NAME
- splat - A Signal Propagation, Loss, And Terrain analysis
- tool
+ splat - An RF Signal Propagation, Loss, And Terrain analy-
+ sis tool
SYNOPSIS
- splat [-t transmitter_site.qth] [-r receiver_site.qth] [-c
- rx_antenna_height_for_los_coverage_analysis (feet)
- (float)] [-L rx_antenna_height_for_Longley-Rice_cover-
- age_analysis (feet) (float)] [-p terrain_profile.ext] [-e
- elevation_profile.ext] [-h height_profile.ext] [-l Long-
- ley-Rice_profile.ext] [-o topographic_map_filename.ppm]
- [-b cartographic_boundary_filename.dat] [-s
- site/city_database.dat] [-d sdf_directory_path] [-m
+ splat [-t transmitter_site.qth] [-r receiver_site.qth]
+ [-c rx_antenna_height_for_los_coverage_analysis (feet)
+ (float)] [-L rx_antenna_height_for_Longley-Rice_cover-
+ age_analysis (feet) (float)] [-p terrain_profile.ext] [-e
+ elevation_profile.ext] [-h height_profile.ext] [-l Long-
+ ley-Rice_profile.ext] [-o topographic_map_filename.ppm]
+ [-b cartographic_boundary_filename.dat] [-s
+ site/city_database.dat] [-d sdf_directory_path] [-m
earth_radius_multiplier (float)] [-R maximum_cover-
- age_range (for -c or -L) (miles) (float)] [-n] [-N]
+ age_range (for -c or -L) (miles) (float)] [-dB maximum
+ attenuation contour to display on path loss maps (80-230
+ dB)] [-n] [-N]
DESCRIPTION
- SPLAT! is a simple, yet powerful terrain analysis tool
- written for Unix and Linux-based workstations. SPLAT! is
- free software. Redistribution and/or modification is per-
- mitted under the terms of the GNU General Public License
- as published by the Free Software Foundation, either ver-
- sion 2 of the License or any later version. Adoption of
- SPLAT! source code in proprietary or closed-source appli-
- cations is a violation of this license, and is strictly
- forbidden.
-
- SPLAT! is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY, without even the implied war-
- ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
+ SPLAT! is a powerful terrestrial RF propagation and ter-
+ rain analysis tool covering the spectrum between 20 MHz
+ and 20 GHz. It is designed for operation on Unix and
+ Linux-based workstations. SPLAT! is free software.
+ Redistribution and/or modification is permitted under the
+ terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 2 of the
+ License or any later version. Adoption of SPLAT! source
+ code in proprietary or closed-source applications is a
+ violation of this license, and is strictly forbidden.
+
+ SPLAT! is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY, without even the implied war-
+ ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE. See the GNU General Public License for more details.
INTRODUCTION
- SPLAT! is a terrestrial RF propagation analysis tool for
- the spectrum between 20 MHz and 20 GHz, and provides
- information of interest to communication system designers
- and site engineers. SPLAT! determines great circle dis-
- tances and bearings between sites, antenna elevation
- angles (uptilt), depression angles (downtilt), antenna
- height above mean sea level, antenna height above average
- terrain, bearings and distances to known obstructions,
- Longley-Rice path loss, and minimum antenna height
- requirements needed to establish line-of-sight communica-
- tion paths absent of obstructions due to terrain. SPLAT!
- produces reports, graphs, and highly detailed and care-
- fully annotated topographic maps depicting line-of-sight
- paths, path loss, and expected coverage areas of transmit-
- ters and repeater systems. When performing line-of-sight
- analysis in situations where multiple transmitter or
- repeater sites are employed, SPLAT! determines individual
- and mutual areas of coverage within the network specified.
-
- SPLAT! operates in two modes: point-to-point mode, and
- area prediction mode. These modes may be invoked using
- either line-of-sight (LOS) or Irregular Terrain (ITM)
+ Applications of SPLAT! include the visualization, design,
+ and link budget analysis of wireless Wide Area Networks
+ (WANs), commercial and amateur radio communication systems
+ above 20 MHz, microwave links, frequency coordination, and
+ the determination of analog and digital terrestrial radio
+ and television contour regions.
