SPLAT!(1) KD2BD Software SPLAT!(1) NNAAMMEE splat An RF SSignal PPropagation, LLoss, AAnd TTerrain analysis tool SSYYNNOOPPSSIISS splat [-t _t_r_a_n_s_m_i_t_t_e_r___s_i_t_e_._q_t_h] [-r _r_e_c_e_i_v_e_r___s_i_t_e_._q_t_h] [-c _r_x _a_n_t_e_n_n_a _h_e_i_g_h_t _f_o_r _L_O_S _c_o_v_e_r_a_g_e _a_n_a_l_y_s_i_s _(_f_e_e_t_/_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [-L _r_x _a_n_t_e_n_n_a _h_e_i_g_h_t _f_o_r _L_o_n_g_l_e_y_-_R_i_c_e _c_o_v_e_r_a_g_e _a_n_a_l_y_s_i_s _(_f_e_e_t_/_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [-p _t_e_r_r_a_i_n___p_r_o_f_i_l_e_._e_x_t] [-e _e_l_e_v_a_t_i_o_n___p_r_o_f_i_l_e_._e_x_t] [-h _h_e_i_g_h_t___p_r_o_f_i_l_e_._e_x_t] [-H _n_o_r_m_a_l_i_z_e_d___h_e_i_g_h_t___p_r_o_f_i_l_e_._e_x_t] [-l _L_o_n_g_l_e_y_-_R_i_c_e___p_r_o_f_i_l_e_._e_x_t] [-o _t_o_p_o_g_r_a_p_h_i_c___m_a_p___f_i_l_e_n_a_m_e_._p_p_m] [-b _c_a_r_t_o_g_r_a_p_h_i_c___b_o_u_n_d_a_r_y___f_i_l_e_n_a_m_e_._d_a_t] [-s _s_i_t_e_/_c_i_t_y___d_a_t_a_b_a_s_e_._d_a_t] [-d _s_d_f___d_i_r_e_c_t_o_r_y___p_a_t_h] [-m _e_a_r_t_h _r_a_d_i_u_s _m_u_l_t_i_p_l_i_e_r _(_f_l_o_a_t_)] [-f _f_r_e_q_u_e_n_c_y _(_M_H_z_) _f_o_r _F_r_e_s_n_e_l _z_o_n_e _c_a_l_c_u_l_a_t_i_o_n_s _(_f_l_o_a_t_)] [-R _m_a_x_i_m_u_m _c_o_v_e_r_a_g_e _r_a_d_i_u_s _(_m_i_l_e_s_/_k_i_l_o_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [-dB _t_h_r_e_s_h_o_l_d _b_e_y_o_n_d _w_h_i_c_h _c_o_n_t_o_u_r_s _w_i_l_l _n_o_t _b_e _d_i_s_p_l_a_y_e_d] [-gc _g_r_o_u_n_d _c_l_u_t_t_e_r _h_e_i_g_h_t _(_f_e_e_t_/_m_e_t_e_r_s_) _(_f_l_o_a_t_)] [-fz _F_r_e_s_n_e_l _z_o_n_e _c_l_e_a_r_a_n_c_e _p_e_r_- _c_e_n_t_a_g_e _(_d_e_f_a_u_l_t _= _6_0_)] [-ano _a_l_p_h_a_n_u_m_e_r_i_c _o_u_t_p_u_t _f_i_l_e _n_a_m_e] [-ani _a_l_p_h_a_n_u_m_e_r_i_c _i_n_p_u_t _f_i_l_e _n_a_m_e] [-udt _u_s_e_r___d_e_f_i_n_e_d___t_e_r_r_a_i_n___f_i_l_e_._d_a_t] [-n] [-N] [-nf] [-dbm] [-ngs] [-geo] [-kml] [-gpsav] [-metric] DDEESSCCRRIIPPTTIIOONN SSPPLLAATT!! is a powerful terrestrial RF propagation and terrain analysis tool for the spectrum between 20 MHz and 20 GHz. SSPPLLAATT!! is free soft- ware, and is designed for operation on Unix and Linux-based worksta- tions. Redistribution and/or modification is permitted under the terms of the GNU General Public License, Version 2, as published by the Free Software Foundation. Adoption of SSPPLLAATT!! source code in proprietary or closed-source applications is a violation of this license and is ssttrriiccttllyy forbidden. SSPPLLAATT!! 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. IINNTTRROODDUUCCTTIIOONN Applications of SSPPLLAATT!! include the visualization, design, and link bud- get analysis of wireless Wide Area Networks (WANs), commercial and ama- teur radio communication systems above 20 MHz, microwave links, fre- quency coordination and interference studies, and the prediction of analog and digital terrestrial radio and television contour regions. SSPPLLAATT!! provides RF site engineering data such as great circle distances and bearings between sites, antenna elevation angles (uptilt), depres- sion angles (downtilt), antenna height above mean sea level, antenna height above average terrain, bearings, distances, and elevations to known obstructions, Longley-Rice path attenuation, and received signal strength. In addition, the minimum antenna height requirements needed to clear terrain, the first Fresnel zone, and any user-definable per- centage of the first Fresnel zone are also provided. SSPPLLAATT!! produces reports, graphs, and high resolution topographic maps that depict line-of-sight paths, and regional path loss and signal strength contours through which expected coverage areas of transmitters and repeater systems can be obtained. When performing line-of-sight and Longley-Rice analyses in situations where multiple transmitter or repeater sites are employed, SSPPLLAATT!! determines individual and mutual areas of coverage within the network specified. IINNPPUUTT FFIILLEESS SSPPLLAATT!! is a command-line driven application and reads input data through a number of data files. Some files are mandatory for success- ful execution of the program, while others are optional. Mandatory files include digital elevation topography models in the form of SPLAT Data Files (SDF files), site location files (QTH files), and Longley- Rice model parameter files (LRP files). Optional files include city location files, cartographic boundary files, user-defined terrain files, path loss input files, antenna radiation pattern files, and color definition files. SSPPLLAATT DDAATTAA FFIILLEESS SSPPLLAATT!! imports topographic data in the form of SPLAT Data Files (SDFs). These files may be generated from a number of information sources. In the United States, SPLAT Data Files can be generated through U.S. Geo- logical Survey Digital Elevation Models (DEMs) using the ppoossttddoowwnnllooaadd and uussggss22ssddff utilities included with SSPPLLAATT!!. USGS Digital Elevation Models compatible with these utilities may be downloaded from: _h_t_t_p_:_/_/_e_d_c_f_t_p_._c_r_._u_s_g_s_._g_o_v_/_p_u_b_/_d_a_t_a_/_D_E_M_/_2_5_0_/. 