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This is a typically cheap walkie-talkie. Well, what's a walkie-talkie? Funkgeräte are mobile, wearable transceivers: They communicates in a wireless way (over wireless waves) on a common spectrum only. Every battery-powered device includes a transmitter/receiver and aerial (for transmitting and transmitting audio waves), a speaker, often used as a mic when you speak into it, and a key called "push-to-talk" (PTT).
Refined walkie-talkies (such as the Motorola shown in our photos) include their own speakers and mics. Walkies are entering the 21 st centuries with applications like these. Turns your smart phone (or iPod touch) into a walkie-talkie that can talk to others close by. Many similar applications can be found by searching the iTunes Store or Google Player (for Android) for "walkie-talkie".
What do you do with a walkie-talkie? One group of persons using transceivers to communicate with each other must adjust to the same bandwidth known as the canal. Your workstations are all "ready to receive," so your microphone-loudspeaker assemblies work as speakers and are likely to hiss with statics, a little like a traditional non-transmitter matched workstation.
If someone wants to speak to the others, they press and hold the PTT key on their mobile part. Your listener will become quieter as your speaker changes to a mic. While they are speaking in, their words are transformed into audio signals and transmitted to the prepared channels (typically at a 460-MHz frequency).
Being part of the electro-magnetic range, they move at the velocity of daylight (300,000 km/second or 186,000 miles/second), so the ripples are received almost immediately by the other mobile phones. Radiowaves are transformed back into oscillating electrical current and the speakers use these to produce the tone of the speaker's speech.
At this point the handset returns to hearing and someone else can speak. In contrast to a regular wireless system that only receives voice or musical transmissions from a wireless transmitter, a walkie-talkie is a two-way radio: you can both speak and hear (transmit and receive). However, the biggest disadvantage is that the same FM channels are used for both things so that only one speaker can speak at a given moment.
If communications equipment works in this way, it is called halfduplex ( a lone port allows simultaneous one-way communication), as compared to fullduplex ( where you can speak and hear at the same moment, like a telephone). It receives things like musical programs from radios, but it can't broadcast.
Walkies can transmit and recieve, so they are known as two-way radios. Radios are rugged, as well as extremely user-friendly and straightforward (with relatively few parts and functions), making them ideal for outdoor use and for kids (or for kids who need to keep in contact with a parent, e.g. on holiday). They are very practical in a situation where many listeners need to hear and only one person needs to speak at a time (e.g. when you give directions to employees at a campsite).
Walkies usually have more than one channel (from about 8 to 25 or more), so you can change to a different channel quickly and simply when other persons also use walkie-talkies in the vicinity. You can also use some walkie-talkies as babyphone intercom systems. The majority of cheap radios are analogue devices, so they can be disturbed and listened to relatively readily (more costly discrete radios avoid noise, but generally only defence radios use cryptography to prevent eavesdropping).
Radios are not intended for long distance communications (where you need something like local loop radios or a mobile phone). Well, who made up the walkie-talkie? It' an illustrated copy of one of Gross's transceiver licenses. More about how it works can be found in US Patent 2,698,380: Work of art with kind permission of the US Office of Trademarks and Designs.
In 1937, walkie-talkies (originally known as two-way stereos or "packsets") were designed by the Canadian Donald Hings (1907-2004) and at about the same period by the US creator (Irving) Alfred Gross (1918-2000). Great is attributed to the invention of the pager, which was a beloved way to stay in contact on the move before mobile phones became omnipresent, while Hing designed countless enhancements to wireless radars, speed radars, floor magnetometers, and atmospheric pollutant measurement instruments (he has 39 different innovations registered with the U.S. Patent and Trademark Office).
Danny Gregory and Paul Sahre's A Life-in-Ham Russe. Prior to the advent of the web, listeners used the wireless to get together and speak with kind foreigners in other states. At the same time, a bicycle helmet is a walkie-talkie by Roy Furchgott. Checks a basic wireless helmet that allows bikers to speak with their close buddies.
Cell phones become walkie-talkies: Announcement of the emergence of breakthrough chat room chat room service for mobile phones that are like a mix of IM on a computer and classic walkie-talkie notifications. Family Radios comes with the walkie-talkie Comes of Age by Roy Furchgott. That old Times paper is still a good synthesis of the benefits of two-way radios over mobile phones for short-range communications.
U.S. Intellectual Property 2,698,380: That is Alfred Gross's initial transceiver license, in which he described his goal of developing a small, light -weight, high-portability transceiver and transceiver that was robust enough to "withstand the shock and misuse it was subjected to by civil or armed use. "Another goal was to produce a so-called "stable" wireless device that could maintain its frequencies very dependably - and this patented device described an electronics design developed specifically for this purpose.
U.S. License 2,760,056: Irving A. Gross voting machine, issued August 21, 1956. About the same day, this annotated annotation described the voting mechanisms in Gross's walkie-talkie.