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



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

SYNOPSIS
       splat  [-t  transmitter_site.qth] [-r receiver_site.qth] [-c rx antenna
       height for LOS coverage analysis (feet/meters) (float)] [-L rx  antenna
       height  for  Longley-Rice  coverage analysis (feet/meters) (float)] [-p
       terrain_profile.ext] [-e elevation_profile.ext] [-h height_profile.ext]
       [-H  normalized_height_profile.ext]  [-l  Longley-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)] [-f frequency (MHz) for Fresnel  zone  calculations
       (float)]  [-R  maximum coverage radius (miles/kilometers) (float)] [-dB
       maximum attenuation contour to display on path loss maps  (80-230  dB)]
       [-fz   Fresnel   zone   clearance  percentage  (default  =  60)]  [-plo
       path_loss_output_file.txt]   [-pli   path_loss_input_file.txt]    [-udt
       user_defined_terrain_file.dat]  [-n]  [-N]  [-nf]  [-ngs] [-geo] [-kml]
       [-gpsav] [-metric]

DESCRIPTION
       SPLAT! is a powerful terrestrial RF propagation  and  terrain  analysis
       tool  for the spectrum between 20 MHz and 20 GHz.  SPLAT! is free soft-
       ware, and is designed for operation on Unix  and  Linux-based  worksta-
       tions.  Redistribution and/or modification is permitted under the terms
       of the GNU General Public License, Version 2, as published by the  Free
       Software Foundation.  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 warranty of  MERCHANTABILITY  or
       FITNESS  FOR  A PARTICULAR PURPOSE.  See the GNU General Public License
       for more details.

INTRODUCTION
       Applications of SPLAT! include the visualization, design, and link bud-
       get analysis of wireless Wide Area Networks (WANs), commercial and ama-
       teur radio communication systems above 20 MHz,  microwave  links,  fre-
       quency  coordination  and  interference  studies, and the prediction 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 elevation angles (uptilt), depres-
       sion angles (downtilt), antenna height above mean  sea  level,  antenna
       height  above  average  terrain, bearings, distances, and elevations to
       known obstructions, Longley-Rice path attenuation, and received  signal
       strength.   In addition, the minimum antenna height requirements needed
       to clear terrain, the first Fresnel zone, and any  user-definable  per-
       centage of the first Fresnel zone are also provided.

       SPLAT!  produces  reports, graphs, and high resolution topographic maps
       that depict line-of-sight paths, and  regional  path  loss  and  signal
       strength contours through which expected coverage areas of transmitters
       and repeater systems can be obtained.   When  performing  line-of-sight
       and  Longley-Rice  analyses in situations where multiple transmitter or
       repeater sites are employed, SPLAT! determines  individual  and  mutual
       areas of coverage within the network specified.

       Simply  typing  splat  on  the  command  line  will return a summary of
       SPLAT!'s command line options:

                    --==[ SPLAT! v1.2.3 Available Options... ]==--

            -t txsite(s).qth (max of 4 with -c, max of 30 with -L)
            -r rxsite.qth
            -c plot coverage of TX(s) with an RX antenna at X feet/meters AGL
            -L plot path loss map of TX based on an RX at X feet/meters AGL
            -s filename(s) of city/site file(s) to import (5 max)
            -b filename(s) of cartographic boundary file(s) to import (5 max)
            -p filename of terrain profile graph to plot
            -e filename of terrain elevation graph to plot
            -h filename of terrain height graph to plot
            -H filename of normalized terrain height graph to plot
            -l filename of Longley-Rice graph to plot
            -o filename of topographic map to generate (.ppm)
            -u filename of user-defined terrain file to import
            -d sdf file directory path (overrides path in ~/.splat_path file)
            -m earth radius multiplier
            -n do not plot LOS paths in .ppm maps
            -N do not produce unnecessary site or obstruction reports
            -f frequency for Fresnel zone calculation (MHz)
            -R modify default range for -c or -L (miles/kilometers)
           -db maximum loss contour to display on path loss maps (80-230 dB)
           -nf do not plot Fresnel zones in height plots
           -fz Fresnel zone clearance percentage (default = 60)
          -ngs display greyscale topography as white in .ppm files
          -erp override ERP in .lrp file (Watts)
          -pli filename of path-loss input file
          -plo filename of path-loss output file
          -udt filename of user defined terrain input file
          -kml generate Google Earth (.kml) compatible output
          -geo generate an Xastir .geo georeference file (with .ppm output)
        -gpsav preserve gnuplot temporary working files after SPLAT! execution
       -metric employ metric rather than imperial units for all user I/O