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 ssrrttmm22ssddff utility. SRTM-3 Version 2 data may be obtained through anonymous FTP from: _f_t_p_:_/_/_e_0_s_r_p_0_1_u_._e_c_s_._n_a_s_a_._g_o_v_:_2_1_/_s_r_t_m_/_v_e_r_- _s_i_o_n_2_/_S_R_T_M_3_/ 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 lati- tude and longitude provided in the SRTM filename. The ssrrttmm22ssddff utility may also be used to convert 3-arc second SRTM data in Band Interleaved by Line (.BIL) format for use with SSPPLLAATT!!. This data is available via the web at: _h_t_t_p_:_/_/_s_e_a_m_l_e_s_s_._u_s_g_s_._g_o_v_/_w_e_b_- _s_i_t_e_/_s_e_a_m_l_e_s_s_/ Band Interleaved by Line data must be downloaded in a very specific manner to be compatible with ssrrttmm22ssddff and SSPPLLAATT!!. Please consult ssrrttmm22ssddff's documentation for instructions on downloading .BIL topo- graphic 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 down- loaded from: _f_t_p_:_/_/_e_0_s_r_p_0_1_u_._e_c_s_._n_a_s_a_._g_o_v_:_2_1_/_s_r_t_m_/_v_e_r_s_i_o_n_2_/_S_R_T_M_1_/ High resolution SDF files for use with SSPPLLAATT!! HHDD may be generated from data in this format using the ssrrttmm22ssddff--hhdd utility. Despite the higher accuracy that SRTM data has to offer, some voids in the data sets exist. When voids are detected, the ssrrttmm22ssddff and ssrrttmm22ssddff--hhdd utilities replace them with corresponding data found in uussggss22ssddff generated SDF files. 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 elevations in meters referenced to mean sea level for 1-degree by 1-degree regions of the Earth. SDF files can be read by SSPPLLAATT!! in either standard format (_._s_d_f) as generated directly by the uussggss22ssddff, ssrrttmm22ssddff, and ssrrttmm22ssddff--hhdd utilities, or in bzip2 compressed format (_._s_d_f_._b_z_2). Since uncom- pressed files can be read slightly faster than files that have been compressed, SSPPLLAATT!! searches for needed SDF data in uncompressed format first. If uncompressed data cannot be located, SSPPLLAATT!! then searches for data in bzip2 compressed format. If no compressed SDF files can be found for the region requested, SSPPLLAATT!! assumes the region is over water, and will assign an elevation of sea-level to these areas. This feature of SSPPLLAATT!! makes it possible to perform path analysis not only over land, but also between coastal areas not represented by Digi- tal Elevation Model data. However, this behavior of SSPPLLAATT!! under- scores the importance of having all the SDF files required for the region being analyzed if meaningful results are to be expected. SSIITTEE LLOOCCAATTIIOONN ((QQTTHH)) FFIILLEESS SSPPLLAATT!! imports site location information of transmitter and receiver sites analyzed by the program from ASCII files having a _._q_t_h extension. QTH files contain the site's name, the site's latitude (positive if North of the equator, negative if South), the site's longitude (in degrees West, 0 to 360 degrees, or degrees East 0 to -360 degrees), and the site's antenna height above ground level (AGL), each separated by a single line-feed character. The antenna height is assumed to be speci- fied in feet unless followed by the letter _m or the word _m_e_t_e_r_s 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 (_w_n_j_t_-_d_t_._q_t_h) might read as follows: WNJT-DT 40.2828 74.6864 990.00 Each transmitter and receiver site analyzed by SSPPLLAATT!! must be repre- sented by its own site location (QTH) file. LLOONNGGLLEEYY--RRIICCEE PPAARRAAMMEETTEERR ((LLRRPP)) FFIILLEESS Longley-Rice parameter data files are required for SSPPLLAATT!! to determine RF path loss, field strength, or received signal power level 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 transmitter site QTH file, but with a _._l_r_p extension. SSPPLLAATT!! LRP files share the following format (_w_n_j_t_-_d_t_._l_r_p): 15.000 ; Earth Dielectric Constant (Relative permittivity) 0.005 ; Earth Conductivity (Siemens per meter) 301.000 ; Atmospheric Bending Constant (N-units) 647.000 ; Frequency in MHz (20 MHz to 20 GHz) 5 ; Radio Climate (5 = Continental Temperate) 0 ; Polarization (0 = Horizontal, 1 = Vertical) 0.50 ; Fraction of situations (50% of locations) 0.90 ; Fraction of time (90% of the time) 46000.0 ; ERP in Watts (optional) If an LRP file corresponding to the tx_site QTH file cannot be found, SSPPLLAATT!! scans the current working directory for the file "splat.lrp". If this file cannot be found, then default parameters will be assigned by SSPPLLAATT!! and a corresponding "splat.lrp" file containing these default parameters will be written to the current working directory. The gen- erated "splat.lrp" file can then be edited by the user as needed. Typical Earth dielectric constants and conductivity values are as fol- lows: Dielectric Constant Conductivity Salt water : 80 5.000 Good ground : 25 0.020 Fresh water : 80 0.010 Marshy land : 12 0.007 Farmland, forest : 15 0.005 Average ground : 15 0.005 Mountain, sand : 13 0.002 City : 5 0.001 Poor ground : 4 0.001 Radio climate codes used by SSPPLLAATT!! are as follows: 1: Equatorial (Congo) 2: Continental Subtropical (Sudan) 3: Maritime Subtropical (West coast of Africa) 4: Desert (Sahara) 5: Continental Temperate 6: Maritime Temperate, over land (UK and west coasts of US & EU) 7: Maritime Temperate, over sea The Continental Temperate climate is common to large land masses in the temperate zone, such