Radio propagation calculator

Path loss models take into account both the free space loss (as per Rays are an optical approximation of the electromagnetic wave; as seen earlier, in free space it is convenient to focus on the propagation of the electric field. OpenAPI with user friendly interfaces for web, Google Earth and ATAK. The maximum usable frequency (MUF) is the highest frequency that, with a probability of 50% of the time, can be used for radio communication between two points at a specified distance (but not necessary in all directions) via refraction by the ionosphere. Fuller, Measured and Predicted Long Nov 2, 2011 · The Link Plot tab depicts the radio link loss contributions from the hardware and the channel (propagation path) from start to finish. The maximum service range is therefore. In terms of the propagation and attenuation of sound, the inverse square law is a principle in physics whereby a point source emits a sound wave uniformly in all directions (essentially spherically), where the intensity of the sound wave energy at any given point away from the source Jun 16, 2016 · AUVs and surface stations may communicate over optical links. High Frequency (HF) propagation calculators are tools for estimating and forecasting radio wave propagation. This frequency belongs to the radio waves spectrum. 0 is a planning tool for: - Mobile networks: 5G (NR), LTE, UMTS, GSM, GSM-R, WCDMA - Public safety land mobile networks: P25, TETRA, DMR, dPMR, NXDN - Wireless IoT LPWAN networks: LoRa, SigFox - Precision agriculture systems - Terrestrial radio and television broadcast networks: ATSC, DVB-T, DVB-T2, ISDB-T, DTMB, DAB, DAB+ - Air-to-ground communication and radio navigation The Radio Horizon service range is given by. If you have any comments or suggestions for improving this calculator send us a message. Underwater Radio Wave Communication Systems (UW-RCSs) operate on radio waves in which the frequencies are generally of the order from kHz to GHz . Congrats! K = 7 Severe storm. OUTPUTS: Propagation time = 16. 12 * √h where h is the antenna height in metres and d is the distance in kilometres. Reasoner, and V. 6375. e. Jun 10, 2024 · To calculate free space path loss for isotropic antennas, follow the given instructions: Take the square of the wavelength of the carrier wave. Longley, R. The (complex) transmitted electric field is noted S ( t ), the received field is R ( t ), we define the ratio p0 ( t) = R ( t) ∕S ( t ). Calculate intermodulation for 2 and 3 frequency's up to the 9th order. Where: PD represents the propagation delay in seconds. Apr 14, 2021 · Free Download. Tailor your calculations to the frequency of your choice. Jun 5, 2021 · The Antenna CalculatorforHalf-Wave Dipoles. There are more calculators on the world wide web than the ones on this This live HF propagation map is a real-time tool that visualizes the current conditions of High-Frequency radio wave propagation across the globe. 1 HF propagation. 5 MHz as early as 7 PM local time (Figure 1). The tool will display the wave speed (. The tools are collected from all over the web. The HF Bands assigned for Radio Amateurs. (page refreshed every 20 minutes) Use the indicated color (red, yellow, green, blue, white, etc. It uses digital terrain information and a mathematical model to simulate radio transmissions between two fixed sites (radio link) or between a fixed site and a mobile (Radio coverage). A collection of real-time HF propagation tools, tutorials & plates. Jun 5, 2017 · Since the radio waves reflect at varying altitudes due to the changes in ionospheric conditions, the total path length and maximum altitude reached are not the same for each radio wave. 2. Frequency Flexibility. 7. 221 m) in the respective fields. More after the form. As indicated on the Radio Mobile Online website, it uses digital terrain information and a mathematical model to simulate radio transmissions between two fixed sites or between a The formula used by the Propagation Delay Calculator is: PD = (B – A) / S. 2 Non-LOS Propagation 5 1. Radio Propagation & Diffraction Calculator. Explanation Calculation Example: The wavelength of a radio wave is the distance between two consecutive crests or troughs of the wave. Range and path budget margin can be rapidly calculated and viewed while modifying the model parameters conveniently using the graphic mode main window. Copy Command. Ground waves exist only for vertical polarization, produced by vertical antennas, when the transmitting and receiving antennas are close to the surface of the earth. Introduction Welcome to our Electromagnetic Wave Propagation Calculator! This tool is designed to assist you in calculating various parameters related. Create publication quality Point-to-Point predictions for multiple circuits. Available in French and English. The term is used in radio communication, satellite communications, and