NAME¶
splat An RF
Signal
Propagation,
Loss,
And
Terrain analysis tool
SYNOPSIS¶
splat [-t
transmitter_site.qth] [-r
receiver_site.qth] [-c
rx
antenna height for LOS coverage analysis (feet/meters) (float)] [-L
rx
antenna height for ITM coverage analysis (feet/meters) (float)] [-p
terrain_profile.ext] [-e
elevation_profile.ext] [-h
height_profile.ext] [-H
normalized_height_profile.ext] [-l
ITM_profile.ext] [-o
topographic_map_filename.ppm] [-b
cartographic_boundary_filename.dat] [-s
site/city_database.dat]
[-d
sdf_directory_path] [-m
earth radius multiplier (float)] [-f
frequency (MHz) for Fresnel zone calculations (float)] [-R
maximum
coverage radius (miles/kilometers) (float)] [-dB
threshold beyond which
contours will not be displayed] [-gc
ground clutter height
(feet/meters) (float)] [-fz
Fresnel zone clearance percentage (default
= 60)] [-ano
alphanumeric output file name] [-ani
alphanumeric
input file name] [-udt
user_defined_terrain_file.dat] [-n] [-N]
[-nf] [-sc] [-dbm] [-ngs] [-geo] [-kml] [-gpsav] [-metric] [-olditm]
DESCRIPTION¶
SPLAT! is a powerful terrestrial RF propagation and terrain analysis tool
for the spectrum between 20 MHz and 20 GHz.
SPLAT! is free software,
and is designed for operation 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 violation of this license and is
strictly forbidden.
SPLAT! is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY, without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
INTRODUCTION¶
Applications of
SPLAT! include the visualization, design, and link 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 elevation angles (uptilt), depression
angles (downtilt), antenna height above mean sea level, antenna height above
average terrain, bearings, distances, and elevations to known obstructions,
Irregular Terrain Model 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 topographic maps
that depict line-of-sight paths, and regional path loss and signal strength
contours through which expected coverage areas of transmitters and repeater
systems can be obtained. When performing line-of-sight and Irregular Terrain
Model analyses in situations where multiple transmitter or repeater sites are
employed,
SPLAT! determines individual and mutual areas of coverage
within the network specified.
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 digital
elevation topography models in the form of SPLAT Data Files (SDF files), site
location files (QTH files), and Irregular Terrain 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
postdownload and
usgs2sdf utilities included with
SPLAT!. USGS Digital Elevation
Models compatible with these utilities 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 Version 2 digital elevation models, especially when supplemented by
USGS-derived SDF data. These one-degree by one-degree models are the product
of the Space Shuttle STS-99 Radar Topography Mission, and are available for
most populated regions of the Earth. SPLAT Data Files may be generated from 3
arc-second SRTM-3 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/SRTM3/
Note that SRTM filenames refer to the latitude and longitude of the southwest
corner of the topographic dataset contained within the file. Therefore, the
region of interest must lie north and east of the latitude and longitude
provided in the SRTM filename.
The
srtm2sdf 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.
Even greater resolution and accuracy can be obtained by using 1 arc-second
SRTM-1 Version 2 topography data. This data is available for the United States
and its territories and possessions, and may be downloaded from:
ftp://e0srp01u.ecs.nasa.gov:21/srtm/version2/SRTM1/
High resolution SDF files for use with
SPLAT! HD may be generated from
data in this format using the
srtm2sdf-hd utility.
Despite the higher accuracy that SRTM data has to offer, some voids in the data
sets exist. When voids are detected, the
srtm2sdf and
srtm2sdf-hd utilities replace them with corresponding data found in
usgs2sdf generated SDF files. If USGS-derived SDF data is not
available, voids are handled through adjacent pixel averaging, or direct
replacement.
SPLAT Data Files contain integer value topographic elevations in meters
referenced to mean sea level for 1-degree by 1-degree regions of the Earth.
SDF files can be read by
SPLAT! in either standard format (
.sdf) as generated directly by the
usgs2sdf,
srtm2sdf,
and
srtm2sdf-hd utilities, or in bzip2 compressed format (
.sdf.bz2). Since uncompressed files can be read slightly faster than
files that have been compressed,
SPLAT! searches for needed SDF data in
uncompressed format first. If uncompressed data cannot be located,
SPLAT! then searches for data in bzip2 compressed format. If no
compressed SDF files can be found for the region requested,
SPLAT!
assumes the region is over water, and will assign an elevation of sea-level to
these areas.