as the United States. For paths shorter than 100 km, there is little difference between Continental and Maritime Temper- ate climates. The seventh and eighth parameters in the _._l_r_p file correspond to the statistical analysis provided by the Longley-Rice model. In this exam- ple, SSPPLLAATT!! will return the maximum path loss occurring 50% of the time (fraction of time) in 90% of situations (fraction of situations). This is often denoted as F(50,90) in Longley-Rice studies. In the United States, an F(50,90) criteria is typically used for digital television (8-level VSB modulation), while F(50,50) is used for analog (VSB- AM+NTSC) broadcasts. For further information on these parameters, see: _h_t_t_p_:_/_/_f_l_a_t_- _t_o_p_._i_t_s_._b_l_d_r_d_o_c_._g_o_v_/_i_t_m_._h_t_m_l and _h_t_t_p_:_/_/_w_w_w_._s_o_f_t_w_r_i_g_h_t_._c_o_m_/_f_a_q_/_e_n_g_i_- _n_e_e_r_i_n_g_/_p_r_o_p___l_o_n_g_l_e_y___r_i_c_e_._h_t_m_l The final parameter in the _._l_r_p file corresponds to the transmitter's effective radiated power, and is optional. If it is included in the _._l_r_p file, then SSPPLLAATT!! will compute received signal strength levels and field strength level contours when performing Longley-Rice studies. If the parameter is omitted, path loss is computed instead. The ERP pro- vided in the _._l_r_p file can be overridden by using SSPPLLAATT!!'s _-_e_r_p com- mand-line switch. If the _._l_r_p 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 _-_e_r_p switch without having to edit the _._l_r_p file to accomplish the same result. CCIITTYY LLOOCCAATTIIOONN FFIILLEESS The names and locations of cities, tower sites, or other points of interest may be imported and plotted on topographic maps generated by SSPPLLAATT!!. SSPPLLAATT!! imports the names of cities and locations from ASCII files containing the location of interest's name, latitude, and longi- tude. Each field is separated by a comma. Each record is separated by a single line feed character. As was the case with the _._q_t_h files, latitude and longitude information may be entered in either decimal or degree, minute, second (DMS) format. For example (_c_i_t_i_e_s_._d_a_t): 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. SSPPLLAATT!! 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 SSPPLLAATT!! 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 cciittyyddeeccooddeerr utility included with SSPPLLAATT!!. Such data is available free of charge via the Internet at: _h_t_t_p_:_/_/_w_w_w_._c_e_n_s_u_s_._g_o_v_/_g_e_o_/_w_w_w_/_c_o_b_/_b_d_y___f_i_l_e_s_._h_t_m_l, and must be in ASCII format. CCAARRTTOOGGRRAAPPHHIICC BBOOUUNNDDAARRYY DDAATTAA FFIILLEESS Cartographic boundary data may also be imported to plot the boundaries of cities, counties, or states on topographic maps generated by SSPPLLAATT!!. 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: _h_t_t_p_:_/_/_w_w_w_._c_e_n_- _s_u_s_._g_o_v_/_g_e_o_/_w_w_w_/_c_o_b_/_c_o_2_0_0_0_._h_t_m_l_#_a_s_c_i_i and _h_t_t_p_:_/_/_w_w_w_._c_e_n_- _s_u_s_._g_o_v_/_g_e_o_/_w_w_w_/_c_o_b_/_p_l_2_0_0_0_._h_t_m_l_#_a_s_c_i_i. A total of five separate carto- graphic boundary files may be imported at a time. It is not necessary to import state boundaries if county boundaries have already been imported. PPRROOGGRRAAMM OOPPEERRAATTIIOONN SSPPLLAATT!! is invoked via the command-line using a series of switches and arguments. Since SSPPLLAATT!! is a CPU and memory intensive application, this type of interface minimizes overhead and lends itself well to scripted (batch) operations. SSPPLLAATT!!'s CPU and memory scheduling prior- ity may be modified through the use of the Unix nniiccee command. The number and type of switches passed to SSPPLLAATT!! determine its mode of operation and method of output data generation. Nearly all of SSPPLLAATT!!'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 SSPPLLAATT!!'s command line options: --==[ SPLAT! v1.3.0 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) -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 The command-line options for splat and splat-hd are identical. SSPPLLAATT!! operates in two distinct modes: _p_o_i_n_t_-_t_o_-_p_o_i_n_t _m_o_d_e, and _a_r_e_a _p_r_e_d_i_c_t_i_o_n _m_o_d_e. Either a line-of-sight (LOS) or Longley-Rice Irregu- lar Terrain (ITM) propagation model may be invoked by the user. True Earth, four-thirds Earth, or any other user-defined Earth radius may be specified when performing line-of-sight analysis. PPOOIINNTT--TTOO--PPOOIINNTT AANNAALLYYSSIISS SSPPLLAATT!! may be used to perform line-of-sight terrain analysis between two specified site locations. For example: splat -t tx_site.qth -r rx_site.qth invokes a line-of-sight terrain analysis between the transmitter speci- fied in _t_x___s_i_t_e_._q_t_h and receiver specified in _r_x___s_i_t_e_._q_t_h using a True Earth radius model, and writes a SSPPLLAATT!! Path Analysis Report to the current working directory. The report contains details of the trans- mitter and receiver sites, and identifies the location of any obstruc- tions detected along the line-of-sight path. If an obstruction can be cleared by raising the receive antenna to a greater altitude, SSPPLLAATT!! 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 _-_m_e_t_r_i_c switch is added to SSPPLLAATT!!'