SPLAT!(1)                 KD2BD Software                SPLAT!(1)



NAME
       splat - An RF Signal Propagation, Loss, And Terrain analy-
       sis tool

SYNOPSIS
       splat [-t  transmitter_site.qth]  [-r   receiver_site.qth]
       [-c    rx_antenna_height_for_los_coverage_analysis  (feet)
       (float)]  [-L    rx_antenna_height_for_Longley-Rice_cover-
       age_analysis (feet) (float)] [-p  terrain_profile.ext] [-e
       elevation_profile.ext] [-h  height_profile.ext] [-l  Long-
       ley-Rice_profile.ext]  [-o   topographic_map_filename.ppm]
       [-b         cartographic_boundary_filename.dat]        [-s
       site/city_database.dat]   [-d    sdf_directory_path]   [-m
       earth_radius_multiplier   (float)]   [-R    maximum_cover-
       age_range  (for  -c  or  -L) (miles) (float)] [-dB maximum
       attenuation contour to display on path loss  maps  (80-230
       dB)] [-n] [-N]

DESCRIPTION
       SPLAT!  is  a powerful terrestrial RF propagation and ter-
       rain analysis tool covering the spectrum  between  20  MHz
       and  20  GHz.   It  is  designed for operation on Unix and
       Linux-based  workstations.   SPLAT!  is   free   software.
       Redistribution  and/or modification is permitted under the
       terms of the GNU General Public License  as  published  by
       the  Free  Software  Foundation,  either  version 2 of the
       License or any later version.  Adoption of  SPLAT!  source
       code  in  proprietary  or  closed-source applications is a
       violation of this license, and is strictly forbidden.

       SPLAT! is distributed in the hope that it will be  useful,
       but  WITHOUT  ANY  WARRANTY, without even the implied war-
       ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PUR-
       POSE. See the GNU General Public License for more details.

INTRODUCTION
       Applications of SPLAT! include the visualization,  design,
       and  link  budget  analysis of wireless Wide Area Networks
       (WANs), commercial and amateur radio communication systems
       above 20 MHz, microwave links, frequency coordination, and
       the determination of analog and digital terrestrial  radio
       and television contour regions.

       SPLAT!  provides  RF  site  engineering data such as great
       circle distances and bearings between sites, antenna  ele-
       vation  angles  (uptilt),  depression  angles  (downtilt),
       antenna height above mean sea level, antenna height  above
       average  terrain, bearings and distances to known obstruc-
       tions, Longley-Rice path attenuation, and minimum  antenna
       height requirements needed to establish line-of-sight com-
       munication paths absent of obstructions  due  to  terrain.
       SPLAT!  produces  reports, graphs, and highly detailed and
       carefully annotated topographic  maps  depicting  line-of-
       sight  paths,  path  loss,  and expected coverage areas of
       transmitters and repeater systems.  When performing  line-
       of-sight analysis in situations where multiple transmitter
       or repeater sites are employed, SPLAT! determines individ-
       ual and mutual areas of coverage within the network speci-
       fied.

       SPLAT! operates  in  two  distinct  modes:  point-to-point
       mode,  and  area prediction mode, and may be invoked using
       either line-of-sight  (LOS)  or  Irregular  Terrain  (ITM)
       propagation models.  True Earth, four-thirds Earth, or any
       other Earth radius may be specified by the user when  per-
       forming line-of-sight analysis.

INPUT FILES
       SPLAT!  is  a  command-line  driven application, and reads
       input data through a number of data files.  Some files are
       mandatory  for  successful execution of the program, while
       others are optional.  Mandatory files include  SPLAT  Data
       Files  (SDF  files),  site location files (QTH files), and
       Longley-Rice model parameter files (LRP files).   Optional
       files  include  city/site location files, and cartographic
       boundary files.