INPUT FILES
       SPLAT!  is  a  command-line  driven  application  and  reads input data
       through a number of data files.  Some files are mandatory for  success-
       ful  execution  of  the  program, while others are optional.  Mandatory
       files include 3-arc second topography models in the form of SPLAT  Data
       Files  (SDF  files),  site location files (QTH files), and Longley-Rice
       model parameter files (LRP files).  Optional files include  city  loca-
       tion  files,  cartographic  boundary files, user-defined terrain files,
       path-loss input files, antenna radiation pattern files, and color defi-
       nition 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.  Geo-
       logical Survey Digital Elevation Models (DEMs) using the usgs2sdf util-
       ity  included  with  SPLAT!.   USGS Digital Elevation Models compatible
       with      this      utility      may      be      downloaded      from:
       http://edcftp.cr.usgs.gov/pub/data/DEM/250/.

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

       The strm2sdf utility may also be used to convert 3-arc second SRTM data
       in Band Interleaved by Line (.BIL) format for use  with  SPLAT!.   This
       data   is  available  via  the  web  at:  http://seamless.usgs.gov/web-
       site/seamless/

       Band Interleaved by Line data must be downloaded  in  a  very  specific
       manner  to  be  compatible  with  srtm2sdf  and SPLAT!.  Please consult
       srtm2sdf's documentation for instructions  on  downloading  .BIL  topo-
       graphic data through the USGS's Seamless Web Site.

       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 corresponding data found in existing SDF files (that
       were presumably created from earlier USGS  data  through  the  usgs2sdf
       utility).  If USGS-derived SDF data is not available, voids are handled
       through adjacent pixel averaging, or direct replacement.

       SPLAT Data Files  contain  integer  value  topographic  elevations  (in
       meters)  referenced  to mean sea level for 1-degree by 1-degree regions
       of the earth with a resolution 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  read slightly faster than files that have
       been compressed, SPLAT! searches for needed SDF  data  in  uncompressed
       format  first.   If  uncompressed  data  cannot be 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 Digi-
       tal  Elevation  Model  data.   However, this behavior of SPLAT!  under-
       scores the importance of having all the  SDF  files  required  for  the
       region being analyzed 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, or degrees East 0 to -360 degrees), and
       the site's antenna height above ground level (AGL), each separated by a
       single line-feed character.  The antenna height is assumed to be speci-
       fied 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 decimal format (74.6864) or degree, minute,  second
       (DMS) format (74 41 11.0).

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

               WNJT-DT
               40.2828
               74.6864
               990.00

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

LONGLEY-RICE PARAMETER (LRP) FILES
       Longley-Rice  parameter data files are required for SPLAT! to determine
       RF path loss in either point-to-point or area prediction  mode.   Long-
       ley-Rice  model  parameter data is read from files having the same base
       name as the transmitter site QTH  file,  but  with  a  .lrp  extension.
       SPLAT! LRP files share the following format (wnjt-dt.lrp):

               15.000  ; Earth Dielectric Constant (Relative permittivity)
               0.005   ; Earth Conductivity (Siemens per meter)
               301.000 ; Atmospheric Bending Constant (N-units)
               647.000 ; Frequency in MHz (20 MHz to 20 GHz)
               5       ; Radio Climate (5 = Continental Temperate)
               0       ; Polarization (0 = Horizontal, 1 = Vertical)
               0.50    ; Fraction of situations (50% of locations)
               0.90    ; Fraction of time (90% of the time)
               46000.0 ; ERP in Watts (optional)

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

       Typical Earth dielectric constants and conductivity values are as  fol-
       lows:
                                  Dielectric Constant  Conductivity
               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 Temper-
       ate climates.

       The  seventh  and  eighth parameters in the .lrp file correspond to the
       statistical analysis provided by the Longley-Rice model.  In this exam-
       ple, SPLAT! will return the maximum path loss occurring 50% of the time
       (fraction of time) in 90% of situations (fraction of situations).  This
       is  often  denoted  as F(50,90) in Longley-Rice studies.  In the United
       States, an F(50,90) criteria is typically used for  digital  television
       (8-level  VSB  modulation),  while  F(50,50)  is  used for analog (VSB-
       AM+NTSC) broadcasts.