other system that transmit signals over long distances. To fully understand the results obtained by this calculator, please take a few minutes to read the Feb 4, 2022 · SignalServer is a simulation that can provide insight into geographical coverage of a transmitting system. As compared to UW-ACSs, the UW-RCSs have the luxury of high bandwidth, high data rates and low propagation delays . In telecommunication, the free-space path loss ( FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). Conversion from and to various RF units. Use Minimuf 3. Current Ham Radio Propagation Conditions Below you will find charts showing the live conditions HF - High Frequency radio, ranging from 3 MHz to 30 MHz (10-100 meters), often referred to as "shortwaves". see: In the From pull down menu, select the link transmitter site (in many cases this is the studio), and the height of the center of the antenna above the ground in meters. The home of the online HF propagation prediction tool, 'proppy', providing on-demand point-to-point and area predictions using the ITU's ITURHFProp application in accordance with ITU-R P. On the other hand, oblique DX signals from Russia on 80 m remain unaffected as MUF 3000 km, the maximum usable frequency This website offers a collection of on-line RF tools. The Egli model is a terrain model for radio frequency propagation. 1 Line-of-Sight Propagation and the Radio Horizon 3 1. It does not take into account any obstacles in the line of sight and considers the effect of the atmosphere on the propagation of VHF and UHF RF signals. This line of sight calculator calculates how far the horizon is from an antenna placed at a particular height. 6 + 36. In order to determine an estimate of a sound pressure level at a distance the Inverse Square Law can be used. DXCC Asia DXCC Europe DXCC North America DXCC Oceania DXCC South America. Following the Fresnel Zone calculator you can find a short tutorial of RF propagation effects and the requirement for Fresnel zone clearance. It is given by the formula PL = 140. A series of RF calculators for radio frequency engineers. The analysis of RF propagation is essential in understanding how electromagnetic waves incur losses from a transmitter to a receiver in different scenarios. The R&S®PCT propagation calculation tool offers operators full support, allowing them to optimally deploy their radio monitoring systems. 1 The Regions of the Ionosphere. RadioCalc. rf coverage mapping software category is a curation of 11 web resources on , Proppy Online HF Propagation Prediction, Radio Mobile, GEOG UK terrain heights. Sets: Dipoles Verticals, high dipoles 3-el Yagis 5-el Yagis 8-el Yagis. Enter the antenna height and pick the units (meters or feet). You can do this by providing your name or callsign and email address. d r = 4. This equation includes the effect of atmosphere on the propagation path of RF signals. L. We will consider the same example as in the previous section: Enter the wave frequency (. This is a radio frequency propagation calculator for the transmission path between an RF Feb 7, 2020 · As the frequency increases beyond the MUF for longer and longer distances, the skip zone grows, until no propagation is possible. Click "Wall+" to add a reflective surface behind the source/receiver. VOACAP is free professional high-frequency (3-30 MHz) propagation prediction software from NTIA / ITS, originally developed for Voice of America (VOA). Please see this link for more information. Enter your desired frequency (MHz) of operation (i. nautel. And that's it! You can now copy the result into your Project and continue your work! Here’s what you should. * Earth-Ionosphere Waveguide Propagation. Guide to using VOACAP, free professional HF prediction software from NTIA/ITS. 3 Propagation Effects as a Function of Frequency 9 1. In order to cover a defined area of interest, the tool relies on topographic data of the terrain (terrain profiling data) to calculate the best reception sites within a particular sector. 2 Tropospheric Propagation 6 1. Popularity: ⭐⭐⭐. The online map provides a graphical representation of the ionospheric state, enabling radio operators to assess the best frequencies and paths for effective communication. WSPR sends and receives low-power data transmissions consisting of Callsign + 4 digit locator + dBm transmit power, a total of 50 Bits. 55). 4 Model Selection and Application 11 To use the calculator, simply type in your antenna height above ground in the appropriate window below and click the "Compute" button. Near-Vertical Incident Skywave propagation is generally considered to be F-layer reflection at angles of 70-90 degrees. Radio waves can propagate from transmitter to receiver in four ways: through ground waves, sky waves, free space waves, and open field waves. 1412. 