Engineers demonstrate how heat can transmit data

Researchers from Imperial College London have created a low-cost, wireless communications technology that exploits black-body radiation in the infrared heat spectrum, which is currently used for thermal imaging. This part of the spectral range is currently underused, offering opportunities for the development of a new type of ''niche'' communications.

The prototype technology that uses bursts of heat to transmit information over short distances has been developed by a team of engineers.

The team behind the technology believe it could provide a new form of secure communication that could be concealed in background noise, making it harder to intercept or jam using conventional technology.

Wireless ship-to-ship communication was introduced by the Royal British Navy in 1867, which saw sailors using oil lamps to transmit signals using heat at the visual part of the spectrum.

Today, NATO forces still use signal lamps, which emit heat at the near-infrared part of the spectrum, when radio communications has to be silent. However, these communications need to occur at night for them to be effective, and users employ infrared telescopes to receive information.

The prototype technology being developed by the team is the first to have potential civilian applications. It currently consists of a transmitter with miniature incandescent light bulbs that emit bursts of heat in patterns that encode information.

This data is picked up by a receiver that filters out external interference to detect the information in the thermal infrared spectrum as it is transmitted and is then decoded by a silicon chip.

So far the team has shown that it can transmit information over 17 centimetres, but the ultimate aim is for it to be used over distances up to 10 metres.

The researchers believe that their prototype device could improve technologies such as wireless door entry systems so that information can be sent more securely to other devices in the future.

Dr Stepan Lucyszyn, inventor from the Department of Electrical and Electronic Engineering at Imperial, says, ''Code grabbing is a major problem for wireless door entry systems. For example, thieves are currently able to intercept information wirelessly transmitted from your key fob to your car's door entry system, which they can then use later on to break into your car when it is left unattended. One potential application for our technology could see the development of a new type of key fob for cars that transmits data via bursts of infrared heat, which would be much harder to intercept by crooks.''

The Imperial team has so far demonstrated that they can partition infrared heat into four frequency channels to transmit information. Currently, the team can transmit data at the rate of 4000 bits per second, which enables voice and data communications to be sent. They are now working on a 16-channel system and the team expect to increase this rate significantly with the addition of more channels.

The next step will see the researchers upgrading the hardware so that it can transmit information at faster speeds over longer distances. Following that the team plan to integrate the technology into one complete system, which will be miniaturised into handheld applications like smart phones or door entry smart key fobs.