SPLAT DATA FILES
       SPLAT! imports topographic data in the form of SPLAT  Data
       Files  (SDFs).  These files may be generated from a number
       of information sources.  In the United States, SPLAT  Data
       Files  can  be  generated  through U.S.  Geological Survey
       Digital Elevation Models (DEMs) using the usgs2sdf utility
       included  with SPLAT!.  USGS Digital Elevation Models com-
       patible  with  this  utility  may  be   downloaded   from:
       http://edcftp.cr.usgs.gov/pub/data/DEM/250/.

       Significantly  better  resolution  can be obtained through
       the use of SRTM-3  Version  2  digital  elevation  models.
       These  models  are  the result of the STS-99 Space Shuttle
       Radar Topography Mission, and are available for most popu-
       lated  regions of the Earth.  SPLAT Data Files may be gen-
       erated from SRTM data using the included srtm2sdf utility.
       SRTM-3  Version  2  data may be obtained through anonymous
       FTP from: ftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/

       Despite the higher accuracy that SRTM data has  to  offer,
       some  voids  in  the  data  sets  exist.   When  voids are
       detected, the srtm2sdf utility replaces them  with  corre-
       sponding  data found in existing SDF files (that were pre-
       sumably  created  from  earlier  USGS  data  through   the
       usgs2sdf utility).  If USGS-derived SDF data is not avail-
       able, voids are handled through adjacent pixel  averaging,
       or direct replacement.

       SPLAT  Data Files contain integer value topographic eleva-
       tions  (in  meters)  referenced  to  mean  sea  level  for
       1-degree  by  1-degree regions of the earth with a resolu-
       tion of 3-arc seconds.  SDF files can be  read  in  either
       standard  format  (.sdf)  as generated by the usgs2sdf and
       srtm2sdf  utilities,  or  in   bzip2   compressed   format
       (.sdf.bz2).   Since  uncompressed  files  can be processed
       slightly faster than  files  that  have  been  compressed,
       SPLAT!  searches  for  the needed SDF data in uncompressed
       format first.  If uncompressed data cannot located, SPLAT!
       then  searches for data in bzip2 compressed format.  If no
       compressed  SDF  files  can  be  found  for   the   region
       requested,  SPLAT!  assumes  the region is over water, and
       will assign an elevation of sea-level to these areas.

       This feature of SPLAT! makes it possible to  perform  path
       analysis  not  only  over  land,  but also between coastal
       areas not represented by  Digital  Elevation  Model  data.
       This behavior of SPLAT! underscores the importance of hav-
       ing all the SDF files required for the region  being  ana-
       lyzed if meaningful results are to be expected.

SITE LOCATION (QTH) FILES
       SPLAT!  imports  site  location information of transmitter
       and receiver sites analyzed  by  the  program  from  ASCII
       files  having  a  .qth  extension.   QTH files contain the
       site's name, the site's latitude (positive if North of the
       equator,  negative  if  South),  the  site's longitude (in
       degrees West, 0 to 360 degrees), and  the  site's  antenna
       height above ground level (AGL).  A single line-feed char-
       acter separates each field.  The antenna height is assumed
       to be specified in feet unless followed by the letter m or
       the word meters in either upper or lower  case.   Latitude
       and longitude information may be expressed in either deci-
       mal format (74.6889) or degree, minute, second (DMS)  for-
       mat (74 41 20.0).

       For  example,  a  site location file describing television
       station WNJT, Trenton, NJ (wnjt.qth) might  read  as  fol-
       lows:

               WNJT
               40.2833
               74.6889
               990.00

       Each transmitter and receiver site analyzed by SPLAT! must
       be represented by its own site location (QTH) file.