       For  further  information  on  these  parameters,   see:   http://flat-
       top.its.bldrdoc.gov/itm.html   and  http://www.softwright.com/faq/engi-
       neering/prop_longley_rice.html

       The final parameter in the .lrp file corresponds to  the  transmitter's
       effective  radiated  power,  and is optional.  If it is included in the
       .lrp file, then SPLAT! will compute received signal strength levels and
       field strength level contours when performing Longley-Rice studies.  If
       the parameter is omitted, path loss is computed instead.  The ERP  pro-
       vided  in  the  .lrp file can be overridden by using SPLAT!'s -erp com-
       mand-line switch.  If the .lrp file contains an ERP parameter  and  the
       generation  of  path-loss  rather  than  signal  strength  contours  is
       desired, the ERP can be assigned to zero using the -erp switch  without
       having to edit the .lrp file to accomplish the same result.

CITY LOCATION FILES
       The  names  and  locations  of  cities, tower sites, or other points of
       interest may be imported and plotted on topographic maps  generated  by
       SPLAT!.   SPLAT!  imports  the names of cities and locations from ASCII
       files containing the location of interest's name, latitude, and  longi-
       tude.  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 longitude 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  annotations  do  not conflict with annotations of locations read
       earlier in the current city data file,  or  in  previous  files.   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 locations less important 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 citydecoder utility included with  SPLAT!.
       Such   data   is   available  free  of  charge  via  the  Internet  at:
       http://www.census.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 topographic 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 carto-
       graphic 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) operations.  SPLAT!'s CPU and memory scheduling prior-
       ity 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 generation.  Nearly all of SPLAT!'s
       switches may be cascaded in any order on the command line when invoking
       the program.

       SPLAT!  operates  in  two distinct modes: point-to-point mode, and area
       prediction mode.  Either a line-of-sight (LOS) or Longley-Rice  Irregu-
       lar  Terrain  (ITM) propagation model may be invoked by the user.  True
       Earth, four-thirds Earth, or any other user-defined Earth radius may be
       specified when performing line-of-sight analysis.

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

       splat -t tx_site.qth -r rx_site.qth

       invokes a line-of-sight terrain analysis between the transmitter speci-
       fied  in tx_site.qth and receiver specified in rx_site.qth using a True
       Earth radius model, and writes a SPLAT! Path  Analysis  Report  to  the
       current  working  directory.  The report contains details of the trans-
       mitter and receiver sites, and identifies the location of any  obstruc-
       tions  detected along the line-of-sight path.  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.
       Note that imperial units (miles, feet) are specified unless the -metric
       switch is added to SPLAT!'s command line options:

       splat -t tx_site.qth -r rx_site.qth -metric

       If the antenna must be raised a significant amount, this  determination
       may take a few moments.  Note that the results provided are the minimum
       necessary for a line-of-sight path to exist, and in the  case  of  this
       simple  example,  do  not take Fresnel zone clearance requirements into
       consideration.

       qth extensions are assumed by SPLAT! for QTH files,  and  are  optional
       when  specifying -t and -r arguments on the command-line.  SPLAT! auto-
       matically reads all SPLAT Data Files necessary to conduct  the  terrain
       analysis  between  the  sites  specified.   SPLAT!   searches  for  the
       required 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 of last resort to 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.png

       SPLAT! invokes gnuplot when generating graphs.  The filename  extension
       specified  to SPLAT! determines the format of the graph produced.  .png
       will produce a 640x480 color PNG graphic file, while .ps or .postscript
       will  produce  postscript output.  Output in formats such as GIF, Adobe
       Illustrator, AutoCAD dxf, LaTeX, and many others are available.  Please
       consult  gnuplot,  and  gnuplot's  documentation 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 gener-
       ated by using the -e switch:

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

       The graph produced using this  switch  illustrates  the  elevation  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 elevation 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 obstruc-
       tions can be clearly identified on the graph at the point(s) of  inter-
       section.

       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.png

       A  terrain  height  plot  normalized  to  the  transmitter and receiver
       antenna heights can be obtained using the -H switch:

       splat -t tx_site -r rx_site -H normalized_height_profile.png

       A contour of the Earth's curvature is also plotted in this mode.

       The first Fresnel Zone, and 60% of the first Fresnel Zone can be  added
       to height profile graphs by adding the -f switch, and specifying a fre-
       quency (in MHz) at which the Fresnel Zone should be modeled:

       splat -t tx_site -r rx_site -f 439.250 -H normalized_height_profile.png

       Fresnel Zone clearances other 60% can be specified using the -fz switch
       as follows:

       splat -t tx_site -r rx_site -f 439.250 -fz 75 -H height_profile2.png

       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.png

       As  before,  adding  the -metric switch forces the graphs to be plotted
       using metric units of measure.  The -gpsav switch instructs  SPLAT!  to
       preserve  (rather than delete) the gnuplot working files generated dur-
       ing SPLAT! execution, allowing the user to edit these files and  re-run
       gnuplot if desired.

