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/meters) (float)] [-L rx antenna height for  Longley-
       Rice  coverage  analysis  (feet/meters)  (float)] [-p ter-
       rain_profile.ext]    [-e    elevation_profile.ext]     [-h
       height_profile.ext] [-H normalized_height_profile.ext] [-l
       Longley-Rice_profile.ext]    [-o     topographic_map_file-
       name.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 con-
       tour to display on path loss maps (80-230 dB)] [-fz  Fres-
       nel  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] [-metric]

DESCRIPTION
       SPLAT! is a powerful terrestrial RF propagation  and  ter-
       rain  analysis tool for the spectrum between 20 MHz and 20
       GHz.  SPLAT! is free software, and is designed for  opera-
       tion on Unix and Linux-based workstations.  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 viola-
       tion 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
       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 ele-
       vation  angles  (uptilt),  depression  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  percentage  of
       the first Fresnel zone are also provided.

       SPLAT! produces reports, graphs, and high resolution topo-
       graphic maps that depict line-of-sight paths, and regional
       path  loss  and  signal  strength  contours  through which
       expected coverage areas of transmitters and repeater  sys-
       tems  can  be obtained.  When performing line-of-sight and
       Longley-Rice analyses in situations where multiple  trans-
       mitter  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 sum-
       mary of SPLAT!'s command line options:


                    --==[  SPLAT!  v1.2.1  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/kilome-
       ters)
           -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)  -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 successful 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  location  files,  cartographic boundary files, user-
       defined terrain  files,  path-loss  input  files,  antenna
       radiation pattern files, and color definition 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  and  accuracy  can   be
       obtained  through the use of SRTM-3 Version 2 digital ele-
       vation 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 utility.  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/website/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 topographic 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 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 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  com-
       pressed  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.
       However, this behavior of SPLAT!  underscores  the  impor-
       tance  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  specified  in  feet
       unless  followed  by  the  letter  m or the word meters in
       either upper or lower case.  Latitude and longitude infor-
       mation 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 represented 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.   Longley-Rice  model  parameter data is
       read from files having the same base name as the transmit-
       ter site QTH file, but with a format (wnjt-dt.lrp):

               15.000  ; Earth Dielectric Constant (Relative per-
       mittivity)
               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  Temper-
       ate)
               0       ; Polarization (0 = Horizontal, 1 = Verti-
       cal)
               0.50    ; Fraction of  situations  (50%  of  loca-
       tions)
               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 can-
       not 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  direc-
       tory.   The  generated "splat.lrp" file 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 seventh and eighth parameters in the .lrp file  corre-
       spond to the statistical analysis provided by the Longley-
       Rice model.  In this example, SPLAT! will return the maxi-
       mum 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://flattop.its.bldrdoc.gov/itm.html                and
       http://www.softwright.com/faq/engineering/prop_long-
       ley_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 levels and field strength level
       contours when performing  Longley-Rice  studies.   If  the
       parameter  is omitted, path loss is computed instead.  The
       ERP provided in the .lrp file can be overridden  by  using
       SPLAT!'s  -erp command-line switch.  If the .lrp file con-
       tains 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 hav-
       ing 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  topo-
       graphic  maps  generated  by  SPLAT!.   SPLAT! imports the
       names of cities and locations from ASCII files  containing
       the  location of interest's name, latitude, and longitude.
       Each field is separated by a comma.  Each record is  sepa-
       rated  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 anno-
       tations 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!  gener-
       ated  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 fur-
       ther 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.

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

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  line-of-sight  terrain  analysis  between  the
       transmitter  specified  in tx_site.qth and receiver speci-
       fied in rx_site.qth using a True Earth radius  model,  and
       writes  a SPLAT! Path Analysis Report to the current work-
       ing directory.  The report contains details of the  trans-
       mitter  and receiver sites, and identifies the location of
       any obstructions 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  exam-
       ple,  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! automatically 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 file-
       name 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 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.png

       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.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_pro-
       file.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 frequency (in MHz) at which the
       Fresnel Zone should be modeled:

       splat  -t  tx_site  -r  rx_site  -f  439.250  -H   normal-
       ized_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.