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 _m_i_n_i_m_u_m 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. _q_t_h extensions are assumed by SSPPLLAATT!! for QTH files, and are optional when specifying -t and -r arguments on the command-line. SSPPLLAATT!! auto- matically reads all SPLAT Data Files necessary to conduct the terrain analysis between the sites specified. SSPPLLAATT!! searches for the required SDF files in the current working directory first. If the needed files are not found, SSPPLLAATT!! 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 _$_H_O_M_E_/_._s_p_l_a_t___p_a_t_h 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 SSPPLLAATT!! invokes ggnnuupplloott when generating graphs. The filename extension specified to SSPPLLAATT!! determines the format of the graph produced. _._p_n_g will produce a 640x480 color PNG graphic file, while _._p_s or _._p_o_s_t_s_c_r_i_p_t will produce postscript output. Output in formats such as GIF, Adobe Illustrator, AutoCAD dxf, LaTeX, and many others are available. Please consult ggnnuupplloott, and ggnnuupplloott's documentation for details on all the supported output formats. A graph of elevations subtended by the terrain between the receiver and transmitter as a function of distance from the receiver can be gener- ated by using the _-_e switch: splat -t tx_site -r rx_site -e elevation_profile.png The graph produced using this switch illustrates the elevation and depression angles resulting from the terrain between the receiver's location and the transmitter site from the perspective of the receiver's location. A second trace is plotted between the left side of the graph (receiver's location) and the location of the transmitting antenna on the right. This trace illustrates the elevation angle required for a line-of-sight path to exist between the receiver and transmitter locations. If the trace intersects the elevation profile at any point on the graph, then this is an indication that a line-of- sight path does not exist under the conditions given, and the obstruc- tions can be clearly identified on the graph at the point(s) of inter- section. A graph illustrating terrain height referenced to a line-of-sight path between the transmitter and receiver may be generated using the _-_h switch: splat -t tx_site -r rx_site -h height_profile.png A terrain height plot normalized to the transmitter and receiver antenna heights can be obtained using the _-_H switch: splat -t tx_site -r rx_site -H normalized_height_profile.png A contour of the Earth's curvature is also plotted in this mode. The first Fresnel Zone, and 60% of the first Fresnel Zone can be added to height profile graphs by adding the _-_f switch, and specifying a fre- quency (in MHz) at which the Fresnel Zone should be modeled: splat -t tx_site -r rx_site -f 439.250 -H normalized_height_profile.png Fresnel Zone clearances other 60% can be specified using the _-_f_z switch as follows: splat -t tx_site -r rx_site -f 439.250 -fz 75 -H height_profile2.png A graph showing Longley-Rice path loss may be plotted using the _-_l switch: splat -t tx_site -r rx_site -l path_loss_profile.png As before, adding the _-_m_e_t_r_i_c switch forces the graphs to be plotted using metric units of measure. The _-_g_p_s_a_v switch instructs SSPPLLAATT!! to preserve (rather than delete) the ggnnuupplloott working files generated dur- ing SSPPLLAATT!! execution, allowing the user to edit these files and re-run ggnnuupplloott if desired. When performing a point-to-point analysis, a SSPPLLAATT!! Path Analysis Report is generated in the form of a text file with a _._t_x_t filename extension. The report contains bearings and distances between the transmitter and receiver, as well as the free-space and Longley-Rice path loss for the path being analyzed. The mode of propagation for the path is given as _L_i_n_e_-_o_f_-_S_i_g_h_t, _S_i_n_g_l_e _H_o_r_i_z_o_n, _D_o_u_b_l_e _H_o_r_i_z_o_n, _D_i_f_f_r_a_c_t_i_o_n _D_o_m_i_n_a_n_t, or _T_r_o_p_o_s_c_a_t_t_e_r _D_o_m_i_n_a_n_t. Distances and locations to known obstructions along the path between transmitter and receiver are also provided. If the transmitter's effective radiated power is specified in the transmitter's correspond- ing _._l_r_p file, then predicted signal strength and antenna voltage at the receiving location is also provided in the Path Analysis Report. To determine the signal-to-noise (SNR) ratio at remote location where random Johnson (thermal) noise is the primary limiting factor in recep- tion: _S_N_R=_T-_N_J-_L+_G-_N_F where TT is the ERP of the transmitter in dBW in the direction of the receiver, NNJJ is Johnson Noise in dBW (-136 dBW for a 6 MHz television channel), LL is the path loss provided by SSPPLLAATT!! in dB (as a _p_o_s_i_t_i_v_e number), GG is the receive antenna gain in dB over isotropic, and NNFF is the receiver noise figure in dB. TT may be computed as follows: _T=_T_I+_G_T where TTII is actual amount of RF power delivered to the transmitting antenna in dBW, GGTT is the transmitting antenna gain (over isotropic) in the direction of the receiver (or the horizon if the receiver is over the horizon). To compute how much more signal is available over the minimum to neces- sary to achieve a specific signal-to-noise ratio: _S_i_g_n_a_l__M_a_r_g_i_n=_S_N_R-_S where SS 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 SSPPLLAATT!! to visualize the path between the transmitter and receiver sites from yet another perspec- tive. Topographic maps generated by SSPPLLAATT!! 