Simplex Versus Duplex Channel Systems

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When it comes to radio jargon, there is an awful lot of terminology to sift through.

What is a police police scanner? What’s a trunked radio? What does HAM radio do? If you’re researching all this for the first time, then it can sometimes seem like a daunting task.

The good news is that so long as you know what it is you want to achieve, you won’t have to worry about a lot of this stuff at first.

Knowing the difference between simplex and duplex for example is not required if you are planning on using a walkie talkie with a friend when out hiking. That said, if you plan on setting up a business two-way radio system, then you might benefit from understanding the distinction. Read on for elucidation.

Simplex Vs Duplex : The Basics

You are most likely to hear the word Simplex in the context of a simplex operation. This simply means that the radio stations are communicating with each other directly and on the same frequency.

So, for example, if you are using a hunting two-way radio in order to communicate with another hunter while you track dear and rabbits, then that is an example of a simplex operation. An easy way to remember it is that this is a ‘simple’ form of communication!

Now you may be wondering what the alternative to this is: seeing as the majority of operations that you might have witnessed or taken part in were probably simplex.

Well, the obvious alternative is duplex.

Duplex is easy to remember because ‘dup’ as a prefix normally denotes the number two. A duplex operation describes a communication where transmission is handled on one frequency, while being received on a different frequency.

More Types of Operation

There are also distinctions between different types of duplex operation however – just to keep things good and complicated!

For example, a ‘full duplex’ means that the system is capable of transmitting and receiving simultaneously. This means that you can hear what the other person is saying and be talking at the same time. This requires two different frequencies at least, and is something that a number of different applications might benefit from. This is something you might see from an emergency radio for example.

Half duplex on the other hand means that the radio uses a duplex operation but is not capable of doing both at the same time – instead needing to switch between the two.

In some cases, this might involve a repeater. The job of the repeater is to receive a signal that it hears on its receiver and then retransmit that on the transmitter frequency. These must therefore operate in full duplex mode in order to perform both these functions at once. Repeaters are referred to by their transmit frequency – the frequency that the user listens to.

Closing Thoughts

As mentioned, many radio applications won’t require an understanding of what terms like this mean. However, if you are a hobbyist who wants to understand all the information being picked up on the police scanner, or if you are setting up a radio system for an important event or business operation, then it can be useful to understand these differences.

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