Posts Tagged ‘low frequency’
July 2nd, 2009 | 
Author: There are various ways in which an electromagnetic field can be seen. Case in point, static magnetic fields become active when medical instruments like magnetic resonance imaging (MRI) and X-rays are being used. In ultra-violet ray form, electromagnetic radiation showers down from the sun to the earth. An electromagnetic charge is held by radioactive elements, deep under the earth’s surface. In addition, microwaves, refrigerators, mobile phones, and other devices that are electronic send out their own waves that are electromagnetic. The most captivating thing, though, is the application of electromagnetic fields to cure and restore the body.
Today electromagnetic fields can be used to treat depression and is approved by the FDA. A total of 37 million Americans, one quarter being females and one tenth males, are under the spell of depression. Trans-magnetic stimulation is a process in which the left frontal lobe of the brain is stimulated by a strong electromagnet. This stimulates brain cells, which cause brain chemicals, referred to as neurotransmitters, to be activated. While more study is needed in this area, the electromagnetic pulse has the advantages of being fast, causing no side effects and frequently being effective for patients for which other treatments have failed.
In a number of studies, those suffering from multiple sclerosis have also exhibited good results from electromagnetic field therapy. Patients were able to walk and balance better after two 20-30 minute treatments of picoTesla range, low-frequency electromagnetic fields, with a 15 minute break in between each treatment. People with MS were still able to get around even when there was external stimulus. In other studies, 10 days of electromagnetic field therapy reduced excessive fatigue and, in some cases, electromagnetic stimulation resulted in diminished spasticity.
Magnets and electromagnetic field treatment is delightful in that magnets can be traced and followed once they get into the body. Lately, researchers are applying magnets and nanotechnology to seek out a more effective cure for cancer. For an example, they have been able to use nano-magnets attached to antibodies to bind to cancerous cells in order that high-powered radio waves can heat up and kill the cancerous cells, all the while leaving the surrounding healthy tissue and cells untouched. This very new and exciting field is still in its infancy; it has not reached the stage where human testing can be done, yet it holds great promise for the future of electromagnetics and cancer research.
There are some who are concerned about the impact of long-term exposure to electromagnetic fields; you may have heard this expressed in relation to radiation emanating from cell phones, laptops, refrigerators, televisions, radios, and other electronic devices. The World Health Organization, nevertheless, has discovered no connection between electromagnetic wave radiation and cancer, nor other impairment. In the hope of the ability to treat other types of physical and mental illness, scientists are still researching how magnets do their work in the body.
Cameron Tacassi loves his job as a private electronics consultant as it allows him to work with chip inductors and other electronic components. Cameron’s extensive knowledge of custom inductors and magnetics has earned him a good reputation with customers and local vendors.
Article Source: The use of Electromagnetic Fields & Magnets in the Medical World
The networking standards of Bluetooth will transmit data via low power radio frequency. Bluetooth communicates on a 2.45 GHz frequency. This very band of frequency has been set aside by international agreement for the use of industrial and medical devices.
Many devices that you already known and use take advantage of this frequency band. Garage door openers, baby monitors, and the next generation of mobile phones all use this frequency within the ISM band. Ensuring that Bluetooth and the other devices don’t interfere with each other is a crucial part of the design process.
One of the ways Bluetooth will avoid interfering with other electronic devices is by sending out weak signals of around 1 mw. In comparison, even the most powerful of cell phones can transmit a signal of 3 watts.
The low power signals will limit the range of a Bluetooth device to around 32 feet, which cut the chances of interference between your computer and other electronic devices. Even though it has low power, Bluetooth doesn’t require a line of sight between the communicating devices. The walls in your home won’t stop the signal, making it great for rooms throughout the house.
Bluetooth can connect 8 devices at the same time. With each of those devices on the same radius, you may think they would interfere with each other, although it’s very unlikely. Bluetooth utilizes a technique known as low frequency hopping, which makes it harder for more than one device to transmit on the same frequency at the same time.
With this technique, a device will use 79 individual, randomly chosen frequencies within a designated range, which change from one another on a regular basis.
In the case of Bluetooth, the transmitters will change frequency 1,600 times or more every second, meaning that more devices can make full use of the radio spectrum. Since every transmitter of Bluetooth will use spread spectrum automatically, it’s very unlikely that two transmitters will be on the same frequency at the exact same time.
When the Bluetooth devices come within close range of each other, an electronic conversation will occur to determine whether or not they have data to share or whether one needs to take total control. The user doesn’t have any buttons to press or commands to give – as the conversation will occur automatically.
Once the conversation has occured, the devices will form a network. Bluetooth devices will create a PAN (Personal Area Network) or piconet that may fill a room. Once the piconet has been established, the devices will randomly hop in frequencies.
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Article Source: The Essentials of Bluetooth Operation
The phenomenon of electromagnetic induction was first discovered by Michael Faraday in 1831, and it is evident that he realised at least a part of its future potential in the modern world. A contemporary politician asked him about the usefulness of the discovery; he answered ‘at present I do not know, but one day you will be able to put a tax on it.’
The earliest record of using electromagnetic technology to locate buried cables dates from around 1910. More portable locators were made over the next years and the Sharman Main Finder was just one example. The user instructions give a tinge of envy to anyone trying to trace gas pipes .. ..’just clip the generator to a gas bracket in the nearest house or onto a street lamp.’
American and German schools of design emerged during the years leading up to the Second World War. In North America roads were wide and wide cables hung on poles so the main requirement for a locator was to locate widely spaced buried pipes. The result was a simple, high frequency, low power and low cost locator.
In Germany, cables as well as pipes were buried under narrow streets, so elaborate low frequency and high power locators were developed that required considerable expertise to obtain satisfactory results.
Dr Gerhard Fisher of California designed the Metallascope, the first high performance buried pipe and cable locating set. His system made use of the latest scientific developments and his company exists today and still produces the M-scope, an up-to-date descendent of the original Metallascope.
One of the engineering sections of Bell Laboratories studied the problem of accurate location of newly buried cables and recognised that an antenna with twin sensing aerials would give more positive plan definition, and also measure the depth of a target cable. The subsequent design, called the Depthometer, was engineered and manufactured in 1964. It was another 12 years before the first commercial twin aerial antenna locator was made by the Electrolocation company in Bristol England.
The twin aerial system was found to have substantial advantages over single aerial locators. Twin sensing aerials combined the seemingly contradictory qualities of discrimination with sensitivity. For the first time it was possible to locate buried cables below an overhead power line and to sort out crowded utility services under a city street intersection.
The introduction of the twin aerial antenna coupled with miniaturised electronic circuitry coincided with a programme of extending and upgrading utility distribution systems. This growing demand and technical progress resulted in a series of advances and new features to make locating more certain and more simple. Some of these advances included:
” Combination of active and passive signal reception
” Multi-frequency locating sets enabling the user to select the most suitable frequency for each application
” Electronic depth measurement.
” Current measurement along the length of a pipe or cable to detect coating or insulation defects.
” Current direction recognition to verify the identity of a target line.
” Permanently installed signal transmitters to apply a signal tone to a telephone cable over distances up to 150km/100 miles.
Today, electromagnetic locators are the worldwide standard for locating buried pipes and cables. A number of specialised manufacturers offer a choice of locators ranging from simple equipment used to detect the presence of buried cables to sophisticated instruments for pinpointing, identifying and fault finding buried pipes and cables in the most complex situations.
Written by Select Surveys, one of the UK’s leading independent surveying companies specialising in using electromagnetic, CAT and ground penetrating radar equipment to detect underground cables and utilities.
Article Source: A History of Underground Electromagnetic Surveying