       When  performing  a  point-to-point  analysis,  a  SPLAT! Path Analysis
       Report is generated in the form of a text file  with  a  .txt  filename
       extension.   The  report  contains  bearings  and distances between the
       transmitter and receiver, as well as the  free-space  and  Longley-Rice
       path loss for the path being analyzed.  The mode of propagation for the
       path  is  given  as  Line-of-Sight,  Single  Horizon,  Double  Horizon,
       Diffraction Dominant, or Troposcatter Dominant.

       Distances  and  locations  to known obstructions along the path between
       transmitter and receiver  are  also  provided.   If  the  transmitter's
       effective  radiated power is specified in the transmitter's correspond-
       ing .lrp file, then predicted signal strength and  antenna  voltage  at
       the receiving location is also provided in the Path Analysis Report.

       To  determine  the signal-to-noise (SNR) ratio at remote location where
       random Johnson (thermal) noise is the primary limiting factor in recep-
       tion:

       SNR=T-NJ-L+G-NF

       where  T  is  the ERP of the transmitter in dBW in the direction of the
       receiver, NJ is Johnson Noise in dBW (-136 dBW for a 6  MHz  television
       channel),  L  is the path loss provided by SPLAT!  in dB (as a positive
       number), 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 horizon).

       To compute how much more signal is available over the minimum to neces-
       sary to achieve a specific signal-to-noise ratio:

       Signal_Margin=SNR-S

       where  S  is  the minimum required SNR ratio (15.5 dB for ATSC (8-level
       VSB) 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 perspec-
       tive.  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.

       Topographic output is invoked 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  locations  of  the
       transmitter  and receiver sites specified.  In addition, the great cir-
       cle 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  loca-
       tions  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  fol-
       lowing 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.png

       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.

       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.  ImageMagick's command-line utility easily converts SPLAT!'s PPM
       files to PNG format:

       convert splat_map.ppm splat_map.png

       Another excellent PPM to PNG  command-line  utility  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.

       The -ngs option assigns all terrain to the color white, and can be used
       when it is desirable to generate a map that is devoid of terrain:

       splat -t tx_site -r rx_site -b co34_d00.dat -ngs -o white_map

       The resulting .ppm image file can be converted to .png  format  with  a
       transparent background using ImageMagick's convert utility:

       convert -transparent "#FFFFFF" white_map.ppm transparent_map.png


REGIONAL COVERAGE ANALYSIS
       SPLAT! can analyze a transmitter or repeater site, or network of sites,
       and predict the regional coverage for each  site  specified.   In  this
       mode,  SPLAT!  can  generate a topographic map displaying the geometric
       line-of-sight coverage 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.  A regional analysis may be performed by SPLAT! using
       the -c switch 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_cover-
       age.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).  If the -metric switch is used, the  argument  fol-
       lowing  the  -c switch is interpreted as being in meters rather than in
       feet.  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 bend-
       ing.   However, this behavior may be modified by using the Earth radius
       multiplier (-m) switch:

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

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

       When performing a regional analysis, 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 aver-
       age  terrain,  and  the height of the average terrain calculated toward
       the bearings of 0, 45, 90, 135, 180, 225, 270, and 315 degrees azimuth.

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

       splat -t site1 site2 site3 site4 -c 10.0 -metric -o network.ppm

       plots  the  regional line-of-sight coverage of site1, site2, site3, and
       site4 based on a receive  antenna  located  10.0  meters  above  ground
       level.  A topographic map is then written to the file network.ppm.  The
       line-of-sight coverage area of the transmitters are plotted as  follows
       in  the  colors indicated (along with their corresponding RGB values 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  loca-
       tions on a single tower may be generated by SPLAT!.

LONGLEY-RICE PATH LOSS ANALYSIS
       If  the  -c switch is replaced by a -L switch, a Longley-Rice path loss
       map for a transmitter site may be generated:

       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 illustrating  expected
       signal  levels  in areas surrounding the transmitter site.  A legend at
       the bottom of the map correlates each color with a specific  path  loss
       range in decibels or signal strength in decibels over one microvolt per
       meter (dBuV/m).

       The Longley-Rice analysis range may  be  modified  to  a  user-specific
       value  using  the  -R  switch.  The argument must be given in miles (or
       kilometers if the -metric switch is used).  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  pre-
       diction map.