LONGLEY-RICE PARAMETER (LRP) FILES
       SPLAT! imports  Longley-Rice  model  parameter  data  from
       files  having  the  same base name as the transmitter site
       QTH file, but with a .lrp extension, thus providing simple
       and  accurate  correlation  between  these associated data
       sets.  The format for  the  Longley-Rice  model  parameter
       files is as follows (wnjt.lrp):

               15.000  ; Earth Dielectric Constant (Relative per-
       mittivity)
               0.005   ; Earth Conductivity (Siemens per meter)
               301.000 ; Atmospheric Bending Constant (N-units)
               700.000 ; Frequency in MHz (20 MHz to 20 GHz)
               5       ; Radio Climate (5 =  Continental  Temper-
       ate)
               0       ; Polarization (0 = Horizontal, 1 = Verti-
       cal)
               0.5     ; Fraction of  situations  (50%  of  loca-
       tions)
               0.5     ; Fraction of time (50% of the time)

       If  an LRP file corresponding to the tx_site QTH file can-
       not be found, SPLAT! scans the current  working  directory
       for  the  file "splat.lrp".  If this file cannot be found,
       then the default parameters listed above will be  assigned
       by  SPLAT! and a corresponding "splat.lrp" file containing
       this data will be written to the  current  working  direc-
       tory.   "splat.lrp"  can  then  be  edited  by the user as
       needed.

       Typical Earth dielectric constants and conductivity values
       are as follows:

                                  Dielectric Constant  Conductiv-
       ity
               Salt water       :        80                5.000
               Good ground      :        25                0.020
               Fresh water      :        80                0.010
               Marshy land      :        12                0.007
               Farmland, forest :        15                0.005
               Average ground   :        15                0.005
               Mountain, sand   :        13                0.002
               City             :         5                0.001
               Poor ground      :         4                0.001

       Radio climate codes used by SPLAT! are as follows:

               1: Equatorial (Congo)
               2: Continental Subtropical (Sudan)
               3: Maritime Subtropical (West coast of Africa)
               4: Desert (Sahara)
               5: Continental Temperate
               6: Maritime Temperate,  over  land  (UK  and  west
       coasts of US & EU)
               7: Maritime Temperate, over sea

       The  Continental Temperate climate is common to large land
       masses in the temperate zone, such as the  United  States.
       For  paths shorter than 100 km, there is little difference
       between Continental and Maritime Temperate climates.

       The final two parameters in the .lrp  file  correspond  to
       the  statistical  analysis  provided  by  the Longley-Rice
       model.  In this example, SPLAT!  will return  the  maximum
       path  loss occurring 50% of the time (fraction of time) in
       50% of situations (fraction of situations).  Use  a  frac-
       tion  of  time  parameter  of 0.97 for digital television,
       0.50 for analog in the United States.  Isotropic  antennas
       are assumed.

       For   further   information   on  these  parameters,  see:
       http://flattop.its.bldrdoc.gov/itm.html                and
       http://www.softwright.com/faq/engineering/prop_long-
       ley_rice.html

CITY LOCATION FILES
       The names and locations of cities, tower sites,  or  other
       points  of  interest  may be imported and plotted on topo-
       graphic maps generated  by  SPLAT!.   SPLAT!  imports  the
       names  of cities and locations from ASCII files containing
       the location's name,  the  location's  latitude,  and  the
       location's longitude.  Each field is separated by a comma.
       Each record is separated by a single line feed  character.
       As  was  the case with the .qth files, latitude and longi-
       tude information may  be  entered  in  either  decimal  or
       degree, minute, second (DMS) format.

       For example (cities.dat):

               Teaneck, 40.891973, 74.014506
               Tenafly, 40.919212, 73.955892
               Teterboro, 40.859511, 74.058908
               Tinton Falls, 40.279966, 74.093924
               Toms River, 39.977777, 74.183580
               Totowa, 40.906160, 74.223310
               Trenton, 40.219922, 74.754665

       A  total  of five separate city data files may be imported
       at a time, and there is no limit  to  the  size  of  these
       files.   SPLAT!  reads  city  data  on a "first come/first
       served" basis, and plots only those locations whose  anno-
       tations  do  not  conflict  with  annotations of locations
       plotted earlier during SPLAT's execution.   This  behavior
       minimizes  clutter  in  SPLAT! generated topographic maps,
       but also  mandates  that  important  locations  be  placed
       toward  the  beginning  of  the  first city data file, and
       disposable locations be positioned further down  the  list
       or in subsequent data files.

