+++ /dev/null
-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)] [-nf do not
- plot Fresnel zones in height plots] [-plo path_loss_out-
- put_file.txt] [-pli path_loss_input_file.txt] [-udt
- user_defined_terrain_file.dat] [-n] [-N] [-geo] [-kml]
- [-metric]
-
-DESCRIPTION
- SPLAT! is a powerful terrestrial RF propagation and ter-
- rain analysis tool covering the spectrum between 20 MHz
- and 20 GHz. SPLAT! is free software, and is designed for
- operation on Unix and Linux-based workstations. Redistri-
- bution 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 pro-
- prietary or closed-source applications is a violation of
- this license, and is strictly forbidden.
-
- SPLAT! is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY, without even the implied war-
- ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
- POSE. See the GNU General Public License for more details.
-
-INTRODUCTION
- Applications of SPLAT! include the visualization, design,
- and link budget analysis of wireless Wide Area Networks
- (WANs), commercial and amateur radio communication systems
- above 20 MHz, microwave links, frequency coordination and
- interference studies, 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, and Longley-Rice path attenuation. In addition,
- the minimum antenna height requirements needed to clear
- terrain, the first Fresnel zone, and 60% 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 contours through which expected coverage areas
- of transmitters and repeater systems can be obtained.
- 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.
-
- Simply typing splat on the command line will return a sum-
- mary of SPLAT!'s command line options:
-
- --==[ SPLAT! v1.2.0 Available Options...
- ]==--
-
- -t txsite(s).qth (max of 4)
- -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 (max
- of 5)
- -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)
- -n no analysis, brief report
- -N no analysis, no report
- -m earth radius multiplier
- -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
- -plo filename of path-loss output file
- -pli filename of path-loss input file
- -udt filename of user defined terrain input file
- -geo generate a .geo georeference file (with .ppm out-
- put)
- -kml generate a Google Earth .kml file (for point-to-
- point links)
- -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, and antenna
- radiation pattern 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/
-
- 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 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 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), and the site's antenna
- height above ground level (AGL), each separated by a sin-
- gle 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 deci-
- mal format (74.6889) or degree, minute, second (DMS) for-
- mat (74 41 20.0).
-
- For example, a site location file describing television
- station WNJT, Trenton, NJ (wnjt.qth) might read as fol-
- lows:
-
- WNJT
- 40.2833
- 74.6889
- 990.00
-
- Each transmitter and receiver site analyzed by SPLAT! must
- be represented by its own site location (QTH) file.
-
-LONGLEY-RICE PARAMETER (LRP) FILES
- 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.lrp):
-
- 15.000 ; Earth Dielectric Constant (Relative per-
- mittivity)
- 0.005 ; Earth Conductivity (Siemens per meter)
- 301.000 ; Atmospheric Bending Constant (N-units)
- 700.000 ; Frequency in MHz (20 MHz to 20 GHz)
- 5 ; Radio Climate (5 = Continental Temper-
- ate)
- 0 ; Polarization (0 = Horizontal, 1 = Verti-
- cal)
- 0.5 ; Fraction of situations (50% of loca-
- tions)
- 0.5 ; Fraction of time (50% of the time)
-
- If an LRP file corresponding to the tx_site QTH file can-
- not be found, SPLAT! scans the current working directory
- for the file "splat.lrp". If this file cannot be found,
- then the default parameters listed above will be assigned
- by SPLAT! and a corresponding "splat.lrp" file containing
- this data will be written to the current working direc-
- tory. "splat.lrp" can then be edited by the user as
- needed.
-
- Typical Earth dielectric constants and conductivity values
- are as follows:
-
- Dielectric Constant Conductiv-
- ity
- Salt water : 80 5.000
- Good ground : 25 0.020
- Fresh water : 80 0.010
- Marshy land : 12 0.007
- Farmland, forest : 15 0.005
- Average ground : 15 0.005
- Mountain, sand : 13 0.002
- City : 5 0.001
- Poor ground : 4 0.001
-
- Radio climate codes used by SPLAT! are as follows:
-
- 1: Equatorial (Congo)
- 2: Continental Subtropical (Sudan)
- 3: Maritime Subtropical (West coast of Africa)
- 4: Desert (Sahara)
- 5: Continental Temperate
- 6: Maritime Temperate, over land (UK and west
- coasts of US & EU)
- 7: Maritime Temperate, over sea
-
- The Continental Temperate climate is common to large land
- masses in the temperate zone, such as the United States.
