Communication device with reduced noise speech coding
View Patent ↗A communication device includes memory, an input interface, a processing module, and a transmitter. The processing module receives a digital signal from the input interface, wherein the digital signal includes a desired digital signal component and an undesired digital signal component. The processing module identifies one of a plurality of codebooks based on the undesired digital signal component. The processing module then identifies a codebook entry from the one of the plurality of codebooks based on the desired digital signal component to produce a selected codebook entry. The processing module then generates a coded signal based on the selected codebook entry, wherein the coded signal includes a substantially unattenuated representation of the desired digital signal component and an attenuated representation of the undesired digital signal component. The transmitter converts the coded signal into an outbound signal in accordance with a signaling protocol and transmits it.
1. A communication device comprising:
a input interface;
a communications interface; and
a processing module coupled to the input interface and the communications interface, the input interface, communications interface, and processing module operable to:
receive a digital signal via the input interface that includes a desired digital signal component and an undesired digital signal component;
select one of a plurality of codebooks based on the undesired digital signal component;
select a code book entry from the selected code book based on the desired digital signal component; and
generate a coded signal based on the selected codebook entry;
convert the coded signal into an outbound signal in accordance with a signaling protocol; and
transmit the outbound signal via the communications interface.
2. The communication device of claim 1 wherein:
when the undesired digital signal component has a first noise level, a first one of the plurality of code books is selected; and
when the undesired digital signal component has a second noise level that exceeds the first noise level, a second one of the plurality of code books is selected.
3. The communication device of claim 2 , wherein the second one of the plurality of code books has lesser resolution than the first one of the plurality of code books.
4. The communication device of claim 1 , wherein the input interface, communications interface, and processing module are further operable to iteratively select the code book from the plurality of code books by comparing the encoded signal to the desired digital signal component.
5. The communication device of claim 1 , wherein the input interface, communications interface, and processing module are further operable to select the one of the plurality of code books by:
detecting when the undesired digital signal component is a dominant signal component of the digital signal;
when the undesired digital signal component is the dominant signal component, determining magnitude of the undesired digital signal component; and
selecting the one of the plurality of codebooks based on an inverse proportional relationship between resolution of a codebook and the magnitude of the undesired digital signal component, wherein the plurality of codebooks includes at least one higher resolution codebook and at least one lower resolution codebook.
6. The communication device of claim 1 , wherein the input interface, communications interface, and processing module are further operable to select the codebook entry by:
loading a vocal tract filter with an entry of the one of the plurality of codebooks to produce a loaded filter;
filtering, by the loaded filter, the entry to produce a representative coded signal;
determining error rate of the representative coded signal; and
when the error rate is favorable, identifying the entry as the selected codebook entry.
7. The communication device of claim 6 , wherein the input interface, communications interface, and processing module are further operable to select the codebook entry by:
when the error rate is unfavorable, loading the vocal tract filter with another entry of the one of the plurality of codebooks;
filtering, by the loaded filter, the another entry to produce a second representative coded signal;
determining a second error rate of the second representative coded signal; and
when the second error rate is favorable, identifying the other entry as the selected codebook entry.
8. The communication device of claim 6 wherein the input interface, communications interface, and processing module are further operable to determine the error rate by:
loading a reference vocal tract filter with an entry of a high resolution code book of the plurality of codebooks to produce a reference loaded filter;
filtering, by the reference loaded filter, the entry to produce a reference coded signal; and
comparing the representative coded signal with the reference coded signal to produce the error rate.
9. A method comprising:
receiving a digital signal via an input interface that includes a desired digital signal component and an undesired digital signal component;
selecting one of a plurality of codebooks based on the undesired digital signal component;
selecting a code book entry from the selected code book based on the desired digital signal component; and
generating a coded signal based on the selected codebook entry;
converting the coded signal into an outbound signal in accordance with a signaling protocol; and
transmitting the outbound signal via the communications interface.
10. The method of claim 9 wherein:
when the undesired digital signal component has a first noise level, a first one of the plurality of code books is selected; and
when the undesired digital signal component has a second noise level that exceeds the first noise level, a second one of the plurality of code books is selected.
11. The method of claim 10 , wherein the second one of the plurality of code books has lesser resolution than the first one of the plurality of code books.
12. The method of claim 9 , further comprising iteratively selecting the code book from the plurality of code books by comparing the encoded signal to the desired digital signal component.
13. The method of claim 9 , wherein selecting one of a plurality of codebooks based on the undesired digital signal component comprises:
detecting when the undesired digital signal component is a dominant signal component of the digital signal;
when the undesired digital signal component is the dominant signal component, determining magnitude of the undesired digital signal component; and
selecting the one of the plurality of codebooks based on an inverse proportional relationship between resolution of a codebook and the magnitude of the undesired digital signal component, wherein the plurality of codebooks includes at least one higher resolution codebook and at least one lower resolution codebook.
14. The method of claim 9 , further comprising:
loading a vocal tract filter with an entry of the one of the plurality of codebooks to produce a loaded filter;
filtering, by the loaded filter, the entry to produce a representative coded signal;
determining error rate of the representative coded signal; and
when the error rate is favorable, identifying the entry as the selected codebook entry.
15. The method of claim 14 , wherein selecting the codebook entry further comprises:
when the error rate is unfavorable, loading the vocal tract filter with another entry of the one of the plurality of codebooks;
filtering, by the loaded filter, the another entry to produce a second representative coded signal;
determining a second error rate of the second representative coded signal; and
when the second error rate is favorable, identifying the other entry as the selected codebook entry.
16. The method of claim 14 , wherein determining the error rate comprises:
loading a reference vocal tract filter with an entry of a high resolution code book of the plurality of codebooks to produce a reference loaded filter;
filtering, by the reference loaded filter, the entry to produce a reference coded signal; and
comparing the representative coded signal with the reference coded signal to produce the error rate.
17. A method comprising:
receiving a digital signal via a communications interface that includes a desired digital signal component and an undesired digital signal component;
selecting one of a plurality of codebooks based on the undesired digital signal component;
selecting a code book entry from the selected code book based on the desired digital signal component; and
generating a coded signal based on the selected codebook entry;
converting the coded signal into an outbound signal in accordance with a signaling protocol; and
transmitting the outbound signal via the communications interface.
18. The method of claim 17 , wherein:
when the undesired digital signal component has a first noise level, a first one of the plurality of code books is selected; and
when the undesired digital signal component has a second noise level that exceeds the first noise level, a second one of the plurality of code books is selected.
19. The method of claim 17 , wherein the second one of the plurality of code books has lesser resolution than the first one of the plurality of code books.
20. The method of claim 17 , further comprising iteratively selecting the code book from the plurality of code books by comparing the encoded signal to the desired digital signal component.