSPPLLAATT!! software
1273 is available through the official SSPPLLAATT!! software web page
1274 located at: _h_t_t_p_:_/_/_w_w_w_._q_s_l_._n_e_t_/_k_d_2_b_d_/_s_p_l_a_t_._h_t_m_l.
1275AAUUTTHHOORRSS
1277 John A. Magliacane, KD2BD <_k_d_2_b_d_@_a_m_s_a_t_._o_r_g>
1278 Creator, Lead Developer
1279 Doug McDonald <_m_c_d_o_n_a_l_d_@_s_c_s_._u_i_u_c_._e_d_u>
1281 Original Longley‐Rice Model integration
1282 Ron Bentley <_r_o_n_b_e_n_t_l_e_y_@_e_a_r_t_h_l_i_n_k_._n_e_t>
1284 Fresnel Zone plotting and clearance determination
1285KD2BD Software 16 September 2007 SPLAT!(1)
1290