mgrant@MIMSY.UMD.EDU.UUCP (01/28/87)
I just talked with several people at AT&T and a company called Visual Communications. I have determined that PicturePhone's are still alive, and could be in the home in 10 years or less. What we're waiting for is all the local phone companies to make available to it's residential customers the ISDN, (the Integrated Service Digital Network), aparently called PSDS, (Public Switched Digital Service). What is required between 2 points is a 56 kbps link. There is already a service called Switched-56 offered by AT&T which is somewhat reasonably priced, (some monthly + usage which is suposedly about twice what voice long distance runs--affordable). The klintcher is the equipment--at $75,000 a phone, not to many people are willing to jump into the water today. There are aparently several manufacturers. I spoke with some people at Visual Communications who sell equipment manufactured by Widcom, which is what AT&T uses. The phones use full color NTSC video. They digitize it at something like 80 megabits/sec which they compress *real time* down to 1.5 megabits/sec. I'm told there is some loss of quality in compression. What I want to know is how to they sqeeze 1.5 mbps over a 56 kbps line? As of today, anyone can walk out and buy one of these suckers and call people. AT&T will set you up and give you a special phone number. I guess either they have their own NPA-NXX, or several, one or more in each city they offer the service in. Video Communications is going to be having a demo soon, which I am going to try and attend. Does anyone know anything more? -Mike Grant
MYERSTON@SRI-KL.ARPA.UUCP (01/28/87)
Ref Michael Grant's submission on Picture Phones. It is my opinion that this service is 10 years away and will ALWAYS be 10 years away. TECHNOLOGY: All current narrow band (less than 6MHz) systems whether digital or analog provide MUCH less than NTSC quality full motion, full video. NTSC itself is not all that hot either. The Widcom system which send a color, semi-motion (fast movements blur badly) does work over 56 Kbps circuits wheter full time (DDS) or swiitched (Swictched 56). e entire bandwidth is dedicated to video, an additional connection is required for voice. Widcom has filed for Chapter 11 after being sued by Compression Labs (CLI) for patent infringment. AT&T is NOT marketing the product. CLI makes a 1.5 MHz video codec. ECONOMICS: Both DDS and Switched 56 are high dollar options. Switched 56 requires FULL TIME "tail" connections at both ends between the AT&T Class 4 switch and the customers location. ISDN will (some day) provide two 64Kbps channnels to the user but we are still talking reduced video unless some breakthrough in compression occurs or some laws of physics are revoked. CULTURE: Do you really want to see the folks you talk to?. Would you pay a premium to actually SEE the guy selling home insulation? I think it more likely that video-phones will remain a special application for conferences etc. Then again, Western Union thought that Bell was crazy. Who needs voice when the telegraph works so well? :-) ------- -------