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Adaptive Multi Rate - WideBand or AMR-WB is a speech coding standard developed after the AMR using same technology like ACELP. The codec provides excellent speech quality due to wider speech bandwidth of 50 - 7000 Hz compared to narrowband speech codecs which in general are optimized for POTS wireline quality of 300-3400Hz. AMR-WB is codified as G.722.2, an ITU-T standard speech codec.
AMR modes
AMR operates like AMR with various bit rates. The bit rates are following: 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 and 23.85 kbit/s. The lowest bit rate providing excellent speech quality in clean environtment is 12.65 kbit/s. Higher bit rates are useful in back ground noise conditions and in case of music. Also lower bit rates of 6.60 and 8.85 provide reasonable quality especially if compared to narrow band codecs.
Future
AMR-WB is already standardized for future usage in networks such as UMTS. There it provides so much higher speech quality that it seems probable that also older networks will have to gradually be transformed to support wide band.
See also
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