Nippon Telegraph and Telephone Corp (NTT) and NTT Electronics Corp announced that they commercialized RedTacton, a human body communication technology utilizing the human body surface as a transmission path.
Based on the technology, the companies developed "Firmo," an authentication system for admission/exit management. They started selling samples of the Firmo evaluation kit on April 23, 2008. The kit comes with one embeddable receiver, five card-type transmitters and a touch plate for the receiver at a price of ¥800,000 (US$7,722, price may vary depending on country).
NTT's latest human body communication technology utilizes a capacitive coupling method. The method is designed to transmit information based on the variation in potential on the human body surface, not by applying current through the body. The method is advantageous in that information can be transmitted in the presence of not just human bodies but also insulators such as clothes and rubber soles.
The Firmo system is composed of a 7mm card-type ID transmitter and a receiver with sensor electrodes. The transmitter repeatedly transmits the ID number recorded in the card at a transfer rate of approximately 230kbps.
For example, when the user stands at the door of a room he wants to enter with a transmitter in the pocket of a shirt or in some other place, the ID number information will be sent from the shirt through the body or the soles of the feet to the sensor electrodes in a receiver embedded in the door or placed on the floor in front of the door. In this way, the system is able to authenticate the ID.
No touch operation, yet safer than other systems
Various kinds of admission/exit authentication systems have been developed so far. Some of them use a contactless IC card such as SUICA and ICOCA, while others use the short-range wireless communication like the automotive keyless entry. Systems based on a contactless IC card, however, require users to touch the dedicated authentication reader with the card.
"We've heard many users say that having to touch the reader is troublesome," NTT said.
With the Firmo system, authentication is carried out just by standing at the receiver-installed door or by holding the door knob when the transmitter is in a pocket or elsewhere.
The short-range wireless communication involves concerns about security because it may allow unauthenticated people to open the door even when the authentic ID holder is several to several tens of meters away from the door.
In contrast, the Firmo system ensures a higher security because the signal range is limited to "several millimeters to several centimeters from the surface of the human body or clothes," NTT said. The name "Firmo" comes from the idea that the range of the signal surrounds the body.
"'Firmo' means 'fairy motion,' which is the idea that the motion resembles that of a fairy," NTT said.
Transmission on the HF band
The card-type ID transmitter runs on a battery with a life of about 1 year. It reportedly uses a commercial battery, which can be replaced by users. The system uses a 5MH carrier wave in communications. This is equivalent to the high frequency band used by ham radio.
"We are sure that the system will not interfere with ham radio because the system's output is 20dB lower than the regulation on extremely low power radio waves," NTT said. "In addition, we improved the electrode structure to prevent the waves from being emitted."