       City  data  files may be generated manually using any text
       editor, imported from other sources, or derived from  data
       available  from  the  U.S. Census Bureau using the cityde-
       coder utility included with SPLAT!.  Such data  is  avail-
       able  free  of charge via the Internet at: http://www.cen-
       sus.gov/geo/www/cob/bdy_files.html, and must be  in  ASCII
       format.

CARTOGRAPHIC BOUNDARY DATA FILES
       Cartographic  boundary  data  may also be imported to plot
       the boundaries of cities, counties,  or  states  on  topo-
       graphic  maps  generated  by SPLAT!.  Such data must be of
       the form of ARC/INFO Ungenerate  (ASCII  Format)  Metadata
       Cartographic  Boundary  Files,  and are available from the
       U.S.  Census Bureau via the Internet  at:  http://www.cen-
       sus.gov/geo/www/cob/co2000.html#ascii  and http://www.cen-
       sus.gov/geo/www/cob/pl2000.html#ascii.  A  total  of  five
       separate  cartographic boundary files may be imported at a
       time.  It is not necessary to import state  boundaries  if
       county boundaries have already been imported.

PROGRAM OPERATION
       SPLAT!  is  invoked via the command-line using a series of
       switches and arguments.  Since SPLAT! is a CPU and  memory
       intensive  application,  this  type of interface minimizes
       overhead and lends itself well to scripted (batch)  opera-
       tions.  SPLAT!'s CPU and memory scheduling priority may be
       modified through the use of the Unix nice command.

       The number and type of switches passed to SPLAT! determine
       its  mode  of  operation and method of output data genera-
       tion.  Nearly all of SPLAT!'s switches may be cascaded  in
       any order on the command line when invoking the program.

POINT-TO-POINT ANALYSIS
       SPLAT! may be used to perform line-of-sight terrain analy-
       sis between two specified site locations.  For example:

       splat -t tx_site.qth -r rx_site.qth

       invokes a terrain analysis between the transmitter  speci-
       fied in tx_site.qth and receiver specified in rx_site.qth,
       and writes a SPLAT!  Obstruction  Report  to  the  current
       working  directory.   The  report  contains details of the
       transmitter and receiver sites, and identifies  the  loca-
       tion of any obstructions detected during the analysis.  If
       an obstruction can  be  cleared  by  raising  the  receive
       antenna  to  a greater altitude, SPLAT!  will indicate the
       minimum antenna height required for a  line-of-sight  path
       to  exist  between  the transmitter and receiver locations
       specified.  If the antenna must be  raised  a  significant
       amount,  this determination may take some time.  Note that
       the results provided are the minimum necessary for a line-
       of-sight  path  to  exist,  and  do  not take Fresnel zone
       clearance requirements into consideration.

       qth extensions are assumed by SPLAT! for  QTH  files,  and
       are  optional when invoking the program.  SPLAT! automati-
       cally reads all SPLAT Data Files necessary to conduct  the
       terrain  analysis  between  the  sites  specified.  SPLAT!
       searches for the needed SDF files in the  current  working
       directory  first.   If  the  needed  files  are not found,
       SPLAT! then searches in  the  path  specified  by  the  -d
       command-line switch:

       splat -t tx_site -r rx_site -d /cdrom/sdf/

       An  external  directory path may be specified by placing a
       ".splat_path" file under the user's home directory.   This
       file  must  contain  the  full  directory path to the last
       resort location of all the SDF files.   The  path  in  the
       $HOME/.splat_path  file  must  be  of the form of a single
       line of ASCII text:

       /opt/splat/sdf/

       and can be generated using any text editor.