       The  -db  switch  allows  a constraint to be placed on the maximum path
       loss region plotted on the map.  A maximum 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
       attenuation contour as follows:

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


SIGNAL CONTOUR COLOR DEFINITION PARAMETERS
       The colors used to illustrate signal strength and path loss contours in
       SPLAT! generated coverage maps may be tailored by the user by  creating
       or  modifying SPLAT!'s color definition files.  SPLAT! color definition
       files have the same base name as the transmitter's .qth file, but carry
       .lcf and .scf extensions.

       When  a  regional  Longley-Rice analysis is performed and the transmit-
       ter's ERP is not specified or is zero, a .lcf path loss  color  defini-
       tion  file  corresponding  to  the  transmitter  site (.qth) is read by
       SPLAT! from the current working directory.  If a .lcf file  correspond-
       ing  to the transmitter site is not found, then a default file suitable
       for manual editing by the user is automatically  generated  by  SPLAT!.
       If  the  transmitter's  ERP is specified, then a signal strength map is
       generated and a signal strength color definition file (.scf)  is  read,
       or  generated if one is not available in the current working directory.

       A path-loss color definition file  possesses  the  following  structure
       (wnjt-dt.lcf):

        ;  SPLAT!  Auto-generated  Path-Loss  Color Definition ("wnjt-dt.lcf")
       File
        ;
        ; Format for the parameters held in this file is as follows:
        ;
        ;    dB: red, green, blue
        ;
        ; ...where "dB" is the path loss (in dB) and
        ; "red", "green", and "blue" are the corresponding RGB color
        ; definitions ranging from 0 to 255 for the region specified.
        ;
        ; The following parameters may be edited and/or expanded
        ; for future runs of SPLAT!  A total of 32 contour regions
        ; may be defined in this file.
        ;
        ;
         80: 255,   0,   0
         90: 255, 128,   0
        100: 255, 165,   0
        110: 255, 206,   0
        120: 255, 255,   0
        130: 184, 255,   0
        140:   0, 255,   0
        150:   0, 208,   0
        160:   0, 196, 196
        170:   0, 148, 255
        180:  80,  80, 255
        190:   0,  38, 255
        200: 142,  63, 255
        210: 196,  54, 255
        220: 255,   0, 255
        230: 255, 194, 204

       If the path loss is less than 80 dB, the color Red (RGB = 255, 0, 0) is
       assigned  to  the region.  If the path-loss is greater than or equal to
       80 dB, but less than 90 db, then Dark Orange (255, 128, 0) is  assigned
       to  the  region.   Orange (255, 165, 0) is assigned to regions having a
       path loss greater than or equal to 90 dB, but less than 100 dB, and  so
       on.   Greyscale  terrain  is displayed beyond the 230 dB path loss con-
       tour.

       SPLAT! signal strength color definition  files  share  a  very  similar
       structure (wnjt-dt.scf):

        ; SPLAT! Auto-generated Signal Color Definition ("wnjt-dt.scf") File
        ;
        ; Format for the parameters held in this file is as follows:
        ;
        ;    dBuV/m: red, green, blue
        ;
        ; ...where "dBuV/m" is the signal strength (in dBuV/m) and
        ; "red", "green", and "blue" are the corresponding RGB color
        ; definitions ranging from 0 to 255 for the region specified.
        ;
        ; The following parameters may be edited and/or expanded
        ; for future runs of SPLAT!  A total of 32 contour regions
        ; may be defined in this file.
        ;
        ;
        128: 255,   0,   0
        118: 255, 165,   0
        108: 255, 206,   0
         98: 255, 255,   0
         88: 184, 255,   0
         78:   0, 255,   0
         68:   0, 208,   0
         58:   0, 196, 196
         48:   0, 148, 255
         38:  80,  80, 255
         28:   0,  38, 255
         18: 142,  63, 255
          8: 140,   0, 128

       If the signal strength is greater than or equal to 128 db over 1 micro-
       volt per meter (dBuV/m), the color Red (255, 0, 0) is displayed for the
       region.  If the signal strength is greater than or equal to 118 dbuV/m,
       but less than 128 dbuV/m, then the color Orange (255, 165, 0)  is  dis-
       played,  and  so  on.   Greyscale terrain is displayed for regions with
       signal strengths less than 8 dBuV/m.

