Digital system ends phone calls with echo

A UK-developed digital processing system aims to improve the quality of phone calls by reducing echo and other distortion on advanced communications networks. London-based Tecteon claimed its newly developed system offers the prospect of ‘cleaner’ voice communications across the world’s data transmission technologies.

Telecoms have become increasingly plagued by echo, which occurs when a section of the energy used to carry a speech signal is reflected back to its sender. Echo is most common when a call leaves public transmission networks to begin the ‘last mile’ of its journey on a much lower-capacity local subscriber line.

When access to telephone networks was controlled by national monopoly operators they could place echo filtering hardware at strategic points to deal with the problem. However, with networks now almost completely deregulated and signals able to enter and leave them at any point, there is a growing risk of echo cancellation hardware being bypassed altogether.

Once the echo problem was confined to international satellite calls, which regularly had a hollow ring to them. But a voice signal could soon have to travel from a microphone connected by a Bluetooth link to a mobile phone operating on a 3G network and on to a recipient using a traditional telephone landline.

According to Tecteon, its echo cancellation technology – which has just undergone final testing before commercialisation – is the first to ‘hunt’ for echoes in a signal and automatically process them out, even if the problem is on a different network to the one on which it is deployed.

Currently, most echo cancellers are deployed in hardware as special equipment, or are developed in-house for specific devices. Most are provided on physically separate hardware devices. Tecteon, on the other hand, has opted for a hardware-independent software solution.

Tecteon claimed chips running its DSP software could be cost-effectively built into switches across the network, removing the need for traditional ‘black box’ filters.

It eventually hopes to place its technology in phone handsets, negating echo and other distortions at source.

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