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 _._p_p_m extension on the output filename is assumed by SSPPLLAATT!!, and is optional. In this example, _t_o_p_o___m_a_p_._p_p_m will illustrate the locations of the transmitter and receiver sites specified. In addition, the great cir- cle path between the two sites will be drawn over locations for which an unobstructed path exists to the transmitter at a receiving antenna height equal to that of the receiver site (specified in _r_x___s_i_t_e_._q_t_h). It may desirable to populate the topographic map with names and loca- tions of cities, tower sites, or other important locations. A city file may be passed to SSPPLLAATT!! 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 SSPPLLAATT!! at a time fol- lowing the _-_s switch. County and state boundaries may be added to the map by specifying up to five U.S. Census Bureau cartographic boundary files using the _-_b switch: splat -t tx_site -r rx_site -b co34_d00.dat -o topo_map In situations where multiple transmitter sites are in use, as many as four site locations may be passed to SSPPLLAATT!! 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 SSPPLLAATT!!. 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. SSPPLLAATT!! 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 xxvv, TThhee GGIIMMPP, IImmaaggeeMMaaggiicckk, and XXPPaaiinntt. PNG format is highly recommended for lossless compressed storage of SSPPLLAATT!! generated topographic output files. IImmaaggeeMMaaggiicckk's command-line utility easily converts SSPPLLAATT!!'s PPM files to PNG format: convert splat_map.ppm splat_map.png Another excellent PPM to PNG command-line utility is available at: _h_t_t_p_:_/_/_w_w_w_._l_i_b_p_n_g_._o_r_g_/_p_u_b_/_p_n_g_/_b_o_o_k_/_s_o_u_r_c_e_s_._h_t_m_l. As a last resort, PPM files may be compressed using the bzip2 utility, and read directly by TThhee GGIIMMPP in this format. The _-_n_g_s 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 IImmaaggeeMMaaggiicckk's ccoonnvveerrtt utility: convert -transparent "#FFFFFF" white_map.ppm transparent_map.png RREEGGIIOONNAALL CCOOVVEERRAAGGEE AANNAALLYYSSIISS SSPPLLAATT!! can analyze a transmitter or repeater site, or network of sites, and predict the regional coverage for each site specified. In this mode, SSPPLLAATT!! 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 SSPPLLAATT!! 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, SSPPLLAATT!! generates a topographic map called _t_x___c_o_v_e_r_- _a_g_e_._p_p_m that illustrates the predicted line-of-sight regional coverage of _t_x___s_i_t_e to receiving locations having antennas 30.0 feet above ground level (AGL). If the _-_m_e_t_r_i_c switch is used, the argument fol- lowing the _-_c switch is interpreted as being in meters rather than in feet. The contents of _c_i_t_i_e_s_._d_a_t are plotted on the map, as are the cartographic boundaries contained in the file _c_o_3_4___d_0_0_._d_a_t. When plotting line-of-sight paths and areas of regional coverage, SSPPLLAATT!! by default does not account for the effects of atmospheric bend- ing. However, this behavior may be modified by using the Earth radius multiplier (_-_m) switch: splat -t wnjt-dt -c 30.0 -m 1.333 -s cities.dat -b counties.dat -o map.ppm An earth radius multiplier of 1.333 instructs SSPPLLAATT!! to use the "four- thirds earth" model for line-of-sight propagation analysis. Any appro- priate earth radius multiplier may be selected by the user. When performing a regional analysis, SSPPLLAATT!! generates a site report for each station analyzed. SSPPLLAATT!! site reports contain details of the site's geographic location, its height above mean sea level, the antenna's height above mean sea level, the antenna's height above aver- age terrain, and the height of the average terrain calculated toward the bearings of 0, 45, 90, 135, 180, 225, 270, and 315 degrees azimuth. DDEETTEERRMMIINNIINNGG MMUULLTTIIPPLLEE RREEGGIIOONNSS OOFF LLOOSS CCOOVVEERRAAGGEE SSPPLLAATT!! can also display line-of-sight coverage areas for as many as four separate transmitter sites on a common topographic map. For exam- ple: splat -t site1 site2 site3 site4 -c 10.0 -metric -o network.ppm plots the regional line-of-sight coverage of site1, site2, site3, and site4 based on a receive antenna located 10.0 meters above ground level. A topographic map is then written to the file _n_e_t_w_o_r_k_._p_p_m. 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 _._q_t_h files are generated, each representing a common site location but a different antenna height, a single topographic map illustrating the regional coverage from as many as four separate loca- tions on a single tower may be generated by SSPPLLAATT!!. PPAATTHH LLOOSSSS AANNAALLYYSSIISS If the _-_c switch is replaced by a _-_L switch, a Longley-Rice path loss map for a transmitter site may be generated: splat -t wnjt -L 30.0 -s cities.dat -b co34_d00.dat -o path_loss_map In this mode, SSPPLLAATT!! 