Out in Front: August 15, 1996

Using only two ICs, the Apollo modem chip set (L33DAS) from Lucent Technologies provides a V.34 modem, a Class 1 fax, digital simultaneous voice and data (DSVD), caller ID, and video-conferencing capability using traditional plain-old-telephone-system lines. The two ICs are a ROM-based DSP1642 DSP and a CSP1034 codec.

The video-ready interface, supporting the ITU-T V.80 standard, lets you use either a software- or a hardware-accelerated ITU-T H.324 implementation for video-conferencing. Implementing H.324 in software allows you to implement the video-conferencing algorithms on the host PC's CPU; this approach will derive much benefit from Intel's MMX technology (see "Multimedia instructions boost host-based processing," EDN, May 23, 1996, pg 67). Host-based processing helps to minimize the modem chip-set circuitry and eases upgrading the algorithms stored on the host's disk drive. Another often-overlooked benefit of host-based processing is that it lets you reduce the memory that the DSP1642 DSP accelerator requires. This reduction occurs because the host CPU runs the algorithm out of the PC's memory.

Adding an audio codec to the Apollo chip set provides support for a full-duplex speaker phone (FDSP) and telephone-answering machine. The speaker phone provides adaptive acoustic echo cancellation for dynamic speaker/microphone positioning. Apollo also provides a direct connection to a host PC's ISA bus. The two-chip set sells for $60 (10,000).

—by Markus Levy

Lucent Technologies, Allentown, PA. (800) 372-2447, Department P91.