There are quite a few police earpieces on the market right now, Renée, so the high likelihood is that whatever you need, someone, somewhere will be selling it. If it helps, I’ll give you a bit of an overview…
If you’re in the market for an overt earpiece, or even if you fancy something a bit more discreet (like, um, a covert earpiece), you’ll certainly be able to find it on the World Wide Web. Police organizations across the world employ a wide variety of communications equipment, from ‘listen only’ devices to PTT (Push To Talk) earpieces and, as I said, a significant portion of that equipment is available for consumer purchase. Continue reading ‘What earpieces work with tetra radios’ »
After doing a little research, I can now tell you (basically) everything you ever wanted to know about black boxes…
In the average commercial aircraft, you’ll find the presence of multiple (usually four) microphones in the cockpit at any given time. They are located in the pilot and co-pilot’s headsets, as well as in the cockpit itself. Not only do these microphones record conversations between the pilots and cabin crew, they also record any ambient noise (such as switches being thrown or sounds generated by technical issues). The microphones all connect to the cockpit voice recorder (CVR), a master unit that stores the last 30 minutes of sound. The tape operates on a loop, essentially erasing itself every half hour. Continue reading ‘How does an aeroplane’s ‘black box’ work?’ »
(Asked by Preeta from Newcastle)
This is actually a pretty common question. However, just because it is a common query does not mean that it isn’t a valid one. Radio static is something that most people simply take for granted and never question (which is actually quite silly of them, really). Anyway, the point is that I’m glad you asked.
Essentially, radio static is the sound you get when there is no broadcast on a specific frequency. This can mean anything from, ‘my friend/colleague doesn’t know how to use the radio’ to ‘the zombies have taken over and we’re all going to die!’ (As well as any number of options in between). Continue reading ‘What causes the ‘static’ sound on my two-way radio?’ »
OK, To have the ‘flaking’ part of the answer out of our way nice and first, I have to mention that it depends completely on what you would like from the headphone. There is not much point spending out on an all-singing, all-dancing tremendous-headphones if all you would like is a basic model, but, by the same token, great superiority does not come cheap in the planet of electronics.
Though, that’s not what you wanted to hear, is it? Continue reading ‘I need a earpiece, is it worth purchasing a bluetooth one?’ »
Yahoo!’s policy of recycling inactive email accounts has backfired on them, as new account owners are receiving personal emails that aren’t meant for them.
The policy, active since June, means that Yahoo IDs and addresses are reassigned to a new user if left inactive for a year or more. But obviously both Yahoo! and some of its users got more than they bargained for. Continue reading ‘Yahoo! Becomes ‘Yikes!’ as Recycled Accounts Relay Sensitive Information to the Wrong People’ »
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.
Continue reading ‘Innovative or Simply Post-Modern? New Paradigms in the Study of “Radio”’ »
Lemme get this straight, you live in Spain (where all the nice weather is) and you want to go on holiday to a cold, snowy place? To quote the great French thinker Obelix, “These Romans are crazy!” However, I shall answer your question, but only if you send me a postcard from your trip!
Well, I actually have bad news for you. When I wrote the piece above, I was all set to get online and find you a bargain. However, a little bit of research (together with some applied common sense) tells me that there actually aren’t any radios around (or at least commercially available) that are specifically adapted to skiing (or any mountainous activity, for that matter). Continue reading ‘I’m going Skiing in November and I’m looking for a Good Two-Way Radio Set. Any Suggestions?’ »
To answer your question (that is, after all, why I’m here): It depends entirely on which models you are planning to use. For example, if you had two PMR446 variants that were both on the same band, they ought to work fine (even if one was Kenwood and the other was Motorola).
If two radios are the same basic type and set to the same channel, then I don’t personally see why they wouldn’t work. However, if they aren’t of the same type, then they probably won’t work, it’s that simple. Continue reading ‘Can a Kenwood Radio be used to Communicate with a Motorola Radio?’ »
This is year that windows 8 makes its mark inside the tablet pc marketplace. With the modern nokia lumia 2520, the microsoft surface 2 plus a few others (including the Razer Edge Pro, that is basically what this short article is all about). We will be seeing a few more come through the door before next christmas time. The Razer Edge Pro is a little disappointing compared to everything else that is out on the market (ipad, nexus 7) but read to the end to find out the final assesment of this windows 8 tablet. Continue reading ‘Review: Razer Edge Pro tablet—insane performance that’s completely impractical’ »