This feature of
SPLAT! makes it possible to perform path analysis not
only over land, but also between coastal areas not represented by Digital
Elevation Model data. 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.
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 information may be expressed in either decimal format
(74.6864) or degree, minute, second (DMS) format (74 41 11.0).
For example, a site location file describing television station WNJT-DT,
Trenton, NJ (
wnjt-dt.qth) might read as follows:
WNJT-DT
40.2828
74.6864
990.00
Each transmitter and receiver site analyzed by
SPLAT! must be represented
by its own site location (QTH) file.
IRREGULAR TERRAIN MODEL PARAMETER (LRP) FILES¶
Irregular Terrain Model Parameter data files are required for
SPLAT! to
determine RF path loss, field strength, or received signal power level in
either point-to-point or area prediction mode. Irregular Terrain Model
parameter data is read from files having the same base name as the transmitter
site QTH file, but with a
.lrp extension.
SPLAT! LRP files share
the following format (
wnjt-dt.lrp):
15.000 ; Earth Dielectric Constant (Relative permittivity)
0.005 ; Earth Conductivity (Siemens per meter)
301.000 ; Atmospheric Bending Constant (N-units)
647.000 ; Frequency in MHz (20 MHz to 20 GHz)
5 ; Radio Climate (5 = Continental Temperate)
0 ; Polarization (0 = Horizontal, 1 = Vertical)
0.50 ; Fraction of situations (50% of locations)
0.90 ; Fraction of time (90% of the time)
46000.0 ; Effective Radiated Power (ERP) in Watts (optional)
If an LRP file corresponding to the tx_site QTH file cannot be found,
SPLAT! scans the current working directory for the file
"splat.lrp". If this file cannot be found, then default parameters
will be assigned by
SPLAT! and a corresponding "splat.lrp"
file containing these default parameters will be written to the current
working directory. The 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 Conductivity
Salt water : 80 5.000
Good ground : 25 0.020
Fresh water : 80 0.010
Marshy land : 12 0.007
Farmland, forest : 15 0.005
Average ground : 15 0.005
Mountain, sand : 13 0.002
City : 5 0.001
Poor ground : 4 0.001
Radio climate codes used by
SPLAT! are as follows:
1: Equatorial (Congo)
2: Continental Subtropical (Sudan)
3: Maritime Subtropical (West coast of Africa)
4: Desert (Sahara)
5: Continental Temperate
6: Maritime Temperate, over land (UK and west coasts of US & EU)
7: Maritime Temperate, over sea
The Continental Temperate climate is common to large land masses in the
temperate zone, such as the United States. For paths shorter than 100 km,
there is little difference between Continental and Maritime Temperate
climates.
The seventh and eighth parameters in the
.lrp file correspond to the
statistical analysis provided by the ITM model. In this example,
SPLAT!
will return the maximum path loss occurring 50% of the time (fraction of time,
or Time Variability) in 90% of situations (fraction of situations, or Location
Variability). 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 ITM propagation model parameters, please refer to:
http://flattop.its.bldrdoc.gov/itm.html and
http://www.softwright.com/faq/engineering/prop_longley_rice.html
The last parameter in the
.lrp file corresponds to the transmitter's
Effective Radiated Power (ERP), and is optional. If it is included in the
.lrp file, then
SPLAT! will compute received signal strength
levels and field strength level contours when performing ITM 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 contains an ERP parameter and the
generation of path loss rather than field strength contours is desired, the
ERP can be assigned to zero using the
-erp switch without having to
edit the
.lrp file to accomplish the same result.
CITY LOCATION FILES¶
The names and locations of cities, tower sites, or other points of interest may
be imported and plotted on topographic maps generated by
SPLAT!.
SPLAT! imports the names of cities and locations from ASCII files
containing the location of interest's name, latitude, and 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 longitude
information may be entered in either decimal or degree, minute, second (DMS)
format.
For example (
cities.dat):
Teaneck, 40.891973, 74.014506
Tenafly, 40.919212, 73.955892
Teterboro, 40.859511, 74.058908
Tinton Falls, 40.279966, 74.093924
Toms River, 39.977777, 74.183580
Totowa, 40.906160, 74.223310
Trenton, 40.219922, 74.754665
A total of five separate city data files may be imported at a time, and there is
no limit to the size of these files.
