SPLAT!(1) splat SPLAT!(1)

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NAME

6       splat - An RF Signal Propagation, Loss, And Terrain analysis tool
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SYNOPSIS

10       splat
11       [-t   transmitter_site.qth]
12       [-r   receiver_site.qth]
13       [-c    rx  antenna  height  for  LOS  coverage  analysis  (feet/meters)
14       (float)]
15       [-L    rx  antenna  height  for  ITM  coverage  analysis  (feet/meters)
16       (float)]
17       [-p   terrain_profile.ext]
18       [-e   elevation_profile.ext]
19       [-h   height_profile.ext]
20       [-H   normalized_height_profile.ext]
21       [-l   ITM_profile.ext]
22       [-o   topographic_map_filename.ppm]
23       [-b   cartographic_boundary_filename.dat]
24       [-s   site/city_database.dat]
25       [-d   sdf_directory_path]
26       [-m   earth radius multiplier (float)]
27       [-f   frequency (MHz) for Fresnel zone calculations (float)]
28       [-R   maximum coverage radius (miles/kilometers) (float)]
29       [-dB  threshold beyond which contours will not be displayed]
30       [-gc  ground clutter height (feet/meters) (float)]
31       [-fz  Fresnel zone clearance percentage (default = 60)]
32       [-ano alphanumeric output file name]
33       [-ani alphanumeric input file name]
34       [-udt user_defined_terrain_file.dat]
35       [-log logfile.ext]
36       [-n]  [-N]  [-nf]  [-sc] [-dbm] [-ngs] [-geo] [-kml] [-gpsav] [-metric]
37       [-olditm]
38

DESCRIPTION

40       SPLAT! is a powerful terrestrial RF propagation  and  terrain  analysis
41       tool  for  the spectrum between 20 MHz and 20 GHz. SPLAT! is free soft‐
42       ware, and is designed for operation on Unix and Linux-based work-  sta‐
43       tions.  Redistribution and/or modification is permitted under the terms
44       of the GNU General Public License, Version 2, as published by the  Free
45       Software  Foundation.  Adoption of SPLAT! source code in proprietary or
46       closed-source applications is  a  violation  of  this  license  and  is
47       strictly forbidden.
48
49       SPLAT!  is  distributed in the hope that it will be useful, but WITHOUT
50       ANY WARRANTY, without even the implied warranty of  MERCHANTABILITY  or
51       FITNESS  FOR  A  PARTICULAR PURPOSE. See the GNU General Public License
52       for more details.
53

INTRODUCTION

55       Applications of SPLAT! include the visualization, design, and link bud‐
56       get analysis of wireless Wide Area Networks (WANs), commercial and ama‐
57       teur radio communication systems above 20 MHz,  microwave  links,  fre‐
58       quency  coordination  and  interference  studies, and the prediction of
59       analog and digital terrestrial radio and television contour regions.
60
61       SPLAT! provides RF site engineering data such as great circle distances
62       and  bearings between sites, antenna elevation angles (uptilt), depres‐
63       sion angles (downtilt), antenna height above mean  sea  level,  antenna
64       height  above  average  terrain, bearings, distances, and elevations to
65       known obstructions,  Irregular  Terrain  Model  path  attenuation,  and
66       received  signal  strength.  In  addition,  the  minimum antenna height
67       requirements needed to clear terrain, the first Fresnel zone,  and  any
68       user-definable percentage of the first Fresnel zone are also provided.
69
70       SPLAT!  produces  reports, graphs, and high resolution topographic maps
71       that depict line-of-sight paths, and  regional  path  loss  and  signal
72       strength contours through which expected coverage areas of transmitters
73       and repeater systems can be obtained. When performing line-of-sight and
74       Irregular Terrain Model analyses in situations where multiple transmit‐
75       ter or repeater sites are employed, SPLAT!  determines  individual  and
76       mutual areas of coverage within the network specified.
77

INPUT FILES

79       SPLAT!  is  a  command-line  driven  application  and  reads input data
80       through a number of data files. Some files are mandatory for successful
81       execution  of  the  program, while others are optional. Mandatory files
82       include digital elevation topography models in the form of  SPLAT  Data
83       Files  (SDF files), site location files (QTH files), and Irregular Ter‐
84       rain Model parameter files (LRP files).  Optional  files  include  city
85       location  files,  cartographic  boundary  files,  user-defined  terrain
86       files, path loss input files,  antenna  radiation  pattern  files,  and
87       color definition files.
88

SPLAT DATA FILES

90       SPLAT! imports topographic data in the form of SPLAT Data Files (SDFs).
91       These files may be generated from a number of information  sources.  In
92       the  United States, SPLAT Data Files can be generated through U.S. Geo‐
93       logical Survey Digital Elevation Models (DEMs) using  the  postdownload
94       and  usgs2sdf  utilities  included  with SPLAT!. USGS Digital Elevation
95       Models compatible with these utilities may be down- loaded from:
96
97              http://edcftp.cr.usgs.gov/pub/data/DEM/250/
98
99       Significantly better resolution and accuracy can  be  obtained  through
100       the  use  of  SRTM  Version 2 digital elevation models, especially when
101       supplemented by USGS-derived SDF data. These one-degree by one-  degree
102       models  are  the  product  of the Space Shuttle STS-99 Radar Topography
103       Mission, and are available for most populated  regions  of  the  Earth.
104       SPLAT  Data  Files may be generated from 3 arc-second SRTM-3 data using
105       the included srtm2sdf utility. SRTM-3 Version 2.1 data may be  obtained
106       through anonymous FTP from:
107
108              http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/
109
110       Note  that  SRTM  filenames  refer to the latitude and longitude of the
111       southwest corner of the topographic dataset contained within the  file.
112       Therefore,  the region of interest must lie north and east of the lati‐
113       tude and longitude provided in the SRTM filename.  Even greater resolu‐
114       tion  and accuracy can be obtained by using 1 arc-second SRTM-1 Version
115       2.1 topography data. This data is available for the United  States  and
116       its territories and possessions, and may be down- loaded from:
117
118              http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/
119
120       High  resolution  SDF files for use with SPLAT! HD may begenerated from
121       data in this format using the srtm2sdf-hd utility.  Despite the  higher
122       accuracy  that  SRTM  data  has  to  offer, some voids in the data sets
123       exist. When voids are detected, the srtm2sdf and srtm2sdf-hd  utilities
124       replace  them  with  corresponding data found in usgs2sdf generated SDF
125       files. If USGS-derived SDF data is not  available,  voids  are  handled
126       through adjacent pixel averaging, or direct replacement.
127
128       SPLAT!  Data  Files  contain  integer  value  topographic elevations in
129       meters referenced to mean sea level for 1-degree by 1-degree regions of
130       the  Earth.  SDF  files can be read by SPLAT! in either standard format
131       (.sdf) as generated directly by the usgs2sdf, srtm2sdf, and srtm2sdf-hd
132       utilities, or in bzip2 compressed format (.sdf.bz2). Since uncompressed
133       files can be read slightly faster than files that have been compressed,
134       SPLAT!  searches  for  needed SDF data in uncompressed format first. If
135       uncompressed data cannot be located, SPLAT! then searches for  data  in
136       bzip2  compressed  format.  If no compressed SDF files can be found for
137       the region requested, SPLAT! assumes the region is over water, and will
138       assign an elevation of sea-level to these areas.
139
140       This  feature  of SPLAT! makes it possible to perform path analysis not
141       only over land, but also between coastal areas not represented by Digi‐
142       tal  Elevation Model data. However, this behavior of SPLAT! underscores
143       the importance of having all the SDF  files  required  for  the  region
144       being analyzed if meaningful results are to be expected.
145

