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How Do Remote Controls Work?

Remote control car key.
Remote control for a toy airplane.
Most entertainment devices utilize IR remote controls, which use pulses of infrared light to communicate with an object.
Batteries for a remote control.
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  • Written By: R. Kayne
  • Edited By: O. Wallace
  • Last Modified Date: 26 August 2014
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Generally, there are two types of remote controls: infrared (IR), and radio frequency (RF). Infrared remote controls work by sending pulses of infrared light to a device, while RF remote controls use radio waves in much the same way. Pragmatically, the biggest difference between the two is range. IR remote controls require a clear line of sight to the receiving device and their range maxes out at about 30 feet (9.14 meters). RF remote controls can go through walls and around corners, with a range of roughly 100 feet (30.48 meters).

Most home entertainment components such as stereos, televisions and home entertainment centers use IR remote controls. The remote contains an internal circuit board, processor, and one or two Light Emitting Diodes (LEDs).

When you push a button on a remote control, it transmits a corresponding code to the receiving device by way of LED infrared pulses. The idea is somewhat akin to flashing an SOS signal, but instead of letters, the flashing LED light is transmitting a series of 1s and 0s. The “1” might be represented by a long flash, while “0,” a short flash. A receiver, built into the component, receives the pulses of light and a processor decodes the flashes into the digital bits required to activate the function.

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Along with the desired function, remote controls must also piggyback other data. Firstly, they transmit the code for the device they are controlling. This lets the IR receiver in the component know that the IR signals it is picking up are intended for it. It essentially tells the component to start listening. The function data follows, capped by a stop command to tell the IR device go back into passive mode.

Some remote controls can be very finicky, requiring the user point the remote directly at the component. This is due to a weak transmitter. Changing the batteries can help, but if the transmitter itself is poor, pulses are transmitted in a narrow beam. More robust IR transmitters, and remote controls with double LEDs, transmit broader beams that allow the user to point the remote in the general direction of the transmitter.

Sometimes it happens that a recliner or favorite spot on the couch does not have a clear line-of-sight to the entertainment center or television. Often a coffee table or some other object is in the way. When this happens we find ourselves raising an arm, trying to control the object “around” the device. This can get quite annoying, but there’s an easy alternative.

Since light bounces off objects it is sometimes more convenient to point remote controls towards a flanking wall or even the ceiling to change a channel or send a function command. The light will bounce off the surface of the wall or ceiling and scatter. If you bounce it at an advantageous angle, the scattering light will reach the component. Often it’s easiest, with elbow resting on an armrest, to flip your wrist back and point the remote up at a wall behind you. This can work quite well, even though the remote is pointing in the exact opposite direction of the component. Once you find the easiest sweet spots around the room from which to bounce your signal, you can use these instead of struggling with trying to get around your obstructed line of sight.

Garage door openers, alarm systems, key fobs and radio-controlled toys use RF remote controls. RF remote controls work essentially the same as IR remote controls, except they use radio waves. As stated, radio waves can also penetrate walls and go around objects and corners, making RF arguably more convenient than IR.

Some high-end entertainment systems come with RF remote controls for expanded remote range. There are also IR-to-RF remote control converters that allow IR remote controls to extend their range through utilizing a RF translator that basically acts as a middleman. The RF converter relays the IR signal in RF waves to get it further. The converter on the component side reverts the RF signal back to IR so the component can understand it.

If you have been overrun by remote controls, you might consider a master universal controller. Low-end universal remotes, available for about 10 US dollars (USD), will allow one to control several devices. However, original remotes might still be required for accessing and controlling advanced component features. Some high-end universal remote controls feature LCD screens and are more like electronic pads than common remote controls. These universal master controllers will eliminate the need to use original remotes, but may require some ramp-up to learn.

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Discuss this Article

anon963289
Post 17

Toy car remotes typically operate in the 27 Mhz range (the same area as CB radios.

anon931965
Post 15

I am having problems with my TV. I don't have a remote and the remote I bought does not have an option with a Soniq Qasa (model no: QSL420T/3) or a Soniq in general for that matter. This TV has also been discontinued for two years. Is it possible to override a code with a universal remote? Can anyone tell me how?

anon354366
Post 13

Will someone tell me which AM or FM radio station can be used to see if a signal is being transmitted by a radio controller for a toy car? I used to know this but cannot find it online.

anon336049
Post 12

How does a remote work even if I point it anywhere inside the room?

anon119777
Post 8

usually we transmit the signals with carrier waves... in AM the signals are send with carrier waves and the code is differentiated by varying the amplitude. In FM variations in frequency (no of waves per second).

anon81197
Post 7

but how does the processor decode the flashes when it is off as it will need energy to do so?

anon72983
Post 6

@gadgetmen: Neither amplitude modulated radio (AM radio) or frequency modulated radio (FM radio) will work if you are trying to see if a toy car is RF controlled or IR.

If this worked at all it would be FM but FM radio only has a range of 88.1-107.9. above 108 is NASA communications, and below 88.1 are television channels; channel 6, is right below 88.

The easiest way to determine if your remote is IR or RF is to look at the remote and the receiver. on the receiver it looks for an LED that doesn't light up (just a diode) and it will say IR sensor next to it. if you look on the remote there should be an LED labeled transmitter. if you can't find either of those your device is most likely RF controlled. -SK

anon47581
Post 5

I have a FTA receiver "nfusion Phoenix Nuveno" and the control that came with it worked for a couple of days. Now it doesn't do anything with the receiver but it changes the channels on other components. How do I program this remote so that it can work with the receiver, is there a way to do this or do I need to purchase a new receiver with its control again.

anon39191
Post 4

Can I remove the annoying blue LED light in my AV sender or will the remote extender stop working if I do?

gadgetmen
Post 3

using 49mhz controller & on a specific radio station every time I would move the joystick you could hear a high pitch sound to let me know that my transmitter is working.

gadgetmen
Post 2

Will someone tell me which am or fm radio station can be used to see if signal is being transmitted by radio controller for toy car. I used to know this but can not find it online. thanks

anon8907
Post 1

What are the different modulations used to send the signal (Frequency modulation, AM,....?) please with explanation

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