Peter Cochrane BT Laboratories Martlesham Heath, Ipswich
In contrast to our recent past we now have an abundance of bandwidth with optical fibre, information processing and storage power, and the promise of increasingly higher levels of circuit density and clock speed at costs that are becoming truly insignificant. We are thus approaching the realisation of a dream - to access everything everywhere within 3 clicks (of the mouse button - not hyper space) and have all material appearing on the screen within a second. For real-time, interactive communication, the dream is for realism to ear, eye and touch by making delays much less than 100 milliseconds. Why should we foster such a dream? The principal reasons are twofold: firstly, delay limits human creativity and output, and secondly, it can be done. Trying to interact with anything at less than natural human speed soon becomes counter productive and extremely irritating. For anyone who has tried to communicate using a telephone operating on a circuit over a geo-stationery satellite, which introduces over 300 milliseconds of delay, it is obvious. Soon the combination of a digital mobile telephone, with an internal 120 millisecond coding and decoding delay, and networks with concatenated ATM switches adding undefined transmission delays of random duration, will add new, non-linear dimensions to the problem, and take us away from realising our dream.
For anyone trying to communicate effectively over a modern video conferencing circuit, where the Codec and signal path can introduce delays in excess of 500 millisecond in the visual image, with a different delay in the speech circuit- it is even more obvious. Even with a high degree of practice and familiarity such circuits are a far from realistic replication of true human presence and communication. You just cannot communicate and work effectively with such long and variable delays.
In the not too distant future our ability to transmit sight and sound will beaugmented by an ability to transmit touch. It is interesting to note that sticking a pin into the end of our finger results in a message arriving at the brain some 30 milliseconds later. This approximates well to the 30 millisecond period for sound discrimination of the human ear and the movement of objects by the eye. So in a telepresence future a surgeon may wish toreach out and touch a patient in the operating theatre in New York whilst actually being in London. The effective distance between the brain and finger tips will then have doubled from the present 25 to 50cm. Furthermore, without the synchronisation of sight, sound and touch it will be impossible to interact with these three senses in any co-ordinated way.
The only prospect of realising this dream relies on optical fibre to provided a true super information highway with minimal electronic delays, bottlenecks, and processing and bandwidth restrictions. It also requires a new attitude to software, and the processing and storage of information. All the technology is available now: all we have to do is implement the solution. In the meantime, we will continue to be frustrated by international telephone calls, the automatic bank teller, the internet, and PC applications that waste increasing Mbits of RAM to just make the front end prettier rather than more effective.