       Signal strength contours for some common VHF and UHF broadcasting  ser-
       vices in the United States are as follows:

              Analog Television Broadcasting
              ------------------------------
              Channels 2-6:       City Grade: >= 74 dBuV/m
                                     Grade A: >= 68 dBuV/m
                                     Grade B: >= 47 dBuV/m
              --------------------------------------------
              Channels 7-13:      City Grade: >= 77 dBuV/m
                                     Grade A: >= 71 dBuV/m
                                     Grade B: >= 56 dBuV/m
              --------------------------------------------
              Channels 14-69:   Indoor Grade: >= 94 dBuV/m
                                  City Grade: >= 80 dBuV/m
                                     Grade A: >= 74 dBuV/m
                                     Grade B: >= 64 dBuV/m

              Digital Television Broadcasting
              -------------------------------
              Channels 2-6:       City Grade: >= 35 dBuV/m
                           Service Threshold: >= 28 dBuV/m
              --------------------------------------------
              Channels 7-13:      City Grade: >= 43 dBuV/m
                           Service Threshold: >= 36 dBuV/m
              --------------------------------------------
              Channels 14-69:     City Grade: >= 48 dBuV/m
                           Service Threshold: >= 41 dBuV/m

              NOAA Weather Radio (162.400 - 162.550 MHz)
              ------------------------------------------
                         Reliable: >= 18 dBuV/m
                     Not reliable: <  18 dBuV/m
              Unlikely to receive: <  0 dBuV/m

              FM Radio Broadcasting (88.1 - 107.9 MHz)
              ----------------------------------------
              Analog Service Contour:  60 dBuV/m
              Digital Service Contour: 65 dBuV/m


ANTENNA RADIATION PATTERN PARAMETERS
       Normalized field voltage patterns for a transmitting antenna's horizon-
       tal and vertical planes are imported automatically into SPLAT!  when  a
       Longley-Rice  coverage  analysis is performed.  Antenna pattern data is
       read from a pair of files having the same base name as the  transmitter
       and  LRP  files, but with .az and .el extensions for azimuth and eleva-
       tion pattern files,  respectively.   Specifications  regarding  pattern
       rotation  (if any) and mechanical beam tilt and tilt direction (if any)
       are also contained within SPLAT! antenna pattern files.

       For example, the first few lines of a SPLAT! azimuth pattern file might
       appear as follows (kvea.az):

               183.0
               0       0.8950590
               1       0.8966406
               2       0.8981447
               3       0.8995795
               4       0.9009535
               5       0.9022749
               6       0.9035517
               7       0.9047923
               8       0.9060051

       The  first  line of the .az file specifies the amount of azimuthal pat-
       tern rotation (measured clockwise in degrees from  True  North)  to  be
       applied  by SPLAT! to the data contained in the .az file.  This is fol-
       lowed by azimuth headings (0 to 360 degrees) and their associated  nor-
       malized field patterns (0.000 to 1.000) separated by whitespace.

       The  structure of SPLAT! elevation pattern files is slightly different.
       The first line of the .el file specifies the amount of mechanical  beam
       tilt  applied  to  the  antenna.   Note that a downward tilt (below the
       horizon) is expressed as a positive angle, while an upward tilt  (above
       the  horizon)  is expressed as a negative angle.  This data is followed
       by the azimuthal direction of the tilt, separated by whitespace.

       The remainder of the file consists of elevation angles and their corre-
       sponding  normalized  voltage radiation pattern (0.000 to 1.000) values
       separated by whitespace.  Elevation angles must  be  specified  over  a
       -10.0  to  +90.0  degree  range.  As was the convention with mechanical
       beamtilt, negative elevation angles are used  to  represent  elevations
       above  the  horizon,  while positive angles represents elevations below
       the horizon.

       For example, the first few lines a SPLAT! elevation pattern file  might
       appear as follows (kvea.el):

               1.1    130.0
              -10.0   0.172
              -9.5    0.109
              -9.0    0.115
              -8.5    0.155
              -8.0    0.157
              -7.5    0.104
              -7.0    0.029
              -6.5    0.109
              -6.0    0.185

       In  this  example,  the  antenna  is  mechanically  tilted downward 1.1
       degrees towards an azimuth of 130.0 degrees.

       For best results, the resolution of  azimuth  pattern  data  should  be
       specified  to  the  nearest  degree azimuth, and elevation pattern data
       resolution should be specified to the nearest  0.01  degrees.   If  the
       pattern  data specified does not reach this level of resolution, SPLAT!
       will interpolate the values provided  to  determine  the  data  at  the
       required resolution, although this may result in a loss in accuracy.


IMPORTING AND EXPORTING REGIONAL PATH LOSS CONTOUR DATA
       Performing  a Longley-Rice coverage analysis can be a very time consum-
       ing process, especially if the analysis is repeated repeatedly to  dis-
       cover  what  effects  changes to the antenna radiation patterns make to
       the predicted coverage area.