+
+ SPLAT! provides RF site engineering data such as great
+ circle distances and bearings between sites, antenna ele-
+ vation angles (uptilt), depression angles (downtilt),
+ antenna height above mean sea level, antenna height above
+ average terrain, bearings and distances to known obstruc-
+ tions, Longley-Rice path attenuation, and minimum antenna
+ height requirements needed to establish line-of-sight com-
+ munication paths absent of obstructions due to terrain.
+ SPLAT! produces reports, graphs, and highly detailed and
+ carefully annotated topographic maps depicting line-of-
+ sight paths, path loss, and expected coverage areas of
+ transmitters and repeater systems. When performing line-
+ of-sight analysis in situations where multiple transmitter
+ or repeater sites are employed, SPLAT! determines individ-
+ ual and mutual areas of coverage within the network speci-
+ fied.
+
+ SPLAT! operates in two distinct modes: point-to-point
+ mode, and area prediction mode, and may be invoked using
+ either line-of-sight (LOS) or Irregular Terrain (ITM)
propagation models. True Earth, four-thirds Earth, or any
- other Earth radius may be specified by the user when per-
+ other Earth radius may be specified by the user when per-
forming line-of-sight analysis.
INPUT FILES
- SPLAT! is a command-line driven application, and reads
- input data through a number of data files. Each has its
- own format. Some files are mandatory for successful exe-
- cution of the program, while others are optional. Manda-
- tory files include SPLAT Data Files (SDF files), site
- location files (QTH files), and Longley-Rice model parame-
- ter files (LRP files). Optional files include city/site
- location files, and cartographic boundary files.
+ SPLAT! is a command-line driven application, and reads
+ input data through a number of data files. Some files are
+ mandatory for successful execution of the program, while
+ others are optional. Mandatory files include SPLAT Data
+ Files (SDF files), site location files (QTH files), and
+ Longley-Rice model parameter files (LRP files). Optional
+ files include city/site location files, and cartographic
+ boundary files.
SPLAT DATA FILES
- SPLAT! imports topographic data in the form of SPLAT Data
- Files (SDFs) that may be generated from a number of infor-
- mation sources. In the United States, SPLAT Data Files
- are most often derived from U.S. Geological Survey Digi-
- tal Elevation Models (DEMs) using the usgs2sdf utility
- included with SPLAT!. USGS Digital Elevation Models com-
- patible with this utility are available at no cost via the
- Internet at: http://edc-
- sgs9.cr.usgs.gov/glis/hyper/guide/1_dgr_dem-
- fig/index1m.html.
-
- SPLAT Data Files contain topographic elevations to the
- nearest meter above 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 utility, or in bzip2
- compressed format (.sdf.bz2). Since uncompressed files
- can be slightly faster to load than compressed files,
+ SPLAT! imports topographic data in the form of SPLAT Data
+ Files (SDFs). These files may be generated from a number
+ of information sources. In the United States, SPLAT Data
+ Files can be generated through U.S. Geological Survey
+ Digital Elevation Models (DEMs) using the usgs2sdf utility
+ included with SPLAT!. USGS Digital Elevation Models com-
+ patible with this utility may be downloaded from:
+ http://edcftp.cr.usgs.gov/pub/data/DEM/250/.
+
+ Significantly better resolution can be obtained through
+ the use of SRTM-3 Version 2 digital elevation models.
+ These models are the result of the STS-99 Space Shuttle
+ Radar Topography Mission, and are available for most popu-
+ lated regions of the Earth. SPLAT Data Files may be gen-
+ erated from SRTM data using the included srtm2sdf utility.
+ SRTM-3 Version 2 data may be obtained through anonymous
+ FTP from: ftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/
+
+ Despite the higher accuracy that SRTM data has to offer,
+ some voids in the data sets exist. When voids are
+ detected, the srtm2sdf utility replaces them with corre-
+ sponding data found in existing SDF files (that were pre-
+ sumably created from earlier USGS data through the
+ usgs2sdf utility). If USGS-derived SDF data is not avail-
+ able, voids are handled through adjacent pixel averaging,
+ or direct replacement.
+
+ SPLAT Data Files contain integer value topographic eleva-
+ tions (in meters) referenced to mean sea level for
+ 1-degree by 1-degree regions of the earth with a resolu-
+ tion of 3-arc seconds. SDF files can be read in either
+ standard format (.sdf) as generated by the usgs2sdf and
+ srtm2sdf utilities, or in bzip2 compressed format
+ (.sdf.bz2). Since uncompressed files can be processed
+ slightly faster than files that have been compressed,
SPLAT! searches for the needed SDF data in uncompressed
- format first. If such data cannot located, then SPLAT!
