ENHANCED CONVERSION OF WIDEBAND SIGNALS TO NARROWBAND SIGNALS
First Claim
1. A device, comprising:
- a first element for creating a synthesized wideband speech signal; and
a second element for enhancing the synthesized wideband speech signal,wherein the second element further comprises;
a post-filter element; and
a filter for emphasizing a portion of the frequency spectrum of the synthesized wideband speech signal to output a signal with a non-flat frequency spectrum.
1 Assignment
0 Petitions
Accused Products
Abstract
Wideband speech signals must be converted to narrowband speech signals if the transmission medium or the destination terminal is constructed with narrowband constraints. A typical wideband-to-narrowband conversion method is the elimination of frequencies above 3400 Hz using a low pass filter and a down sampler. However, this method produces a muffled speech sound since the resulting narrowband signal has a flat frequency response. Methods and apparatus are presented herein to enhance the acoustic quality of a wideband-to-narrowband converted signal. A bandwidth switching filter is used to emphasize a mid-range frequency portion of the wideband signal so that the resulting narrowband signal has a non-flat frequency spectrum.
19 Citations
12 Claims
-
1. A device, comprising:
-
a first element for creating a synthesized wideband speech signal; and a second element for enhancing the synthesized wideband speech signal, wherein the second element further comprises; a post-filter element; and a filter for emphasizing a portion of the frequency spectrum of the synthesized wideband speech signal to output a signal with a non-flat frequency spectrum. - View Dependent Claims (2, 3)
-
-
4. A method for transmitting wideband waveforms originating in a wireless communication system, comprising:
-
creating a synthesized wideband speech signal; and enhancing the synthesized wideband speech signal, wherein the enhancing further comprises; post-filtering the synthesized wideband speech signal; and emphasizing a portion of the frequency spectrum of the post-filtered synthesized wideband speech signal to output a signal with a non-flat frequency spectrum. - View Dependent Claims (5, 6)
-
-
7. A device, comprising:
-
means for creating a synthesized wideband speech signal; and means for enhancing the synthesized wideband speech signal, wherein the means for enhancing further comprises; means for post-filtering the synthesized wideband speech signal; and means for emphasizing a portion of the frequency spectrum of the post-filtered synthesized wideband speech signal to output a signal with a non-flat frequency spectrum. - View Dependent Claims (8, 9)
-
-
10. A device comprising:
-
a memory; a processor for executing an instruction set stored within the memory, the instruction set for performing the steps of; creating a synthesized wideband speech signal; and enhancing the synthesized wideband speech signal, wherein the enhancing further comprises; post-filtering the synthesized wideband speech signal; and emphasizing a portion of the frequency spectrum of the post-filtered synthesized wideband speech signal to output a signal with a non-flat frequency spectrum. - View Dependent Claims (11, 12)
-
Specification