The  AMR codec adopts the algebraic code excitation linear prediction (ACELP), a hybrid coding scheme. UMTS  AMR and UMTS  AMR2 areboth the AMR algorithms, which only differ in their compatibilities in rate control with other systems such as the GSM system. The coding rate canbe12.2 kbit/s, 10.2 kbit/s, 7.95 kbit/s, 7.40 kbit/s, 6.70 kbit/s, 5.90 kbit/s, 5.15 kbit/s, or4.75 kbit/s. The packetization time is20 ms, and the delay is20 ms. The  AMR algorithm is mainly applied in the UMTS network. UMTS  AMR can convert the encoding mode within20 ms in rate control; however , GSM  AMRneeds40 ms in rate control. Thus, in the multi-mode system, UMTS  AMR canbe compatible with itself only .

The  AMR codec provides the multi-rate codec, voice activation detection (V AD), comfort noise generation (CNG), and the error concealment mechanism to combat the effects of transmission errors and packet loss.

The UMG8900 supports the UMTS  AMR codec. It can implement the conversionbetween voice in the UMTS  AMR format and TDM-based voice in the G .711 format.

This feature complies with the3GPP TS26.xxx standard series.

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