SPLAT! reads city data on a
"first come/first served" basis, and plots only those locations
whose annotations do not conflict with annotations of locations read earlier
in the current city data file, or in previous files. This behavior minimizes
clutter in
SPLAT! generated topographic maps, but also mandates that
important locations be placed toward the beginning of the first city data
file, and locations less important be positioned further down the list or in
subsequent data files.
City data files may be generated manually using any text editor, imported from
other sources, or derived from data available from the U.S. Census Bureau
using the
citydecoder utility included with
SPLAT!. Such data is
available free of charge via the Internet at:
http://www.census.gov/geo/www/cob/bdy_files.html, and must be in ASCII
format.
CARTOGRAPHIC BOUNDARY DATA FILES¶
Cartographic boundary data may also be imported to plot the boundaries of
cities, counties, or states on topographic maps generated by
SPLAT!.
Such data must be of the form of ARC/INFO Ungenerate (ASCII Format) Metadata
Cartographic Boundary Files, and are available from the U.S. Census Bureau via
the Internet at:
http://www.census.gov/geo/www/cob/co2000.html#ascii
and
http://www.census.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)
operations.
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 generation. Nearly all of
SPLAT!'s
switches may be cascaded in any order on the command line when invoking the
program.
Simply typing splat on the command line will return a summary of
SPLAT!'s
command line options:
--==[ SPLAT! v1.4.0 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 path loss graph to plot
-o filename of topographic map to generate (.ppm)
-u filename of user-defined terrain file to import
-d sdf file directory path (overrides path in ~/.splat_path file)
-m earth radius multiplier
-n do not plot LOS paths in .ppm maps
-N do not produce unnecessary site or obstruction reports
-f frequency for Fresnel zone calculation (MHz)
-R modify default range for -c or -L (miles/kilometers)
-sc display smooth rather than quantized contour levels
-db threshold beyond which contours will not be displayed
-nf do not plot Fresnel zones in height plots
-fz Fresnel zone clearance percentage (default = 60)
-gc ground clutter height (feet/meters)
-ngs display greyscale topography as white in .ppm files
-erp override ERP in .lrp file (Watts)
-ano name of alphanumeric output file
-ani name of alphanumeric input 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)
-dbm plot signal power level contours rather than field strength
-gpsav preserve gnuplot temporary working files after SPLAT! execution -metric
employ metric rather than imperial units for all user I/O -olditm invoke older
ITM propagation model rather than the newer ITWOM
The command-line options for splat and splat-hd are identical.
SPLAT! operates in two distinct modes:
point-to-point mode, and
area prediction mode. Either a line-of-sight (LOS) or 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 specified when performing
line-of-sight analysis.
POINT-TO-POINT ANALYSIS¶
SPLAT! may be used to perform line-of-sight terrain analysis between two
specified site locations. For example:
splat -t tx_site.qth -r rx_site.qth
invokes a line-of-sight terrain analysis between the transmitter specified in
tx_site.qth and receiver specified in
rx_site.qth using a True
Earth radius model, and writes a
SPLAT! Path Analysis Report to the
current working directory. The report contains details of the transmitter 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 example, do
not take Fresnel zone clearance requirements into consideration.
qth extensions are assumed by
SPLAT! for QTH files, and are
optional when specifying -t and -r arguments on the command-line.
SPLAT! 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 filename
extension specified to
SPLAT! determines the format of the graph
produced.
.png will produce a 640x480 color PNG graphic file, while
.ps or
.postscript will produce postscript output. Output in
formats such as GIF, Adobe Illustrator, AutoCAD dxf, LaTeX, and many others
are available. Please consult
gnuplot, and
gnuplot's
documentation for details on all the supported output formats.
A graph of elevations subtended by the terrain between the receiver and
transmitter as a function of distance from the receiver can be 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 elevation and depression
angles resulting from the terrain between the receiver's location and the
transmitter site from the perspective of the receiver's location. A second
trace is plotted between the left side of the graph (receiver's location) and
the location of the transmitting antenna on the right. This trace illustrates
the elevation angle required for a line-of-sight path to exist between the
receiver and transmitter locations. If the trace intersects the elevation
profile at any point on the graph, then this is an indication that a
line-of-sight path does not exist under the conditions given, and the
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_profile.png
A contour of the Earth's curvature is also plotted in this mode.
