T.20B When will better quality speech at higher encoding rates be available?

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4-bit ADPCM was introduced in 07-05-1994, with v6.13 of the ZyXEL ROMs.  The
increased number of bits improves the voice quality noticeably.

Brent Mosbrook (brentm@zyxel.com) [ZyXEL USA] adds:
"Currently, the sample rate is 9600 samples/second.  3-bit ADPCM requires 
the DTE speed to be 38.4K."

The new 4-bit ADPCM requires a 57,600 DTE speed.

Question Q.10 mentions that there will be a faster DTE rate in the next
generation of modems.  This raises the possibility that even higher
encoding rates may arise in the future.

Top Document: ZyXEL modem FAQ List v4.2, Nov 20 1995, Part 3 of 5 [Technical FAQs]
Previous Document: T.20A How does the voice quality compare versus the Rockwell chipset?
Next Document: T.21 Can a voice call be detected by the modem?

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