SPLAT!(1) KD2BD Software SPLAT!(1) NNAAMMEE splat - An RF SSignal PPropagation, LLoss, AAnd TTerrain analy- sis 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 _m_a_x_i_m_u_m _a_t_t_e_n_u_a_t_i_o_n _c_o_n_- _t_o_u_r _t_o _d_i_s_p_l_a_y _o_n _p_a_t_h _l_o_s_s _m_a_p_s _(_8_0_-_2_3_0 _d_B_)] [-nf _d_o _n_o_t _p_l_o_t _F_r_e_s_n_e_l _z_o_n_e_s _i_n _h_e_i_g_h_t _p_l_o_t_s] [-plo _p_a_t_h___l_o_s_s___o_u_t_- _p_u_t___f_i_l_e_._t_x_t] [-pli _p_a_t_h___l_o_s_s___i_n_p_u_t___f_i_l_e_._t_x_t] [-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] [-geo] [-kml] [-metric] DDEESSCCRRIIPPTTIIOONN SSPPLLAATT!! is a powerful terrestrial RF propagation and ter- rain analysis tool covering the spectrum between 20 MHz and 20 GHz. SSPPLLAATT!! 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 SSPPLLAATT!! source code in pro- prietary 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 war- ranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR- POSE. See the GNU General Public License for more details. IINNTTRROODDUUCCTTIIOONN Applications of SSPPLLAATT!! 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. SSPPLLAATT!! 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. SSPPLLAATT!! 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, SSPPLLAATT!! determines individual and mutual areas of coverage within the network specified. Simply typing splat on the command line will return a sum- mary of SSPPLLAATT!!'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 IINNPPUUTT FFIILLEESS SSPPLLAATT!! 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. 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. Geological Survey Digital Elevation Models (DEMs) using the uussggss22ssddff utility included with SSPPLLAATT!!. USGS Digital Elevation Models com- patible with this utility 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-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 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_/ Despite the higher accuracy that SRTM data has to offer, some voids in the data sets exist. When voids are detected, the ssrrttmm22ssddff utility replaces them with corre- sponding data found in existing SDF files (that were pre- sumably created from earlier USGS data through the uussggss22ssddff 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 (_._s_d_f) as generated by the uussggss22ssddff and ssrrttmm22ssddff utilities, or in bzip2 compressed format (_._s_d_f_._b_z_2). Since uncompressed files can be processed 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 Digital Elevation Model data. However, this behavior of SSPPLLAATT!! underscores the impor- tance 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), 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 _m_e_t_e_r_s 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 (_w_n_j_t_._q_t_h) might read as fol- lows: WNJT 40.2833 74.6889 990.00 Each transmitter and receiver site analyzed by SSPPLLAATT!! must be represented 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 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 (_w_n_j_t_._l_r_p): 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, SSPPLLAATT!! 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 SSPPLLAATT!! 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 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 Temperate climates. The final two parameters in the _._l_r_p file correspond to the statistical analysis provided by the Longley-Rice model. In this example, SSPPLLAATT!! 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: _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 CCIITTYY LLOOCCAATTIIOONN FFIILLEESS The names and locations of cities, tower sites, or other points of interest may be imported and plotted on topo- graphic maps generated by SSPPLLAATT!!. SSPPLLAATT!! 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 _._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 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 SSPPLLAATT!! 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 cciittyyddee-- ccooddeerr utility included with SSPPLLAATT!!. Such data is avail- able 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 topo- graphic 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 cartographic 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) opera- tions. SSPPLLAATT!!'s CPU and memory scheduling priority 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 genera- tion. Nearly all of SSPPLLAATT!!'s switches may be cascaded in any order on the command line when invoking the program. 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 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. PPOOIINNTT--TTOO--PPOOIINNTT AANNAALLYYSSIISS SSPPLLAATT!! 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 _t_x___s_i_t_e_._q_t_h and receiver speci- fied in _r_x___s_i_t_e_._q_t_h using a True Earth radius model, and writes a SSPPLLAATT!! 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, 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 exam- ple, 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!! automatically 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 file- name 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 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 _-_m_e_t_r_i_c 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 SSPPLLAATT!! in the form of a text file with a _._l_r_o 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 _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, and _T_r_o_p_o_s_c_a_t_t_e_r _D_o_m_i_n_a_n_t. To determine the signal-to-noise (SNR) ratio at remote location where random Johnson (thermal) noise is the pri- mary limiting factor in reception: _S_N_R=_T-_N_J-_L+_G-_N_F where TT is the ERP of the transmitter in dBW in the direc- tion of the receiver, NNJJ is Johnson Noise in dBW (-136 dBW for a 6 MHz television channel), LL is the path loss pro- vided 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 hori- zon). To compute how much more signal is available over the min- imum to necessary 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-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 perspective. 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 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 _r_x___s_i_t_e_._q_t_h). 