SITE LOCATION (QTH) FILES

147       SPLAT!  imports  site  location information of transmitter and receiver
148       sites analyzed by the program from ASCII files having a .qth extension.
149       QTH  files  contain  the  site’s name, the site’s latitude (positive if
150       North of the equator, negative if  South),  the  site’s  longitude  (in
151       degrees West, 0 to 360 degrees, or degrees East 0 to -360 degrees), and
152       the site’s antenna height above ground level (AGL), each separated by a
153       single line- feed character. The antenna height is assumed to be speci‐
154       fied in feet unless followed by the letter m  or  the  word  meters  in
155       either  upper  or lower case. Latitude and longitude information may be
156       expressed in either decimal format (74.6864) or degree, minute,  second
157       (DMS) format (74 41 11.0).
158
159       For  example, aread as follows: site locationfile describing television
160       station WNJT-DT, Trenton, NJ (wnjt-dt.qth) might read as follows:
161
162              WNJT-DT
163              40.2828
164              74.6864
165              990.00
166
167       Each transmitter and receiver site analyzed by SPLAT!  must  be  repre‐
168       sented by its own site location (QTH) file.
169

IRREGULAR TERRAIN MODEL PARAMETER (LRP) FILES

171       Irregular Terrain Model Parameter data files are required for SPLAT! to
172       determine RF path loss, field strength, or received signal power  level
173       in  either  point-to-point  or  area prediction mode. Irregular Terrain
174       Model parameter data is read from files having the same  base  name  as
175       the  transmitter  site  QTH file, but with a .lrp extension. SPLAT! LRP
176       files share the following format (wnjt-dt.lrp):
177
178              15.000  ; Earth Dielectric Constant (Relative permittivity)
179              0.005   ; Earth Conductivity (Siemens per meter)
180              301.000 ; Atmospheric Bending Constant (N-units)
181              647.000 ; Frequency in MHz (20 MHz to 20 GHz)
182              5       ; Radio Climate (5 = Continental Temperate)
183              0       ; Polarization (0 = Horizontal, 1 = Vertical)
184              0.50    ; Fraction of situations (50% of locations)
185              0.90    ; Fraction of time (90% of the time)
186              46000.0 ; Effective Radiated Power (ERP) in Watts (optional)
187
188       If an LRP file corresponding to the tx_site QTH file cannot  be  found,
189       SPLAT! scans the current working directory for the file "splat.lrp". If
190       this file cannot be found, then default parameters will be assigned  by
191       SPLAT!  and  a  corresponding "splat.lrp" file containing these default
192       parameters will be written to the cur- rent working directory. The gen‐
193       erated "splat.lrp" file can then be edited by the user as needed.  Typ‐
194       ical Earth dielectric constants and conductivity values are as follows:
195
196                                 Dielectric Constant    Conductivity
197              Salt water       :        80                  5.000
198              Good ground      :        25                  0.020
199              Fresh water      :        80                  0.010
200              Marshy land      :        12                  0.007
201              Farmland, forest :        15                  0.005
202              Average ground   :        15                  0.005
203              Mountain, sand   :        13                  0.002
204              City             :         5                  0.001
205              Poor ground      :         4                  0.001
206
207       Radio climate codes used by SPLAT! are as follows:
208
209              1: Equatorial (Congo)
210              2: Continental Subtropical (Sudan)
211              3: Maritime Subtropical (West coast of Africa)
212              4: Desert (Sahara)
213              5: Continental Temperate
214              6: Maritime Temperate, over land (UK and west coasts of US & EU)
215              7: Maritime Temperate, over sea
216
217       The Continental Temperate climate is common to large land masses in the
218       temperate  zone,  such as the United States. For paths shorter than 100
219       km, there is little difference between Continental and Maritime Temper‐
220       ate climates.
221
222       The  seventh  and  eighth parameters in the .lrp file correspond to the
223       statistical analysis provided by the ITM model. In this example, SPLAT!
224       will  return  the maximum path loss occurring 50% of the time (fraction
225       of time, or Time Variability) in 90% of situations (fraction of  situa‐
226       tions,  or  Location Variability). This is often denoted as F(50,90) in
227       Longley-Rice studies. In the United States,  an  F(50,90)  criteria  is
228       typically  used  for digital television (8-level VSB modulation), while
229       F(50,50) is used for analog (VSB-AM+NTSC) broadcasts.
230
231       For further information on ITM  propagation  model  parameters,  please
232       refer to:
233
234              http://www.its.bldrdoc.gov/resources/radio-propagation-soft
235              ware/itm/itm.aspx
236              http://www.softwright.com/faq/engineering/prop_longley_rice.html
237
238       The last parameter in the .lrp file corresponds  to  the  transmitter’s
239       Effective  Radiated  Power (ERP), and is optional. If it is included in
240       the .lrp file, then SPLAT! will compute received signal strength levels
241       and  field  strength level contours when performing ITM studies. If the
242       parameter is omitted, path loss is com- puted instead. The ERP provided
243       in  the .lrp file can be overridden by using SPLAT!’s -erp command-line
244       switch. If the .lrp file contains an ERP parameter and  the  generation
245       of  path  loss  rather than field strength contours is desired, the ERP
246       can be assigned to zero using the -erp switch without  having  to  edit
247       the .lrp file to accomplish the same result.
248

CITY LOCATION FILES

250       The  names  and  locations  of  cities, tower sites, or other points of
251       interest may be imported and plotted on topographic maps  generated  by
252       SPLAT!.  SPLAT!  imports  the  names of cities and locations from ASCII
253       files containing the location of interest’s name, latitude, and  longi‐
254       tude.  Each field is separated by a comma.  Each record is separated by
255       a single line feed character. As was the case with the .qth files, lat‐
256       itude  and  longitude  information  may be entered in either decimal or
257       degree, minute, second (DMS) format.
258
259       For example (cities.dat):
260
261                  Teaneck,        40.891973, 74.014506
262                  Tenafly,        40.919212, 73.955892
263                  Teterboro,      40.859511, 74.058908
264                  Tinton Falls,   40.279966, 74.093924
265                  Toms River,          39.977777, 74.183580
266                  Totowa,         40.906160, 74.223310
267                  Trenton,        40.219922, 74.754665
268
269       A total of five separate city data files may be imported at a time, and
270       there is no limit to the size of these files. SPLAT! reads city data on
271       a "first come/first served" basis, and plots only those locations whose
272       annotations  do not conflict with annotations of locations read earlier
273       in the current city data file, or in previ- ous  files.  This  behavior
274       minimizes  clutter  in SPLAT! generated topographic maps, but also man‐
275       dates that important locations be placed toward the  beginning  of  the
276       first  city  data file, and locations less important be positioned fur‐
277       ther down the list or in subsequent data files.
278
279       City data files may  be  generated  manually  using  any  text  editor,
280       imported  from  other  sources, or derived from data available from the
281       U.S. Census Bureau using the itydecoder utility included  with  SPLAT!.
282       Such   data   is   available  free  of  charge  via  the  Internet  at:
283       http://web.archive.org/web/20130331172800/http://www.cen‐
284       sus.gov/geo/www/cob/bdy_files.html, and must be in ASCII format.
285

CARTOGRAPHIC BOUNDARY DAT A FILES

287       Cartographic  boundary data may also be imported to plot the boundaries
288       of cities, counties, or states on topographic maps generated by SPLAT!.
289       Such  data  must  be  of the form of ARC/INFO Ungenerate (ASCII Format)
290       Metadata Cartographic Boundary Files, and are available from  the  U.S.
291       Census Bureau via the Internet  at these sites:
292
293              http://web.archive.org/web/20130331144934/http://www.cen‐
294              sus.gov/geo/www/cob/co2000.html#ascii
295              http://web.archive.org/web/20130507075658/http://www.cen‐
296              sus.gov/geo/www/cob/pl2000.html#ascii
297
298       A total of five separate cartographic boundary files may be imported at
299       a time. It is not necessary to import state boundaries if county bound‐
300       aries have already been imported.
301

