what is the concept of IR transmitters and receivers?

[crysrose]

I will be using these sensors for a line-following mobile robot project so i want to know how IR really works. What are its characteristics especially those of an IR receiver. please help. thanks. :lol:

 

[Itay Reiss]

Concept of IR Transmitter and Receiver

The concept of IR Transmitter and Receiver is as follows:

Transmitter must have the following functions:

- Keyboard matrix scanning and anti-bouncing (when a key is striked).
- Modulation frequency used for immunity against environmental noises (fluroescent lights, sparks etc) usually this frequency is 38kHz or 40kHz.
The code of the striked key is modulated over this frequency.
- IR LED driver (usually a transistor).

The Transmitter is usually implemented by a uP if you can't implement it with a uP, you have to use CMOS technology devices and implement each block in a separate way. You can use a pair of decoder encoder in this case: The encoder will be in the transmitter side and the decoder in the receiver side a good choice will be the pair of HT12D AND HT12E .

Receiver

- Infrared Module like TSOP-1138 or equivalent.
- Pulse Shaper
- uP that will encode the information (or decoder).

Most important to pay attention to a low current consumption in STBY mode (when a key is not striked).