       A graph of the terrain profile between  the  receiver  and
       transmitter  locations  as a function of distance from the
       receiver can be generated by adding the -p switch:

       splat -t tx_site -r rx_site -p terrain_profile.gif

       SPLAT! invokes gnuplot when generating graphs.  The  file-
       name  extension  specified to SPLAT! determines the format
       of the graph produced.  .gif will produce a 640x480  color
       GIF  graphic  file,  while .ps or .postscript will produce
       postscript output.  Output in formats such as  PNG,  Adobe
       Illustrator,  AutoCAD  dxf,  LaTeX,  and  many  others are
       available.  Please consult gnuplot, and gnuplot's documen-
       tation for details on all the supported output formats.

       A graph of elevations subtended by the terrain between the
       receiver and transmitter as a function  of  distance  from
       the receiver can be generated by using the -e switch:

       splat -t tx_site -r rx_site -e elevation_profile.gif

       The  graph produced using this switch illustrates the ele-
       vation and depression angles resulting  from  the  terrain
       between  the  receiver's location and the transmitter site
       from the perspective of the receiver's location.  A second
       trace  is  plotted  between  the  left  side  of the graph
       (receiver's location) and the location of the transmitting
       antenna  on  the right.  This trace illustrates the eleva-
       tion angle required for  a  line-of-sight  path  to  exist
       between  the  receiver  and transmitter locations.  If the
       trace intersects the elevation profile at any point on the
       graph,  then  this  is  an indication that a line-of-sight
       path does not exist under the conditions  given,  and  the
       obstructions can be clearly identified on the graph at the
       point(s) of intersection.

       A graph illustrating terrain height referenced to a  line-
       of-sight  path between the transmitter and receiver may be
       generated using the -h switch:

       splat -t tx_site -r rx_site -h height_profile.gif

       The Earth's curvature is  clearly  evident  when  plotting
       height profiles.

       A  graph  showing  Longley-Rice  path  loss may be plotted
       using the -l switch:

       splat -t tx_site -r rx_site -l path_loss_profile.gif

       When performing path loss profiles, a  Longley-Rice  Model
       Path  Loss  Report is generated by SPLAT! in the form of a
       text file with a .lro filename extension.  The report con-
       tains  bearings  and distances between the transmitter and
       receiver, as well as the Longley-Rice path loss for  vari-
       ous  distances  between the transmitter and receiver loca-
       tions.  The mode of propagation for points along the  path
       are  given  as Line-of-Sight, Single Horizon, Double Hori-
       zon, Diffraction Dominant, and Troposcatter Dominant.

       To determine the signal-to-noise  (SNR)  ratio  at  remote
       location  where random Johnson (thermal) noise is the pri-
       mary limiting factor in reception:

       SNR=T-NJ-L+G-NF

       where T is the ERP of the transmitter in dBW, NJ is  John-
       son  Noise  in dBW (-136 dBW for a 6 MHz TV channel), L is
       the path loss provided by SPLAT! in dB (as a positive num-
       ber),  G is the receive antenna gain in dB over isotropic,
       and NF is the receiver noise figure in dB.

       T may be computed as follows:

       T=TI+GT

       where TI is actual amount of RF  power  delivered  to  the
       transmitting  antenna  in  dBW,  GT  is  the  transmitting
       antenna gain (over isotropic)  in  the  direction  of  the
       receiver (or the horizon if the receiver is over the hori-
       zon).

       To compute how much more signal is available over the min-
       imum  to  necessary  to achieve a specific signal-to-noise
       ratio:

       Signal_Margin=SNR-S

       where S is the minimum desired SNR ratio (15.5 dB for ATSC
       DTV, 42 dB for analog NTSC television).

       A  topographic map may be generated by SPLAT! to visualize
       the path between the transmitter and receiver  sites  from
       yet  another  perspective.   Topographic maps generated by
       SPLAT! display elevations using a  logarithmic  grayscale,
       with higher elevations represented through brighter shades
       of gray.  The dynamic range of the image is scaled between
       the highest and lowest elevations present in the map.  The
       only exception to this is sea-level, which is  represented
       using the color blue.