PROGRAM OPERATION

303       SPLAT!  is  invoked via the command-line using a series of switches and
304       arguments. Since SPLAT! is a CPU and memory intensive application, this
305       type  of interface minimizes overhead and lends itself well to scripted
306       (batch) operations. SPLAT!’s CPU and memory scheduling priority may  be
307       modified through the use of the Unix nice command.
308
309       The  number and type of switches passed to SPLAT! determine its mode of
310       operation and method of output data generation. Nearly all of  SPLAT!’s
311       switches may be cascaded in any order on the command line when invoking
312       the program. Simply typing splat on the command line will return a sum‐
313       mary of SPLAT!’s command line options:
314
315       BSPLAT! v1.4.1 Available Options... ]
316              -t  txsite(s).qth (max of 4 with -c, max of 30 with -L)
317              -r  rxsite.qth
318              -c   plot  coverage of TX(s) with an RX antenna at X feet/meters
319              AGL
320              -L  plot path loss map of TX based on an RX at X feet/meters AGL
321              -s  filename(s) of city/site file(s) to import (5 max)
322              -b  filename(s) of cartographic boundary file(s)  to  import  (5
323              max)
324              -p  filename of terrain profile graph to plot
325              -e  filename of terrain elevation graph to plot
326              -h  filename of terrain height graph to plot
327              -H  filename of normalized terrain height graph to plot
328              -l  filename of path loss graph to plot
329              -o  filename of topographic map to generate (.ppm)
330              -u  filename of user-defined terrain file to import
331              -d   sdf  file  directory path (overrides path in  ̃/.splat_path
332              file)
333              -m  earth radius multiplier
334              -n  do not plot LOS paths in .ppm maps
335              -N  do not produce unnecessary site or obstruction reports
336              -f  frequency for Fresnel zone calculation (MHz)
337              -R  modify default range for -c or -L (miles/kilometers)
338              -sc display smooth rather than quantized contour levels
339              -db threshold beyond which contours will not be displayed
340              -nf do not plot Fresnel zones in height plots
341              -fz Fresnel zone clearance percentage (default = 60)
342              -gc ground clutter height (feet/meters)
343              -ngs display greyscale topography as white in .ppm files
344              -erp override ERP in .lrp file (Watts)
345              -ano name of alphanumeric output file
346              -ani name of alphanumeric input file
347              -udt name of user defined terrain input file
348              -kml generate Google Earth (.kml) compatible output
349              -geo generate an Xastir .geo georeference file (with  .ppm  out‐
350              put)
351              -dbm plot signal power level contours rather than field strength
352              -log copy command line string to this output file
353              -gpsav  preserve  gnuplot  temporary  working files after SPLAT!
354              execution
355              -metric employ metric rather than imperial units  for  all  user
356              I/O
357              -olditm invoke older ITM propagation model rather than the newer
358              ITWOM
359
360       The command-line options for splat and splat-hd are identical. The -log
361       command  line  switch  causes  all  invoked  command line options to be
362       logged to a file of your choosing (logfile.txt):
363
364              splat -t tx_site -r rx_site -s nj_cities -o topo_map  -log  log‐
365              file.txt
366
367       SPLAT!  operates  in  two distinct modes: point-to-point mode, and area
368       prediction mode. Either a line-of- sight  (LOS)  or  Irregular  Terrain
369       (ITM)  propagation  model  may  be  invoked  by  the  user. True Earth,
370       fourthirds Earth, or any other user-defined Earth radius may be  speci‐
371       fied when performing line-of-sight analysis.
372

