anthony@uqcspe.cs.uq.oz (Anthony Lee) (02/03/89)
I been reading the October 1988 issue of Electronics (A VNU Business public- ation). The October issue is a special issue on the technology outlook. There was a section on ISDN "... As a result, areas of ISDN services served only by ISDN switches will pre- dominate through the mid-1990s at least. In the meantime, complementary technologies are taking a crack at delivering ISDN like services over the installed central-office switching systems that were primarily envisioned for voice and low speed data. Not supprisingly, these data-over-voice technologies depend on multiplexing signals and must be face the difficult trade-off between attaining a useful local-loop transmission distance and the level of interference between voice and and data channels. A breakthrough is likely next year with Integrated Network Corps....system, which delivers 19.2Kbits/s of encoded digital data capacity with simultaneous voice over dial up lines." Question is how are they going to achieve this on dial up lines ? (Should I throw out my modem now ?) The article goes on " Instead of using frequency-key-shifting techniques, the Bridgewater , N.J. company's patented algorithm reduces energy in the voice frequency band by using partial response alternate-mark-in version sinusoidal coding techniques ... minimizing energy overlap between the 4KHz voice and remainder 56KHz baseband for data...interference-free over a 18000ft local loop - compared to the 6000ft max of data over voice technologies." Frequency-key-shifting ? Is that what is currently used by modems ? What is alternate-mark-in coding technique ? Why do they talk about 4KHz voice and 56KHz baseband for data when current local loop is really 4KHz voice ? Is data-over-voice meaning modem technologies ? -- Anthony Lee (Humble PhD student) (alias Doctor(Time Lord)) ACSnet: anthony@uqcspe.cs.uq.oz TEL: (07) 3712651 (07) 3774139 (w) SNAIL: 243 Carmody Rd, St Lucia, 4067 Australia