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Walkie talkie

Description ...

Walkie-talkies are handheld, portable radios: they communicate wirelessly (using radio waves) on a single, shared frequency band. Each battery-powered unit contains a transmitter/receiver and antenna (for sending and receiving radio waves), a loudspeaker that often doubles up as a microphone when you talk into it, and a button that you "push-to-talk" (PTT). The loudspeaker/microphone works in much the same way as an intercom: because a speaker and a microphone contain essentially the same components (a coil of wire, a magnet, and a paper or plastic cone to pick up or generate sounds), you can use a single device to do both jobs essentially by switching the electrical circuit into which it's connected and reversing the current. More sophisticated walkie-talkies (like the Motorola model shown in our photos) contain separate loudspeakers and microphones. A group of people who are using walkie-talkies to talk to one another have to tune in to the same frequency band, which is called a channel. Their radios are all "receiving," so their microphone/loudspeaker units are working as loudspeakers and probably hissing with static, a bit like a conventional radio that's not tuned into any particular station. When someone wants to to talk to the others, they hold the push-to-talk button on their handset. Their radio goes quiet as their loudspeaker switches over to a microphone. As they talk into it, their words are converted into radio waves and beamed out on the prearranged channel (typically at a frequency around 460 MHz). Since radio waves are part of the electromagnetic spectrum, they travel at the speed of light (300,000 km/second or 186,000 miles/second), so the waves are picked up almost instantaneously by the other handsets. The radio waves are converted back into fluctuating electric currents and the loudspeakers use those to reproduce the sound of the talker's voice. When the talker has finished, he or she says "over" (meaning my bit of talking is finished) and releases the push-to-talk button. The radio now switches back into listening mode and someone else can talk.

Properties ...
    name properties
    numvalue floatvalue textvalue ntextvalue multi enabled
    Walkie talkie name 0 0 1 0 0 1
    Walkie talkie brand 0 0 1 0 0 1
    Walkie talkie model 0 0 1 0 0 1
    pattern 0 0 1 0 1 1
    color group 0 0 2 0 0 1
    Frame Color 0 0 1 0 1 1
    Frame Material 0 0 2 0 0 1
    Mode type 0 0 2 0 0 1
    Frequency Bands 0 0 2 0 0 1
    Frequency Range (MHz) 0 0 1 0 0 1
    Frequency Stability (PPM) 0 0 1 0 0 1
    Number of Channel 1 0 0 0 0 1
    Number of Storage Channel 1 0 0 0 0 1
    Number of weather channels 1 0 0 0 0 1
    operating temperature (°C) 0 0 1 0 0 1
    Antenna Impedance (ohm) 0 1 0 0 0 1
    Working Voltage (V) 0 0 1 0 0 1
    Transmit power (W) 0 1 0 0 0 1
    Output Power (W) 0 0 1 0 0 1
    Maximum Frequency Deviation (broadband/narrowband) 0 0 1 0 0 1
    FM Noise (broadband/narrowband) 0 0 1 0 0 1
    Adjacent Channel Power 0 0 1 0 0 1
    Emission Current (mA) 0 0 1 0 0 1
    CTCSS/CTTCS Frequency Deviation (broadband/narrowband) 0 0 1 0 0 1
    Modulation Distortion 0 0 1 0 0 1
    Receiving Sensitivity (broadband/narrowband) 0 0 1 0 0 1
    Audio Power (W) 0 1 0 0 0 1
    Audio Distortion 0 0 1 0 0 1
    Intermodulation (broadband/narrowband) 0 0 1 0 0 1
    Adjacent Channel Selectivity (wide/narrow) 0 0 1 0 0 1
    Talk Range/Talking Distance range (m) 0 0 1 0 0 1
    Communication range (m) 0 0 1 0 1 1
    Functions 0 0 2 0 0 1
    Number of Batteries 1 0 0 0 0 1
    Battery Size 0 0 2 0 0 1
    Battery Type 0 0 2 0 0 1
    Battery Capacity (mAh) 0 1 0 0 0 1
    battery voltage (v) 0 1 0 0 0 1
    Working time (hours) 0 0 1 0 0 1
    Charging time (hours) 0 0 1 0 0 1
    Standby Time (hours) 0 0 1 0 0 1
    Work mode 0 0 1 0 0 1
    IP Rating 0 0 1 0 0 1
    Display Type 0 0 2 0 0 1
    Display size (inch) 0 1 0 0 0 1
    Backlight color 0 0 1 0 0 1
    Number of call tones 1 0 0 0 0 1
    Dimensions (cm) 0 0 1 0 0 1
    weight (gr) 0 0 1 0 0 1
    Features 0 0 2 0 0 1
    Accessories 0 0 2 0 0 1
    guarantee 0 0 2 0 0 1
    guarantee period 0 0 2 1 1 1
    guarantee Conditions 0 0 1 0 1 1
    Certification 0 0 1 0 1 1
    descriptions 0 0 0 1 1 1
    thumbnail original 0 0 1 0 0 1
    Thumbnail 1 0 0 1 0 0 1
    Thumbnail 2 0 0 1 0 0 1
    Thumbnail 3 0 0 1 0 0 1
    subject 1
    Descriptions 1
    Age Range 1 1 0 0 1 1
Groups ...
  1. 1. Robots and Gadgets
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