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 _-_d_b 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, SSPPLLAATT!!'s path loss plot can be constrained to the region bounded by the 140 dB attenuation con- tour 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 dis- tance using the _-_R switch. The argument must be given in miles (or kilometers if the _-_m_e_t_r_i_c switch is used). If a range wider than the generated topographic map is specified, SSPPLLAATT!! will perform Longley- Rice path loss calculations between all four corners of the area pre- diction map. The colors used to illustrate contour regions in SSPPLLAATT!! generated cov- erage maps may be tailored by the user by creating or modifying SSPPLLAATT!!'s color definition files. SSPPLLAATT!! color definition files have the same base name as the transmitter's _._q_t_h file, but carry _._l_c_f, _._s_c_f, and _._d_c_f extensions. If the necessary file does not exist in the current working when SSPPLLAATT!! 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 Longley-Rice analysis is performed and the transmit- ter's ERP is not specified or is zero, a _._l_c_f path loss color defini- tion file corresponding to the transmitter site (_._q_t_h) is read by SSPPLLAATT!! from the current working directory. If a _._l_c_f file correspond- ing to the transmitter site is not found, then a default file suitable for manual editing by the user is automatically generated by SSPPLLAATT!!. A path loss color definition file possesses the following structure (_w_n_j_t_-_d_t_._l_c_f): ; SPLAT! Auto-generated Path-Loss Color Definition ("wnjt-dt.lcf") File ; ; Format for the parameters held in this file is as follows: ; ; dB: red, green, blue ; ; ...where "dB" is the path loss (in dB) and ; "red", "green", and "blue" are the corresponding RGB color ; definitions ranging from 0 to 255 for the region specified. ; ; The following parameters may be edited and/or expanded ; for future runs of SPLAT! A total of 32 contour regions ; may be defined in this file. ; ; 80: 255, 0, 0 90: 255, 128, 0 100: 255, 165, 0 110: 255, 206, 0 120: 255, 255, 0 130: 184, 255, 0 140: 0, 255, 0 150: 0, 208, 0 160: 0, 196, 196 170: 0, 148, 255 180: 80, 80, 255 190: 0, 38, 255 200: 142, 63, 255 210: 196, 54, 255 220: 255, 0, 255 230: 255, 194, 204 If the path loss is less than 80 dB, the color Red (RGB = 255, 0, 0) is assigned to the region. If the path loss is greater than or equal to 80 dB, but less than 90 db, then Dark Orange (255, 128, 0) is assigned to the region. Orange (255, 165, 0) is assigned to regions having a path loss greater than or equal to 90 dB, but less than 100 dB, and so on. Greyscale terrain is displayed beyond the 230 dB path loss con- tour. FFIIEELLDD SSTTRREENNGGTTHH AANNAALLYYSSIISS If the transmitter's effective radiated power (ERP) is specified in the transmitter's _._l_r_p file, or expressed on the command-line using the _-_e_r_p 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 _-_d_b 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. SSPPLLAATT!! field strength color definition files share a very similar structure to _._l_c_f 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 micro- volt per meter (dBuV/m), the color Red (255, 0, 0) is displayed for the region. If the signal strength is greater than or equal to 118 dBuV/m, but less than 128 dBuV/m, then the color Orange (255, 165, 0) is dis- played, and so on. Greyscale terrain is displayed for regions with signal strengths less than 8 dBuV/m. Signal strength contours for some common VHF and UHF broadcasting ser- vices in the United States are as follows: Analog Television Broadcasting ------------------------------ Channels 2-6: City Grade: >= 74 dBuV/m Grade A: >= 68 dBuV/m Grade B: >= 47 dBuV/m -------------------------------------------- Channels 7-13: City Grade: >= 77 dBuV/m Grade A: >= 71 dBuV/m Grade B: >= 56 dBuV/m -------------------------------------------- Channels 14-69: Indoor Grade: >= 94 dBuV/m City Grade: >= 80 dBuV/m Grade A: >= 74 dBuV/m Grade B: >= 64 dBuV/m Digital Television Broadcasting ------------------------------- Channels 2-6: City Grade: >= 35 dBuV/m Service Threshold: >= 28 dBuV/m -------------------------------------------- Channels 7-13: City Grade: >= 43 dBuV/m Service Threshold: >= 36 dBuV/m -------------------------------------------- Channels 14-69: City Grade: >= 48 dBuV/m Service Threshold: >= 41 dBuV/m NOAA Weather Radio (162.400 - 162.550 MHz) ------------------------------------------ Reliable: >= 18 dBuV/m Not reliable: < 18 dBuV/m Unlikely to receive: < 0 dBuV/m FM Radio Broadcasting (88.1 - 107.9 MHz) ---------------------------------------- Analog Service Contour: 60 dBuV/m Digital Service Contour: 65 dBuV/m RREECCEEIIVVEEDD PPOOWWEERR LLEEVVEELL AANNAALLYYSSIISS If the transmitter's effective radiated power (ERP) is specified in the transmitter's _._l_r_p file, or expressed on the command-line using the _-_e_r_p switch, and the _-_d_b_m switch is invoked, received power level con- tours 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 _-_d_b 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. SSPPLLAATT!! 