4 days ago · The Geospace Timeline Plot displays real-time solar wind values ballistically propagated from L1 orbit to the upstream boundary of the Geospace model, located at 32 Re (top four plots). Select Contour Type: F (50,50) Service Contour -- FM and NTSC (analog) TV F (50,10) Interfering Contour F (50,90) Digital TV Service Contour. The calculators also calculates the radio horizon. When this happens, all NVIS signals on 80 m literally fade away. This page covers RF propagation time calculator . 4. Global data, reasonable pricing. 1) via the: ground wave: near the ground for short distances, up to 100 km over land and 300 km over sea. Enter a description for the link, and then the center frequency of the link in MHz. The calculator takes into consideration the height of the antenna and the curvature of the earth to determine the radio horizon distance. [1] The computation of radiowave attenuation in the atmosphere is a series of radio propagation models and methods to estimate the path loss due to attenuation of the signal passing through the atmosphere by the absorption of its different components. VOACAP-based Apr 1, 2021 · In fact, learning about radio propagation has been a big part of our history since Hertz and Marconi. You can use propagation models to calculate the coverage, SINR, signal strength, path loss, and link loss between a transmitter and a receiver in basic, urban, terrain, and multipath May 3, 2024 · The propagation delay calculator will allow you to calculate the time it takes for a signal to travel from its source to its final destination. λ = 0. [1] Abstract: The ITS model of radio propagation for frequencies between 20 MHz and 20 GHz (the Longley-Rice model) (named for Anita Longley & Phil Rice, 1968) is a general purpose model that can be applied to a large variety of engineering problems. RF Line-of-Sight The RF Line-of-Sight tool allows users to easily drag-and-drop locations and obtain point-to-point line-of-sight information anywhere using Google Maps. f = 1500 Hz. 800-2. Vertical vs ants @10m AGL Vertical vs ants @20m AGL Vertical vs ants @40m AGL Vertical vs ants @60m AGL. Ionospheric propagation The radio wave that is being reflected by the ionosphere can travel back to Earth under the right angle. These include free space path loss, atmospheric attenuation due to rain, fog and gas, and multipath propagation due to bounces on the ground. As an example using "Height in Feet" in the calculator This study focuses on HF radio communications with the primary goal of bridging the gap between theory and on the air operation. P. This refers to the total loss that an RF signal experiences as it propagates from the transmitter to the receiver. Calculation Example: The path loss is a measure of the reduction in power density of a radio wave as it propagates through space. There it will be reflected down again. Supplementing the book are PowerPoint presentations which taken together constitutes a lecture series on HF May 1, 2024 · Ionospheric Propagation: Radio waves with upper medium and high frequencies, typically between 3 and 40 MHz, are refracted or reflected back to Earth by the ionosphere. Enter the height of the receiver antenna above the ground, the receiving range, and the minimum vertical standoff: And get this map, with required antenna height in meters plotted in color: You can get a similar map for the required Nov 30, 2014 · Radio Mobile Online is a radio wave propagation prediction tool created and maintained by Roger Coudé, VE2DBE, which is dedicated for use by the ham radio community. Radio Propagation Data. Other on-line calculators. 12*√(h) It’s important to note that the k-factor is not static; its average value may fluctuate based on prevailing weather conditions. distance, including (in some scenarios) the deep transmission fades associated From the “Raster GIS” menu, choose “Required Antenna Height”, then double-click on the antenna site. This calculator provides the calculation of path loss for radio propagation in free space. Radio Wave Propagation Calculation. Generally, radio wave Mar 8, 2024 · It also features several propagation forecasting tools, allowing you to quickly and easily estimate current HF (Shortwave) propagation conditions between any two locations in the world. Measurements were recorded between 1944 and 1969 in several countries with different climatic conditions and discussed in Anita G. This example shows how to model several RF propagation effects. Figure 10 (right) shows the attenuation calculation using electron density profiles that vary as a function of hour and month and the 20 March 2010 at 10 UT 1. Create an account with Radio Mobile. The usual effect of the declining pressure of the atmosphere with height is to bend radio waves down toward the surface of the Earth, effectively increasing the Earth's radius 3 days ago · It's easy! Just use our wavelength calculator in the following way: Determine the frequency of