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Environmental ReviewsVIDEO ON THE TOPIC: How does an Antenna work? - ICT #4
Last updated: November 15, F ree music, news, and chat wherever you go! Until the Internet came along, nothing could rival the reach of radio —not even television. A radio is a box filled with electronic components that catches radio waves sailing through the air, a bit like a baseball catcher's mitt, and converts them back into sounds your ears can hear. Radio was first developed in the lateth century and reached the height of its popularity several decades later. Although radio broadcasting is not quite as popular as it once was, the basic idea of wireless communication remains hugely important: in the last few years, radio has become the heart of new technologies such as wireless Internet , cellphones mobile phones , and RFID radio frequency identification chips.
Meanwhile, radio itself has recently gained a new lease of life with the arrival of better-quality digital radio sets. Photo: An antenna to catch waves, some electronics to turn them back into sounds, and a loudspeaker so you can hear them—that's pretty much all there is to a basic radio receiver like this.
What's inside the case? Check out the photo in the box below! You might think "radio" is a gadget you listen to, but it also means something else. Radio means sending energy with waves. In other words, it's a method of transmitting electrical energy from one place to another without using any kind of direct, wired connection. That's why it's often called wireless. The equipment that sends out a radio wave is known as a transmitter ; the radio wave sent by a transmitter whizzes through the air—maybe from one side of the world to the other—and completes its journey when it reaches a second piece of equipment called a receiver.
When you extend the antenna aerial on a radio receiver, it snatches some of the electromagnetic energy passing by.
Tune the radio into a station and an electronic circuit inside the radio selects only the program you want from all those that are broadcasting. Artwork: How radio waves travel from a transmitter to a receiver. This process can happen between one powerful transmitter and many receivers—which is why thousands or millions of people can pick up the same radio signal at the same time.
How does this happen? The electromagnetic energy, which is a mixture of electricity and magnetism , travels past you in waves like those on the surface of the ocean.
These are called radio waves. Like ocean waves, radio waves have a certain speed, length, and frequency. The speed is simply how fast the wave travels between two places. The wavelength is the distance between one crest wave peak and the next, while the frequency is the number of waves that arrive each second.
Frequency is measured with a unit called hertz , so if seven waves arrive in a second, we call that seven hertz 7 Hz. If you've ever watched ocean waves rolling in to the beach, you'll know they travel with a speed of maybe one meter three feet per second or so. The wavelength of ocean waves tends to be tens of meters or feet, and the frequency is about one wave every few seconds.
When your radio sits on a bookshelf trying to catch waves coming into your home, it's a bit like you standing by the beach watching the breakers rolling in. Radio waves are much faster, longer, and more frequent than ocean waves, however. Their wavelength is typically hundreds of meters—so that's the distance between one wave crest and the next.
But their frequency can be in the millions of hertz—so millions of these waves arrive each second. If the waves are hundreds of meters long, how can millions of them arrive so often? It's simple. Radio waves travel unbelievably fast—at the speed of light , km or , miles per second. Photo: A radio studio is essentially a soundproof box that converts sounds into high-quality signals that can be broadcast using a transmitter.
Credit: Photographs in the Carol M. Ocean waves carry energy by making the water move up and down. In much the same way, radio waves carry energy as an invisible, up-and-down movement of electricity and magnetism.
This carries program signals from huge transmitter antennas, which are connected to the radio station, to the smaller antenna on your radio set. A program is transmitted by adding it to a radio wave called a carrier.
This process is called modulation. Sometimes a radio program is added to the carrier in such a way that the program signal causes fluctuations in the carrier's frequency. This is called frequency modulation FM. Another way of sending a radio signal is to make the peaks of the carrier wave bigger or smaller. Since the size of a wave is called its amplitude, this process is known as amplitude modulation AM. Frequency modulation is how FM radio is broadcast; amplitude modulation is the technique used by AM radio stations.
An example makes this clearer. Suppose I'm on a rowboat in the ocean pretending to be a radio transmitter and you're on the shore pretending to be a radio receiver.
Let's say I want to send a distress signal to you. I could rock the boat up and down quickly in the water to send big waves to you. If there are already waves traveling past my boat, from the distant ocean to the shore, my movements are going to make those existing waves much bigger.
In other words, I will be using the waves passing by as a carrier to send my signal and, because I'll be changing the height of the waves, I'll be transmitting my signal by amplitude modulation. Alternatively, instead of moving my boat up and down, I could put my hand in the water and move it quickly back and forth. Now I'll make the waves travel more often—increasing their frequency. So, in this case, my signal will travel to you by frequency modulation. Sending information by changing the shapes of waves is an example of an analog process.