POINT-TO-POINT ANALYSIS

374       SPLAT!  may  be  used to perform line-of-sight terrain analysis between
375       two specified site locations. For example:
376
377              splat -t tx_site.qth -r rx_site.qth
378
379       invokes a line-of-sight terrain analysis between the transmitter speci‐
380       fied  in tx_site.qth and receiver specified in rx_site.qth using a True
381       Earth radius model, and writes a SPLAT! Path  Analysis  Report  to  the
382       current working directory. The report contains details of the transmit‐
383       ter and receiver sites, and identifies the loca- tion of  any  obstruc‐
384       tions  detected  along the line-of-sight path. If an obstruction can be
385       cleared by raising the receive antenna to a  greater  altitude,  SPLAT!
386       will  indicate the minimum antenna height required for a line- of-sight
387       path to exist between the transmitter and receiver locations specified.
388       Note that imperial units (miles, feet) are specified unless the -metric
389       switch is added to SPLAT!’s command line options:
390
391              splat -t tx_site.qth -r rx_site.qth -metric
392
393       If the antenna must be raised a significant amount, this  determination
394       may  take a few moments. Note that the results provided are the minimum
395       necessary for a line-of-sight path to exist, and in the  case  of  this
396       sim-  ple example, do not take Fresnel zone clearance requirements into
397       consideration.  qth extensions are assumed by SPLAT! for QTH files, and
398       are  optional  when specifying -t and -r arguments on the command-line.
399       SPLAT! automatically reads all SPLAT Data Files  necessary  to  conduct
400       the  terrain  analysis between the sites specified. SPLAT! searches for
401       the required SDF files in the current working directory first.  If  the
402       needed  files are not found, SPLAT! then searches in the path specified
403       by the -d com- mand-line switch:
404
405              splat -t tx_site -r rx_site -d /cdrom/sdf/
406
407       An external directory path may be specified by placing a  ".splat_path"
408       file  under the user’s home directory.  This file must contain the full
409       directory path of last resort to all the SDF files.  The  path  in  the
410       $HOME/.splat_path  file  must  be of the form of a single line of ASCII
411       text:
412
413              /opt/splat/sdf/
414
415       and can be generated using any text editor.
416
417       A graph of the terrain profile between  the  receiver  and  transmitter
418       locations  as a function of distance from the receiver can be generated
419       by adding the -p switch:
420
421              splat -t tx_site -r rx_site -p terrain_profile.png
422
423       SPLAT! invokes gnuplot when generating graphs. The  filename  extension
424       specified to SPLAT! deter- mines the format of the graph produced. .png
425       will produce a 640x480 color PNG graphic file, while .ps or .postscript
426       will  produce  postscript  output. Output in formats such as GIF, Adobe
427       Illustrator, AutoCAD dxf, LaTeX, and many others are available.  Please
428       consult  gnuplot,  and  gnuplot’s  documentation for details on all the
429       supported output formats.
430
431       A graph of elevations subtended by the terrain between the receiver and
432       transmitter  as  a function of distance from the receiver can be gener‐
433       ated by using the -e switch:
434
435              splat -t tx_site -r rx_site -e elevation_profile.png
436
437       The graph produced using this  switch  illustrates  the  elevation  and
438       depression  angles  resulting  from  the terrain between the receiver’s
439       location  and  the  transmitter  site  from  the  perspective  of   the
440       receiver’s  location.   A second trace is plotted between the left side
441       of the graph (receiver’s location) and the location of the transmitting
442       antenna  on  the  right.  This  trace  illustrates  the elevation angle
443       required for a line-of-sight path to exist  between  the  receiver  and
444       transmitter locations. If the trace intersects the elevation profile at
445       any point on the graph, then this is an indication that a line-of-sight
446       path  does  not  exist under the conditions given, and the obstructions
447       can be clearly identified on the graph at the point(s) of intersection.
448
449       A graph illustrating terrain height referenced to a line-of-sight  path
450       between  the  transmitter  and  receiver  may be generated using the -h
451       switch:
452
453              splat -t tx_site -r rx_site -h height_profile.png
454
455       A terrain height  plot  normalized  to  the  transmitter  and  receiver
456       antenna heights can be obtained using the -H switch:
457
458              splat -t tx_site -r rx_site -H normalized_height_profile.png
459
460       A  contour  of the Earth’s curvature is also plotted in this mode.  The
461       first Fresnel Zone, and 60% of the first Fresnel Zone can be  added  to
462       height  profile  graphs  by adding the -f switch, and specifying a fre‐
463       quency (in MHz) at which the Fresnel Zone should be modeled:
464
465              splat -t tx_site -r rx_site -f 439.250 -H normalized_height_pro‐
466              file.png
467
468       Fresnel Zone clearances other 60% can be specified using the -fz switch
469       as follows:
470
471              splat -t tx_site -r rx_site -f 439.250  -fz  75  -H  height_pro‐
472              file2.png
473
474       A graph showing ITM path loss may be plotted using the -l switch:
475
476              splat -t tx_site -r rx_site -l path_loss_profile.png
477
478       As  before,  adding  the -metric switch forces the graphs to be plotted
479       using metric units of measure. The -gpsav switch  instructs  SPLAT!  to
480       preserve  (rather than delete) the gnuplot working files generated dur‐
481       ing SPLAT! execution, allowing the user to edit these files and  re-run
482       gnuplot if desired.
483
484       When  performing  a  point-to-point  analysis,  a  SPLAT! Path Analysis
485       Report is generated in the form of a text file  with  a  .txt  filename
486       extension.  The  report  contains  bearings  and  distances between the
487       transmitter and receiver, as well as the free-space and ITM  path  loss
488       for  the  path  being analyzed. The mode of propagation for the path is
489       given as Line-of-Sight, Single  Horizon,  Double  Horizon,  Diffraction
490       Dominant,  or  Tr oposcatter Dominant. Additionally, if the receiver is
491       located at the peak of a single obstruction or at the peak of a  second
492       obstruction,  SPLAT!  will  report  RX  at Peak Terrain Along Path when
493       operating under the ITWOM propagation model.
494
495       Distances and locations to known obstructions along  the  path  between
496       transmitter  and  receiver  are  also  pro- vided. If the transmitter’s
497       effective radiated power is specified in the transmitter’s  correspond‐
498       ing  .lrp  file,  then predicted signal strength and antenna voltage at
499       the receiving location is also provided in the Path Analysis Report.
500
501       To determine the signal-to-noise (SNR) ratio at remote  location  where
502       random Johnson (thermal) noise is the primary limiting factor in recep‐
503       tion:
504
505              SNR = T − NJ − L + G − NF
506
507       where T is the ERP of the transmitter in dBW in the  direction  of  the
508       receiver,  NJ  is Johnson Noise in dBW (-136 dBW for a 6 MHz television
509       channel), L is the path loss provided by SPLAT! in dB  (as  a  positive
510       number),  G is the receive antenna gain in dB over isotropic, and NF is
511       the receiver noise figure in dB.  ,T may be computed as follows:
512
513              T = TI + GT
514
515       where TI is actual amount of RF power  delivered  to  the  transmitting
516       antenna  in dBW, GT is the transmit- ting antenna gain (over isotropic)
517       in the direction of the receiver (or the horizon  if  the  receiver  is
518       over the horizon).
519
520       To compute how much more signal is available over the minimum to neces‐
521       sary to achieve a specific signal-to-noise ratio:
522
523              Signal_Margin = SNR − S
524
525       where S is the minimum required SNR ratio (15.5 dB  for  ATSC  (8-level
526       VSB) DTV, 42 dB for analog NTSC television).
527
528       A  topographic  map  may  be  generated by SPLAT! to visualize the path
529       between the transmitter and receiver sites from  yet  another  perspec‐
530       tive.  Topographic  maps generated by SPLAT! display elevations using a
531       log- arithmic grayscale, with  higher  elevations  represented  through
532       brighter  shades  of  gray.  The  dynamic  range of the image is scaled
533       between the highest and lowest elevations present in the map. The  only
534       exception  to  this  is sea-level, which is represented using the color
535       blue.
536
537       Topographic output is invoked using the -o switch:
538
539              splat -t tx_site -r rx_site -o topo_map.ppm
540
541       The .ppm extension on the output filename is assumed by SPLAT!, and  is
542       optional.   In this example, topo_map.ppm will illustrate the locations
543       of the transmitter and receiver sites specified. In addition, the great
544       circle  path  between  the  two  sites will be drawn over locations for
545       which an unobstructed path exists to the  transmitter  at  a  receiving
546       antenna  height  equal  to  that  of  the  receiver  site (specified in
547       rx_site.qth).
548
549       It may desirable to populate the topographic map with names  and  loca‐
550       tions of cities, tower sites, or other important locations. A city file
551       may be passed to SPLAT! using the -s switch:
552
553              splat -t tx_site -r rx_site -s cities.dat -o topo_map
554
555       Up to five separate city files may be passed to SPLAT! at a  time  fol‐
556       lowing  the -s switch.  County and state boundaries may be added to the
557       map by specifying up to five U.S. Census Bureau  cartographic  boundary
558       files using the -b switch:
559
560              splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map
561
562       In  situations  where multiple transmitter sites are in use, as many as
563       four site locations may be passed to SPLAT! at a time for analysis:
564
565              splat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p  pro‐
566              file.png
567
568       In this example, four separate terrain profiles and obstruction reports
569       will be generated by SPLAT!. A sin- gle topographic map can  be  speci‐
570       fied  using  the -o switch, and line-of-sight paths between each trans‐
571       mitter and the receiver site indicated will be  produced  on  the  map,
572       each in its own color. The path between the first transmitter specified
573       to the receiver will be in green, the path between the second transmit‐
574       ter and the receiver will be in cyan, the path between the third trans‐
575       mitter and the receiver will be in violet, and  the  path  between  the
576       fourth transmitter and the receiver will be in sienna.
577
578       SPLAT!  generated topographic maps are 24-bit TrueColor Portable PixMap
579       (PPM) images. They may be viewed, edited, or converted to other graphic
580       formats  by  popular  image  viewing applications such as xv, The GIMP,
581       ImageMagick, and XPaint. PNG format is highly recommended for  lossless
582       compressed  storage  of  SPLAT!  generated  topographic  output  files.
583       ImageMagick’s command-line utility easily con- verts SPLAT!’s PPM files
584       to PNG format:
585
586              convert splat_map.ppm splat_map.png
587
588       Another excellent PPM to PNG command-line utility is available at:
589
590              http://www.libpng.org/pub/png/book/sources.html
591
592       As  a last resort, PPM files may be compressed using the bzip2 utility,
593       and read directly by The GIMP in this format.  The -ngs option  assigns
594       all terrain to the color white, and can be used when it is desirable to
595       generate a map that is devoid of terrain:
596
597              splat -t tx_site -r rx_site -b co34_d00.dat -ngs -o white_map
598
599       The resulting .ppm image file can be converted to .png  format  with  a
600       transparent background using ImageMagick’s convert utility:
601
602              convert -transparent #FFFFFF white_map.ppm transparent_map.png
603