the wave. It includes algorithms for line-of-sight, free space, through-building and obstructed (diffracting) paths. The program can decode signals with a signal to noise ratio as low as −34 dB in a 2500 Hz bandwidth. It is depend on the distance traveled by electromagnetic energy between two points. For instance our indoor/outdoor Wi-Fi calculator was built from the findings of a research study. Radio waves bended by the ionosphere 4. Amateur radio operators, military communications, and organizations that rely on long-distance radio communication can all benefit from such calculators. Formula d = 4. K. Free Space Path Loss (FSPL) is a measure of the signal loss in a communications link. The RSGB’s Propagation Studies Committee has a number of online tools to help you work out the best band and time to make a contact Propagation tools available RadCom Tools. The indoor-to-indoor and also outdoor -to-in-door study of radio wave propagation for long-term evolution (LTE Propagation data and prediction methods for the planning of short-range outdoor radiocommunication systems and radio local area networks in the frequency range 300 MHz to 100 GHz. 3 Ionospheric Propagation 6 1. Ionisation is the process in which electrons, which are negatively charged, are removed from neutral atoms or The Velocity of Propagation calculator computes the speed of signal transmission through a medium relative to the speed of light in a vacuum. Amateur Radio: Usable HF Frequencies. Planner. This calculator provides the calculation of received power for radio wave propagation in free space. Feb 23, 2021 · In (Al-Samman et al. com focuses on products and tools developed by Silicon DSP Corporation for Radio Propagation in Irregular Terrain as well as Propagation through the Ionosphere. For each form of propagation, you’ll learn the best ham radio practices to increase your chances of “making the hop”, whether that’s across town or across the globe. In a region extending from a height of about 50 km to over 500 km, most of the molecules of the atmosphere are ionised by radiation from the Sun. It mentions formula/equation used for this RF propagation time calculator. 0/5. This online guide should get you well started with the software. RFProp is a utility for calculating signal characteristics of radio propagation paths. 15 for the 40 meter band). 3 Why Model Propagation? 10 1. RF Calculator. Propagation data for the evaluation of coordination between Earth stations working in the bidirectionally allocated frequency bands. The propagated solar wind values are then used to drive the Geospace model (SWMF) which outputs 1-minute predicted Kp and Dst values (bottom two plots). Last update of this index page: Saturday, March 23, 2024. Mechanisms of Radio Wave Propagation. 533-14. The Ionosphere The calculator takes into account the earth’s curvature and effects from refraction in the atmosphere. Mar 23, 2024 · Indispensable amateur radio information, including: multiband antenna designs, on-line HF propagation prediction, calculators, live ham radio and GNU/Linux. Delve into the mysteries of Free Space Path Loss with our calculator. Radio Propagation Calculator is a lightweight Windows application designed to help you calculate the transmission path between an RF transmitter Feb 14, 2015 · To generate an RF coverage map using Radio Mobile Online, all you need to do if follow the three easy steps below. The Radio Coverage Tool is based on the Longley-Rice VHF/UHF “ITS” model [2], and includes a nearly 1 terabyte digitized worldwide terrain database, based on NASA Shuttle Radar Terrain Mapping data as well as other sources. Multiply the distance between the transmitter and receiver antennas by 4π, and take the square of the result. This radio line of sight distance calculator determines the line of sight distance between the transmitter and the receiver. f=1500\ \text {Hz} f = 1500 Hz) and wavelength (. * Line-of-sight Propagation (It’s almost never line of sight!) * Terrestrial ScatterPropagation. Hover over a line to read about band's characteristics. Path Loss. Use my OpenPGP public key to encrypt messages for: The first version of this web site came on-line on Thursday, December 13, 2001. High Frequency radio waves can propagate to a distant receiver ( Figure 2. This calculator calculates this for you based on frequency and distance. The accuracy We are the basis for Machine Learning and analytics and have the API which can provide answers Machine Learning cannot without empirical measurements. 3. As a default, our calculator uses a value of 299,792,458 m/s - the speed of light propagating in a vacuum. Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. May 1, 2024 · HF propagation prediction is a statistical science. Choose the velocity of the wave. The model, which is based on electromagnetic theory and on statistical analyses of both terrain . RF Line-of-Sight provides radio path information for mapping long distance SCADA radio communications by using antenna height and topography. 