October 19, 2021

I, Science

The science magazine of Imperial College

Lizzie Norris explains new how data can be encoded in heat, and why that's useful

spectrum jason morrison 3472644050_71a99604fe_oImperial College researchers have developed a prototype technology which uses heat to transmit information over short distances. Data sent in this way has the potential to be more secure, as it is much harder to intercept compared with radio transmission, which is currently used in many wireless technologies such as car keys.

The use of a type of radiation in the infrared spectrum (blackbody) as a tool for communication has a long history of use in naval applications and is still in use today. The technology developed by the group at Imperial is the first of its kind to have potential civilian applications. The prototype works by transmitting encoded information via a tiny incandescent light bulb which emits bursts of heat which are picked up by a receiver. The receiver detects the information in the thermal spectrum and is designed to filter out external interference. The relevant information is then decoded by a silicon chip.

Thievery of codes is a major problem of wireless door entry systems. Thieves are able to intercept wirelessly transmitted information which they then can use to break into cars and buildings. This technology makes it harder for thieves to intercept as the signal can be concealed in background noise. The system is very robust to interference and jamming as signals can only get confused if they are operating in the same spectral range, in direct line of sight and when the signalling frequency is the same. The team have demonstrated that they can transmit information over 17cm and can transmit data at the rate of 4,000 bits per second, enabling voice and data communications to be sent. The team can partition the infrared heat into four frequency channels to transmit information and a 16 channel system is now in development. There are high hopes to increase the number of channels significantly in the future. The next step in the technology will include upgrades to the hardware so information can be transmitted at faster speeds over longer distances.

Lizzie Norris is a first year PhD student studying Advanced Materials Characterisation

Image: Spectrum of an incandescent light bulb by Jason Morrison