- tries to read the data in bzip2 compressed format. If no
+ format first. If uncompressed data cannot located, SPLAT!
+ then searches for data in bzip2 compressed format. If no
compressed SDF files can be found for the region
- requested, SPLAT! assumes the region is over water or out-
- side the United States, 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 USGS Digital
- Elevation Model Data since they are devoid of any land
- masses. However, this behavior of SPLAT! underscores the
- importance of having all the SDF files required for the
- region being analyzed if meaningful results are to be
- expected.
+ requested, SPLAT! assumes the region is over water, and
+ will assign an elevation of sea-level to these areas.
+
+ This feature of SPLAT! makes it possible to perform path
+ analysis not only over land, but also between coastal
+ areas not represented by Digital Elevation Model data.
+ This behavior of SPLAT! underscores the importance of hav-
+ ing all the SDF files required for the region being ana-
+ lyzed if meaningful results are to be expected.
SITE LOCATION (QTH) FILES
- SPLAT! imports site location information of transmitter
- and receiver sites analyzed by the program from ASCII
- files having a .qth extension. QTH files contain the
- site's name, the site's latitude (in degrees North), the
- site's longitude (in degrees West), and the site's antenna
+ SPLAT! imports site location information of transmitter
+ and receiver sites analyzed by the program from ASCII
+ files having a .qth extension. QTH files contain the
+ site's name, the site's latitude (positive if North of the
+ equator, negative if South), the site's longitude (in
+ degrees West, 0 to 360 degrees), and the site's antenna
height above ground level (AGL). A single line-feed char-
acter separates each field. The antenna height is assumed
to be specified in feet unless followed by the letter m or
LONGLEY-RICE PARAMETER (LRP) FILES
SPLAT! imports Longley-Rice model parameter data from
files having the same base name as the transmitter site
- QTH file, but carrying a .lrp extension, thus providing
- simple and accurate correlation between these associated
- data sets. The format for the Longley-Rice model parame-
- ter files is as follows (wnjt.lrp):
+ QTH file, but with a .lrp extension, thus providing simple
+ and accurate correlation between these associated data
+ sets. The format for the Longley-Rice model parameter
+ files is as follows (wnjt.lrp):
15.000 ; Earth Dielectric Constant (Relative per-
mittivity)
then the default parameters listed above will be assigned
by SPLAT! and a corresponding "splat.lrp" file containing
this data will be written to the current working direc-
- tory.
+ tory. "splat.lrp" can then be edited by the user as
+ needed.
Typical Earth dielectric constants and conductivity values
are as follows:
3: Maritime Subtropical (West coast of Africa)
4: Desert (Sahara)
5: Continental Temperate
- 6: Maritime Temperate, over land (UK and west
+ 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
+ The Continental Temperate climate is common to large land
+ masses in the temperate zone, such as the United States.
+ For paths shorter than 100 km, there is little difference
between Continental and Maritime Temperate climates.
- The final two parameters in the .lrp file correspond to
- the statistical analysis provided by the Longley-Rice
- model. In this example, SPLAT! will return the maximum
- path loss occurring 50% of the time (fraction of time) in
- 50% of situations (fraction of situations). Use a
- fraction of time parameter of 0.97 for digital television,
- 0.50 for analog in the United States. Isotropic antennas
+ The final two parameters in the .lrp file correspond to
+ the statistical analysis provided by the Longley-Rice
+ model. In this example, SPLAT! will return the maximum
+ path loss occurring 50% of the time (fraction of time) in
+ 50% of situations (fraction of situations). Use a frac-
+ tion of time parameter of 0.97 for digital television,
+ 0.50 for analog in the United States. Isotropic antennas
are assumed.
- For further information on these parameters, see:
- http://elbert.its.bldrdoc.gov/itm.html and
+ For further information on these parameters, see:
+ http://flattop.its.bldrdoc.gov/itm.html and
http://www.softwright.com/faq/engineering/prop_long-
ley_rice.html
CITY LOCATION FILES
- The names and locations of cities, tower sites, or other
- points of interest may imported and be plotted on topo-
- graphic maps generated by SPLAT!. SPLAT! imports the
- names of cities and locations from ASCII files containing
- the location's name, the location's latitude, and the
+ The names and locations of cities, tower sites, or other
+ points of interest may be imported and plotted on topo-
+ graphic maps generated by SPLAT!. SPLAT! imports the
+ names of cities and locations from ASCII files containing
+ the location's name, the location's latitude, and the
location's longitude. Each field is separated by a comma.
