Additional features of twisted-pair HDMI extenders: Transmitting the infrared signal

When purchasing a twisted-pair HDMI extender, it is useful to check if it has any additional functions. One of them is the ability to transmit the IR signal. In this article, i will look at the types of IR transmission, and explain what they are needed for and how they are implemented.

Let's look at an example of two extenders: Lenkeng LKV372AE-4.0 and Lenkeng LKV676E (twisted-pair HDMI extenders up to 230 feet)

IR signal pass-back

The Lenkeng LKV372AE-4.0 is a simple twisted-pair HDMI extender that has the additional function of sending the IR signal back. This means that i send an HDMI signal from the transmitter to the receiver (i.e. from the TV tuner to the TV) and i can send an IR signal back (i.e. from the TV to the tuner).

In other words, if your TV tuner is in the living room and you want to watch TV in the bedroom, you need to lay a twisted pair from the tuner to the TV in the bedroom. Then connect an HDMI transmitter to the tuner and a receiver to the TV, as in the diagram above.

Now i need to ensure a comfortable switching of the TV tuner channels. To do this, i additionally connect the IR blaster (included with the extension cord) to the HDMI transmitter and attach it to the TV tuner with the included double-sided adhesive tape. Connect the IR receiver (also included in the package) to the HDMI receiver, and attach it with double-sided tape in a convenient place where i will direct the IR remote control. Usually, this is the frame of your TV set.

Now the video signal will be transmitted over twisted pair from the tuner to the TV, and the IR signal will go back from the TV to the tuner.

And this is the principle of IR signal pass-back.

Bi-directional IR signal transmission

Bi-directional IR transmission can be explained in the example of the Lenkeng LKV676E twisted-pair HDMI extender.

On the body of the transmitter and receiver, you can see two ports to connect the IR: In and Out. Depending on the task i have to use the right input.

If i have already solved the first problem (the IR signal pass-back), then why should i transmit the IR signal from a transmitter to a receiver?

This is more used in commercial applications, e.g. the TV is in the lounge in the cafe, and the TV set is somewhere at the bartender's workplace. The bartender wants to turn off the TV, or switch the input source without going close to the TV set. So with the feature, i kind of extending the IR remote control signal of the TV over a long distance.

In this way, i get a more versatile transmission of the IR signal in both directions. This does not mean that you have to buy a device with a bi-directional IR signal function. Just think if this scenario is required or not.

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