The first Fresnel Zone, and 60% of the first Fresnel Zone can be added to height
profile graphs by adding the
-f switch, and specifying a frequency (in
MHz) at which the Fresnel Zone should be modeled:
splat -t tx_site -r rx_site -f 439.250 -H normalized_height_profile.png
Fresnel Zone clearances other 60% can be specified using the
-fz switch
as follows:
splat -t tx_site -r rx_site -f 439.250 -fz 75 -H height_profile2.png
A graph showing ITM path loss may be plotted using the
-l switch:
splat -t tx_site -r rx_site -l path_loss_profile.png
As before, adding the
-metric switch forces the graphs to be plotted
using metric units of measure. The
-gpsav switch instructs
SPLAT! to preserve (rather than delete) the
gnuplot working
files generated during
SPLAT! execution, allowing the user to edit
these files and re-run
gnuplot if desired.
When performing a point-to-point analysis, a
SPLAT! Path Analysis Report
is generated in the form of a text file with a
.txt filename extension.
The report contains bearings and distances between the transmitter and
receiver, as well as the free-space and ITM 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. Additionally, if
the receiver is located at the peak of a single obstruction or at the peak of
a second obstruction,
SPLAT! will report
RX at Peak Terrain
Along Path when operating under the ITWOM propagation model.
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
predicted signal strength and antenna voltage at the receiving location is
also provided in the Path Analysis Report.
To determine the signal-to-noise (SNR) ratio at remote location where random
Johnson (thermal) noise is the primary limiting factor in reception:
where
T is the ERP of the transmitter in dBW in the direction of the
receiver,
NJ is Johnson Noise in dBW (-136 dBW for a 6 MHz television
channel),
L is the path loss provided by
SPLAT! in dB (as a
positive number),
G is the receive antenna gain in dB over
isotropic, and
NF is the receiver noise figure in dB.
T may be computed as follows:
where
TI is actual amount of RF power delivered to the transmitting
antenna in dBW,
GT is the transmitting antenna gain (over isotropic) in
the direction of the receiver (or the horizon if the receiver is over the
horizon).
To compute how much more signal is available over the minimum to necessary to
achieve a specific signal-to-noise ratio:
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 locations 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 transparent_map.png
REGIONAL COVERAGE ANALYSIS¶
SPLAT! can analyze a transmitter or repeater site, or network of sites,
and predict the regional coverage for each site specified. In this mode,
SPLAT! can generate a topographic map displaying the geometric
line-of-sight coverage area of the sites based on the location of each site
and the height of receive antenna wishing to communicate with the site in
question. A regional analysis may be performed by
SPLAT! using the
-c switch as follows:
splat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o tx_coverage
In this example,
SPLAT! generates a topographic map called
tx_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 counties.dat -o map.ppm
An earth radius multiplier of 1.333 instructs
SPLAT! to use the
"four-thirds earth" model for line-of-sight propagation analysis.
Any 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 network.ppm
plots the regional line-of-sight coverage of site1, site2, site3, and site4
based on a receive antenna located 10.0 meters above ground level. A
topographic map is then written to the file
network.ppm. The
line-of-sight coverage area of the transmitters are plotted as follows in the
colors indicated (along with their corresponding RGB values in decimal):
site1: Green (0,255,0)
site2: Cyan (0,255,255)
site3: Medium Violet (147,112,219)
site4: Sienna 1 (255,130,71)
site1 + site2: Yellow (255,255,0)
site1 + site3: Pink (255,192,203)
site1 + site4: Green Yellow (173,255,47)
site2 + site3: Orange (255,165,0)
site2 + site4: Dark Sea Green 1 (193,255,193)
site3 + site4: Dark Turquoise (0,206,209)
site1 + site2 + site3: Dark Green (0,100,0)
site1 + site2 + site4: Blanched Almond (255,235,205)
site1 + site3 + site4: Medium Spring Green (0,250,154)
site2 + site3 + site4: Tan (210,180,140)
site1 + site2 + site3 + site4: Gold2 (238,201,0)
If separate
.qth files are generated, each representing a common site
location but a different antenna height, a single topographic map illustrating
the regional coverage from as many as four separate locations on a single
tower may be generated by
SPLAT!.