This means the information you are trying to send is represented by a direct physical change the water moving up and down or back and forth more quickly. The trouble with AM and FM is that the program signal becomes part of the wave that carries it. So, if something happens to the wave en-route, part of the signal is likely to get lost. And if it gets lost, there's no way to get it back again. Imagine I'm sending my distress signal from the boat to the shore and a speedboat races in between.
The waves it creates will quickly overwhelm the ones I've made and obliterate the message I'm trying to send. That's why analog radios can sound crackly, especially if you're listening in a car. Digital radio can help to solve that problem by sending radio broadcasts in a coded, numeric format so that interference doesn't disrupt the signal in the same way.
We'll talk about that in a moment, but first let's see take a peek inside an analog radio. Let's lift the lid on an old-style analog transistor radio and see what we can find inside! Click the image to see a slightly bigger photo. But here's a problem. Imagine you're a radio receiver and you pick up some waves passing by.
How do you know what they mean? How do you know if they're even AM or FM? Radios pick up these different waves using different kinds of antennas and use different methods to turn AM and FM waves back into recognizable sounds. Radios like the one pictured above have circuits inside them called detectors whose job is to convert modulated AM or FM radio signals back to copies of the sounds from which they were made.
This process is the reverse of modulation, so it's called demodulation. Without getting into the technical details, you can probably imagine how it would work in an AM radio tuned to one frequency, but what about FM, where the frequency is varying? How can a station be broadcasting on a specific frequency if the frequency of the waves coming out of the transmitter is constantly changing? Well it's not as random as that suggests: the frequency can vary only so much "deviate" either side of the central, carrier frequency.
FM radios use various kinds of detector circuits to convert that varying frequency back into a varying amplitude that recreates the original sounds. Exactly how these work is beyond the scope of this simple article. If you're interested, you can find out more in Wikipedia's article about detectors in radios.
The big orange button in the middle lets you pause a live radio broadcast and restart it later. You're driving along the freeway and your favorite song comes on the radio. You go under a bridge and—buzz, hiss, crackle, pop—the song disappears in a burst of static.
Just as people have got used to such niggles, inventors have come up with a new type of radio that promises almost perfect sound. Digital radio , as it's called, sends speech and songs through the air as strings of numbers. No matter what comes between your radio and the transmitter, the signal almost always gets through. That's why digital radio sounds better.
But digital technology also brings many more stations and displays information about the program you're listening to such as the names of music tracks or programs. Let's go back to the earlier example of sending information from a boat to the shore—but this time using a digital method. In case of emergency, I could store hundreds of plastic ducks on my boat, each one carrying a number. If I get into trouble, as before, and want to send a distress signal, I could send you an emergency coded message "" by releasing just the ducks with those numbers.
Let's suppose I do have a problem. I release ducks with the numbers 1, 2, 3, 4, and 5—but instead of sending just five numbered ducks, I send maybe 10 or 20 of each duck to increase the chances of the message arriving.
Now, even if the sea is choppy or a speedboat cuts through, there's still a high chance enough of the ducks will get through. Eventually, waves will carry ducks with the numbers 1, 2, 3, 4, and 5 ashore. You collect the ducks together and work out what I'm trying to say.
To help avoid interference, a digital radio signal travels on a huge, broad band of radio frequencies about times wider than those used in analog radio. To return to our rowboat example, if I could send a wave times wider, it would bypass any speedboats that got in the way and get to the shore more easily.
It may interest ham radio enthusiasts, hardware hackers, tinkerers and anyone interested in RF. Since its first flight in , ham radio has flown on more than two-dozen space shuttle missions. Ham radio transceivers are available in a variety of styles by a number of different brands. Most ham radios are designed with special hardware that can reach high frequencies. I am so pleased with it and glad I am using it for satellite work.
US8789116B2 - Satellite television antenna system - Google Patents
Definition of NAICS Code : This industry comprises establishments primarily engaged in manufacturing radio and television broadcast and wireless communications equipment. Examples of products made by these establishments are: transmitting and receiving antennas, cable television equipment, GPS equipment, pagers, cellular phones, mobile communications equipment, and radio and television studio and broadcasting equipment. What codes are similar to this classification that might be a more applicable code? The cross-reference guide below displays the codes for other similar industries. Please review to find the most applicable classification. The North American Industry Classification System contains multiple index entries that are each descriptive of the same code. The bulleted list below shows all applicable index entries Current and former that are associated with this classification.
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With the recent significant growth in mobile traffic, there are rising expectations for the early realization of 5G mobile networks, which are forecast to have a larger capacity than current 4G mobile networks, along with capabilities such as ultra-high speed and ultra-low latency. NEC is aiming to achieve large-capacity communications by incorporating massive-element antennas into wireless units at mobile phone base stations, and by utilizing beam-forming with massive-element antennas. However, in wireless units for 5G small cell systems that use massive-element antennas, a large amount of heat is generated due to the increased power consumption associated with the greater number of analog devices. For this reason, heat sinks with a larger volume are required to dissipate the heat, which increases the size of wireless units and poses restrictions on where they can be installed.