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 speci- fied. ; ; The following parameters may be edited and/or expanded ; for future runs of SPLAT! A total of 32 contour regions ; may be defined in this file. ; ; +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 AANNTTEENNNNAA RRAADDIIAATTIIOONN PPAATTTTEERRNN PPAARRAAMMEETTEERRSS Normalized field voltage patterns for a transmitting antenna's horizon- tal and vertical planes are imported automatically into SSPPLLAATT!! 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 _._a_z and _._e_l 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 SSPPLLAATT!! antenna pattern files. For example, the first few lines of a SSPPLLAATT!! azimuth pattern file might appear as follows (_k_v_e_a_._a_z): 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 _._a_z file specifies the amount of azimuthal pat- tern rotation (measured clockwise in degrees from True North) to be applied by SSPPLLAATT!! to the data contained in the _._a_z file. This is fol- lowed by azimuth headings (0 to 360 degrees) and their associated nor- malized field patterns (0.000 to 1.000) separated by whitespace. The structure of SSPPLLAATT!! elevation pattern files is slightly different. The first line of the _._e_l file specifies the amount of mechanical beam tilt applied to the antenna. Note that a _d_o_w_n_w_a_r_d _t_i_l_t (below the horizon) is expressed as a _p_o_s_i_t_i_v_e _a_n_g_l_e, while an _u_p_w_a_r_d _t_i_l_t (above the horizon) is expressed as a _n_e_g_a_t_i_v_e _a_n_g_l_e. This data is followed by the azimuthal direction of the tilt, separated by whitespace. The remainder of the file consists of elevation angles and their corre- sponding normalized voltage radiation pattern (0.000 to 1.000) values separated by whitespace. Elevation angles must be specified over a -10.0 to +90.0 degree range. As was the convention with mechanical beamtilt, _n_e_g_a_t_i_v_e _e_l_e_v_a_t_i_o_n _a_n_g_l_e_s are used to represent elevations _a_b_o_v_e _t_h_e _h_o_r_i_z_o_n, while _p_o_s_i_t_i_v_e _a_n_g_l_e_s represents elevations _b_e_l_o_w _t_h_e _h_o_r_i_z_o_n. For example, the first few lines a SSPPLLAATT!! elevation pattern file might appear as follows (_k_v_e_a_._e_l): 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, SSPPLLAATT!! will interpolate the values provided to determine the data at the required resolution, although this may result in a loss in accuracy. EEXXPPOORRTTIINNGG AANNDD IIMMPPOORRTTIINNGG RREEGGIIOONNAALL CCOONNTTOOUURR DDAATTAA Performing a regional coverage analysis based on a Longley-Rice path analysis can be a very time consuming process, especially if the analy- sis 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 SSPPLLAATT!! to an alphanumeric output _(_._a_n_o_) file. The data contained in this file can then be modified to incorporate antenna pattern effects, and imported back into SSPPLLAATT!! to quickly produce a revised contour map. Depending on the way in which SSPPLLAATT!! 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 informa- tion can be generated by SSPPLLAATT!! 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 _._l_r_p 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 _._l_r_p file or on the command line through the _-_e_r_p switch, the alphanumeric output file will instead contain pre- dicted field values in dBuV/m. If the _-_d_B_m command line switch is used, then the alphanumeric output file will contain receive signal power levels in dBm. SSPPLLAATT!! 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) wwiitthhoouutt rreeggaarrdd ttoo tthhee ttrraannssmmiittttiinngg aanntteennnnaa''ss rraaddiiaattiioonn ppaatttteerrnn. The first few lines of a SSPPLLAATT!! alphanumeric output file could take on the following appearance (_p_a_t_h_l_o_s_s_._d_a_t): 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 proceeded by a semicolon character. The vviimm 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 _i_f 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 SSPPLLAATT!! 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 Longley-Rice 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 SSPPLLAATT!! path loss files to reflect antenna pattern data, _o_n_l_y _t_h_e _l_a_s_t _n_u_m_e_r_i_c _c_o_l_u_m_n 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 SSPPLLAATT!! 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 SSPPLLAATT!! to pro- duce signal strength or received power level contours, etc. UUSSEERR--DDEEFFIINNEEDD TTEERRRRAAIINN IINNPPUUTT FFIILLEESS A user-defined terrain file is a user-generated text file containing latitudes, longitudes, and heights above ground level of specific ter- rain features believed to be of importance to the SSPPLLAATT!! analysis being conducted, but noticeably absent from the SDF files being used. A user-defined terrain file is imported into a SSPPLLAATT!! analysis using the _-_u_d_t 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 _m_e_t_e_r_s, and is added _o_n _t_o_p _o_f the terrain specified in the SDF data for the locations specified. Be aware that each user-defined terrain feature specified will be inter- preted as being 3-arc seconds in both latitude and longitude 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 SSPPLLAATT!! to avoid ambiguity. GGRROOUUNNDD