PATH LOSS ANALYSIS¶
If the
-c switch is replaced by a
-L switch, an ITM path loss map
for a transmitter site may be generated:
splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -o path_loss_map
In this mode,
SPLAT! generates a multi-color map illustrating expected
signal levels in areas surrounding the transmitter site. A legend at the
bottom of the map correlates each color with a specific path loss range in
decibels.
The
-db switch allows a threshold to be set beyond which contours will
not be plotted on the map. 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
The path loss contour threshold may be expressed as either a positive or
negative quantity.
The path loss analysis range may be modified to a user-specific distance 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 ITM path loss
calculations between all four corners of the area prediction map.
The colors used to illustrate contour regions 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,
.scf, and
.dcf extensions. If the necessary file
does not exist in the current working when
SPLAT! is run, a file
containing default color definition parameters that is suitable for manual
editing by the user is written into the current directory.
When a regional ITM analysis is performed and the transmitter's ERP is not
specified or is zero, a
.lcf path loss color definition file
corresponding to the transmitter site (
.qth) is read by
SPLAT!
from the current working directory. If a
.lcf file corresponding to the
transmitter site is not found, then a default file suitable for manual editing
by the user is automatically generated by
SPLAT!.
A path loss color definition file possesses the following structure (
wnjt-dt.lcf):
; SPLAT! Auto-generated Path-Loss Color Definition ("wnjt-dt.lcf")
File
;
; Format for the parameters held in this file is as follows:
;
; dB: red, green, blue
;
; ...where "dB" is the path loss (in dB) and
; "red", "green", and "blue" are the
corresponding RGB color
; definitions ranging from 0 to 255 for the region specified.
;
; The following parameters may be edited and/or expanded
; for future runs of SPLAT! A total of 32 contour regions
; may be defined in this file.
;
;
80: 255, 0, 0
90: 255, 128, 0
100: 255, 165, 0
110: 255, 206, 0
120: 255, 255, 0
130: 184, 255, 0
140: 0, 255, 0
150: 0, 208, 0
160: 0, 196, 196
170: 0, 148, 255
180: 80, 80, 255
190: 0, 38, 255
200: 142, 63, 255
210: 196, 54, 255
220: 255, 0, 255
230: 255, 194, 204
If the path loss is less than 80 dB, the color Red (RGB = 255, 0, 0) is assigned
to the region. If the path loss is greater than or equal to 80 dB, but less
than 90 db, then Dark Orange (255, 128, 0) is assigned to the region. Orange
(255, 165, 0) is assigned to regions having a path loss greater than or equal
to 90 dB, but less than 100 dB, and so on. Greyscale terrain is displayed
beyond the 230 dB path loss contour. Adding the
-sc switch will smooth
the transitions between the specified quantized contour levels.
FIELD STRENGTH ANALYSIS¶
If the transmitter's effective radiated power (ERP) is specified in the
transmitter's
.lrp file, or expressed on the command-line using the
-erp switch, field strength contours referenced to decibels over one
microvolt per meter (dBuV/m) rather than path loss are produced:
splat -t wnjt-dt -L 30.0 -erp 46000 -db 30 -o plot.ppm
The
-db switch can be used in this mode as before to limit the extent to
which field strength contours are plotted. When plotting field strength
contours, however, the argument given is interpreted as being expressed in
dBuV/m.
SPLAT! field strength color definition files share a very similar
structure to
.lcf files used for plotting path loss:
; SPLAT! Auto-generated Signal Color Definition ("wnjt-dt.scf") File
;
; Format for the parameters held in this file is as follows:
;
; dBuV/m: red, green, blue
;
; ...where "dBuV/m" is the signal strength (in dBuV/m) and
; "red", "green", and "blue" are the
corresponding RGB color
; definitions ranging from 0 to 255 for the region specified.
;
; The following parameters may be edited and/or expanded
; for future runs of SPLAT! A total of 32 contour regions
; may be defined in this file.
;
;
128: 255, 0, 0
118: 255, 165, 0
108: 255, 206, 0
98: 255, 255, 0
88: 184, 255, 0
78: 0, 255, 0
68: 0, 208, 0
58: 0, 196, 196
48: 0, 148, 255
38: 80, 80, 255
28: 0, 38, 255
18: 142, 63, 255
8: 140, 0, 128
If the signal strength is greater than or equal to 128 dB over 1 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
RECEIVED POWER LEVEL ANALYSIS¶
If the transmitter's effective radiated power (ERP) is specified in the
transmitter's
.lrp file, or expressed on the command-line using the
-erp switch, and the
-dbm switch is invoked, received power
level contours referenced to decibels over one milliwatt (dBm) are produced:
splat -t wnjt-dt -L 30.0 -erp 46000 -dbm -db -100 -o plot.ppm
The
-db switch can be used to limit the extent to which received power
level contours are plotted. When plotting power level contours, the argument
given is interpreted as being expressed in dBm.
