Some people may have thought walkie-talkies would disappear with the advent of mobile phones. But walkie-talkies have remained a critical communication tool today. They’ve also kept up with the technological pace.
Walkie-talkies are simple devices, typically allowing you to communicate with a button push. But how do they work?
In this article, we will discuss the essential components of walkie-talkies. We will also take you through a step-by-step guide on how the device operates to help you understand how they work.
Definition of Walkie-Talkies
Walkie-talkies are wireless two-way communication systems that depend on radio frequencies to transmit and receive messages. They are also called handheld transceivers (transmitter-receiver) (HT) or two-way radios. They got these names because they allow users to transmit and receive voice signals.
The walkie-talkie works in half duplex mode, which means while a user is talking (transmitting), the receiver in the same frequency will be in the receiving mode. Two users can’t talk at a time, and the other party can only talk once the sender has finished talking. Hence, it works differently from smartphones, where both parties can talk simultaneously.
Walkie-talkies can be traced back to the early 20th century, during World War II, when the US military needed a portable communication device for soldiers on the battlefield. Donald L. Hings invented the first walkie-talkies, called “pack sets,” in 1940. Another version was also independently created by a Canadian Engineer, Alfred J. Gross, around the same time.
The early models of two-way radios were bulky, weighing approximately 25 pounds (11.3kg). They named them “walkie-talkies” because they allow users to walk and talk. And this remains the most common name for this portable two-way device.
Basic Components of A Walkie-Talkie
While walkie-talkies have advanced over the years, they maintain the same basic features. They include:
The antenna is a crucial part of the walkie-talkies as it sends and receives radio signals. Walkie-talkies can either have fixed or detachable antennas. Fixed antennas are built into the walkie-talkies. But detachable ones are not fixed onto the radio, and you can remove and replace them with different antennas.
Most basic radios, like PMR446 and FRS radios, are regulated to have fixed antennas. But other radios, like the GMRS, mobile radio, and base station radios, have detachable antennas.
The transmitter converts your voice message into radio signals. Once you press the push-to-talk (PTT) button, the transmitter activates. It then sends your message as a radio signal through the antenna. The next topic will explain how it works.
Watts is the standard measurement for the transmitter’s power output. And the power output is one of the factors that significantly decides the walkie-talkie’s range (how far it can transmit) and signal strength.
Walkie-talkies are always in receiver mode until you press the PTT button. If the squelch function is not activated to mute the speaker, you will hear a constant static nose. The primary function of the receiver is to pick up radio signals transmitted by other walkie-talkies.
When the receiver picks up a signal, it decodes it and changes it to an audio message. Then, you can hear the message through the speaker. The receiver’s sensitivity significantly impacts the clarity and quality of the received audio.
4. Speaker and Microphone
You are probably familiar with speakers and microphones, and the ones in walkie-talkies are no different. The speaker plays received audio from other handheld transceivers. On the other hand, the microphone captures your voice when you are transmitting.
Some manufacturers place the speaker and microphone side by side. But some have separate speakers and microphones and may put multiple microphones to capture the environmental noise for noise reduction. Many walkie-talkies also have a connector for external speakers or headsets. Hence, you can use the walkie-talkie hands-free.
5. Controls and Display
Typically, walkie-talkie models have several control buttons and knobs for adjusting settings and navigating menus. They include volume, channel selection, Push-to-Talk (PTT), and menu navigation buttons. Most modern two-way radios also have a backlit LCD. The LCD shows the channel number, battery life, signal strength, and other statuses.
6. Battery and Power Source
Rechargeable or disposable batteries power walkie-talkies. Rechargeable batteries are more cost-effective and environmentally friendly. Walkie-talkie uses lithium-ion or nickel-metal hydride rechargeable batteries.
Some product models are also designed to power by disposable batteries. Disposable batteries include AA or AAA alkaline batteries. Such batteries are most helpful when recharging is not an option.
How Walkie-talkies Work
This section examines how these two-way devices allow you to send and receive voice transmissions.
It’s important to note that there are two types of radios: analog and digital. And in this section, our explanation will cover both types. You can follow this link to learn more about the differences between analog and digital radios.
The Process of Setting Up Walkie-talkies
Before you can even talk to others using your two-way radio, you must set it up. Doing so involves choosing a channel. Channels are the numbers assigned to frequencies.
So, choosing a channel number means you are choosing a frequency. But this is not always the case. Some digital radios, particularly those using Frequency Distribution Multiple Access (FDMA), have two channels on a frequency.
Walkie-talkies use Ultra High Frequencies (UHF) of 400 to 512 MHz, and Very High Frequencies range from 300 to 3000 MHz (3 GHz). These ranges are called the frequency band. While you can use some walkie-talkie frequencies freely, others require licensing.
You must ensure you are on the same channel as the person you want to talk with. Doing so enables both of you to communicate. If you intend to use a privacy code for better privacy, remember to set the same privacy code as the other party as well. Now, you are ready to talk, but how do walkie-talkies send and receive voice signals?
Transmission and Reception Process
Here are steps on the transmission and reception process of two-way radios:
Step 1: Voice Input
To talk, you press the PTT button and speak to the microphone. When you do so, your voice creates sound waves that travel through the air. The microphone, a transducer, captures the sound waves and converts them into an electrical signal. This electric signal is the audio signal, and the conversion process is called transduction.