       SPLAT!  generated  topographic  maps  are 24-bit TrueColor
       Portable PixMap (PPM) images.  They may be viewed, edited,
       or  converted  to  other  graphic formats by popular image
       viewing applications such as xv,  The  GIMP,  ImageMagick,
       and XPaint.  PNG format is highly recommended for lossless
       compressed storage of SPLAT!  generated topographic output
       files.   An excellent command-line utility capable of con-
       verting SPLAT! PPM graphic files to PNG files is wpng, and
       is                      available                      at:
       http://www.libpng.org/pub/png/book/sources.html.    As   a
       last  resort,  PPM files may be compressed using the bzip2
       utility, and read directly by The  GIMP  in  this  format.
       Topographic output is specified using the -o switch:

       splat -t tx_site -r rx_site -o topo_map.ppm

       The  .ppm  extension  on the output filename is assumed by
       SPLAT!, and is optional.

       In this example, topo_map.ppm will  illustrate  the  loca-
       tions of the transmitter and receiver sites specified.  In
       addition, the great circle path between the two sites will
       be  drawn  over  locations  for which an unobstructed path
       exists to the transmitter at a  receiving  antenna  height
       equal   to   that  of  the  receiver  site  (specified  in
       rx_site.qth).

       It may desirable to  populate  the  topographic  map  with
       names  and  locations  of  cities,  tower  sites, or other
       important locations.  A city file may be passed to  SPLAT!
       using the -s switch:

       splat -t tx_site -r rx_site -s cities.dat -o topo_map

       Up  to five separate city files may be passed to SPLAT! at
       a time following the -s switch.

       County and state boundaries may be added  to  the  map  by
       specifying  up  to  five  U.S.  Census Bureau cartographic
       boundary files using the -b switch:

       splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map

       In situations where multiple transmitter sites are in use,
       as  many as four site locations may be passed to SPLAT! at
       a time for analysis:

       splat -t tx_site1 tx_site2 tx_site3 tx_site4 -r rx_site -p
       profile.gif

       In  this  example,  four  separate  terrain  profiles  and
       obstruction reports will be generated by SPLAT!.  A single
       topographic  map can be specified using the -o switch, and
       line-of-sight  paths  between  each  transmitter  and  the
       receiver  site indicated will be produced on the map, each
       in its own color.  The path between the first  transmitter
       specified  to  the  receiver  will  be  in green, the path
       between the second transmitter and the receiver will be in
       cyan,  the  path  between  the  third  transmitter and the
       receiver will be in  violet,  and  the  path  between  the
       fourth transmitter and the receiver will be in sienna.

DETERMINING REGIONAL COVERAGE
       SPLAT! can analyze a transmitter or repeater site, or net-
       work of sites, and predict the regional coverage for  each
       site specified.  In this mode, SPLAT! can generate a topo-
       graphic map displaying the geometric line-of-sight  cover-
       age  area  of the sites based on the location of each site
       and the height of receive antenna wishing  to  communicate
       with the site in question.  SPLAT! switches from point-to-
       point analysis mode to area prediction mode  when  the  -c
       switch is invoked as follows:

       splat  -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o
       tx_coverage

       In this example, SPLAT! generates a topographic map called
       tx_coverage.ppm  that  illustrates  the predicted line-of-
       sight regional coverage of tx_site to receiving  locations
       having  antennas  30.0 feet above ground level (AGL).  The
       contents of cities.dat are plotted on the map, as are  the
       cartographic    boundaries    contained    in   the   file
       co34_d00.dat.

       When plotting line-of-sight paths and  areas  of  regional
       coverage,  SPLAT!  by  default  does  not  account for the
       effects of atmospheric bending.   However,  this  behavior
       may  be modified by using the Earth radius multiplier (-m)
       switch:

       splat -t wnjt -c 30.0 -m  1.333  -s  cities.dat  -b  coun-
       ties.dat -o map.ppm

       An  earth  radius  multiplier of 1.333 instructs SPLAT! to
       use the "four-thirds earth" model for line-of-sight propa-
       gation  analysis.  Any appropriate earth radius multiplier
       may be selected by the user.