SPLAT! received power level color definition files share a very similar
structure to the color definition files described earlier, except that the
power levels in dBm may be either positive or negative, and are limited to a
range between +40 dBm and -200 dBm:
; SPLAT! Auto-generated DBM Signal Level Color Definition
("wnjt-dt.dcf") File
;
; Format for the parameters held in this file is as follows:
;
; dBm: red, green, blue
;
; ...where "dBm" is the received signal power level between +40 dBm
; and -200 dBm, and "red", "green", and "blue"
are the corresponding
; RGB color definitions ranging from 0 to 255 for the region specified.
;
; The following parameters may be edited and/or expanded
; for future runs of SPLAT! A total of 32 contour regions
; may be defined in this file.
;
;
+0: 255, 0, 0
-10: 255, 128, 0
-20: 255, 165, 0
-30: 255, 206, 0
-40: 255, 255, 0
-50: 184, 255, 0
-60: 0, 255, 0
-70: 0, 208, 0
-80: 0, 196, 196
-90: 0, 148, 255
-100: 80, 80, 255
-110: 0, 38, 255
-120: 142, 63, 255
-130: 196, 54, 255
-140: 255, 0, 255
-150: 255, 194, 204
ANTENNA RADIATION PATTERN PARAMETERS¶
Normalized field voltage patterns for a transmitting antenna's horizontal and
vertical planes are imported automatically into
SPLAT! when a path
loss, field strength, or received power level coverage analysis is performed.
Antenna pattern data is read from a pair of files having the same base name as
the transmitter and LRP files, but with
.az and
.el extensions
for azimuth and elevation pattern files, respectively. Specifications
regarding pattern rotation (if any) and mechanical beam tilt and tilt
direction (if any) are also contained within
SPLAT! antenna pattern
files.
For example, the first few lines of a
SPLAT! azimuth pattern file might
appear as follows (
kvea.az):
183.0
0 0.8950590
1 0.8966406
2 0.8981447
3 0.8995795
4 0.9009535
5 0.9022749
6 0.9035517
7 0.9047923
8 0.9060051
The first line of the
.az file specifies the amount of azimuthal pattern
rotation (measured clockwise in degrees from True North) to be applied by
SPLAT! to the data contained in the
.az file. This is followed
by azimuth headings (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 specifies the amount of mechanical beam
tilt applied to the antenna. Note that a
downward tilt (below the
horizon) is expressed as a
positive angle, while an
upward tilt
(above the horizon) is expressed as a
negative angle. This data is
followed by the azimuthal direction of the tilt, separated by whitespace.
The remainder of the file consists of elevation angles and their corresponding
normalized voltage radiation pattern (0.000 to 1.000) values separated by
whitespace. Elevation angles must be specified over a -10.0 to +90.0 degree
range. As was the convention with mechanical beamtilt,
negative elevation
angles are used to represent elevations
above the horizon, while
positive angles represents elevations
below the horizon.
For example, the first few lines a
SPLAT! elevation pattern file might
appear as follows (
kvea.el):
1.1 130.0
-10.0 0.172
-9.5 0.109
-9.0 0.115
-8.5 0.155
-8.0 0.157
-7.5 0.104
-7.0 0.029
-6.5 0.109
-6.0 0.185
In this example, the antenna is mechanically tilted downward 1.1 degrees towards
an azimuth of 130.0 degrees.
For best results, the resolution of azimuth pattern data should be specified to
the nearest degree azimuth, and elevation pattern data resolution should be
specified to the nearest 0.01 degrees. If the pattern data specified does not
reach this level of resolution,
SPLAT! will interpolate the values
provided to determine the data at the required resolution, although this may
result in a loss in accuracy.
EXPORTING AND IMPORTING REGIONAL CONTOUR DATA¶
Performing a regional coverage analysis based on an ITM path analysis can be a
very time consuming process, especially if the analysis is performed
repeatedly to discover what effects changes to a transmitter's antenna
radiation pattern make to the predicted coverage area.