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 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 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 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. RREEGGIIOONNAALL CCOOVVEERRAAGGEE AANNAALLYYSSIISS SSPPLLAATT!! can analyze a transmitter or repeater site, or net- work of sites, and predict the regional coverage for each site specified. In this mode, SSPPLLAATT!! 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. SSPPLLAATT!! 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, 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 following 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 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 SSPPLLAATT!! 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, 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 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. 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 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 _n_e_t_w_o_r_k_._p_p_m. 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 _._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 locations on a single tower may be generated by SSPPLLAATT!!. LLOONNGGLLEEYY--RRIICCEE 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 gener- ated: 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 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 _-_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 prediction map. The _-_d_b 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, SSPPLLAATT!!'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 AANNTTEENNNNAA RRAADDIIAATTIIOONN PPAATTTTEERRNN PPAARRAAMMEETTEERRSS Normalized field voltage patterns for a transmitting antenna's horizontal and vertical planes are imported automatically into SSPPLLAATT!! 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 _._a_z and _._e_l 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 SSPPLLAATT!! antenna pattern files. For example, the first few lines of a SSPPLLAATT!! azimuth pat- tern 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 pattern rotation (measured clockwise in degrees from True North) to be applied by SSPPLLAATT!! to the data con- tained in the _._a_z 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 SSPPLLAATT!! elevation pattern files is slightly different. The first line of the _._e_l file speci- fies 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, 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, _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 eleva- tions _b_e_l_o_w _t_h_e _h_o_r_i_z_o_n. For example, the first few lines a SSPPLLAATT!! elevation pat- tern 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 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, SSPPLLAATT!! will interpolate the values provided to determine the data at the required resolution, although this may result in a loss in accuracy. IIMMPPOORRTTIINNGG AANNDD EEXXPPOORRTTIINNGG RREEGGIIOONNAALL PPAATTHH LLOOSSSS CCOONNTTOOUURR DDAATTAA 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 SSPPLLAATT!! to rapidly produce a revised path loss map. For example, a path loss output file 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 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 SSPPLLAATT!! 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 SSPPLLAATT!! path loss output file take on the fol- lowing appearance (_p_a_t_h_l_o_s_s_._d_a_t): 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 SSPPLLAATT!! 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 vviimm 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 _i_f 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 SSPPLLAATT!!. 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 SSPPLLAATT!! path loss files to reflect antenna pattern data, _o_n_l_y _t_h_e _l_a_s_t _c_o_l_u_m_n _(_p_a_t_h _l_o_s_s_) 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 SSPPLLAATT!! for generating revised coverage maps: splat -t kvea -pli pathloss.dat -s city.dat -b county.dat -o map.ppm SSPPLLAATT!! path loss files can also be used for conducting coverage or interference studies outside of SSPPLLAATT!!. 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 terrain 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 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 SSPPLLAATT!!. 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 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 _-_m_e_t_r_i_c switch is used). If the _-_o switch and output filename are omitted in these operations, topographic output is written to a file named _m_a_p_._p_p_m in the current 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) soft- ware 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 interpretation 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 generated by SSPPLLAATT!! when performing point-to-point analyses by invoking the _-_k_m_l 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 _._k_m_l extension. Once loaded into GGooooggllee EEaarrtthh (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. GGooooggllee EEaarrtthh's navigation tools allow the user to "fly" around the path, identify landmarks, roads, and other featured content. DDEETTEERRMMIINNAATTIIOONN OOFF AANNTTEENNNNAA HHEEIIGGHHTT AABBOOVVEE AAVVEERRAAGGEE TTEERRRRAAIINN SSPPLLAATT!! 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 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 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 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. RREESSTTRRIICCTTIINNGG TTHHEE MMAAXXIIMMUUMM SSIIZZEE OOFF AANN AANNAALLYYSSIISS RREEGGIIOONN SSPPLLAATT!! 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 _#_d_e_f_i_n_e _M_A_X_S_L_O_T_S statement in the first several lines of _s_p_l_a_t_._c_p_p sets the maximum number of "slots" available for holding topography data. It also sets the maximum size of the topographic maps generated by SSPPLLAATT!!. MAXSLOTS is set to 9 by default. If SSPPLLAATT!! 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 SSPPLLAATT!! 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 SSPPLLAATT!! 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. 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> Longley-Rice Model integration Ron Bentley <_r_o_n_b_e_n_t_l_e_y_@_e_a_r_t_h_l_i_n_k_._n_e_t> Fresnel Zone plotting and clearance determination KD2BD Software 20 December 2006 SPLAT!(1)