There are different types of speakers. They include dynamic, condenser, and electret microphones. But most walkie-talkies use electret microphones because of their compact size and durability. They also produce a clear audio signal with minimal background noise.
Step 2: Modulation
Once the microphone changes the sound wave into an audio signal, the walkie-talkie combines the signal with a carrier wave. This process enables the walkie-talkie to transmit the signal via radio waves. Usually, the carrier wave is of a higher frequency than the audio.
Modulation is the process of varying the carrier wave’s properties with the audio signal. This modulation process helps to encode the information (that is, the original message sent) in an audio signal.
Analog radios use either frequency modulation (FM) or amplitude modulation (AM) to vary signals. FM varies the carrier wave’s frequency according to the message sent. But the amplitude remains constant.
AM, however, varies the amplitude of the carrier wave according to the message sent while the frequency remains constant. Most analog walkie-talkies use FM modulation because it provides better audio quality and is less prone to interference.
Digital walkie-talkies work differently. They use modulation techniques like Phase Shift Keying (PSK) or Quadrature Amplitude Modulation (QAM) to encode audio signals. Typically, they convert the audio signal into a digital signal. This digital signal comprises streams of bits (zeros and ones). Digital modulation methods significantly reduce the risk of interference than analog.
Step 3: Transmission
After modulation encodes the audio signal, the walkie-talkie’s antenna receives it. Next, the antenna changes the electrical (audio) signal into an electromagnetic wave.
This conversion allows the voice signal to travel through the air as a radio wave. Radio waves are usually transmitted across the selected frequency.
For maximum efficiency, the antenna’s length and design must match the walkie-talkie frequency. Hence, you must find the most suitable antenna for your radio. An adequately matched antenna can make the most of transmitting power to radiate radio signals efficiently. And this leads to a stronger signal and increased communication range.
Step 4: Propagation
Propagation is how radio waves travel. So, once the antenna generates the radio wave, it propagates (travels) through the air. This process usually happens at the speed of light. The wave propagation methods include groundwave, skywave, and free space wave propagation.
Walkie-talkie signals usually travel through free space waves. The free space wave is also called line-of-sight propagation. It happens when radio waves travel directly from the transmitting antenna to the receiving antenna.
But line-of-sight doesn’t mean two users must be within sight to communicate. It only means that the wave travels in a straight line from the transmitter to the receiver. Usually, both walkie-talkies are just several miles apart, depending on their power output.
In an ideal environment, these waves don’t encounter obstacles. They keep traveling in a straight line. But in reality, radio waves meet obstacles like trees and buildings, and weather also affects them. And these factors, in turn, affect the strength and range of communication.
Step 5: Reception
After the long travel from the transmitter, the radio wave goes to the receiver. Typically, anyone tuned to your frequency receives your voice transmission. When sent, the receiving antenna captures the radio waves and converts them back into an electrical signal.
Likewise transmitting process, the receiving antenna must be appropriately matched to the walkie-talkie’s operating frequency for the best audio quality. Once the antenna receives the radio wave, it converts it into electrical signals and sends it for demodulation.
Step 6: Filtering and Amplification
During the transmission process, audio signals often get mixed up with unwanted noise and interference. These unwanted properties affect audio clarity, so the radio must filter them.
The receiver can use an analog or digital signal processing technique to filter the electrical signal.
Such methods include bandpass filters and adaptive noise reduction algorithms. Both techniques remove frequencies that are unintelligible, including noise.
Once the filtering process ends, the audio signal goes to the amplifier. The role of the amplifier is to increase the signal’s amplitude. Doing so makes it easier for demodulation
Step 7: Demodulation
Demodulation reverses the modulation process that the transmitting radio uses to encode the audio signal. The demodulation technique usually depends on the modulation method.
For example, a message encoded with frequency modulation (FM) will be demodulated by an FM demodulation method, like F3E. The receiver detects the variations in the carrier wave’s frequency. It then converts the signal back into amplitude variations which represent the original audio signal.
Step 8: Audio Output
The output stage is the final step. Here, the radio sends the amplified signal to the speaker. The speaker then changes it back into sound waves that you can hear.
Like the microphone, the speaker is also a transducer. It converts electrical signals into sound waves through a process called electroacoustic transduction. So, it does the exact opposite of what microphones do. That is, it reverses the conversion process of the microphone.
Speakers are of different types, like dynamic, electrostatic, and piezoelectric speakers. But, most walkie-talkies use dynamic speakers because they are portable and durable. They also produce clear and loud audio. Hence, they are a perfect fit for the electret microphones mentioned earlier.
If you want to reply to a walkie-talkie transmission, press the PTT button. Then, the whole process will start again. Always remember to release the PTT button once you finish talking. Doing so will allow the other party to reply.
Walkie-talkies are two-way communication devices. And while they’ve undergone several transformations over the years, their essential components remain the same. They comprise an antenna, speaker, microphone, batteries, transmitter, and receiver. These components help in achieving the transmission and reception process.
When a sender presses the PTT (Push-to-talk) button, it creates sound waves. The sound waves go through several processes before finally reaching the receiver. Thus, users can communicate over several miles, usually over short ranges.