CSR announced their Bluecore 6 chip today. It will ship in production volumes in January 2008. CSR claims a more robust connection – with increased transmit power and receive sensitivity. CSR also claims a breakthrough in sound quality, achieved by going from a Continuous Variable Slope Delta (CVSD) codec to Adaptive Differential Pulse Code Modulation (ADPCM). This enables packet retransmission and a halving of transmission bandwidth. The reduced bandwidth requirement results in a reduction in power consumption, and the ADPCM codec yields a MOS of 4.14 compared with a maximum of 2.41 for CVSD.
This is a welcome change, but doesn’t really go far enough. What’s needed is a wideband codec like AMR-WB to yield better-than-toll quality sound. While this would be redundant in a regular cell phone – ADPCM is more than adequate to carry a signal that has been encoded in GSM – it would make a huge difference in dual-mode phones carrying Voice over Wi-Fi.