- Each record is separated by a single line feed character.
- As was the case with the .qth files, latitude and longi-
- tude information may be entered in either decimal or
+ Each record is separated by a single line feed character.
+ As was the case with the .qth files, latitude and longi-
+ tude information may be entered in either decimal or
degree, minute, second (DMS) format.
For example (cities.dat):
Totowa, 40.906160, 74.223310
Trenton, 40.219922, 74.754665
- A total of five separate city data files may be imported
- at a time. There is no limit to the size of these files.
- SPLAT! reads city data sequentially, and plots only those
- locations whose positions do not conflict with previously
- plotted locations when generating topographic maps.
-
- 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
+ A total of five separate city data files may be imported
+ at a time, and there is no limit to the size of these
+ files. SPLAT! reads city data on a "first come/first
+ served" basis, and plots only those locations whose anno-
+ tations do not conflict with annotations of locations
+ plotted earlier during SPLAT's execution. This behavior
+ minimizes clutter in SPLAT! generated topographic maps,
+ but also mandates that important locations be placed
+ toward the beginning of the first city data file, and
+ disposable locations be positioned further down the list
+ or in subsequent data files.
+
+ City data files may be generated manually using any text
+ editor, imported from other sources, or derived from data
+ available from the U.S. Census Bureau using the cityde-
+ coder utility included with SPLAT!. Such data is avail-
+ able free of charge via the Internet at: http://www.cen-
+ sus.gov/geo/www/cob/bdy_files.html, and must be in ASCII
format.
CARTOGRAPHIC BOUNDARY DATA FILES
- Cartographic boundary data may also be imported to plot
- the boundaries of cities, counties, or states on topo-
- graphic maps generated by SPLAT!. Such data must be of
- the form of ARC/INFO Ungenerate (ASCII Format) Metadata
- Cartographic Boundary Files, and are available from the
- U.S. Census Bureau via the Internet at: http://www.cen-
- sus.gov/geo/www/cob/co2000.html#ascii and http://www.cen-
- sus.gov/geo/www/cob/pl2000.html#ascii. A total of five
- separate cartographic boundary files may be imported at a
- time. It is not necessary to import state boundaries if
+ 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 also lends itself well to scripted opera-
+ 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
- adjusted through the use of the Unix nice command.
+ 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 to
- include all the features described by those switches when
- performing an analysis.
+ its mode of operation and method of output data genera-
+ tion. Nearly all of SPLAT!'s switches may be cascaded in
+ any order on the command line when invoking the program.
POINT-TO-POINT ANALYSIS
SPLAT! may be used to perform line-of-sight terrain analy-
splat -t tx_site.qth -r rx_site.qth
- invokes a terrain analysis between the transmitter speci-
+ invokes a terrain analysis between the transmitter speci-
fied in tx_site.qth and receiver specified in rx_site.qth,
- and writes a SPLAT! Obstruction Report to the current
- working directory. The report contains details of the
- transmitter and receiver sites, and identifies the loca-
+ and writes a SPLAT! Obstruction Report to the current
+ working directory. The report contains details of the
+ transmitter and receiver sites, and identifies the loca-
tion of any obstructions detected during the analysis. If
- an obstruction can be cleared by raising the receive
- antenna to a greater altitude, SPLAT! will indicate the
- minimum antenna height required for a line-of-sight path
- to exist between the transmitter and receiver locations
- specified. If the antenna must be raised a significant
- amount, this determination may take some time.
-
- are optional when invoking the program. SPLAT! automati-
- cally reads all SPLAT Data Files necessary to conduct the
- terrain analysis between the sites specified. By default,
- the location of SDF files is assumed to be in the current
- working directory unless a ".splat_path" file is present
- under the user's home directory. If this file is present,
- it must contain the full directory path to the location of
- all the SDF files required by SPLAT! to perform its analy-
- sis for the region containing the transmitter and receiver
- sites specified. The path in this file must be of the
- form of a single line of ASCII text:
+ an obstruction can be cleared by raising the receive
+ antenna to a greater altitude, SPLAT! will indicate the
+ minimum antenna height required for a line-of-sight path
+ to exist between the transmitter and receiver locations
+ specified. If the antenna must be raised a significant
+ amount, this determination may take some time. Note that
+ the results provided are the minimum necessary for a line-
+ of-sight path to exist, and do not take Fresnel zone
+ clearance requirements into consideration.
