One fiber does it all


A short note, as I've been busy with a number of things including trying out PC based HDTV recording and mythtv, which I will write about shortly.

In a VoIP pricing debate, I calculated an interesting observation. Today we have voice codecs that can do very fine voice quality in about 25 kilobits. FM radio quality. Cell phone quality can be done in 7 kilobits. Anyway, that means all 200 million adult Americans could be on the phone at once and it would use 5 terabits.

Using DWDM -- dense wave division multiplexing -- where many colours of photon co-exist in an optical fiber, 5 terabits is now well within the range of a single optical fiber.

So yes, everybody could be on the phone at once, in FM quality, with just one optical fiber. Of course one fiber doesn't pass by every town, and multiplexing it all together costs money too and has overhead. But it should be clear just how silly the idea of per minute charges for voice are in the face of this statistic. And indeed they are going away.

Of course we are finding uses for more bandwidth. HDTV file transfers for example (which use 16 megabits but can be credibly done in about 6 with better codecs.) But how long before we can all have an HDTV videophone call at once over a moderate number of fibers?

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