What is a transponder? The principle of operation and scope

Often when installing and setting up satellite television, people come across confusing terms. This happens when you first try to tune the antenna or tuner, for example. And if incomprehensible words appear in the instructions, then they must be interpreted. Often users do not know what a transponder is. Let's get it right.

transponder what is

What is a transponder?

This is a device that transmits a signal in response to a received signal. A transponder can receive a signal at one frequency and transmit it to another, amplify it. It is also able to create a response signal when the request is received correctly, etc. Often it is used to transmit a predetermined message in the event of a specific signal.

Scope of application

Given the possibilities, the scope of use of the device is very extensive. It should be noted right away that these devices are used not only in the field of satellite television, as many mistakenly believe. Yes, thanks to the TV transponder, satellite channels are formed, and the device itself plays the role of a repeater or transceiver.

The device can be used for digital compression, when several different digital streams are transmitted through transponders of channels at the same frequency. They are very actively used in aviation, including in the military. The famous friend-or-foe system is based on the use of a transponder. Also, its role is great in recognizing signals on the radar. Some models can transmit information about altitude, airspeed, and a special transponder code.

channel transponders

But even this is not limited to the scope. The device allows you to search for skiers littered with snow. There are even special devices for finding keys in the house (in this case, the transponder will give a signal to a specific whistle of the user, for example). On ships, sonar transponders are used that measure distances to objects.

Transponders in Aviation

And although it has already been said above that this device is used in aviation, this area of โ€‹โ€‹application deserves special attention. It is in aviation that the role of this device is really great, therefore, when answering the question of what a transponder is, we should first talk about aviation, and only then about satellite communications.

The transponder, which is always on board a civil aircraft, allows the air traffic controller on the ground to identify this aircraft. The dispatching service locator sends a signal, the transponder receives it and sends a special four-digit code in response. So the dispatcher will see the position of the vessel and a special code on the monitor screen. These codes may be different, they show the situation on board.

tv transponder

For example, code 7500 means hijacking, code 7700 indicates an accident on board, code 7600 means loss of communication. These are special codes upon receipt of which an alert is automatically activated in the dispatch service. Of course, this is a very rough description of the principle of operation of a transponder in aviation. In fact, the system is quite complex, but accurate. But in general, the work scheme looks exactly like that.


There are a lot of applications for this device. They are even impossible to list all. But the main thing is that now you understand what a transponder is and how it works. The most important thing is to understand how it works. The device in response to the received signal sends another signal. This simple principle is the extremely complex system of aviation communications and object recognition. The device allows you to establish communication of the satellite dish directly with the satellite itself, with its help the car keychain responds to the user's whistle, etc. You can continue to give examples of the use of this device for an infinitely long time.

Source: https://habr.com/ru/post/A1229/

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