That’s actually a pretty good question. Good quality wireless earpieces are available, affordable and would be far more inconspicuous than the classic ‘wired’ models. So why don’t the secret service make their presence a little more, well, secret?
The main reason is largely psychological in nature (though there will be a technical component later on). You see, if a potential troublemaker looks into a crowd and sees nobody there that he/she identifies with as a threat, then said troublemaker will be far more likely to start making trouble. However, if they notice secret service guys using their trademark earpieces, then they might think twice about it and a lot of unpleasantness can actually be avoided. Read More
There are two main methods of noise cancellation (although a third shall also be detailed a bit later on) with regards to headsets, earphones and other portable devices. Here’s a bit about them and how they work…
The first type of noise cancellation basically occurs whenever anything obstructs the inner ear; this has the effect of dulling our ability to hear whatever’s going on around us. If you put your hands over your ears right now, or you stick your fingers in your ears, the background noise will diminish. This, in a very real sense, is a form of noise cancellation. In this regard, any set of headphones that cover the ear, or even the types that sit inside the ear, effectively cancel out background noise and are therefore ‘noise cancelling’. Read More
According to the UK Government, there were an estimated 5.2 billion bus passenger journeys undertaken on our roads in 2011/2012. Public and private transportation is not only big business; it is also of massive importance to the smooth running of the country.
Whilst only 14% of the UK’s 25 million commuters travel to work by bus or train, this still accounts for over 1.7 million people. In order for a country this reliant on public transport to survive and thrive, it is absolutely imperative that transport workers can communicate with each other in a quick, efficient manner, fuelling an industry that, by necessity, spans the length and breadth of the nation. Read More
Radio is the wireless transmission of signals through free space by electromagnetic radiation of a frequency significantly below that of visible light, in the radio frequency range, from about 30 kHz to 300 GHz. These waves are called radio waves. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.
Information, such as sound, is carried by systematically changing some property of the radiated waves, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.
The etymology of “radio” or “radiotelegraphy” reveals that it was called “wireless telegraphy”, which was shortened to “wireless” in Britain. The prefix radio- in the sense of wireless transmission, was first recorded in the word radioconductor, a description provided by the French physicist Édouard Branly in 1897. It is based on the verb to radiate .
The word “radio” also appears in a 1907 article by Lee De Forest. It was adopted by the United States Navy in 1912, to distinguish radio from several other wireless communication technologies, such as the photophone. The term became common by the time of the first commercial broadcasts in the United States in the 1920s. The term was adopted by other languages in Europe and Asia. British Commonwealth countries continued to commonly use the term “wireless” until the mid-20th century, though the magazine of the BBC in the UK has been called Radio Times ever since it was first published in the early 1920s.
In recent years the more general term “wireless” has gained renewed popularity through the rapid growth of short-range computer networking, e.g., Wireless Local Area Network, Wi-Fi, and Bluetooth, as well as mobile telephony, e.g., GSM and UMTS. Today, the term “radio” specifies the actual type of transceiver device or chip, whereas “wireless” refers to the lack of physical connections; one talks about radio transceivers, but another talks about wireless devices and wireless sensor networks.
Radio systems used for communications will have the following elements. With more than 100 years of development, each process is implemented by a wide range of methods, specialized for different communications purposes.
Transmitter and modulation
Each system contains a transmitter. This consists of a source of electrical energy, producing alternating current of a desired frequency of oscillation. The transmitter contains a system to modulate some property of the energy produced to impress a signal on it. This modulation might be as simple as turning the energy on and off, or altering more subtle properties such as amplitude, frequency, phase, or combinations of these properties. The transmitter sends the modulated electrical energy to a tuned resonant antenna; this structure converts the rapidly changing alternating current into an electromagnetic wave that can move through free space.
Amplitude modulation of a carrier wave works by varying the strength of the transmitted signal in proportion to the information being sent. For example, changes in the signal strength can be used to reflect the sounds to be reproduced by a speaker, or to specify the light intensity of television pixels. It
was the method used for the first audio radio transmissions, and remains in use today. “AM” is often used to refer to the mediumwave broadcast band .
