real world columns: infra-red

I used to baby sit for a family that had one of the latest models of television, it was in color (this is going back a bit) and it had a remote control. This was a very early remote and it communicated with the television using bursts of high-frequency sound, the protocol was very simple and supported only very simple actions like click once to switch to the next channel and click twice to adjust the volume.

These days, short-range communication between gadgets is carried out with wireless networks and wireless Bluetooth communication.

In between the two there was a long period where infra-red light was used as the communication medium. It was easy to produce, easy to detect and wasn’t perceivable by humans and so it wouldn’t distract anybody when in use. In fact sometimes it was so imperceptible that people didn’t even know it was there. Commuting on a train once my table was shared by two people – colleagues of each other – who immediately whipped out their laptops and started ticking away. ‘Oh!’, Said one of them, ‘I’ve got a strange folder on my desktop.’ ‘That’s strange’, said the other, ‘so have I’. Clicking away at their respective new folders eventually led to the realization that their two laptops, back to back with one another, had struck up a communication via their infra-red ports with the result that they both now had shared folders on the desktop. The imperceptible nature of infra-red light coupled with its remote nature meant that as it became more widespread there were more opportunities to abuse it. You didn’t have to be physically connected to communicate, as exemplified by the rather antisocial behavior of a young, newspaper-delivery boy who did his paper round with his remote control device in his pocket. After delivering the newspaper he would peep in to the lounge window and if the TV was visible he would try zapping it with his remote control, turn it on, fish about for a channel and turn the volume up full. Victims would never realize what had happened and would probably put it down to a strange technical glitch with the TV, as the idea that someone can interfere with your property without actually having physical access to your space is quite alien.

Even the car manufacturers got into the act and built infra-red communications into the key fobs so that you could turn the car’s alarm on and off and even lock and unlock the car as you walked away or approached your vehicle. A system that was very easy to use and thanks to the encryption used in the signal a secure solution as well. At about the same time electronics manufacturers started producing universal infra-red remote controls. A nifty idea, the device would detect infra-red signals and store them so that you could play them back when you wanted to. In effect you could use them to record the infra-red codes from all your remote controls and then have just one remote for everything. Very nice indeed.

Mix the two previous devices together and you had the perfect scam for stealing cars; someone parks a nice car outside the theater and you sidle up to them with your universal, infra-red remote control. When they zap the car with the encoded signal to operate the alarm, you record the signal, wait till they have gone then replay the signal to switch the alarm off, open the car and away you go.

The message is that whatever communication medium is used it will have its own unique properties which can lead to serendipitous advantages or sinister disadvantages as different devices are developed that utilize the medium. The only real solution is good encryption of the data being communicated.

Strangely enough, even the old ultrasound, remote control had unique advantages that compensated for the simplicity of the communication. The main one was that the high-pitched sound used by the device was very similar to the high-pitched sound used by bats when they are hunting for food. If you were sat watching some boring program on television and there was a moth in the room you could use the remote to zap the moth with bursts of high pitch sound. The poor moth would think it was being targeted by an incoming bat and would immediately take evasive maneuvers. Television was never this much fun!