VoIP Chipsets

Chips from: Broadcom (BCM1103 Gigabit IP Phone Chip), SiTel Semiconductor (SC14461 Green VoIP processor), Zarlink (Legerity VoicePath + VE8910 1FXS chipset), Atmel (AT76C901, AT76C902 for Wi-Fi phones), Centillium (Entropia III >1,000 VoIP channels per chip), Freescale (iMX chip), LSI Corp. (StarPro 2700 multicore media processors), Lantiq (VINETIC-SVIP), DSP Group (XciteR - Vega Firebird Family), Conexant Systems, Inc., Texas Instruments, … .

A common feature is acoustic echo cancellation to enable high quality speakerphone operation.

Transcript

[slide28] Now, not surprisingly, this has led to a whole bunch of companies from Broadcom and others producing chipsets optimized for voice over IP. They do very clever things like acoustic echo cancellation. Why is acoustic echo cancellation so important? [student answers: You want to have all the sounds bouncing around.] That's right. You want to hear what it is that you expect to hear, not the echoes from other people. And it's particularly disturbing when you're talking to someone and you hear your own voice echoing back after some delay because it came out of their speakers reflected against the wall and came back into their microphone. That's what lets you have cord-free desktop devices. And we call them speakerphones. But it turns out you can take this much, much further. So I had a student some time ago who built a system that did spatialized audio. What's the idea of spatialized audio? Well, it turns out that since, if you have two ears, the distance around your head causes a difference of time of arrival based upon the direction the sound is coming from. So I know the sound is coming from over there because it arrives at this ear first and it takes longer before the sound gets around to the other ear. So I know the sound came from there. Well, he showed that it was possible for the group of people he had participate in his tests. to recognize more than ten different locations both radial distances and distances away because what happens if the sound comes from farther away? Its amplitude is decreased. And then he exploited something known as the cocktail party effect. Does anyone know what the cocktail party effect is? Okay, you're at a party and you hear someone who is across the room mention your name. Boom! The antennas go up and suddenly your signal processing kicks in and you can hear everything that they said about you. We have this ability to spatially localize and ignore the other things because we can direct our attention towards a particular angle and distance. Well, he exploited that to say, hey, you're in a call let's say you're in a call, you're a stockbroker and you're listening to the latest report the financial announcement by the company that just announced their quarterly returns you're listening away and now one of your really important customers calls you. What do you do? You take that call and you move it over here and you take the call you were listening to and you move it over there and now you can listen to both of them at the same time. Because your attention can switch back and forth between these depending on what it is that you're hearing and how interested you are. Now of course you have to decide which one you want to talk in but you can listen in multiple ones at the same time. Now why is that such a fundamental change? Because until you've had spatial separation between these how many calls could you be in at the same time? One. And we've all seen people using these traditional handsets where they get a note saying, oh, you have another call and they say, excuse me a moment, I need to go to this other call they put you on hold, they switch to the other call deal with it, come back, okay, I'm back. With this, you can deliver multiple calls to one person at the same time. It suddenly breaks all the idea that, oh, one call at a time one call's worth of bandwidth is enough.