A radio station has got widespread during World War II when the need for fast communications over long distances increased. In those days, a stationary radio was used, but it was huge, and communications men carried such 2-way radios after their officers. Walkie-talkies also already existed, but they were far from a modern compact walkie-talkie.
What does any modern walkie-talkie consist of?
- A receiver of the radio station is responsible for converting radio frequency signals into acoustic vibrations accustomed to the human ear. First, the received signal is filtered out and increased, then there is a decrease in frequency and transferring to a special decoder, which selects the information component from the entire stream. Then there is another amplification and outputting of already processed audio data to the speaker.
- A radio transmitter does the opposite: it converts the data and sends it via radio waves to another subscriber. If we transmit information through a radio station using voice, the signal from the walkie-talkie microphone is fed to a low-frequency amplifier, where it is increased and fed to a modulator.
- A modulator is a device in a radio station that converts voice information into a radio signal according to certain rules (and vice versa).
- An antenna – converts a radio signal into an electromagnetic wave and transmits into space. Or it takes the wave and converts it into a signal, which later is decoded by the modulator.
- A channel switcher – allows you to select the channel, where you and the interlocutor will communicate.
- A volume control – changes the volume
- A speaker – transmits a signal which had been converted into speech.
- A microphone – receives your speech and transfers it to the decoder
- A battery – modern walkie-talkies work on battery or accumulator. Usually, these are Li-Ion ones, convenient to use and durable. As a rule, a walkie-talkie can only work with that native battery.
Frequently Asked Question:
LPD and PMR channels cannot communicate with each other, because they exist at different frequencies.
To understand how walkie-talkie works, let’s start with the basics.
What are radio waves?
A wave is an oscillation. Like a wave on the water surface. Radio waves are electromagnetic radiation, which can be different by their frequencies and lengths. A radio receives these waves and converts it to speech using a modulator. When we transmit a message on the radio, the transmitter receives our speech and encodes it into a radio signal using a modulator. Long waves go around the entire planet and easily overcome obstacles. And short ones are good at short distances, but easily interrupted by obstacles.
In amateur radio communications, amplitude modulation (AM) and frequency modulation (FM) are most often used.
AM Modulation Ranges:
- Long waves – with a frequency of 150–450 kHz and a wavelength of 2000 – 670 m. This type of wave is known for its high ability to go around obstacles.
- Medium waves – with a frequency of 500–1600 kHz and a wavelength of 600 – 190 meters. Good for communication at night over a distance of hundreds of kilometers.
- Short waves – with a frequency of 3–30 MHz and a wavelength of 100 – 10 meters. Coverage is up to several thousand kilometers, regardless of the time of day.
FM Modulation Ranges:
- VHF – with a frequency of 30 – 300 MHz, with a wavelength of 10 – 1 meter.
- UHF – with a frequency of 300 – 3000 MHz, with a wavelength of 1000 mm – 100 mm.
- SHF – with a frequency of 3 – 30 GHz, with a wavelength of 100 – 10 mm.
- EHF – with a frequency of 30 – 300 GHz, with a wavelength of 10 – 1 mm.
- THF – with a frequency of 300 – 3000 GHz, with a wavelength of 1 – 0.1 mm.
The UHF band, which contains FRS channels allowed for free use in the USA, stays in FM modulation. It works within the line of sight. This means that if there are no obstacles between you and the interlocutor, then the communication range will be high. If walls, trees, hills, etc. are between you, then you should not count on a good connection. The quality of reception is also hindered by various radio devices located in the coverage area. They interfere with the broadcast and cause noise.
To receive and transmit radio signals in walkie-talkies there is:
Antennas in walkie-talkies can be:
- Different frequencies (VHF / UHF / CB …)
- Embedded / None Embedded
How does the antenna work in walkie-talkies? The antenna is connected to the receiver and transmitter. Thus, when we transmit a signal, the modulator converts them into a signal and the transmitter sends the signal to the antenna. The antenna receives it, converts the signal into an electromagnetic wave and transmits to the air where the wave spreads.
The quality of the received and transmitted signal, as well as the distance of transmission, depends on the quality of the antenna.
If you find a free channel, but there is a lot of noise on it, use the CTCSS or DCS subtones if your walkie-talkie supports them. How do subtones work? If you activate this function, your walkie-talkie will only receive the signal that contains the specified subtone. That is, any signal that does not contain this code will pass by. To talk with subtones, you and your companions must have the same subtone set. But at the same time, the other participants of the broadcast, who do not have that subtone, will still hear you, it’s just you will not hear them. The subtones are useful in cities, you hardly need them in the forest.