       This process can be expedited by exporting  the  Longley-Rice  regional
       path  loss contour data to an output file, modifying the path loss data
       externally to incorporate antenna pattern effects, and  then  importing
       the  modified  path  loss  data  back into SPLAT!  to rapidly produce a
       revised path loss map.

       For example, a path loss output file can be generated by SPLAT!  for  a
       receive site 30 feet above ground level over a 50 mile radius surround-
       ing a transmitter site to a maximum path loss of 140 dB using the  fol-
       lowing syntax:

       splat -t kvea -L 30.0 -R 50.0 -db 140 -plo pathloss.dat

       SPLAT! path loss output files often exceed 100 megabytes in size.  They
       contain information relating to the boundaries of region they  describe
       followed  by  latitudes  (degrees  North),  longitudes  (degrees West),
       azimuths, elevations (to the first obstruction), and path loss  figures
       (dB) for a series of specific points that comprise the region surround-
       ing the transmitter site.  The first few lines of a  SPLAT!  path  loss
       output file take on the following appearance (pathloss.dat):

               119, 117    ; max_west, min_west
               35, 33      ; max_north, min_north
               34.2265434, 118.0631104, 48.171, -37.461, 67.70
               34.2270355, 118.0624390, 48.262, -26.212, 73.72
               34.2280197, 118.0611038, 48.269, -14.951, 79.74
               34.2285156, 118.0604401, 48.207, -11.351, 81.68
               34.2290077, 118.0597687, 48.240, -10.518, 83.26
               34.2294998, 118.0591049, 48.225, 23.201, 84.60
               34.2304878, 118.0577698, 48.213, 15.769, 137.84
               34.2309799, 118.0570984, 48.234, 15.965, 151.54
               34.2314720, 118.0564346, 48.224, 16.520, 149.45
               34.2319679, 118.0557632, 48.223, 15.588, 151.61
               34.2329521, 118.0544281, 48.230, 13.889, 135.45
               34.2334442, 118.0537643, 48.223, 11.693, 137.37
               34.2339401, 118.0530930, 48.222, 14.050, 126.32
               34.2344322, 118.0524292, 48.216, 16.274, 156.28
               34.2354164, 118.0510941, 48.222, 15.058, 152.65
               34.2359123, 118.0504227, 48.221, 16.215, 158.57
               34.2364044, 118.0497589, 48.216, 15.024, 157.30
               34.2368965, 118.0490875, 48.225, 17.184, 156.36

       It  is  not uncommon for SPLAT! path loss files to contain as many as 3
       million or more lines of data.  Comments can be placed in the  file  if
       they  are  proceeded by a semicolon character.  The vim text editor has
       proven capable of editing files of this size.

       Note as was the case in the antenna pattern files,  negative  elevation
       angles  refer to upward tilt (above the horizon), while positive angles
       refer to downward tilt (below the horizon).  These angles refer to  the
       elevation  to  the  receiving  antenna at the height above ground level
       specified using the -L switch  if  the  path  between  transmitter  and
       receiver  is  unobstructed.   If  the  path between the transmitter and
       receiver is obstructed, then the elevation angle to the first  obstruc-
       tion  is  returned  by  SPLAT!.  This is because the Longley-Rice model
       considers the energy reaching a distant point over an  obstructed  path
       as  a  derivative  of  the  energy  scattered from the top of the first
       obstruction, only.  Since energy cannot reach the  obstructed  location
       directly, the actual elevation angle to that point is irrelevant.

       When  modifying SPLAT! path loss files to reflect antenna pattern data,
       only the last column (path loss)  should  be  amended  to  reflect  the
       antenna's normalized gain at the azimuth and elevation angles specified
       in the file.  (At this time, programs and scripts capable of performing
       this operation are left as an exercise for the user.)

       Modified path loss maps can be imported back into SPLAT! for generating
       revised coverage maps:

       splat -t kvea -pli pathloss.dat -s city.dat -b county.dat -o map.ppm

       SPLAT! path loss files can also be  used  for  conducting  coverage  or
       interference studies outside of SPLAT!.