1 Indirect or Obstructed Propagation 6 1. TX Antenna Analysis Settings. The free space path loss is the loss in signal strength of a signal through free space. Since the geometric line of sight passes at varying heights over the Earth, the propagating radio wave encounters slightly different propagation conditions over the path. It is skywave propagation without the usual skip zone. For example, f = 10 MHz. Online RF planning software for cellular, LTE, 5G, mobile, LPWAN, LoRA, DMR, VHF, WiFi and mesh. 12*(√h1 + √h2). The propagation model is split up in to parts from which some are conditional. These calculators help with unit conversions, VSWR calculations, attenuator design, antenna design, radars, and various other basic calculations that are often required. 160 m (1. Example Calculation For a height of 6 feet, the range of a UHF radio system is 4 miles or 6 km. Then do the same for the To site. Because the Earth is curved, the incidence angle can't be arbitrarily low — even a signal that leaves the Earth completely horizontal is going to reach the ionosphere at an angle of 15-20°, after travelling 1500 3 days ago · Now we will see how to calculate wave speed using our calculator. FSPL, dB92. Sep 23, 2020 · WSPR stands for Weak Signal Propagation Reporting and operates on all bands. ) to determine the recommended HF frequencies for contacts from your nearest BASE (New York, Boston, Atlanta, Orlando, Kansas City, Phoenix, San Francisco, and Seattle). 3 days ago · 2. **If you are planning on using the HF bands, the chart below will assist you in knowing the condition of those bands based on the conditions at the time from 10M to 80M. Intermodulation. Review by: Vladimir Ciobica. It bounces off the Earth’ s surface back up again into the ionosphere. In case of line of sight a 2-ray calculation will be used. * Ground Wave Propagation. 000 MHz) is officially part of the MF range but is also referred to as HF. Background. The digital terrain information comprises two databases: elevation Our Radio Distance Calculator harnesses cutting-edge technology to provide instantaneous and precise measurements, ensuring optimal communication performance. 221\ \text m λ = 0. This region is called the ionosphere (see Figure 1. In "Single Frequency" mode click "Show calculation breakdown" to see the Even then, it may still be possible to have successful communication with a station, however, you’re 100% at the mercy of the movement of radio propagation and band conditions! The calculator does not assume any conditions beyond line-of-sight, as there is SO MANY variables that would contribute to success or failure to talking beyond LOS! Feb 24, 2024 · Radio wave propagation calculation 24 Feb 2024 Tags: Antenna and Wave Propagation Antenna and Wave Propagation Radio wave propagation Radio wave propagation calculation. You will see the actual line of sight distance to the horizon in the "Distance" section before the radio waves are attenuated by the curvature of the Earth. At the core of the website is an in-depth book covering the many aspects of skywave radio communications. Free-space path loss. Pasternack's RF Free Space Path Loss (FSPL) Calculators is the ideal measurement tool that allows loss or attenuation of signal strength calculations between two antennas. In addition, we will focus on transmission line network modeling ( matching networks, microwave filter design, etc). If you are just getting started in ham radio, take time to learn about propagation and it will serve you well. In case of a obstructed path the ITM model is applied. This model was derived from real-world data on UHF and VHF television transmissions in several large cities. Understand signal attenuation like a seasoned radio wave whisperer! Unravel the secrets of signal attenuation in space with our Free It displays current HF propagation data in your status bar. Help. [1] : 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and Mar 28, 2021 · In this system, the user can check the radio wave propagation information that is updated in real-time. com. Need a user manual? Feb 24, 2024 · Radio Propagation Calculation. d r = √(2*R*h*(4/3)) d r = 4. It assumes there is nothing between the radio signals and the antenna horizon. Radio Propagation and Communication Tools. 7 * log10(f) - 13. Go to the Radio Mobile Online website and create a free account. Propagation delay is a ratio of the propagation speed to the distance between the source and destination. Move the barrier/building top to change its position, click the body to toggle on/off. There are many well-known facts on the phenomenon and qualitative treatments in textbooks. This calculator is used to calculate Land Mobile Path Loss. Our calculator adapts to diverse frequency ranges, offering flexibility that meets the demands of New ITURHFPROP propagation prediction tool The RSGB’s Propagation Studies Committee (PSC) has released a new propagation tool for amateurs, based on the ITU’s ITURHFPROP program. 