Patent ID: 7174135
Filing Date: 2007-02-06
Classification: G10L

Abstract:
1. A transmission system comprising a transmitter for transmitting a narrowband audio signal to a receiver via a transmission channel, the receiver comprising a frequency domain bandwidth extender for extending a bandwidth of the received narrowband audio signal by complementing the received narrowband audio signal with a highband extension thereof, the bandwidth extender, comprising an amplitude extender for extending the bandwidth of an amplitude spectrum of the received narrowband audio signal by mapping narrowband amplitudes onto highband amplitudes, the bandwidth extender further comprising a phase extender for extending the bandwidth of a phase spectrum of the received narrowband signal and a combiner for combining the extended amplitude spectrum and the extended phase spectrum into a bandwidth extended audio signal, wherein the amplitude extender comprises an amplitude mapper and first and second frequency scale transformers, the first frequency scale transformer being arranged for transforming a linear frequency scale of the amplitude spectrum into a logarithmic frequency scale, the amplitude mapper being arranged for mapping according to the logarithmic frequency scale the narrowband amplitudes onto the highband amplitudes, the second frequency scale transformer being arranged for transforming the logarithmic frequency scale of the extended amplitude spectrum into the linear frequency scale.