REGIONAL COVERAGE ANALYSIS

605       SPLAT! can analyze a transmitter or repeater site, or network of sites,
606       and predict the regional coverage for  each  site  specified.  In  this
607       mode,  SPLAT!  can  generate a topographic map displaying the geometric
608       line- of-sight coverage area of the sites based on the location of each
609       site  and  the  height of receive antenna wish- ing to communicate with
610       the site in question. A regional analysis may be  performed  by  SPLAT!
611       using the -c switch as follows:
612
613              splat  -t  tx_site  -c  30.0  -s  cities.dat  -b co34_d00.dat -o
614              tx_coverage
615
616       In this example, SPLAT! generates a topographic  map  called  tx_cover‐
617       age.ppm  that illustrates the predicted line-of-sight regional coverage
618       of tx_site to receiving  locations  having  antennas  30.0  feet  above
619       ground level (AGL). If the -metric switch is used, the argument follow‐
620       ing the -c switch is interpreted as being  in  meters  rather  than  in
621       feet.  The  contents  of  cities.dat are plotted on the map, as are the
622       cartographic bound- aries contained in the file co34_d00.dat.
623
624       When plotting line-of-sight  paths  and  areas  of  regional  coverage,
625       SPLAT! by default does not account for the effects of atmospheric bend‐
626       ing. However, this behavior may be modified by using the  Earth  radius
627       mul- tiplier (-m) switch:
628
629              splat  -t wnjt-dt -c 30.0 -m 1.333 -s cities.dat -b counties.dat
630              -o map.ppm
631
632       An earth radius multiplier of 1.333 instructs SPLAT! to use the  "four-
633       thirds  earth" model for line-of-sight propagation analysis. Any appro‐
634       priate earth radius multiplier may be selected by the user.  When  per‐
635       forming  a  regional  analysis, SPLAT! generates a site report for each
636       station analyzed. SPLAT!  site reports contain details  of  the  site’s
637       geographic  location,  its  height  above mean sea level, the antenna’s
638       height above mean sea level, the antenna’s height  above  average  ter‐
639       rain,  and  the  height  of the average ter- rain calculated toward the
640       bearings of 0, 45, 90, 135, 180, 225, 270, and 315 degrees azimuth.
641

DETERMINING MULTIPLE REGIONS OF LOS COVERAGE

643       SPLAT! can also display line-of-sight coverage areas  for  as  many  as
644       four  separate transmitter sites on a common topographic map. For exam‐
645       ple:
646
647              splat -t site1 site2 site3 site4 -c 10.0 -metric -o network.ppm
648
649       plots the regional line-of-sight coverage of site1, site2,  site3,  and
650       site4  based  on  a  receive  antenna  located 10.0 meters above ground
651       level. A topographic map is then written to the file  network.ppm.  The
652       line-of-sight  coverage area of the transmitters are plotted as follows
653       in the colors indicated (along with their corre- sponding RGB values in
654       decimal):
655
656              site1: Green (0,255,0)
657              site2: Cyan (0,255,255)
658              site3: Medium Violet (147,112,219)
659              site4: Sienna 1 (255,130,71)
660              site1 + site2: Yellow (255,255,0)
661              site1 + site3: Pink (255,192,203)
662              site1 + site4: Green Yellow (173,255,47)
663              site2 + site3: Orange (255,165,0)
664              site2 + site4: Dark Sea Green 1 (193,255,193)
665              site3 + site4: Dark Turquoise (0,206,209)
666              site1 + site2 + site3: Dark Green (0,100,0)
667              site1 + site2 + site4: Blanched Almond (255,235,205)
668              site1 + site3 + site4: Medium Spring Green (0,250,154)
669              site2 + site3 + site4: Tan (210,180,140)
670              site1 + site2 + site3 + site4: Gold2 (238,201,0)
671
672       If  separate  .qth files are generated, each representing a common site
673       location but a different  antenna  height,  a  single  topographic  map
674       illustrating  the regional coverage from as many as four separate loca‐
675       tions on a single tower may be generated by SPLAT!.
676

PATH LOSS ANALYSIS

678       If the -c switch is replaced by a -L switch, an ITM path loss map for a
679       transmitter  site may be generated: splat -t wnjt -L 30.0 -s cities.dat
680       -b co34_d00.dat -o path_loss_map  In  this  mode,  SPLAT!  generates  a
681       multi-color  map illustrating expected signal levels in areas surround‐
682       ing the transmitter site. A legend at the bottom of the map  correlates
683       each color with a specific path loss range in decibels.
684
685       The  -db switch allows a threshold to be set beyond which contours will
686       not be plotted on the map. For example, if a path loss beyond  -140  dB
687       is  irrelevant  to  the survey being conducted, SPLAT!’s path loss plot
688       can be constrained to the region bounded by the 140 dB attenuation con‐
689       tour as follows:
690
691              splat  -t  wnjt-dt -L 30.0 -s cities.dat -b co34_d00.dat -db 140
692              -o plot.ppm
693
694       The path loss contour threshold may be expressed as either  a  positive
695       or negative quantity.
696
697       The  path  loss  analysis range may be modified to a user-specific dis‐
698       tance using the -R switch. The argument must  be  given  in  miles  (or
699       kilometers  if  the  -metric switch is used). If a range wider than the
700       generated topographic map is specified, SPLAT! will  perform  ITM  path
701       loss calculations between all four corners of the area prediction map.
702
703       The  colors used to illustrate contour regions in SPLAT! generated cov‐
704       erage maps may be  tailored  by  the  user  by  creating  or  modifying
705       SPLAT!’s color definition files. SPLAT! color definition files have the
706       same base name as the transmitter’s .qth file, but  carry  .lcf,  .scf,
707       and  .dcf  extensions. If the necessary file does not exist in the cur‐
708       rent working when SPLAT! is run, a file containing default color  defi‐
709       nition  parameters  that  is suitable for manual editing by the user is
710       written into the current directory.
711
712       When a regional ITM analysis is performed and the transmitter’s ERP  is
713       not specified or is zero, a .lcf path loss color definition file corre‐
714       sponding to the transmitter site (.qth) is read by SPLAT! from the cur‐
715       rent working directory. If a .lcf file corresponding to the transmitter
716       site is not found, then a default file suitable for manual  editing  by
717       the user is automatically generated by SPLAT!.
718
719       A  path  loss  color  definition file possesses the following structure
720       (wnjt-dt.lcf):
721
722              ;  SPLAT!  Auto-generated  Path-Loss  Color  Definition  ("wnjt-
723              dt.lcf") FIle
724              ; Format for the parameters held in this file is as follows:
725              ;
726              ; dB: red, green, blue
727              ;
728              ; ...where "dB" is the path loss (in dB) and
729              ; "red", "green", and "blue" are the corresponding RGB color
730              ; definitions ranging from 0 to 255 for the region specified.
731              ;
732              ; The following parameters may be edited and/or expanded
733              ; for future runs of SPLAT! A total of 32 contour regions
734              ; may be defined in this file.
735              ;
736              ;
737               80: 255,   0,   0
738               90: 255, 128,   0
739              100: 255, 165,   0
740              110: 255, 206,   0
741              120: 255, 255,   0
742              130: 184, 255,   0
743              140: 0,   255,   0
744              150: 0,   208,   0
745              160: 0,   196, 196
746              170: 0,   148, 255
747              180: 80,   80, 255
748              190: 0,    38, 255
749              200: 142,  63, 255
750              210: 196,  54, 255
751              220: 255,   0, 255
752              230: 255, 194, 204
753
754       If the path loss is less than 80 dB, the color Red (RGB = 255, 0, 0) is
755       assigned to the region. If the path loss is greater than or equal to 80
756       dB,  but less than 90 db, then Dark Orange (255, 128, 0) is assigned to
757       the region. Orange (255, 165, 0) is assigned to regions having  a  path
758       loss  greater  than or equal to 90 dB, but less than 100 dB, and so on.
759       Greyscale terrain is displayed beyond the 230  dB  path  loss  contour.
760       Adding the -sc switch will smooth the transitions between the specified
761       quantized contour levels.
762

