How does the RT97 repeater operations principle?

How does the RT97 repeater operations principle?

In the last article we covered the fundamentals of RT97 repeater, This blog we will talk about the RT97 repeater operations.

In normal conditions, the communication of handhelds is simplex.

two-way radios are transmitting and receiving on the same frequency, When you are saying, the other one is listening. When the other radio is speaking, you are listening.

But if you if your signal travels through a repeater, The transceiver will be inverted.

You speaking will transmit to the repeater, The repeater is going to listen to your signal and retransmit it to the other hand-hold.

But there two problems:

  1. If two radios are transmitting on the same frequency at the same time they will interfere with each other and the listener won’t be able to understand what is being said.
  2. If they have the same frequency, How do you know if you’re on the repeater?

How to solve these problems?

First of all, We’re going to introduce the different frequency and the OFFSET and CTCSS/DCS.

We make the difference frequency between the sender and the receiver.

Then we just use the offset setting to Achieve the same frequency communication.

Finally, we make a CTCSS/DCS to make sure the call is private and not interrupted.


About the different frequency & Offset:

The sender and the repeater each have to transmit on a different frequency. The received and the repeater each have to transmit also on the different frequency.

Sender and receiver are the different frequency, but they work with the same one frequency on the repeater.


For example:

You will receive on the repeater’s transmit frequency is 462.62500MHZ, and you will transmit on the repeater’s receive frequency is 462.02500MHZ,

The difference in frequency between the sender and the repeater is the SHIFT, we also called it or offset.

The shift(offset) have two situations:

  1. If you are transmitting at a lower frequency than you receive (-), it is called the down offset.
  2. If you are transmitting at a higher frequency than you receive (+), It is called the up offset.


The amount of repeater shift and direction of repeater shift is a voluntary standard in the United States, so We can customize the brand and frequency offset according to customer requirements.

Here’s a true story, One of our customers said, his 2 walkie talkie can talk with each other before they use the repeater.

After programming them, they use the repeater, communication as well.

But we when they turn off the repeater, they find their walkie talkie can’t talk with each other, why?

He contacts with us and said the walkie talkie is broken, But is this really the case ? of course not.

Before you use the repeater, you need to change your walkie talkie, make sure they have a different frequency,

but if you just use your walkie talkie not Not through the repeater, you need to reprogram your radio, make sure they have the same frequency.


Details information about the customization, you can check on RT97 products page:


Finally, let us know how to set the Private conversation.

We need to know about the CTCSS/DCS(Continuous Tone-CodedSquelch System).

CTCSS/DCS is a bunch of encrypted symbols, they also are called PL(Private Line) tones,

They are sub-audible tones used to prevent the Repeater from responding to signals that are not meant to be repeated. RT97 certainly have this function.

It has the commonly CTCSS TONE, you can choose in software, it also has some DCS, you can find in software:

This is all the RT97 repeater operations principle. If you have any Suggestions and views, welcome to leave a message in the comments section.

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