USER-DEFINED TERRAIN INPUT FILES
       A  user-defined  terrain  file is a user-generated text file containing
       latitudes, longitudes, and heights above ground level of specific  ter-
       rain features believed to be of importance to the SPLAT! analysis being
       conducted, but noticeably absent from the  SDF  files  being  used.   A
       user-defined  terrain file is imported into a SPLAT! analysis using the
       -udt switch:

        splat -t tx_site -r rx_site -udt udt_file.txt -o map.ppm

       A user-defined terrain file has the following appearance and structure:

              40.32180556, 74.1325, 100.0 meters
              40.321805, 74.1315, 300.0
              40.3218055, 74.1305, 100.0 meters

       Terrain  height  is interpreted as being described in feet above ground
       level unless followed by the word meters, and is added on  top  of  the
       terrain  specified  in  the  SDF  data for the locations specified.  Be
       aware that each user-defined terrain feature specified will  be  inter-
       preted as being 3-arc seconds in both latitude and longitude.  Features
       described in the user-defined  terrain  file  that  overlap  previously
       defined features in the file are ignored by SPLAT!.

SIMPLE 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 follows:

       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  a  topographic  map  centered  about a single site out to a minimum
       specified radius is desired instead, a command similar to the following
       can be used:

       splat -t tx_site -R 50.0 -s NJ_Cities -b NJ_Counties -o topo_map.ppm

       where  -R  specifies the minimum radius of the map in miles (or kilome-
       ters if the -metric switch is used).  Note that the  tx_site  name  and
       location  are not displayed in this example.  If display of this infor-
       mation is desired, simply create a SPLAT! city  file  (-s  option)  and
       append it to the list of command-line options illustrated above.

       If  the  -o switch and output filename are omitted in these operations,
       topographic output is written to a file named tx_site.ppm in  the  cur-
       rent working directory by default.

GEOREFERENCE FILE GENERATION
       Topographic,  coverage  (-c), and path loss contour (-L) maps generated
       by SPLAT! may be imported into Xastir (X Amateur Station  Tracking  and
       Information Reporting) software by generating a georeference file using
       SPLAT!'s -geo switch:

       splat -t kd2bd -R 50.0 -s NJ_Cities -b NJ_Counties -geo -o map.ppm

       The georeference file generated will have the same base name as the  -o
       file specified, but have a  .geo extension, and permit proper interpre-
       tation and display of SPLAT!'s .ppm graphics in Xastir software.

GOOGLE MAP KML FILE GENERATION
       Keyhole Markup Language files compatible with Google Earth may be  gen-
       erated  by  SPLAT!  when performing point-to-point or regional coverage
       analyses by invoking the -kml switch:

       splat -t wnjt-dt -r kd2bd -kml

       The KML file generated will have the same filename structure as a  Path
       Analysis  Report  for  the  transmitter  and receiver site names given,
       except it will carry a  .kml extension.

       Once loaded into Google Earth (File --> Open), the KML file will  anno-
       tate  the  map  display  with the names of the transmitter and receiver
       site locations.  The viewpoint of the image will be from  the  position
       of  the  transmitter site looking towards the location of the receiver.
       The point-to-point path between the sites will be displayed as a  white
       line  while  the  RF  line-of-sight  path  will  be displayed in green.
       Google Earth's navigation tools allow the  user  to  "fly"  around  the
       path, identify landmarks, roads, and other featured content.

       When performing regional coverage analysis, the  .kml file generated by
       SPLAT! will permit path loss or signal strength contours to be  layered
       on  top  of  Google  Earth's display in a semi-transparent manner.  The
       generated .kml file will have the same basename as  that  of  the  .ppm
       file normally generated.

DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
       SPLAT! determines antenna height above average terrain (HAAT) according
       to the procedure defined  by  Federal  Communications  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 available), then those radials are omitted from
       the calculation 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 compliance 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  ques-
       tion  does  not  lie  within 10 miles of the boundary of the topography
       data in memory.

       When performing area prediction analysis,  enough  topography  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 generated site report.  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 "pages" within
       the  structure  of  the program.  Each "page" holds one SDF file repre-
       senting a one degree by one degree region of terrain.  A  #define  MAX-
       PAGES  statement in the first several lines of splat.cpp sets the maxi-
       mum number of "pages" available for holding topography data.   It  also
       sets  the  maximum  size  of  the topographic maps generated by SPLAT!.
       MAXPAGES is set to 9 by default.  If SPLAT!   produces  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  the  number  of  MAXPAGES specified.  In situations where
       available memory is low, MAXPAGES may be reduced to 4 with  the  under-
       standing 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 MAXPAGES may be increased to 16.  This
       will permit operation over a 4-degree by 4-degree region, which is suf-
       ficient  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
       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>
              Original Longley-Rice Model integration

       Ron Bentley <ronbentley@embarqmail.com>
              Fresnel Zone plotting and clearance determination




KD2BD Software                   16 July 2008                        SPLAT!(1)