+
+ qth extensions are assumed by SPLAT! for QTH files, and
+ are optional when invoking the program. SPLAT! automati-
+ cally reads all SPLAT Data Files necessary to conduct the
+ terrain analysis between the sites specified. SPLAT!
+ searches for the needed SDF files in the current working
+ directory first. If the needed files are not found,
+ SPLAT! then searches in the path specified by the -d
+ command-line switch:
- /opt/splat/sdf/
+ splat -t tx_site -r rx_site -d /cdrom/sdf/
- and may be generated with any text editor. The default
- path specified in the $HOME/.splat_path file may be over-
- ridden at any time using the -d switch:
+ An external directory path may be specified by placing a
+ ".splat_path" file under the user's home directory. This
+ file must contain the full directory path to the last
+ resort location of all the SDF files. The path in the
+ $HOME/.splat_path file must be of the form of a single
+ line of ASCII text:
- splat -t tx_site -r rx_site -d /cdrom/sdf/
+ /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
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
- in blue.
+ using the color blue.
SPLAT! generated topographic maps are 24-bit TrueColor
- Portable PixMap (PPM) images, and may be viewed, edited,
+ 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
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,
+ age area of the sites based on the location of each site
and the height of receive antenna wishing to communicate
with the site in question. SPLAT! switches from point-to-
point analysis mode to area prediction mode when the -c
splat -t wnjt -c 30.0 -m 1.333 -s cities.dat -b coun-
ties.dat -o map.ppm
- An earth radius multiplier of 1.333 instructs SPLAT! to
+ 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.
Rice path loss map for a transmitter site may be gener-
ated:
- splat -t tx_site -L 30.0 -s cities.dat -b co34_d00.dat -o
+ 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-
rounding the transmitter site. A legend at the bottom of
the map correlates each color with a specific path loss
level in decibels. Since Longley-Rice area prediction map
- generation is quite CPU intensive, provision for limiting
+ generation is very CPU intensive, provision for limiting
the analysis range is provided by the -R switch. The
argument must be given in miles. If a range wider than
the generated topographic map is specified, SPLAT! will
perform Longley-Rice path loss calculations between all
four corners of the area prediction map.
+ The -db switch allows a constraint to be placed on the
+ maximum path loss region plotted on the map. A path loss
+ between 80 and 230 dB may be specified using this switch.
+ For example, if a path loss beyond -140 dB is irrelevant
+ to the survey being conducted, SPLAT!'s path loss plot can
+ be constrained to the region bounded by the 140 dB attenu-
+ ation contour as follows:
+
+ splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -db
+ 140 -o plot.ppm
+
+
DETERMINING MULTIPLE REGIONS OF COVERAGE
- SPLAT! can also display line-of-sight coverage areas for
- as many as four separate transmitter sites on a common
+ SPLAT! can also display line-of-sight coverage areas for
+ as many as four separate transmitter sites on a common
topographic map. For example:
splat -t site1 site2 site3 site4 -c 30.0 -o network.ppm
plots the regional line-of-sight coverage of site1, site2,
- site3, and site4 based on a receive antenna located 30.0
- feet above ground level. A topographic map is then writ-
- ten 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 val-
+ site3, and site4 based on a receive antenna located 30.0
+ feet above ground level. A topographic map is then
+ written to the file network.ppm. The line-of-sight cover-
+ age area of the transmitters are plotted as follows in the
+ colors indicated (along with their corresponding RGB val-
ues in decimal):
site1: Green (0,255,0)
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
+ If separate .qth files are generated, each representing a
+ common site location but a different antenna height, a
+ single topographic map illustrating the regional coverage
+ from as many as four separate locations on a single tower
may be generated by SPLAT!.
TOPOGRAPHIC MAP GENERATION
- In certain situations, it may be desirable to generate a
- topographic map of a region without plotting coverage
+ 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
+ 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 the -o switch and output filename are omitted when
+ If the -o switch and output filename are omitted when
using either the -n or -N switches, output is written to a
- file named map.ppm in the current working directory by
+ file named map.ppm in the current working directory by
default.
DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN
- SPLAT! determines antenna height above average terrain
- (HAAT) according to the procedure defined by Federal Com-
- munications Commission Part 73.313(d). According to this
+ 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-
+ 2 and 10 miles (3 and 16 kilometers) from the site being
+ analyzed are sampled and averaged for each 45 degrees of
+ azimuth starting with True North. If one or more radials
+ lie entirely over water or over land outside the United
+ States (areas for which no USGS topography data is avail-
able), then those radials are omitted from the calculation
- of average terrain. If part of a radial extends over a
+ of average terrain. If part of a radial extends over a
body of water or over land outside the United States, then
only that part of the radial lying over United States land
is used in the determination of average terrain.
+ Note that SRTM elevation data, unlike older 3-arc second
+ USGS data, extends beyond the borders of the United
+ States. Therefore, HAAT results may not be in full com-
+ pliance with FCC Part 73.313(d) in areas along the borders
+ of the United States if the SDF files used by SPLAT! are
+ SRTM-derived.
+
When performing point-to-point terrain analysis, SPLAT!
determines the antenna height above average terrain only
if enough topographic data has already been loaded by the
as the average terrain above mean sea level for azimuths
of 0, 45, 90, 135, 180, 225, 270, and 315 degrees, and
include such information in the site report generated. If
- one or more of the eight radials surveyed fall over water
- or land outside the United States, SPLAT! reports No Ter-
- rain for those radial paths.
-
-SETTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
- SPLAT! reads SDF files into a series of memory "slots" as
- required within the structure of the program. Each "slot"
- holds one SDF file. Each SDF file represents a one degree
- by one degree region of terrain. A #define MAXSLOTS
- statement in the first several lines of splat.cpp sets the
- maximum number of "slots" available for topography data.
- It also sets the maximum size of the topographic maps gen-
- erated by SPLAT!. MAXSLOTS 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) are available to run SPLAT!
- with this number of MAXSLOTS. In this case, MAXSLOTS may
- be reduced to 4, although this will greatly limit the max-
- imum region SPLAT! will be able to analyze. If 118
- megabytes or more of total memory (swap space plus RAM) is
- available, then MAXSLOTS may be increased to 16. This
- will permit 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
- distances of over 1000 miles.
+ one or more of the eight radials surveyed fall over water,
+ or over regions for which no SDF data is available, SPLAT!
+ reports No Terrain for the radial paths affected.
+
+RESTRICTING THE MAXIMUM SIZE OF AN ANALYSIS REGION
+ SPLAT! reads SDF files as needed into a series of memory
+ "slots" within the structure of the program. Each "slot"
+ holds one SDF file representing a one degree by one degree
+ region of terrain. A #define MAXSLOTS statement in the
+ first several lines of splat.cpp sets the maximum number
+ of "slots" available for topography data. It also sets
+ the maximum size of the topographic maps generated by
+ SPLAT!. MAXSLOTS is set to 9 by default. If SPLAT! pro-
+ duces a segmentation fault on start-up with this default,
+ it is an indication that not enough RAM and/or virtual
+ memory (swap space) is available to run SPLAT! with this
+ number of MAXSLOTS. In situations where available memory
+ is low, MAXSLOTS may be reduced to 4 with the understand-
+ ing that this will greatly limit the maximum region SPLAT!
+ will be able to analyze. If 118 megabytes or more of
+ total memory (swap space plus RAM) is available, then
+ MAXSLOTS may be increased to 16. This will permit opera-
+ tion over a 4-degree by 4-degree region, which is suffi-
+ cient for single antenna heights in excess of 10,000 feet
+ above mean sea level, or point-to-point distances of over
+ 1000 miles.
ADDITIONAL INFORMATION
Invoking SPLAT! without any arguments will display all the
command-line options available with the program along with
a brief summary of each.
- The latest news and information regarding SPLAT! software
+ 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.
-FILES
- $HOME/.splat_path
- User-generated file containing the default path to
- the directory containing the SDF data files.
-
- splat.lrp
- Default Longley-Rice model parameters.
-
AUTHORS
John A. Magliacane, KD2BD <kd2bd@amsat.org>
Creator, Lead Developer
-KD2BD Software 20 January 2004 SPLAT!(1)
projects / debian / splat / blobdiff