CCLLUUTTTTEERR The height of ground clutter can be specified using the _-_g_c switch: splat -t wnjt-dt -r kd2bd -gc 30.0 -H wnjt-dt_path.png The _-_g_c switch as the effect of raising the overall terrain by the specified amount in feet (or meters if the _-_m_e_t_r_i_c switch is invoked), except over areas at sea-level and at the transmitting and receiving antenna locations. Note that the addition of ground clutter does not necessarily modify the Longley-Rice path loss results unless the addi- tional clutter height results in a switch in the propagation mode from a less obstructed path to a more obstructed path (from Line Of Sight to Single Horizon Diffraction Dominant, for example). It does, however, affect Fresnel zone clearances and line of sight determinations. SSIIMMPPLLEE TTOOPPOOGGRRAAPPHHIICC MMAAPP GGEENNEERRAATTIIOONN In certain situations it may be desirable to generate a topographic map of a region without plotting coverage areas, line-of-sight paths, or generating obstruction reports. There are several ways of doing this. If one wishes to generate a topographic map illustrating the location of a transmitter and receiver site along with a brief text report describing the locations and distances between the sites, the _-_n switch should be invoked as follows: splat -t tx_site -r rx_site -n -o topo_map.ppm If no text report is desired, then the _-_N switch is used: splat -t tx_site -r rx_site -N -o topo_map.ppm If a topographic map centered about a single site out to a minimum specified radius is desired instead, a command similar to the following can be used: splat -t tx_site -R 50.0 -s NJ_Cities -b NJ_Counties -o topo_map.ppm where -R specifies the minimum radius of the map in miles (or kilome- ters if the _-_m_e_t_r_i_c switch is used). Note that the tx_site name and location are not displayed in this example. If display of this infor- mation is desired, simply create a SSPPLLAATT!! 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 _t_x___s_i_t_e_._p_p_m in the cur- rent working directory by default. GGEEOORREEFFEERREENNCCEE FFIILLEE GGEENNEERRAATTIIOONN Topographic, coverage (_-_c), and path loss contour (_-_L) maps generated by SSPPLLAATT!! may be imported into XXaassttiirr (X Amateur Station Tracking and Information Reporting) software by generating a georeference file using SSPPLLAATT!!'s _-_g_e_o 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 _._g_e_o extension, and permit proper interpre- tation and display of SSPPLLAATT!!'s .ppm graphics in XXaassttiirr software. GGOOOOGGLLEE MMAAPP KKMMLL FFIILLEE GGEENNEERRAATTIIOONN Keyhole Markup Language files compatible with GGooooggllee EEaarrtthh may be gen- erated by SSPPLLAATT!! when performing point-to-point or regional coverage analyses by invoking the _-_k_m_l 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 _._k_m_l extension. Once loaded into GGooooggllee EEaarrtthh (File --> Open), the KML file will anno- tate the map display with the names of the transmitter and receiver site locations. The viewpoint of the image will be from the position of the transmitter site looking towards the location of the receiver. The point-to-point path between the sites will be displayed as a white line while the RF line-of-sight path will be displayed in green. GGooooggllee EEaarrtthh's navigation tools allow the user to "fly" around the path, identify landmarks, roads, and other featured content. When performing regional coverage analysis, the _._k_m_l file generated by SSPPLLAATT!! will permit path loss or signal strength contours to be layered on top of GGooooggllee EEaarrtthh's display in a semi-transparent manner. The generated _._k_m_l file will have the same basename as that of the _._p_p_m file normally generated. DDEETTEERRMMIINNAATTIIOONN OOFF AANNTTEENNNNAA HHEEIIGGHHTT AABBOOVVEE AAVVEERRAAGGEE TTEERRRRAAIINN SSPPLLAATT!! 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 SSPPLLAATT!! are SRTM-derived. When performing point-to-point terrain analysis, SSPPLLAATT!! determines the antenna height above average terrain only if enough topographic data has already been loaded by the program to perform the point-to-point analysis. In most cases, this will be true, unless the site in ques- tion does not lie within 10 miles of the boundary of the topography data in memory. When performing area prediction analysis, enough topography data is normally loaded by SSPPLLAATT!! to perform average terrain calculations. Under such conditions, SSPPLLAATT!! 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, SSPPLLAATT!! reports _N_o _T_e_r_r_a_i_n for the radial paths affected. AADDDDIITTIIOONNAALL IINNFFOORRMMAATTIIOONN The latest news and information regarding SSPPLLAATT!! software is available through the official SSPPLLAATT!! software web page located at: _h_t_t_p_:_/_/_w_w_w_._q_s_l_._n_e_t_/_k_d_2_b_d_/_s_p_l_a_t_._h_t_m_l. AAUUTTHHOORRSS John A. Magliacane, KD2BD <_k_d_2_b_d_@_a_m_s_a_t_._o_r_g> Creator, Lead Developer Doug McDonald <_m_c_d_o_n_a_l_d_@_s_c_s_._u_i_u_c_._e_d_u> Original Longley-Rice Model integration Ron Bentley <_r_o_n_b_e_n_t_l_e_y_@_e_m_b_a_r_q_m_a_i_l_._c_o_m> Fresnel Zone plotting and clearance determination KD2BD Software 15 November 2008 SPLAT!(1)