Frequency modulation varies the frequency of the carrier. The instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal. Digital data can be sent by shifting the carrier’s frequency among a set of discrete values, a technique known as frequency-shift keying.
FM is commonly used at VHF radio frequencies for high-fidelity broadcasts of music and speech . Normal TV sound is also broadcast using FM.
Angle modulation alters the instantaneous phase of the carrier wave to transmit a signal. It is another term for Phase modulation.
More from the web, i found them funny and i hope you enjoy as well…….
The Digital Camera has changed the way we take photos, the digital camera or Digicam is an electronic device that is able to take still photos as well as video, the digital camera records images with the use of an electronic image sensor and viewed on a mini screen on the camera or photo editor through a PC or MAC.
The digital camera is able to take photos at the click of a switch, excuse the pun! The photo can be seen instantaneously, particularly useful on a night out or for the important holiday snap, capture that moment with the use of the latest technology. Read More
Imagine a young Marlon Brando starring alongside Johnny Depp, or Audrey Hepburn playing rival to Sandra Bullock as Marilyn Monroe stops by for a catty cameo.
Depending on how you look at it, this is either tantalizing ‘fantasy film making’ or else an utterly horrible, cash-in exercise in Hollywood excess. Whatever your viewpoint, it does seem likely that someone, somewhere will try this in the near future.
About three years ago, the news broke that George Lucas, the genius behind the ‘Star Wars’ merchandise (and a couple of related movies), was buying up the likeness rights to a plethora of iconic, yet deceased, leading men and famous actresses from Hollywood’s golden age. His plan? To use a concoction of existing footage, CGI and motion capture to create reasonable facsimiles of classic Hollywood stars and have them appear in future films, despite the notable handicap of being, well, dead. Read More
The real reason is that the signals generated by your radio receiver (yes, it generates signals as well as receives them) can interfere with the aeroplane’s navigation equipment.
In an article for ‘The Straight Dope’, published in 1987, Cecil Adams (who ran a similar, but far superior, column to this one) explained it far better than I could. He said,
“Most modern receivers use something called a “local oscillator,” which is sort of an internal transmitter. The oscillator generates signal A, which is mixed with the somewhat raw incoming signal B to produce nice, easy-to-work-with signal C. There’s usually some sort of shielding around the oscillator, but it’s not always effective and sometimes errant signals leak out to make life difficult for other radio equipment nearby. If the other equipment happens to be an aircraft navigation device, somebody could wind up digging furrows with a $25 million plow. So do your bit for air safety and bring a tape player instead.”
NASCAR officials have enthusiastically embraced MOTOTRBO, and they applaud the benefits it has brought to the NASCAR experience. Smooth Management of Communications Traffic MOTOTRBO “does a super job for us,” according to Kerry Tharp, Director of Communications, NASCAR. “You have to communicate pre-race, during the race, and most importantly for us, post-race because when the race is over, that’s when our media operation kicks in for us full-bore. We bring in our top three drivers for interviews; we bring in our winning driver to the victory lane, and we also check in on the garage to make sure that post-race is going along as it should. We have to make sure we’re communicating quickly and concisely. Through MOTOTRBO, we’re able to do our jobs a whole lot better than we have in the past.” Read More
Virtual reality, which I’m going to define as ‘the creation of a computerized 3D environment that can be interacted with and manipulated in much the same was as the real world can’, is a pretty multi-faceted concept. There are quite a few ways to allow interaction with a virtual environment (VE), but the headset is perhaps the best known.
So, the key thing that a VR headset needs to be able to do is track the movements of the user’s head (and, where possible, their eyes) in order to allow for better interaction with the VE. After all, if I tilt my head from where I’m sitting and look at the ‘Macho Man’ Randy Savage action figure that stands on my desk, the positioning of my eye line will change my perspective of the figure. So VR, in order to be convincing, needs to work on the same principle. Read More