FIELD STRENGTH ANALYSIS

764       If the transmitter’s effective radiated power (ERP) is specified in the
765       transmitter’s  .lrp  file,  or  expressed on the command-line using the
766       -erp switch, field strength contours referenced to  decibels  over  one
767       microvolt per meter (dBuV/m) rather than path loss are produced:
768
769              splat -t wnjt-dt -L 30.0 -erp 46000 -db 30 -o plot.ppm
770
771       The  -db  switch can be used in this mode as before to limit the extent
772       to which field strength  contours  are  plotted.  When  plotting  field
773       strength  contours, however, the argument given is interpreted as being
774       expressed in dBuV/m.  SPLAT!  field  strength  color  definition  files
775       share  avery  similar  structure  to  .lcf files used for plotting path
776       loss:
777
778              ; SPLAT! Auto-generated Signal Color Definition  ("wnjt-dt.scf")
779              File
780              ;
781              ; Format for the parameters held in this file is as follows:
782              ;
783              ; dBuV/m: red, green, blue
784              ;
785              ; ...where "dBuV/m" is the signal strength (in dBuV/m) and
786              ; "red", "green", and "blue" are the corresponding RGB color
787              ; definitions ranging from 0 to 255 for the region specified.
788              ;
789              ; The following parameters may be edited and/or expanded
790              ; for future runs of SPLAT! A total of 32 contour regions
791              ; may be defined in this file.
792              ;
793              ;
794              128: 255,   0,   0
795              118: 255, 165,   0
796              108: 255, 206,   0
797              98:  255, 255,   0
798              88:  184, 255,   0
799              78:    0, 255,   0
800              68:    0, 208,   0
801              58:    0, 196, 196
802              48:    0, 148, 255
803              38:   80,  80, 255
804              28:    0,  38, 255
805              18:  142,  63, 255
806              8:   140,   0, 128
807
808       If the signal strength is greater than or equal to 128 dB over 1 micro‐
809       volt per meter (dBuV/m), the color Red (255, 0, 0) is displayed for the
810       region.  If the signal strength is greater than or equal to 118 dBuV/m,
811       but less than 128 dBuV/m, then the color Orange (255, 165, 0)  is  dis‐
812       played,  and  so  on. Greyscale terrain is dis- played for regions with
813       signal strengths less than 8 dBuV/m.  Signal strength contours for some
814       common  VHF  and  UHF broadcasting services in the United States are as
815       follows:
816
817              Analog Television Broadcasting
818              ------------------------------
819              Channels 2-6:       City Grade: >= 74 dBuV/m
820                                  Grade A: >= 68 dBuV/m
821                                  Grade B: >= 47 dBuV/m
822              --------------------------------------------
823              Channels 7-13:      City Grade: >= 77 dBuV/m
824                                  Grade A: >= 71 dBuV/m
825                                  Grade B: >= 56 dBuV/m
826              --------------------------------------------
827              Channels 14-69:     Indoor Grade: >= 94 dBuV/m
828                                  City Grade: >= 80 dBuV/m
829                                  Grade A: >= 74 dBuV/m
830                                  Grade B: >= 64 dBuV/m
831              Digital Television Broadcasting
832              -------------------------------
833              Channels 2-6:       City Grade: >= 35 dBuV/m
834                           Service Threshold: >= 28 dBuV/m
835              --------------------------------------------
836              Channels 7-13:      City Grade: >= 43 dBuV/m
837                           Service Threshold: >= 36 dBuV/m
838              --------------------------------------------
839              Channels 14-69:     City Grade: >= 48 dBuV/m
840                            Service Threshold: >= 41 dBuV/m
841              NOAA Weather Radio (162.400 - 162.550 MHz)
842              ------------------------------------------
843                        Reliable:  >= 18 dBuV/m
844                     Not reliable: < 18 dBuV/m
845              Unlikely to receive: < 0 dBuV/m
846              FM Radio Broadcasting (88.1 - 107.9 MHz)
847              ----------------------------------------
848              Analog Service Contour: 60 dBuV/m
849              Digital Service Contour: 65 dBuV/m
850
851       RECEIVED POWER LEVEL ANALYSIS If the transmitter’s  effective  radiated
852       power  (ERP)  is specified in the transmitter’s .lrp file, or expressed
853       on the command-line using the -erp  switch,  and  the  -dbm  switch  is
854       invoked,  received  power  level contours ref- erenced to decibels over
855       one milliwatt (dBm) are produced:
856
857              splat -t wnjt-dt -L 30.0 -erp 46000 -dbm -db -100 -o plot.ppm
858
859       The -db switch can be used to limit the extent to which received  power
860       level  contours  are  plotted.  When plotting power level contours, the
861       argument given is  interpreted  as  being  expressed  in  dBm.   SPLAT!
862       received power level color definition files share a very similar struc‐
863       ture to the color definition files described earlier, except  that  the
864       power  levels  in dBm may be either positive or neg ative, and are lim‐
865       ited to a range between +40 dBm and -200 dBm:
866
867              ;  SPLAT!  Auto-generated  DBM  Signal  Level  Color  Definition
868              ("wnjt-dt.dcf") File
869              ;
870              ; Format for the parameters held in this file is as follows:
871              ;
872              ; dBm: red, green, blue
873              ;
874              ;  ...where "dBm" is the received signal power level between +40
875              dBm
876              ; and -200 dBm, and "red", "green", and "blue"  are  the  corre‐
877              sponding
878              ;  RGB  color  definitions  ranging from 0 to 255 for the region
879              specified.
880              ;
881              ; The following parameters may be edited and/or expanded
882              ; for future runs of SPLAT! A total of 32 contour regions
883              ; may be defined in this file.
884              ;
885              ;
886                +0: 255,   0,   0
887               -10: 255, 128,   0
888               -20: 255, 165,   0
889               -30: 255, 206,   0
890               -40: 255, 255,   0
891               -50: 184, 255,   0
892               -60:   0, 255,   0
893               -70:   0, 208,   0
894               -80:   0, 196, 196
895               -90:   0, 148, 255
896              -100:  80,  80, 255
897              -110:   0,  38, 255
898              -120: 142,  63, 255
899              -130: 196,  54, 255
900              -140: 255,   0, 255
901              -150: 255, 194, 204
902

