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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
fresh fuel nuclear fuel which has never participated in a nuclear reaction and is thus only slightly radioactive. Fresnel region the region in space around an antenna at which the fields have both transverse and radial components and the antenna pattern is dependent on the distance from the antenna. The Fresnel, or near-field, region is typically taken to be r < 2D 2 /, where r is the distance from the antenna, D is the maximum dimension of the antenna, and is the wavelength. Fresnel zone an indicator of the significant volume of space occupied by a radio wave propagating along a line-of-sight path between the transmitter and receiver. At an arbitrary point which is at distance d1 from the transmitter and at distance d2 from the receiver, along the axis joining the transmitter and the receiver, a radio wave with wavelength occupies a volume, which at that point between the transmitter and the receiver, has a radius which is given by the radius of the first Fresnel zone. The radius of the first Fresnel zone is given by R= d1 d2 d1 + d2
Wireless Local Area Networks
Published in Stephan S. Jones, Ronald J. Kovac, Frank M. Groom, Introduction to COMMUNICATIONS TECHNOLOGIES, 2015
Stephan S. Jones, Ronald J. Kovac, Frank M. Groom
Sinusoidal waves behave consistently and have certain characteristics: The higher the frequency, the more the waves tend to behave like light. They travel in a straight line and do not bend (although they do bounce). The higher the frequency, the more the waves travel in a line-of-sight characteristic; there must be a clear path between the sending antenna and the receiving antenna.Electromagnetic energy in the form of sinusoidal waves decreases in power exponentially as it travels farther from the source. For example, 1 W of power 15 ft. away from the antenna is only 0.25 W of power 30 ft. away. We also see this effect in light: as we move farther away from a light source, the light becomes dimmer. This is called attenuation.
Deploying and Implementing the Strategy – SPADES Steps 4–5
Published in Jack B. ReVelle, Susan L. Stuffle, Harry K. Jackson, The Strategic Planning and Deployment Excellence System (SPADES), 2019
Jack B. ReVelle, Susan L. Stuffle, Harry K. Jackson
Deployment of the strategic plan is all about line of sight from the strategy to the operational plan to the day-to-day execution of the activities that make the operational plan a reality. Many types of radio transmissions depend, to varying degrees, on line of sight between the transmitter and receiver. Obstacles that commonly cause non-line of sight conditions include buildings, trees, hills, mountains, and, in some cases, high-voltage electric power lines. Some of these obstructions reflect certain radio frequencies, while some simply absorb or garble the signals; but, in either case, they limit the use of many types of radio transmissions.
Smart lighting systems: state-of-the-art and potential applications in warehouse order picking
Published in International Journal of Production Research, 2021
Marc Füchtenhans, Eric H. Grosse, Christoph H. Glock
The achievable data rates of the transmitter depend on the light source, ranging from often-used phosphor-coated blue LEDs with relatively low data rates to more advanced red, green and blue (RGB) LEDs to laser-based lighting technologies with data rates of up to 100 GB/s (Haas 2018; Tsonev, Videv, and Haas 2015). The receiver uses a photo detection device such as a photodiode contained, for example, in smart phones or tablets. LEDs’ high switching capability can be used to transmit data from the transmitter to the receiver by using intensity modulation, following a modulation scheme. The illuminating light is modulated to high frequency flickers, much higher than the refresh rate of a monitor, and is, therefore, not visible to humans (Haas 2018; O'Brien et al. 2008). This connection between transmitter and receiver can only take place in the line of sight. Therefore, the optimal transmitter deployment and location needs to be evaluated accordingly (Sharma et al. 2018; Karunatilaka et al. 2015).
Modelling and Analysis of Received Signal Strength - Based Emitter Geolocation from Single Geostationary Satellite with Multiple Antennas using STK Toolkit
Published in Australian Journal of Electrical and Electronics Engineering, 2020
Anupam Sharma, Suman Agrawal, Charul Bhatnagar, D S Chauhan
Access in STK ensures that transmitter and receiver are in each other line of sight. In the area of interest, assets are assigned using three receivers. The STK accesses each grid point and computes link information. The receiver gain values are contained in each grid point. Using the access window in STK, detailed access link report is generated. The report consists of various columns such as Tx gain, EIRP, Free Space Loss, E0/N0, BEL and Receiver Gain. This is shown in Figure 10.Using ‘Compute Access’ command of STK, three scalar calculations, i.e. gain difference across each receivers within coverage area is evaluated.After the gains across each antenna is completed, next step is to calculate the gain difference between the antennas using the function(x,y) components using STK. Delta gain between Rx1 and Rx2 is calculated using
Direction finder deployment based on the partial set multi-cover problem
Published in International Journal of Management Science and Engineering Management, 2019
Figure 1 illustrates an example, depicting the forward line (FL), which denotes the most forward positions of friendly forces at a specific time in an Army operation; four likely transmitter positions () in the AOI and four potential DF locations () in the friendly area. In Figure 1, transmitter positions 1 and 3 can each be covered by three DF locations ((1, 2, and 4) and (1, 3, and 4)), but position 4 can be covered by only two DF locations (3 and 4), and position 2 cannot be covered from any DF location. We say a transmitter position is k-covered if there is an unobstructed line of sight to it from at least k DF locations. Natural and manmade objects can unavoidably prevent some transmitter positions from being k-covered. This fact motivates us to formulate the DF deployment problem as a partial set multicover problem. Our study provides methods to prescribe DF deployment using the partial set multicover problem.