       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 bear-
       ings 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  corresponding .lrp file, then pre-
       dicted signal strength and antenna voltage at the  receiv-
       ing 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 pri-
       mary limiting factor in reception:

       SNR=T-NJ-L+G-NF

       where T is the ERP of the transmitter in dBW in the direc-
       tion of the receiver, NJ is Johnson Noise in dBW (-136 dBW
       for a 6 MHz television channel), L is the path  loss  pro-
       vided  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 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 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  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.

       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  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.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  transpar-
       ent_map.png

REGIONAL COVERAGE ANALYSIS
       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.  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_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).  If
       the -metric switch is used, the argument following 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 bending.   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  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 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  average
       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 example:

       splat  -t  site1 site2 site3 site4 -c 10.0 -metric -o net-
       work.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 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!.

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  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 in areas surrounding the
       transmitter site.  A legend at the bottom of the map  cor-
       relates  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
       prediction 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
       transmitter's ERP is not specified or is zero, a .lcf path
       loss  color definition file corresponding to the transmit-
       ter site (.qth) is read by SPLAT! from the current working
       directory.   If a .lcf file corresponding to the transmit-
       ter 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 fol-
       lows:
        ;
        ;    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 speci-
       fied.
        ;
        ; 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 contour.

       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  fol-
       lows:
        ;
        ;    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 speci-
       fied.
        ;
        ; 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 microvolt 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 displayed,
       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 services 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 horizontal  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 transmit-
       ter and LRP files, but with .az  and  .el  extensions  for
       azimuth and elevation pattern files, respectively.  Speci-
       fications regarding pattern rotation (if any) and mechani-
       cal  beam  tilt  and tilt direction (if any) are also con-
       tained within SPLAT! antenna pattern files.

       For example, the first few lines of a SPLAT! azimuth  pat-
       tern 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 pattern rotation (measured clockwise in  degrees
       from  True North) to be applied by SPLAT! to the data con-
       tained in the .az file.  This is followed by azimuth head-
       ings  (0  to  360 degrees) and their associated normalized
       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 speci-
       fies 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,  sepa-
       rated by whitespace.

       The remainder of the file consists of elevation angles and
       their corresponding normalized voltage  radiation  pattern
       (0.000  to  1.000) values separated by whitespace.  Eleva-
       tion 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 eleva-
       tions below the horizon.

       For example, the first few lines a SPLAT!  elevation  pat-
       tern 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 down-
       ward 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 consuming process,  especially  if  the  analysis  is
       repeated  repeatedly  to  discover what effects changes to
       the antenna radiation patterns make to the predicted  cov-
       erage 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 surrounding a transmitter site to a maxi-
       mum path loss of 140 dB using the following 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  bound-
       aries  of  region  they  describe  followed  by  latitudes
       (degrees North), longitudes (degrees West), azimuths, ele-
       vations  (to the first obstruction), and path loss figures
       (dB) for a series of specific  points  that  comprise  the
       region  surrounding  the  transmitter site.  The first few
       lines of a SPLAT! path loss output file take on  the  fol-
       lowing 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, nega-
       tive 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  trans-
       mitter  and receiver is unobstructed.  If the path between
       the transmitter and receiver is obstructed, then the  ele-
       vation  angle  to  the  first  obstruction  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  terrain  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  interpreted  as
       being  3-arc seconds in both latitude and longitude.  Fea-
       tures 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 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 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 kilometers if the -metric switch is used).  Note  that
       the  tx_site  name  and location are not displayed in this
       example.  If display of this information is desired,  sim-
       ply 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 current 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)  soft-
       ware 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 interpretation 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 generated 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 struc-
       ture 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  annotate 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  dis-
       played  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 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.

       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 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 representing a one degree by one degree
       region  of  terrain.   A #define MAXPAGES statement in the
       first several lines of splat.cpp sets the  maximum  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!  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  the
       number  of MAXPAGES specified.  In situations where avail-
       able memory is low, MAXPAGES may be reduced to 4 with  the
       understanding  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 avail-
       able, then MAXPAGES may be increased  to  16.   This  will
       permit operation over a 4-degree by 4-degree region, which
       is sufficient for single  antenna  heights  in  excess  of
       10,000  feet  above mean sea level, or point-to-point dis-
       tances 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@earthlink.net>
              Fresnel Zone plotting and clearance determination




KD2BD Software          16 September 2007               SPLAT!(1)
