BT has come up with a technique which it claims can use more of the 99.99 per cent of optic-fibre capacity that is currently unused, and is applying the changes to its infrastructure backbone. As a result of work at its R&D labs at Martelsham Heath, BT reckons it can provide near- infinite bandwidth for its telecoms infrastructure by using three key advances: wave division multiplexing (WDM), optical switching and optical amplification. WDM is already used in the US, where the longer distances involved make laying new fibre more expensive. BT, which has been developing WDM for 15 years, has found too expensive to use. A current trial in East Anglia is using eight-channel WDM - as well as optical amplification, which enhances signal speed by not having the time delay of digital amplifiers which wastefully convert light to digital and return the signal to light. When combined with WDM, optical amplification has the advantage of being able to amplify all the channels at the same time, saving time and increasing available bandwidth. Optical switching increases the ease of network management as signals can be re-routed, and damaged or overloaded parts of the network can switch to low-traffic routes in real time.
Worldwide PC sales soar
Worldwide personal computer sales grew by 16 per cent over the first quarter, compared to 13 per cent year-on-year growth in the fourth quarter of 1996, according to International Data Corp. IDC attributes the growth to the arrival of new products on the market such as MMX-based and sub- $1,000 (pounds 650) desktop computers that spurred upgrades and attracted first- time buyers. The United States saw PC unit shipments increase by 20 per cent, the highest quarterly growth rate since 1995, making it the fastest growth of any major region. Compaq Computer Corp led the way yet again, followed by IBM and Dell Computer Corp, both in the United States and worldwide.