I transmit a light wave through the fiber; my light wave goes on-on-off-on-off-off-on-off-off-on-on-on, or so, by which I mean for you to read out a binary number like 1101 0010 0111. Wi-Fi uses radio waves to transmit information between your device and a router via frequencies. Two radio-wave frequencies can be used, depending on the amount of data being sent: 2.4 gigahertz and 5 gigahertz. What does that mean, though? Well, a hertz is just a measurement of frequency. And receive data, and to do so they rely on waves from different parts of the electromagnetic spectrum. Because these waves are traveling through the vacuum of space, they all travel at the speed of light—the fastest speed at which information can be transmitted. Within the electromagnetic spectrum, radio waves are used for spacecraft. MS-PS4-2 Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials. HS-PS4-5 Communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy.
The ocean is never still. Whether observing from the beach or a boat, we expect to see waves on the horizon. Waves are created by energy passing through water, causing it to move in a circular motion. However, water does not actually travel in waves. Waves transmit energy, not water, across the ocean and if not obstructed by anything, they have the potential to travel across an entire ocean basin.
Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest. These types of waves are found globally across the open ocean and along the coast.
More potentially hazardous waves can be caused by severe weather, like a hurricane. The strong winds and pressure from this type of severe storm causes storm surge, a series of long waves that are created far from shore in deeper water and intensify as they move closer to land. Other hazardous waves can be caused by underwater disturbances that displace large amounts of water quickly such as earthquakes, landslides, or volcanic eruptions. These very long waves are called tsunamis. Storm surge and tsunamis are not the types of waves you imagine crashing down on the shore. These waves roll upon the shore like a massive sea level rise and can reach far distances inland.
The gravitational pull of the sun and moon on the earth also causes waves. These waves are tides or, in other words, tidal waves. It is a common misconception that a tidal wave is also a tsunami. The cause of tsunamis are not related to tide information at all but can occur in any tidal state.
Video Transcript
Waves transmit energy, not water, and are commonly caused by the wind as it blows across the ocean, lakes, and rivers. Waves caused by the gravitational pull of the moon and the sun are called tides. The ebb and flow of waves and tides are the life force of our world ocean.
12 July 2017 | Reading Time: 3minutes
RF wireless infrastructure helps to shape the networks we know today; in fact,an integrated approach to wireless infrastructure can boost-end user adoption, leverage existing infrastructure and applications, enable enhanced working and reduced costs. Supported and complemented by cabling infrastructure, wireless is a core part of effective networks.
But how do wireless networks actually work? What infrastructure is required and what must we consider for successful performance?
How Are RF Signals Transmitted?
Just how is data sent and received across wireless networks?
Radio is the transmission of signals by the modulation of electromagnetic waves.
For example, if you were at a radio studio, sound or voice waves are picked up by a microphone that has electrical current running through it.
These sound waves create vibrations in the current as they travel through wires to a control room. In the control room technicians adjust the volume and they are transmitted out through an aerial or antenna. These signals go out through the air as radio waves. Radio waves are not directional and travel through space in all directions, like ripples on a pond. That is the transmitting of data on RF signals in a nutshell!
The Wireless Network Infrastructure Required to Transmit Data
The process of sending and receiving radio signals through wireless networks involves two devices, the transmitter and the receiver. The receiver picks up the waves with its antenna or aerial and turns the electric signal back into sound where it can be heard.
To transmit sound by radio, the transmitter adds a high frequency carrier wave to the sound signal. This makes the amplitude of the carrier wave change, but the frequency stays the same. This is called Amplitude Modulation. This form of modulation produces frequencies which are the ‘sum and the difference’ of the carrier and modulation frequencies. These frequencies are sometimes called sidebands.
What is QAM?
QAM (Quadrature Amplitude Modulation) is a modulation scheme that enables digital information to be transmitted between two points. Fundamentally, QAM enables an analog signal to efficiently transmit digital information. It also provides the means by which a wireless network operator transmits more bits in the same time period, which effectively increases the bandwidth.
QAM is a modulation scheme that transmits data by changing the amplitude, or power level, of two signals: first in-phase with the incoming data and the second 90 degrees out of phase. QAM relates to the number of bits of information encoded in each time period.
For example, eight bits defines the number of combinations that are possible for those two signals (in phase and 90 degrees out of phase). If there are 256 combinations possible for those eight bits, then it is referred to as 256 QAM.
Understanding Modulation And Its Impact On Radio Communications
Radio Engineers will often talk about their modulation schemes, Mentioning 4QAM, 16QAM, 256QAM and so on. While higher order modulation rates are able to offer much faster data rates and higher levels of spectral efficiency for the radio communications system, this comes at a price.
The higher order modulation schemes are considerably less resilient to noise and interference. The key point here is that the higher the modulation signal, the more symbols are being transmitted and the closer together those symbols are.
As a result of this, many radio communications systems now use dynamic adaptive modulation techniques. They sense the channel conditions and adapt the modulation scheme to obtain the highest data rate for the given conditions.
Avoiding Errors in Data Transmission
What Do Waves Transmit Between Two Points
As signal to noise ratios decrease, errors will increase along with re-sends of the data, thereby slowing throughput. By reverting to a lower order modulation scheme the link can be made more reliable with fewer data errors and re-sends.
This means for a RF signal, the more susceptible the antenna is to interference the more likely the performance will degrade.
What Do Waves Transmit To Humans
Understand the Passive Infrastructure That Underpins Your Network
Of course, RF Infrastructure is just one of multiple aspects of passive infrastructure.
Facilitating ever growing and expanding networks, passive infrastructure is set to increase as demand for global telecommunications infrastructure advances. To stay ahead of demand, you can read more in oureBook: Understand the Passive Infrastructure that Underpins Your Network.
What Is A Mechanical Wave
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