- For paths shorter than 100 km, there is little difference
- between Continental and Maritime Temperate climates.
-
- The final two parameters in the .lrp file correspond to
- the statistical analysis provided by the Longley-Rice
- model. In this example, SPLAT! will return the maximum
- path loss occurring 50% of the time (fraction of time) in
- 50% of situations (fraction of situations). In the United
- States, use a fraction of time parameter of 0.97 for digi-
- tal television (8VSB modulation), or 0.50 for analog (VSB-
- AM+NTSC) transmissions.
-
- For further information on these parameters, see:
- http://flattop.its.bldrdoc.gov/itm.html and
- http://www.softwright.com/faq/engineering/prop_long-
- ley_rice.html
-
-CITY LOCATION FILES
- The names and locations of cities, tower sites, or other
- points of interest may be imported and plotted on topo-
- graphic maps generated by SPLAT!. SPLAT! imports the
- names of cities and locations from ASCII files containing
- the location 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.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) 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! Obstruction 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 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
-
- 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 path loss profiles, a Longley-Rice Model
- Path Loss Report is generated by SPLAT! in the form of a
- text file with a .lro filename extension. The report con-
- tains bearings and distances between the transmitter and
- receiver, as well as the Longley-Rice path loss for vari-
- ous distances between the transmitter and receiver loca-
- tions. The mode of propagation for points along the path
- are given as Line-of-Sight, Single Horizon, Double Hori-
- zon, Diffraction Dominant, and Troposcatter Dominant.
-
- To determine the signal-to-noise (SNR) ratio at remote
- location where random Johnson (thermal) noise is the pri-
- mary limiting factor in reception:
-
- SNR=T-NJ-L+G-NF
-
- where T is the ERP of the transmitter in dBW 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-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.
-
-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. SPLAT! switches from point-to-
- point analysis mode to area prediction mode when the -c
- switch is invoked as follows:
-
- splat -t tx_site -c 30.0 -s cities.dat -b co34_d00.dat -o
- tx_coverage
-
- In this example, SPLAT! generates a topographic map called
- tx_coverage.ppm that illustrates the predicted line-of-
- sight regional coverage of tx_site to receiving locations
- having antennas 30.0 feet above ground level (AGL). 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 -c 30.0 -m 1.333 -s cities.dat -b coun-
- ties.dat -o map.ppm
-
- An earth radius multiplier of 1.333 instructs SPLAT! to
- use the "four-thirds earth" model for line-of-sight propa-
- gation analysis. Any appropriate earth radius multiplier
- may be selected by the user.
-
- When invoked in area prediction mode, SPLAT! generates a
- site report for each station analyzed. SPLAT! site
- reports contain details of the site's geographic location,
- its height above mean sea level, the antenna's height
- above mean sea level, the antenna's height above average
- terrain, and the height of the average terrain calculated
- in the directions of 0, 45, 90, 135, 180, 225, 270, and
- 315 degrees azimuth.
-
-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 (path loss) in areas sur-
- rounding the transmitter site. A legend at the bottom of
- the map correlates each color with a specific path loss
- range in decibels.
-
- 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 -L 30.0 -s cities.dat -b co34_d00.dat -db
- 140 -o plot.ppm
-
-
-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
- 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 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).
-
- If the -o switch and output filename are omitted in these
- operations, topographic output is written to a file named
- map.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
- analyses by invoking the -kml switch:
-
- splat -t wnjt -r kd2bd -kml
-
- The KML file generated will have the same filename struc-
- ture as an Obstruction 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.
-
-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 or "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 holding topography
- data. It also sets the maximum size of the topographic
- maps generated 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) is available
- to run SPLAT! with the number of MAXSLOTS specified. In
- situations where available memory is low, MAXSLOTS 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 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.
-
-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>
- Longley-Rice Model integration
-
- Ron Bentley <ronbentley@earthlink.net>
- Fresnel Zone plotting and clearance determination
-
-
-
-
-KD2BD Software 20 December 2006 SPLAT!(1)
projects / debian / splat / blobdiff