ANTENNA RADIATION PATTERN PARAMETERS

904       Normalized field voltage patterns for a transmitting antenna’s horizon‐
905       tal  and  vertical planes are imported automatically into SPLAT! when a
906       path loss, field strength, or received power level coverage analysis is
907       performed. Antenna pattern data is read from a pair of files having the
908       same base name as the transmitter and LRP files, but with .az  and  .el
909       extensions  for  azimuth  and  elevation  pattern  files, respectively.
910       Specifi- cations regarding pattern rotation  (if  any)  and  mechanical
911       beam  tilt  and  tilt  direction  (if  any) are also con- tained within
912       SPLAT! antenna pattern files.
913
914       For example, the first few lines of a SPLAT! azimuth pattern file might
915       appear as follows (kvea.az):
916
917              183.0
918              0       0.8950590
919              1       0.8966406
920              2       0.8981447
921              3       0.8995795
922              4       0.9009535
923              5       0.9022749
924              6       0.9035517
925              7       0.9047923
926              8       0.9060051
927
928       The  first  line of the .az file specifies the amount of azimuthal pat‐
929       tern rotation (measured clockwise in degrees from  True  North)  to  be
930       applied  by  SPLAT! to the data contained in the .az file. This is fol‐
931       lowed by azimuth headings (0 to 360 degrees) and their associated  nor‐
932       malized field patterns (0.000 to 1.000) sepa- rated by whitespace.
933
934       The  structure of SPLAT! elevation pattern files is slightly different.
935       The first line of the .el file specifies the amount of mechanical  beam
936       tilt applied to the antenna. Note that a downward tilt (below the hori‐
937       zon) is expressed as a positive angle, while an upward tilt (above  the
938       horizon)  is  expressed  as a negative angle.  This data is followed by
939       the azimuthal direction of the tilt, separated by whitespace.
940
941       The remainder of the file consists of elevation angles and their corre‐
942       sponding  normalized  voltage radiation pattern (0.000 to 1.000) values
943       separated by whitespace. Elevation angles  must  be  specified  over  a
944       -10.0  to  +90.0  degree  range.  As was the convention with mechanical
945       beamtilt, negative elevation angles are used  to  represent  elevations
946       above  the  horizon,  while positive angles represents elevations below
947       the horizon.  For example, the first few lines a SPLAT! elevation  pat‐
948       tern file might appear as follows (kvea.el):
949
950                1.1      130.0
951              -10.0      0.172
952               -9.5      0.109
953               -9.0      0.115
954               -8.5      0.155
955               -8.0      0.157
956               -7.5      0.104
957               -7.0      0.029
958               -6.5      0.109
959               -6.0      0.185
960
961       In  this  example,  the  antenna  is  mechanically  tilted downward 1.1
962       degrees towards an azimuth of 130.0 degrees.
963
964       For best results, the resolution of  azimuth  pattern  data  should  be
965       specified  to  the  nearest  degree azimuth, and elevation pattern data
966       resolution should be specified to the nearest 0.01 degrees. If the pat‐
967       tern  data  specified  does  not reach this level of resolution, SPLAT!
968       will interpolate the values provided  to  determine  the  data  at  the
969       required resolution, although this may result in a loss in accuracy.
970

EXPORTING AND IMPORTING REGIONAL CONTOUR DAT A

972       Performing  a  regional coverage analysis based on an ITM path analysis
973       can be a very time consuming process, especially  if  the  analysis  is
974       performed  repeatedly  to  discover what effects changes to a transmit-
975       ter’s antenna radiation pattern make to the predicted coverage area.
976
977       This process can be expedited by exporting the contour data produced by
978       SPLAT!  to  an alphanumeric out- put (.ano) file. The data contained in
979       this file can then be modified to incorporate antenna pattern  effects,
980       and imported back into SPLAT! to quickly produce a revised contour map.
981       Depending on the way in which SPLAT! is  invoked,  alphanumeric  output
982       files  can  describe  regional  path loss, signal strength, or received
983       signal power levels.
984
985       For example, an alphanumeric output file containing path loss  informa‐
986       tion can be generated by SPLAT! for a receive site 30 feet above ground
987       level over a 50 mile radius surrounding a transmitter site to a maximum
988       path loss of 140 dB (assuming ERP is not specified in the transmitter’s
989       .lrp file) using the following syntax:
990
991              splat -t kvea -L 30.0 -R 50.0 -db 140 -ano pathloss.dat
992
993       If ERP is specified in the .lrp file or on the command line through the
994       -erp  switch,  the  alphanumeric  output file will instead contain pre‐
995       dicted field values in dBuV/m. If the -dBm command line switch is used,
996       then  the  alphanumeric  output  file will contain receive signal power
997       levels in dBm.
998
999       SPLAT! alphanumeric output files can exceed many hundreds of  megabytes
1000       in  size.  They contain informa- tion relating to the boundaries of the
1001       region they describe followed by latitudes (degrees North),  longitudes
1002       (degrees West), azimuths (referenced to True North), elevations (to the
1003       first obstruction), followed by either  path  loss  (in  dB),  received
1004       field  strength  (in  dBuV/m),  or received signal power level (in dBm)
1005       without regard to the transmitting antenna’s radiation pattern.
1006
1007       The first few lines of a SPLAT! alphanumeric output file could take  on
1008       the following appearance (pathloss.dat):
1009
1010              119, 117  ; max_west, min_west
1011              35, 34         ; max_north, min_north
1012              34.2265424,    118.0631096, 48.199, -32.747, 67.70
1013              34.2270358,    118.0624421, 48.199, -19.161, 73.72
1014              34.2275292,    118.0617747, 48.199, -13.714, 77.24
1015              34.2280226,    118.0611072, 48.199, -10.508, 79.74
1016              34.2290094,    118.0597723, 48.199, -11.806, 83.26 *
1017              34.2295028,    118.0591048, 48.199, -11.806, 135.47 *
1018              34.2299962,    118.0584373, 48.199, -15.358, 137.06 *
1019              34.2304896,    118.0577698, 48.199, -15.358, 149.87 *
1020              34.2314763,    118.0564348, 48.199, -15.358, 154.16 *
1021              34.2319697,    118.0557673, 48.199, -11.806, 153.42 *
1022              34.2324631,    118.0550997, 48.199, -11.806, 137.63 *
1023              34.2329564,    118.0544322, 48.199, -11.806, 139.23 *
1024              34.2339432,    118.0530971, 48.199, -11.806, 139.75 *
1025              34.2344365,    118.0524295, 48.199, -11.806, 151.01 *
1026              34.2349299,    118.0517620, 48.199, -11.806, 147.71 *
1027              34.2354232,    118.0510944, 48.199, -15.358, 159.49 *
1028              34.2364099,    118.0497592, 48.199, -15.358, 151.67 *
1029
1030       Comments  can  be  placed  in the file if they are preceeded by a semi‐
1031       colon. The vim text editor has proven capable of editing files of  this
1032       size.
1033
1034       Note  as  was the case in the antenna pattern files, negative elevation
1035       angles refer to upward tilt (above the horizon), while positive  angles
1036       refer  to  downward tilt (below the horizon). These angles refer to the
1037       eleva- tion to the receiving antenna at the height above  ground  level
1038       specified  using  the  -L  switch  if  the path between transmitter and
1039       receiver is unobstructed. If  the  path  between  the  transmitter  and
1040       receiver  is  obstructed,  an  asterisk (*) is placed on the end of the
1041       line, and the elevation angle returned by SPLAT!  refers the  elevation
1042       angle  to  the  first  obstruction  rather than the geographic location
1043       specified on the line.  This is done in response to the fact  that  the
1044       ITM  model  considers  the  energy  reaching  a  distant  point over an
1045       obstructed path to be the result of the energy scattered over  the  top
1046       of the first obstruction along the path.  Since energy cannot reach the
1047       obstructed location directly, the actual elevation angle to the  desti‐
1048       nation over such a path becomes irrelevant.
1049
1050       When  modifying SPLAT! path loss files to reflect antenna pattern data,
1051       only the last numeric column should be amended to reflect the antenna’s
1052       normalized  gain  at  the azimuth and elevation angles specified in the
1053       file. Programs and scripts capable of performing this task are left  as
1054       an  exercise  for  the user.  Modified alphanumeric output files can be
1055       imported back into SPLAT! for generating revised coverage maps provided
1056       that  the  ERP and -dBm options are used as they were when the alphanu‐
1057       meric output file was originally generated:
1058
1059              splat -t kvea -ani pathloss.dat -s  city.dat  -b  county.dat  -o
1060              map.ppm
1061
1062       Note  that  alphanumeric output files generated by splat cannot be used
1063       with splat-hd, or vice-versa  due  to  the  resolution  incompatibility
1064       between  the two versions of the program. Also, each of the three types
1065       of alphanumeric output files are incompatible with one  another,  so  a
1066       file  containing  path loss data cannot be imported into SPLAT! to pro‐
1067       duce signal strength or received power level contours, etc.
1068