82 * log10(h) - 1. The Ground Multipath tab requires user inputs for the transmitter and receiver height, and contains a useful plot of path loss vs. Range or Distance in Km (INPUT) : RF propagation time in µs (OUTPUT) : EXAMPLE: INPUTS: Range = 5 Km. The discussion in this example is based on the ITU-R P series recommendations of Mar 2, 2024 · This calculator provides the calculation of wavelength of radio waves for basic understanding of radio wave propagation. Radio propagation can get really complicated indoors. Take-off Angle Analysis Settings. Use this tool to calculate how far a UHF radio can transmit. Modeling the Propagation of Radar Signals. The new tool gives you hour-by-hour monthly median propagation predictions from a location you specify to one of 28 locations around the world, in line with the Edit sound levels and distances (in metres) or click and drag the items in the diagram to modify their position. It's ideal for the ham radio operator, shortwave listener, or other radio enthusiast, and is available for Mac OS, Mac OS X, and Windows. 67 µs. Divide the value from step 1 with that of step 2. Search RF Coverage with DuckDuckGo or with Bing. Resources listed under RF Coverage category belongs to Software main collection, and get reviewed and rated by amateur radio operators. To get maximum line of distance you need to enter the height of the antenna. As shown in Figure 2, the user can also use the web application to estimate and visualize radio wave propagation by specifying any frequency in the range of 3-30 MHz, any two points on the Earth, and any transmission angle. Attenuation of the wave depends on antenna height above ground, polarisation, frequency, ground types, terrain and/or sea state; direct or line-of DXprop is a radiowave propagation forecast freeware for ham radio operators, permits to predict propagation on 12 frequencies. 2. Voice of America Coverage Analysis Program VOACAP. Oct 13, 2023 · This Javascript calculator uses the FM or TV propagation curves to find the distance to a service or interfering contour, or the corresponding field strength at a given contour distance. May 1, 2024 · During the winter of 2015–2016, I became aware that fo,F2 f o, F 2 above Western Europe regularly drops below 3. 1. Explanation May 25, 2024 · This augmentation, referred to as the k-factor, reflects an increased effective radius for radio wave propagation. , 2018), large-scale path loss propagation models were derived from indoor propagation measurements conducted on the ultrawideband and millimetre wave (mmWave) at 28 GHz and 38 GHz in-building communication. Radio Mobile will determine if a radio link is line of sight or not. FCC Office of Engineering and Technology – Radio Propagation Software: Offers software tools for radio propagation analysis and simulations. There is a huge amount of information about radio propagation spanning the range of VLF (Very Low Frequency) signals through microwaves. S denotes the propagation speed of the medium, typically measured in meters per second. Mar 23, 2024 · the make, sed and gpp commands. \lambda = 0. Radio Mobile Online is a radio wave propagation prediction tool dedicated to amateur radio. Explanation. For point-to-point monthly median HF propagation predictions to 28 different locations—some including long path—using user-defined mode, power, antennas. RadioPlanner 3. 221 m. It is used by RF engineers, ham radio operators, mobile communications engineers, and others to help determine placement and effectiveness of antenna structures and repeaters. To determine a line of sight the clearance of the fresnel zone is determined. Multiple bounces and reflections is called ‘multi hop’ propagation. A and B represent the positions of the signal source and destination, respectively, usually measured in meters. In this text, we will focus primarily on propagation delay in computer networks and the delay Mar 8, 2024 · It also features several propagation forecasting tools, allowing you to quickly and easily estimate current HF (Shortwave) propagation conditions between any two locations in the world. 1). If you have no particular preference within a given ham radio band, then simply enter its center frequency (i. K = 9 Extremely severe storm. 5 routine developped for US Navy. Long term distributions of tropospheric transmission loss in observed signal levels as they vary over a period of time. These tools are part of the new Nautel RF Toolkit, available free online at the website www. 2 Modes of Propagation 3 1. K = 8 Very severe storm. The optimum working frequency (OWF) is Line of Sight Calculator. ic yh oi ff hk mk nu df ab lc