Blake Levitt, a Henry Lai b a P. The siting of cellular phone base stations and other cellular infrastructure such as roof-mounted antenna arrays, especially in residential neighborhoods, is a contentious subject in land-use regulation. Local resistance from nearby residents and landowners is often based on fears of adverse health effects despite reassurances from telecommunications service providers that international exposure standards will be followed. Both anecdotal reports and some epidemiology studies have found headaches, skin rashes, sleep disturbances, depression, decreased libido, increased rates of suicide, concentration problems, dizziness, memory changes, increased risk of cancer, tremors, and other neurophysiological effects in populations near base stations. The objective of this paper is to review the existing studies of people living or working near cellular infrastructure and other pertinent studies that could apply to long-term, low-level radiofrequency radiation RFR exposures. While specific epidemiological research in this area is sparse and contradictory, and such exposures are difficult to quantify given the increasing background levels of RFR from myriad personal consumer products, some research does exist to warrant caution in infrastructure siting. Further epidemiology research that takes total ambient RFR exposures into consideration is warranted. Symptoms reported today may be classic microwave sickness, first described in Nonionizing electromagnetic fields are among the fastest growing forms of environmental pollution. Some extrapolations can be made from research other than epidemiology regarding biological effects from exposures at levels far below current exposure guidelines.
Broadcast towers and health
Broadcast towers are used for transmitting a range of communication services including radio and television. The tower will either act as an antenna itself or support one or more antennas on its structure, including microwave dishes. This fact sheet provides information about concern of adverse health effects arising from exposure to RF EME from broadcast towers.
In radio engineering , an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In reception , an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified. Antennas are essential components of all radio equipment. An antenna is an array of conductors elements , electrically connected to the receiver or transmitter. An antenna may include components not connected to the transmitter, parabolic reflectors , horns , or parasitic elements , which serve to direct the radio waves into a beam or other desired radiation pattern. The first antennas were built in by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of waves predicted by the electromagnetic theory of James Clerk Maxwell. Hertz placed dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving. The words antenna and aerial are used interchangeably.
New ham satellite
Every wireless microphone system transmits and receives on a specific radio frequency, called the operating frequency. Allocation and regulation of radio frequencies is supervised by specific government agencies in each country with the result that allowable legal frequencies and frequency bands differ from country to country. In addition to frequency, these government agencies typically specify other aspects of the equipment itself, including: allowable transmitter power, maximum deviation, spurious emissions, etc. These specifications differ from one band to another and from one user to another within a given band. For these reasons, it is not possible to select a specific frequency or frequency band that is legally usable in all parts of the world. Furthermore, it is not possible to design a single type of wireless equipment that will satisfy the specifications of all or even most of these agencies around the world. Certain frequencies within each band have been designated for use by wireless microphones as well as by other services.
SIC Industry Description
This application claims the benefit of U. Provisional Application Ser. The present invention relates generally to satellite television antenna systems, and more particularly, to a satellite television antenna system that interacts with a Set Top Box STB to obtain satellite identification information. The growth in the number of available media channels and improved reception due to digital broadcasts has driven consumers to look beyond normal television antennas and cable systems. Digital signals broadcast from satellites are capable of providing hundreds of video, audio and data channels to users without the constraint of land line connections. The programming is distributed by a constellation of satellites parked in geostationary orbits at 22, miles above the earth. These broadcasts from orbit allow users to receive the broadcasts in many areas; such as mountainous regions or desolate areas, where earth-based transmitters or cable infrastructure traditionally are unable to reach.
US20110250926A1 - Dynamic antenna selection in a wireless device - Google Patents
A radio communication station is a set of equipment necessary to carry on communication via radio waves. Generally, it is a receiver or transmitter or transceiver , an antenna , and some smaller additional equipment necessary to operate them.
Give us a call for a FREE home signal analysis. If your WiFi environment is too congested, you may need to change the channel of your WiFi router to avoid interference. Which network should ClearStream TV be connected to? Most modern routers broadcast both a 2.
This is the generic class for modulated carrier wave communications not elsewhere classifiable. Some art areas excluded from this class are: Alternating or pulsating current telegraphy; Antennas; Broadcast or multiplex stereo; Condition responsive indicating systems with a radio coupling link; Directive carrier wave systems; Multiplex carrier wave communications; Paging via modulated carrier wave; Pulse or digital communications which may be modulated onto a carrier wave; Reflected carrier wave systems e. See References to Other Classes, below, for class references.
Last updated: November 15, F ree music, news, and chat wherever you go!