what is the concept of IR transmitters and receivers? - Electronic Circuits Projects Diagrams Free

crysrose · 18th January 2004, 08:52 AM

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 · 18th January 2004, 06:31 PM

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).

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18th January 2004, 08:52 AM	(permalink)
crysrose	what is the concept of IR transmitters and receivers? 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:

18th January 2004, 06:31 PM	(permalink)
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). __________________ Itay Reiss Electronics Engineer