This process can be expedited by exporting the contour data produced by
SPLAT! to an alphanumeric output
(.ano) file. The data contained
in this file can then be modified to incorporate antenna pattern effects, and
imported back into
SPLAT! to quickly produce a revised contour map.
Depending on the way in which
SPLAT! is invoked, alphanumeric output
files can describe regional path loss, signal strength, or received signal
power levels.
For example, an alphanumeric output file containing path loss information 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 maximum path loss of 140
dB (assuming ERP is not specified in the transmitter's
.lrp file) using
the following syntax:
splat -t kvea -L 30.0 -R 50.0 -db 140 -ano pathloss.dat
If ERP is specified in the
.lrp file or on the command line through the
-erp switch, the alphanumeric output file will instead contain
predicted field values in dBuV/m. If the
-dBm command line switch is
used, then the alphanumeric output file will contain receive signal power
levels in dBm.
SPLAT! alphanumeric output files can exceed many hundreds of megabytes in
size. They contain information relating to the boundaries of the region they
describe followed by latitudes (degrees North), longitudes (degrees West),
azimuths (referenced to True North), elevations (to the first obstruction),
followed by either path loss (in dB), received field strength (in dBuV/m), or
received signal power level (in dBm)
without regard to the transmitting
antenna's radiation pattern.
The first few lines of a
SPLAT! alphanumeric output file could take on
the following appearance (
pathloss.dat):
119, 117 ; max_west, min_west
35, 34 ; max_north, min_north
34.2265424, 118.0631096, 48.199, -32.747, 67.70
34.2270358, 118.0624421, 48.199, -19.161, 73.72
34.2275292, 118.0617747, 48.199, -13.714, 77.24
34.2280226, 118.0611072, 48.199, -10.508, 79.74
34.2290094, 118.0597723, 48.199, -11.806, 83.26 *
34.2295028, 118.0591048, 48.199, -11.806, 135.47 *
34.2299962, 118.0584373, 48.199, -15.358, 137.06 *
34.2304896, 118.0577698, 48.199, -15.358, 149.87 *
34.2314763, 118.0564348, 48.199, -15.358, 154.16 *
34.2319697, 118.0557673, 48.199, -11.806, 153.42 *
34.2324631, 118.0550997, 48.199, -11.806, 137.63 *
34.2329564, 118.0544322, 48.199, -11.806, 139.23 *
34.2339432, 118.0530971, 48.199, -11.806, 139.75 *
34.2344365, 118.0524295, 48.199, -11.806, 151.01 *
34.2349299, 118.0517620, 48.199, -11.806, 147.71 *
34.2354232, 118.0510944, 48.199, -15.358, 159.49 *
34.2364099, 118.0497592, 48.199, -15.358, 151.67 *
Comments can be placed in the file if they are preceeded by a semicolon. The
vim text editor has proven capable of editing files of this size.
Note as was the case in the antenna pattern files, negative elevation angles
refer to upward tilt (above the horizon), while positive angles refer to
downward tilt (below the horizon). These angles refer to the elevation to the
receiving antenna at the height above ground level specified using the
-L switch
if the path between transmitter and receiver is
unobstructed. If the path between the transmitter and receiver is obstructed,
an asterisk (*) is placed on the end of the line, and the elevation angle
returned by
SPLAT! refers the elevation angle to the first obstruction
rather than the geographic location specified on the line. This is done in
response to the fact that the ITM model considers the energy reaching a
distant point over an obstructed path to be the result of the energy scattered
over the top of the first obstruction along the path. Since energy cannot
reach the obstructed location directly, the actual elevation angle to the
destination over such a path becomes irrelevant.
When modifying
SPLAT! path loss files to reflect antenna pattern data,
only the last numeric column should be amended to reflect the antenna's
normalized gain at the azimuth and elevation angles specified in the file.
Programs and scripts capable of performing this task are left as an exercise
for the user.
Modified alphanumeric output files can be imported back into
SPLAT! for
generating revised coverage maps provided that the ERP and -dBm options are
used as they were when the alphanumeric output file was originally generated:
splat -t kvea -ani pathloss.dat -s city.dat -b county.dat -o map.ppm
Note that alphanumeric output files generated by splat cannot be used with
splat-hd, or vice-versa due to the resolution incompatibility between the two
versions of the program. Also, each of the three types of alphanumeric output
files are incompatible with one another, so a file containing path loss data
cannot be imported into
SPLAT! to produce signal strength or received
power level contours, etc.
