THE VX-SP1000 VOICE-SIGNAL processor from VxTel targets carrier-class switches in next-generation packet networks. The device can process as many as 240 G.711 uncompressed channels or 120 G.729A compressed channels, each with 64-msec-tail-length echo cancellation and supporting telephony functions, such as comfort-noise generation, voice-activity detection, and dual-tone-multifrequency tone detection and generation. The VX-SP1000 uses four DSP cores for voice, fax, and other broadband-processing algorithms and integrates a [micro]law/A-law PCM-highway interface with 512 full-duplex, independent, time-division-multiplexed channels. Additional on-chip resources include the 32-bit VX-bus expansion-bus interface), 8 Mbits of memory, and JATG/enhanced-JTAG test ports. I/O voltages are 3.3V, and core inputs are 1.8V.
You can configure the programmable, scalable architecture for various applications and software upgrades. Each channel on the processor can support any of various codecs, including G.711, G.729A, G.723.1, G.726, and fax. Such flexibility comes into play in determining how many channels a chip can support. For example, certain codecs offer higher voice quality but require more processing resources, reducing the number of channels a chip can support. Additionally, a school of thought challenges compressing voice for packet networks. Although voice-over-Internet Protocol applications are on the rise, voice is becoming an increasingly smaller percentage of overall network traffic. The effective gains of compressing a small percentage of traffic may not be worth the processing cost; consider that the VX-SP1000 can process twice as many uncompressed channels as compressed. Designing with dynamic algorithm allocation on a per-channel leaves the door open to future cost reductions via software upgrades alone.
* VxTel, 1-510-979-2100, www.vxtel.com ?? Enter 380 at www. rscahners.ims.ca/ednmag/.
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