Half-Rate-Max mode allows using half of the maximal transmission power while maintaining the speech channel. At some situations, the increase in the power can reach the non-linear operating points of the radio components, such as the power amplifiers, resulting in call drops. Combined with NELP coding at 2 Kbps for coding of unvoiced speech and a sophisticated speech classification algorithm, EVRC-B provides high speech quality at average bit rates much lower than EVRC, allowing dynamic tradeoffs between cell capacity and speech quality.ġ.3 Q: What is Half-Rate-Max mode of operation?Ī:As the distance of a cell phone from the cellular base station increases, the power used for its communication increases. EVRC-B and EVRC-WB use all four rates but EVRC does not use the rate of 2 Kbps.ġ.2 Q: What is the main technology breakthrough in EVRC-B, in comparison to EVRC?Ī: EVRC-B uses the advanced paradigm of harmonic coding in its Prototype Pitch Period (PPP) approach at 2 Kbps for coding of stationary voiced speech. EVRC, EVRC-B, and EVRC-WB are variable rate codecs which use a different rate for the coding of each 20ms frame of speech, as controlled by their speech classification algorithms. INTRODUCTION AND GENERAL INFORMATION EVRC-B/WBġ.1 Q: What is Rate Set 1 in cdma2000 and how it is related to EVRC, EVRC-B and EVRC-WB?Ī: Rate Set 1 in cdma2000 includes four rates: 8.55, 4, 2 and 0.8 Kbps used for the coding of speech.

Ambe vocoder software windows