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Technology Stocks : Voice-on-the-net (VON), VoIP, Internet (IP) Telephony -- Ignore unavailable to you. Want to Upgrade?

To: Frank A. Coluccio who wrote (839)	6/25/1998 12:21:00 PM
From: Ray Jensen	Respond to of 3178

>>We've come full circle here in reinventing the use of analog modem techniques to deliver higher speeds of "digital payloads" over what can only be termed, by any definition,analog technologies. It's going to remain that way for quite some time, unless they un-do the HFC work that has already been done, and unless the price points for digital conversion processes in the outside plant can come down significantly to justify a true digital architecture.<< Yes, Frank, a hybrid fiber coax (HFC) cable system essentially functions like a souped up version of a data modem (modulator / demodulator) in order to send digital signals over a amplitude modulated radio frequency cable system. Baseband digital signals are usually modulated with a version of a QAM (quadrature amplitide modulation) modem for video services, or a QPSK (quatranary phase shift keying) modem for voice or data services. After all the digital signals from dozens or hundreds of sources are modulated into different radio frequencies, they are electrically combined at the cable tv headend so they can be transmitted onto a single piece of coaxial cable. With all the signals combined, they are then able to be routed to a distributed feedback type of optical transmitter, specially designed for amplitude modulated signals over fiber. All of the amplitude modulated signals are transmitted over a radio frequency based HFC network until they reach a set top box at the customer location, where they are demodulated and restored to baseband digital signals. HFC is a wonderful and fairly straightforward way to transmit a big load of information onto a radio frequency network, and I like HFC for many reasons. Its just that the coaxial distribution part of the HFC network better be built very, very tight and designed very well, or the transmission quality of the lower and upper band frequencies (i.e., where the voice and data services usually ride up and downstream!) will be lousy. In summary, HFC differs significantly from a time division multiplexed digital transmission system, where the baseband digital signals are not modulated and demodulated. HFC will be a big part of the cable world for several decades at least... Ray.

To: Frank A. Coluccio who wrote (839)	6/25/1998 5:31:00 PM
From: Daniel G. DeBusschere	Read Replies (2) \| Respond to of 3178

You are right - the data transmission on coax is analog- However, the point I am trying to make is that pricing on circuit switched networks is usually based on as DS-0 equivalent. Because a DS-0 equivalent (i.e. 64kbps) is only 1/100th of the data rate needed for video, then video transport becomes expensive if pricing is based on the DS-0 equivalent circuit price. If they are both carried on the same transport, switched by the same routers (Not TDM circuit switch) then how is voice going to be priced and how is video going to be priced? Sprint says that it will be priced by the bit transported or the data packet transported (somewhat like X.25). Either voice calls are going to be dirt cheap or video calls are going to be very expensive. Carriers that have big voice revenues must be worried about how they recover from the apparent big decrease in what used to be DS-0 equivalent voice calls. I mean equivalent cost per bit will have to be reduced by 95+ percent if video and other high band width consumer and e-business applications are affordable. Right??