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General users share walkie-talkie channels, and this often leads to interference. Having other users interrupt your conversation can frustrate you. However, there are ways you can filter interference to prevent you from hearing other users.
Selective calling offers a solution to a significant problem of two-way radio users: interference.
While it doesn’t prevent interference, it reduces interruption from other users by blocking them out. Thus, you can enjoy smoother and easier conversations.
Selective calling, often referred to as a tone squelch system, is a method used to filter out unwanted signals and allow only designated devices to receive specific communications. It helps to reduce interruption and improve privacy by screening signals meanwhile muting unwanted audio.
For transmissions that don’t have the correct designated squelch code, the radio will not open its speaker, therefore allowing a group of users to communicate without interruption to other users. This technology is widely employed in walkie-talkies and two-way radios to enhance privacy and reduce interference.
Selective calling works by adding a squelch tone to a transmission.
For example, if a sender uses the radio with the squelch code set when transmitting signals, the voice radio signal will come with a squelch tone.
As recipients, when you activate selective calling on your walkie-talkie, it screens incoming transmission. If incoming voice data has the same squelch tone, your radio will unmute you so you can hear the message. But you won’t hear other users’ audio signals that don’t have the same squelch tone. Hence, only people using the same squelch tone can hear each other.
Note: Because you can’t hear others using the same channel doesn’t mean they are not there, the channel is still in use, and there is still interference. Also, other users that use the same tone and code, or users with their radio squelch forced to turn off, can still hear your conversation. Hence, selective calling doesn’t guarantee privacy because people can still eavesdrop on your conversation. For better privacy and security talking through analog radios, consider functions like scrambling.
Selective calling prevents users from hearing other users’ conversations. Because there are limited channels, interceptions are common, and this can be annoying. Luckily, the system helps to filter out other people using the same channel as you. Hence, you will only hear the transmissions meant for you.
By directing messages to a specific group of users, selective calling minimizes the number of disturbances on a channel, which reduces congestion and improves overall communication efficiency. This is especially helpful in crowded environments with multiple walkie-talkie users.
There will be a minimum interruption from other users. Hence, groups can talk well with selective calling. Teams can use different squelch tones to talk without disturbing each other. Thus, they can save time and communicate smoothly and efficiently.
Several selective calling systems make two-way radio communication more private. Some of them are proprietary products developed by walkie-talkie manufacturers for their products. But most walkie-talkie brands use two types:
CTCSS is an analog selective call system that imposes a continuous low-pitch tone (squelch) on a walkie-talkie. It has about 50 different tones. So, if you use one of them, only people with the same tone can communicate with you.
CTCSS is easy to use, but it is susceptible to falsing. Falsing happens when the walkie-talkie detects a false signal and unmutes you. Also, the chances of interference are higher with CTCSS because the squelch tones (50) are fewer. Hence, more users will use a particular tone, making interference more likely.
DCS or CDCSS (Continuous Digital-Coded Squelch System) is a digital selective calling system. DCS is a digital alternative to CTCSS that users can activate on their walkie-talkie to reduce interference.
There are 512 codes, but only 83 to 104 are available to users to prevent falsing. Once you activate the DCS code, your radio will remove the squelch (that is, unmute you) when it detects a voice signal with the same code.
Since DCS has more codes, there are lesser chances of interference. But, DCS may be incompatible with analog radios.
Selcall is a selective calling protocol that adds a quick burst of sequential audio tones to a voice signal. It sends up to 5 inbound tones sequentially when each transmission starts. Only receivers set to the same tone sequence will receive the message. Thus, if you use Selcall, your radio will only unmute you when it detects a voice signal with the same tone sequence.
Selcall is flexible because users can make their unique codes. They mainly use it in Europe, Australia, Asia, and New Zealand. As a result, it may not be compatible with some walkie-talkie brands.
You should use DCS or Selcall if you want fewer interruptions. CTCSS has lesser tones, so there are higher chances of interruptions. Hence, use systems with more tones or codes for smoother conversations. But, if you have basic needs, CTCSS may serve you well too.
Choose less congested channels if there are many walkie-talkie users in your area. (licensed channels are usually less congested). Also, use a selective calling system with more codes or tones, like DCS or Selcall.
You may meet challenges when setting up your selective calling system. Here are some solutions to try:
Hiking, camping, and hunting groups can use selective calling to secure their group conversation. It will help them communicate effectively without interruptions from other groups.
Event management teams and security staff can prevent interruptions from other groups in the hall. Hence, they can all communicate smoothly without interrupting each other’s conversation.
Emergency services and public safety can use selective calling systems to enhance communication quality. Hence, they can relay critical information without interruptions from others.
Selective calling helps construction and utility workers talk with their team members without interruptions. Hence, they can relay information accurately.
Selective calling adds a semi-audible tone to your transmission to screen unwanted conversations. It only turns off the squelch when the incoming voice message has the same code or tone. Hence, walkie-talkie users can communicate without interruptions from other users.
CTCSS, DCS, and other systems like SelCall are the most common types. Selective calling makes communication more smooth and more effective for teams, including recreational, event management, and construction groups.