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 in splat and 1 arc-second in latitude
and longitude in splat-hd. Features described in the user-defined terrain file
that overlap previously defined features in the file are ignored by
SPLAT! to avoid ambiguity.
GROUND CLUTTER¶
The height of ground clutter can be specified using the
-gc switch:
splat -t wnjt-dt -r kd2bd -gc 30.0 -H wnjt-dt_path.png
The
-gc switch as the effect of raising the overall terrain by the
specified amount in feet (or meters if the
-metric switch is invoked),
except over areas at sea-level and at the transmitting and receiving antenna
locations.
SIMPLE TOPOGRAPHIC MAP GENERATION¶
In certain situations it may be desirable to generate a topographic map of a
region without plotting coverage areas, line-of-sight paths, or generating
obstruction reports. There are several ways of doing this. If one wishes to
generate a topographic map illustrating the location of a transmitter and
receiver site along with a brief text report describing the locations and
distances between the sites, the
-n switch should be invoked as
follows:
splat -t tx_site -r rx_site -n -o topo_map.ppm
If no text report is desired, then the
-N switch is used:
splat -t tx_site -r rx_site -N -o topo_map.ppm
If a topographic map centered about a single site out to a minimum specified
radius is desired instead, a command similar to the following can be used:
splat -t tx_site -R 50.0 -s NJ_Cities -b NJ_Counties -o topo_map.ppm
where -R specifies the minimum radius of the map in miles (or 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,
simply create a
SPLAT! city file (
-s option) and append it to
the list of command-line options illustrated above.
If the
-o switch and output filename are omitted in these operations,
topographic output is written to a file named
tx_site.ppm in the
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) software by generating a
georeference file using
SPLAT!'s
-geo switch:
splat -t kd2bd -R 50.0 -s NJ_Cities -b NJ_Counties -geo -o map.ppm
The georeference file generated will have the same base name as the
-o
file specified, but have a
.geo extension, and permit proper
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 structure as a Path Analysis
Report for the transmitter and receiver site names given, except it will carry
a
.kml extension.
Once loaded into
Google Earth (File --> Open), the KML file will
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 displayed in green.
Google Earth's
navigation tools allow the user to "fly" around the path, identify
landmarks, roads, and other featured content.
When performing regional coverage analysis, the
.kml file generated by
SPLAT! will permit path loss or signal strength contours to be layered
on top of
Google Earth's display along with a corresponding color key
in the upper left-hand corner. The generated
.kml file will have the
same basename as that of the
.ppm file normally generated.
DETERMINATION OF ANTENNA HEIGHT ABOVE AVERAGE TERRAIN¶
SPLAT! determines antenna height above average terrain (HAAT) according
to the procedure defined by Federal Communications Commission Part 73.313(d).
According to this definition, terrain elevations along eight radials between 2
and 10 miles (3 and 16 kilometers) from the site being analyzed are sampled
and averaged for each 45 degrees of azimuth starting with True North. If one
or more radials lie entirely over water or over land outside the United States
(areas for which no USGS topography data is available), then those radials are
omitted from the calculation of average terrain.
Note that SRTM-3 elevation data, unlike older USGS data, extends beyond the
borders of the United States. Therefore, HAAT results may not be in full
compliance with FCC Part 73.313(d) in areas along the borders of the United
States if the SDF files used by
SPLAT! are SRTM-derived.
When performing point-to-point terrain analysis,
SPLAT! determines the
antenna height above average terrain only if enough topographic data has
already been loaded by the program to perform the point-to-point analysis. In
most cases, this will be true, unless the site in question does not lie within
10 miles of the boundary of the topography data in memory.
When performing area prediction analysis, enough topography data is normally
loaded by
SPLAT! to perform average terrain calculations. Under such
conditions,
SPLAT! will provide the antenna height above average
terrain as well as the average terrain above mean sea level for azimuths of 0,
45, 90, 135, 180, 225, 270, and 315 degrees, and include such information in
the generated site report. If one or more of the eight radials surveyed fall
over water, or over regions for which no SDF data is available,
SPLAT!
reports
No Terrain for the radial paths affected.
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 ITM Model integration
- Ron Bentley <ronbentley@embarqmail.com>
- Fresnel Zone plotting and clearance determination