USER-DEFINED TERRAIN INPUT FILES

1070       A user-defined terrain file is a user-generated  text  file  containing
1071       latitudes,  longitudes, and heights above ground level of specific ter‐
1072       rain features believed to be of importance to the SPLAT! analysis being
1073       con-  ducted,  but  noticeably  absent from the SDF files being used. A
1074       user-defined terrain file is imported into a SPLAT! analysis using  the
1075       -udt switch:
1076
1077              splat -t tx_site -r rx_site -udt udt_file.txt -o map.ppm
1078
1079       A user-defined terrain file has the following appearance and structure:
1080
1081                40.32180556, 74.1325, 100.0 meters
1082                40.321805, 74.1315, 300.0
1083                40.3218055, 74.1305, 100.0 meters
1084
1085       Terrain  height  is interpreted as being described in feet above ground
1086       level unless followed by the word meters, and is added on  top  of  the
1087       terrain specified in the SDF data for the locations specified. Be aware
1088       that each user-defined terrain feature specified will be interpreted as
1089       being  3-arc seconds in both latitude and longitude in splat and 1 arc-
1090       second in latitude and longitude in splat-hd. Features described in the
1091       user-defined  terrain  file that overlap previously defined features in
1092       the file are ignored by SPLAT! to avoid ambiguity.
1093

GROUND CLUTTER

1095       The height of ground clutter can be specified using the -gc switch:
1096
1097              splat -t wnjt-dt -r kd2bd -gc 30.0 -H wnjt-dt_path.png
1098
1099       The -gc switch as the effect of raising  the  overall  terrain  by  the
1100       specified  amount in feet (or meters if the -metric switch is invoked),
1101       except over areas at sea-level and at the  transmitting  and  receiving
1102       antenna loca- tions.
1103

SIMPLE TOPOGRAPHIC MAP GENERATION

1105       In certain situations it may be desirable to generate a topographic map
1106       of a region without plotting coverage areas,  line-of-sight  paths,  or
1107       generating  obstruction  reports. There are several ways of doing this.
1108       If one wishes to generate a topographic map illustrating  the  location
1109       of  a  transmitter  and  receiver  site  along with a brief text report
1110       describing the locations and distances between the sites, the -n switch
1111       should be invoked as follows:
1112
1113              splat -t tx_site -r rx_site -n -o topo_map.ppm
1114
1115       If no text report is desired, then the -N switch is used:
1116
1117              splat -t tx_site -r rx_site -N -o topo_map.ppm
1118
1119       If  a  topographic  map  centered  about a single site out to a minimum
1120       specified radius is desired instead, a command similar to the following
1121       can be used:
1122
1123              splat  -t  tx_site  -R  50.0  -s  NJ_Cities  -b  NJ_Counties  -o
1124              topo_map.ppm
1125
1126       where -R specifies the minimum radius of the map in miles  (or  kilome‐
1127       ters  if  the  -metric switch is used).  Note that the tx_site name and
1128       location are not displayed in this example. If display of this informa‐
1129       tion  is  desired,  simply  create  a  SPLAT! city file (-s option) and
1130       append it to the list of command-line options illustrated above.
1131
1132       If the -o switch and output filename are omitted in  these  operations,
1133       topographic  output  is written to a file named tx_site.ppm in the cur‐
1134       rent working directory by default.
1135

GEOREFERENCE FILE GENERATION

1137       Topographic, coverage (-c), and path loss contour (-L)  maps  generated
1138       by  SPLAT!  may be imported into Xastir (X Amateur Station Tracking and
1139       Information Reporting) software by generating a georeference file using
1140       SPLAT!’s -geo switch:
1141
1142              splat  -t  kd2bd  -R  50.0  -s  NJ_Cities -b NJ_Counties -geo -o
1143              map.ppm
1144
1145       The georeference file generated will have the same base name as the  -o
1146       file  specified, but have a .geo extension, and permit proper interpre‐
1147       tation and display of SPLAT!’s .ppm graphics in Xastir software.
1148

GOOGLE MAP KML FILE GENERATION

1150       Keyhole Markup Language files compatible with Google Earth may be  gen‐
1151       erated  by SPLAT! when per- forming point-to-point or regional coverage
1152       analyses by invoking the -kml switch:
1153
1154              splat -t wnjt-dt -r kd2bd -kml
1155
1156       The KML file generated will have the same filename structure as a  Path
1157       Analysis  Report  for  the  transmitter  and receiver site names given,
1158       except it will carry a .kml extension.
1159
1160       Once loaded into Google Earth (File --> Open), the KML file will  anno‐
1161       tate  the  map  display  with the names of the transmitter and receiver
1162       site locations. The viewpoint of the image will be from the position of
1163       the  transmitter site looking towards the location of the receiver. The
1164       point-to-point path between the sites will be displayed as a white line
1165       while  the  RF  line-of-sight  path  will be displayed in green. Google
1166       Earth’s navigation tools allow the user to "fly" around the path, iden‐
1167       tify landmarks, roads, and other fea- tured content.
1168
1169       When  performing regional coverage analysis, the .kml file generated by
1170       SPLAT! will permit path loss or signal strength contours to be  layered
1171       on  top  of Google Earth’s display along with a corresponding color key
1172       in the upper left-hand corner. The generated .kml file  will  have  the
1173       same basename as that of the .ppm file normally generated.
1174

DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN

1176       SPLAT! determines antenna height above average terrain (HAAT) according
1177       to the procedure defined  by  Federal  Communications  Commission  Part
1178       73.313(d). According to this definition, terrain elevations along eight
1179       radials between 2 and 10 miles (3 and  16  kilometers)  from  the  site
1180       being  analyzed are sampled and averaged for each 45 degrees of azimuth
1181       starting with True North. If one or  more  radials  lie  entirely  over
1182       water  or  over land outside the United States (areas for which no USGS
1183       topography data is available), then those radials are omitted from  the
1184       calculation of average terrain.
1185
1186       Note that SRTM-3 elevation data, unlike older USGS data, extends beyond
1187       the borders of the United States.  Therefore, HAAT results may  not  be
1188       in  full  compliance with FCC Part 73.313(d) in areas along the borders
1189       of the United States if the SDF files used by SPLAT! are SRTM-derived.
1190
1191       When performing point-to-point terrain analysis, SPLAT! determines  the
1192       antenna  height above average ter- rain only if enough topographic data
1193       has already been loaded by the program to  perform  the  point-to-point
1194       analysis. In most cases, this will be true, unless the site in question
1195       does not lie within 10 miles of the boundary of the topography data  in
1196       memory.
1197
1198       When  performing  area  prediction  analysis, enough topography data is
1199       normally loaded by SPLAT! to per- form  average  terrain  calculations.
1200       Under  such  conditions,  SPLAT!  will provide the antenna height above
1201       average terrain as well as the average terrain above mean sea level for
1202       azimuths of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and include
1203       such information in the generated site report. If one or  more  of  the
1204       eight  radials  surveyed  fall over water, or over regions for which no
1205       SDF data is available, SPLAT! reports No Terrain for the  radial  paths
1206       affected.
1207

ADDITIONAL INFORMATION

1209       The  latest news and information regarding SPLAT! software is available
1210       through the official SPLAT! soft- ware web page located at:
1211
1212              http://www.qsl.net/kd2bd/splat.html.
1213

AUTHORS

1215       John A. Magliacane, KD2BD <kd2bd@amsat.org>  Creator, Lead Developer
1216       Doug McDonald <mcdonald@scs.uiuc.edu>        Original Longley-Rice  ITM
1217       Model integration
1218       Ron  Bentley <ronbentley@embarqmail.com>      Fresnel Zone plotting and
1219       clearance determination
1220
1221
1222
1223KD2BD Software                   25 July 2013                        SPLAT!(1)
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