I have looked at many youtube video on IR led with arduino. I am looking into making arduino to arduino communication using RF or Bluethoot with the intent of transmitting IR information. I have an HDMI splitter allowing me to have a second TV in another room however cannot fully remote control my entertainment system from the other room. I have bought a cheap IR repeater from ebay and can control my Panasonic receiver volume but cannot control my Bell ExpressVU satellite receiver. I think it is because my IR repeater is using 38Khz while my SAT receiver uses 57Khz. Is the IR receiver/transmitter LED used in arduino projects irrelevant in regards to frequencies?
IR LEDs (transmitter) don't care about the frequency, in the range of frequencies used for IR remotes. Receiver/decoders do care. A 38KHz receiver/decoder will not work at 57KHz.
The repeater receives commands from some control, then sends the same commands to some other device.
An IR receiver is a hardware module, with a fixed carrier frequency. If you need more frequencies, e.g. 57kHz, then you need such a receiver module. If you can get such a module, you can build your own repeater from it and an Arduino, and the IRremote library.
opale7000:
Newbie in regards to Infrared Red. When you say "IR receiver" is the an IR led?
No. A LED makes/emits/transmits light. It just emits light at the frequency you pulse it with.
An IR receiver is a combination of an IR photo diode and amplifier/detector. They have three pins.
the TSOPxxxx family is common. The last two digits is the (fixed) center frequency of the receiver.
Leo..
Sorry I understand the principle between transmitter and receivers. I have looked at many videos about receiving and sending IR data with an arduino. However there is never mention about 38K versus 57K frequencies. It appears that IR led used in receivers/transmitters, the IR led itself is frequency unaware.
Regardless of frequency, the IR led can support both 38K and 57K, I think. This is what I am trying to find out.
Second, I need to know which arduino library can be dual band. Fir example this Product is dual band. Wondering if I can with arduino create a dual band IR receiver transmitter.
The IR LED transmitter can be used at either frequency. Arduino libraries generally support 38 kHz transmit, but it shouldn't be a big deal to modify one to support a different carrier frequency.
MrMark:
The IR LED transmitter can be used at either frequency. Arduino libraries generally support 38 kHz transmit, but it shouldn't be a big deal to modify one to support a different carrier frequency.
I think I am beginning to understand the confusion I was having. Please correct me if I am wrong. There is a difference between a IR LED such as a 940nm IR Infrared Diode measured in nano meters versus a IR receiver which is a complete circuit working at either 38Khz or 57Khz
So 940nm led "carrier" frequency is about 300 thousands gigahertz.
the 38 or 57 kilohertz frequencies are used to modulate it in order to make the receiver to distinguish the IR signal from ambient infrared "noise".
The receiver modules have internal circuitry tuned to one of these preset khz frequencies. Such circuitry is quite difficult to implement with just an arduino and a IR photo diode/transistor.
So a receiver made to receive signals at 38 khz can not see signal from a remote control that modulates its led with 57khz.
Although sending signals in both frequencies, with just an arduino and an IR led is easy.
So your problem isn't that (in the room where is the controlled equipment) you can't generate either 38 or 57khz IR led signals with an arduino, but when you want to make an IR extender you need in the other room ( where you are with the remote controls) to have two IR receivers - one for each carrier frequency.
That is right. The LED is just an emitter of, unmodulated. IR light. To make it work with an IR remote you need a circuit to modulate a carrier* at 38KHz or 40KHz or 56KHz with the remote code. The IR receiver has the circuit built in to receive the IR light and strip the IR codes off of the carrier frequency. The receivers are "tuned" to a particular carrier frequency (very narrow range around the carrier center frequency).
OK I think I am beginning to understand IR a bit better.
Just to make things more clear I will call room B (The room with the equipment to be controlled )
Room A, the room where there will be an arduino 38Khz IR transmitter
Room B there will be an arduino repeater unit with an 38Khz IR receiver that can receive the IR signal (line of sight) from Room A receiving at 38Khz and rebroadcast via 2 IR transmitter, 1 sending at 38Khz and another sending at 57Khz to control the equipment.
Receiver is frequency dependent. Receivers have internal modulation decoders. There is a "38KHz receiver".
Transmitting LEDs are not frequency dependent. There is no such thing as a "38KHz transmitter LED".
There's no need for 2 transmitter LEDs to be dedicated to each frequency. That's just wasteful and you're missing out on possible distance gain.