       When invoked in area prediction mode, SPLAT!  generates  a
       site  report  for  each  station  analyzed.   SPLAT!  site
       reports contain details of the site's geographic location,
       its  height  above  mean  sea  level, the antenna's height
       above mean sea level, the antenna's height  above  average
       terrain,  and the height of the average terrain calculated
       in the directions of 0, 45, 90, 135, 180,  225,  270,  and
       315 degrees azimuth.

       If  the  -c  switch is replaced by a -L switch, a Longley-
       Rice path loss map for a transmitter site  may  be  gener-
       ated:

       splat  -t  wnjt  -L  30.0 -s cities.dat -b co34_d00.dat -o
       path_loss_map

       In this mode, SPLAT! generates a  multi-color  map  illus-
       trating  expected  signal levels (path loss) in areas sur-
       rounding the transmitter site.  A legend at the bottom  of
       the  map  correlates  each color with a specific path loss
       level in decibels.  Since Longley-Rice area prediction map
       generation  is  very CPU intensive, provision for limiting
       the analysis range is provided  by  the  -R  switch.   The
       argument  must  be  given in miles.  If a range wider than
       the generated topographic map is  specified,  SPLAT!  will
       perform  Longley-Rice  path  loss calculations between all
       four corners of the area prediction map.

       The -db switch allows a constraint to  be  placed  on  the
       maximum  path loss region plotted on the map.  A path loss
       between 80 and 230 dB may be specified using this  switch.
       For  example,  if a path loss beyond -140 dB is irrelevant
       to the survey being conducted, SPLAT!'s path loss plot can
       be constrained to the region bounded by the 140 dB attenu-
       ation contour as follows:

       splat -t wnjt -L 30.0 -s cities.dat  -b  co34_d00.dat  -db
       140 -o plot.ppm


DETERMINING MULTIPLE REGIONS OF COVERAGE
       SPLAT!  can  also display line-of-sight coverage areas for
       as many as four separate transmitter  sites  on  a  common
       topographic map.  For example:

       splat -t site1 site2 site3 site4 -c 30.0 -o network.ppm

       plots the regional line-of-sight coverage of site1, site2,
       site3, and site4 based on a receive antenna  located  30.0
       feet  above  ground  level.   A  topographic  map  is then
       written to the file network.ppm.  The line-of-sight cover-
       age area of the transmitters are plotted as follows in the
       colors indicated (along with their corresponding RGB  val-
       ues in decimal):

           site1: Green (0,255,0)
           site2: Cyan (0,255,255)
           site3: Medium Violet (147,112,219)
           site4: Sienna 1 (255,130,71)

           site1 + site2: Yellow (255,255,0)
           site1 + site3: Pink (255,192,203)
           site1 + site4: Green Yellow (173,255,47)
           site2 + site3: Orange (255,165,0)
           site2 + site4: Dark Sea Green 1 (193,255,193)
           site3 + site4: Dark Turquoise (0,206,209)

           site1 + site2 + site3: Dark Green (0,100,0)
           site1 + site2 + site4: Blanched Almond (255,235,205)
           site1 + site3 + site4: Medium Spring Green (0,250,154)
           site2 + site3 + site4: Tan (210,180,140)

           site1 + site2 + site3 + site4: Gold2 (238,201,0)

       If separate .qth files are generated, each representing  a
       common  site  location  but  a different antenna height, a
       single topographic map illustrating the regional  coverage
       from  as many as four separate locations on a single tower
       may be generated by SPLAT!.

TOPOGRAPHIC MAP GENERATION
       In certain situations, it may be desirable to  generate  a
       topographic  map  of  a  region  without plotting coverage
       areas,  line-of-sight  paths,  or  generating  obstruction
       reports.   There  are  several ways of doing this.  If one
       wishes to generate  a  topographic  map  illustrating  the
       location  of  a transmitter and receiver site along with a
       brief text report describing the locations  and  distances
       between the sites, the -n switch should be invoked as fol-
       lows:

       splat -t tx_site -r rx_site -n -o topo_map.ppm

       If no text report is desired, then the -N switch is used:

       splat -t tx_site -r rx_site -N -o topo_map.ppm

       If the -o switch and  output  filename  are  omitted  when
       using either the -n or -N switches, output is written to a
       file named map.ppm in the  current  working  directory  by
       default.

DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
       SPLAT!  determines  antenna  height  above average terrain
       (HAAT) according to the procedure defined by Federal  Com-
       munications  Commission Part 73.313(d).  According to this
       definition, terrain elevations along eight radials between
       2  and  10 miles (3 and 16 kilometers) from the site being
       analyzed are sampled and averaged for each 45  degrees  of
       azimuth  starting with True North.  If one or more radials
       lie entirely over water or over land  outside  the  United
       States  (areas for which no USGS topography data is avail-
       able), then those radials are omitted from the calculation
       of  average  terrain.   If part of a radial extends over a
       body of water or over land outside the United States, then
       only that part of the radial lying over United States land
       is used in the determination of average terrain.

       Note that SRTM elevation data, unlike older  3-arc  second
       USGS  data,  extends  beyond  the  borders  of  the United
       States.  Therefore, HAAT results may not be in  full  com-
       pliance with FCC Part 73.313(d) in areas along the borders
       of the United States if the SDF files used by  SPLAT!  are
       SRTM-derived.

       When  performing  point-to-point  terrain analysis, SPLAT!
       determines the antenna height above average  terrain  only
       if  enough topographic data has already been loaded by the
       program to perform the point-to-point analysis.   In  most
       cases, this will be true, unless the site in question does
       not lie within 10 miles of the boundary of the  topography
       data in memory.

       When  performing area prediction analysis, enough topogra-
       phy data is normally loaded by SPLAT! to  perform  average
       terrain  calculations.  Under such conditions, SPLAT! will
       provide the antenna height above average terrain  as  well
       as  the  average terrain above mean sea level for azimuths
       of 0, 45, 90, 135, 180, 225, 270,  and  315  degrees,  and
       include such information in the site report generated.  If
       one or more of the eight radials surveyed fall over water,
       or over regions for which no SDF data is available, SPLAT!
       reports No Terrain for the radial paths affected.

RESTRICTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
       SPLAT! reads SDF files as needed into a series  of  memory
       "slots"  within the structure of the program.  Each "slot"
       holds one SDF file representing a one degree by one degree
       region  of  terrain.   A #define MAXSLOTS statement in the
       first several lines of splat.cpp sets the  maximum  number
       of  "slots"  available  for topography data.  It also sets
       the maximum size of  the  topographic  maps  generated  by
       SPLAT!.   MAXSLOTS is set to 9 by default.  If SPLAT! pro-
       duces a segmentation fault on start-up with this  default,
       it  is  an  indication  that not enough RAM and/or virtual
       memory (swap space) is available to run SPLAT!  with  this
       number  of MAXSLOTS.  In situations where available memory
       is low, MAXSLOTS may be reduced to 4 with the  understand-
       ing that this will greatly limit the maximum region SPLAT!
       will be able to analyze.  If  118  megabytes  or  more  of
       total  memory  (swap  space  plus  RAM) is available, then
       MAXSLOTS may be increased to 16.  This will permit  opera-
       tion  over  a 4-degree by 4-degree region, which is suffi-
       cient for single antenna heights in excess of 10,000  feet
       above  mean sea level, or point-to-point distances of over
       1000 miles.

ADDITIONAL INFORMATION
       Invoking SPLAT! without any arguments will display all the
       command-line options available with the program along with
       a brief summary of each.

       The latest news and information regarding SPLAT!  software
       is available through the official SPLAT! software web page
       located at: http://www.qsl.net/kd2bd/splat.html.

AUTHORS
       John A. Magliacane, KD2BD <kd2bd@amsat.org>
              Creator, Lead Developer

       Doug McDonald <mcdonald@scs.uiuc.edu>
              Longley-Rice Model integration



