SYSTEMS AND METHODS FOR DYNAMIC NORMALIZATION TO REDUCE LOSS IN PRECISION FOR LOW-LEVEL SIGNALS

• US 20080130793A1
• Filed: 01/31/2007
• Published: 06/05/2008
• Est. Priority Date: 12/04/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rajendran, Vivek, Kandhadai, Ananthapadmanabhan A.
• Granted Patent: US 8,005,671 B2
• Time in Patent Office: Days
• US Class Current: 375/317
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 21/00 Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility G10L19/00 takes precedence
• CPC Class Codes: G10L 21/0388 Details of processing therefor

Abstract

A normalization factor for a current frame of a signal may be determined. The normalization factor may depend on an amplitude of the current frame of the signal. The normalization factor may also depend on values of states after one or more operations were performed on a previous frame of a normalized signal. The current frame of the signal may be normalized based on the normalization factor that is determined. The states'"'"' normalization factor may be adjusted based on the normalization factor that is determined.

Claims

1. An apparatus that is configured for dynamic normalization to reduce loss in:

precision for low-level signals, comprising;

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable to;

determine a normalization factor for a current frame of a signal, wherein the normalization factor depends on an amplitude of the current frame of the signal, and wherein the normalization factor also depends on values of states after one or more operations were performed on a previous frame of a normalized signal;

normalize the current frame of the signal based on the normalization factor that is determined; and

adjust the states'"'"' normalization factor based on the normalization factor that is determined.

2. The apparatus of claim 1, wherein the normalization factor is selected so that saturation does not occur.

3. The apparatus of claim 1, wherein determining the normalization factor for the current frame of the signal comprises:

determining an optimal value for the current frame'"'"'s normalization factor based on the amplitude of the current frame of the signal;

determining a scaling factor for the states based on information about the values of the states after the one or more operations were performed on the previous frame of the normalized signal; and

evaluating a saturation condition that depends on the optimal value for the current frame'"'"'s normalization factor, the scaling factor, and the normalization factor for the previous frame of the signal.

4. The apparatus of claim 3, wherein the previous frame'"'"'s normalization factor indicates to what extent bits of the previous frame of the signal were shifted prior to the one or more operations being performed on the previous frame of the normalized signal.

5. The apparatus of claim 3, wherein the optimal value for the current frame'"'"'s normalization factor indicates to what extent bits of the current frame of the signal can be left-shifted without causing saturation.

6. The apparatus of claim 3, wherein the scaling factor for the states indicates to what extent bits of the states can be left-shifted without causing saturation.

7. The apparatus of claim 3, wherein the saturation condition is expressed as Qinp−

prev_Qinp>

Q_states, wherein Qinp is the optimal value for the current frame'"'"'s normalization factor, wherein prev_Qinp is the previous frame'"'"'s normalization factor, and wherein Q_states is the scaling factor for the states.

8. The apparatus of claim 3, wherein if the saturation condition is satisfied, determining the current frame'"'"'s normalization factor further comprises setting the current frame'"'"'s normalization factor to prev_Qinp+Q_states, wherein Qinp is the optimal value for the current frame'"'"'s normalization factor, wherein prev_Qinp is the previous frame'"'"'s normalization factor, and wherein Q_states is the scaling factor for the states.

9. The apparatus of claim 3, wherein if the saturation condition is not satisfied, determining the current frame'"'"'s normalization factor further comprises setting the current frame'"'"'s normalization factor to the optimal value for the current frame'"'"'s normalization factor.

10. The apparatus of claim 1, wherein normalizing the current frame of the signal comprises left-shifting bits of the current frame of the signal by an amount that corresponds to the current frame'"'"'s normalization factor.

11. The apparatus of claim 1, wherein adjusting the states comprises shifting bits of the states by an amount that corresponds to a difference between the current frame'"'"'s normalization factor and the previous frame'"'"'s normalization factor.

12. The apparatus of claim 1, wherein determining the current frame'"'"'s normalization factor, normalizing the current frame of the signal, and adjusting the states are performed for each frame of the signal.

13. The apparatus of claim 1, wherein the signal is a low band excitation signal, wherein the normalized signal is a normalized low band excitation signal, wherein the states are filter states of a high band excitation generator, and wherein the high band excitation generator derives a high band excitation signal from the normalized low band excitation signal.

14. The apparatus of claim 13, wherein deriving the high band excitation signal from the normalized low band excitation signal comprises performing filtering operations on the current frame of the normalized low band excitation signal using normalized filter states.

15. The apparatus of claim 13, wherein the high band excitation generator does not use least significant bits from the normalized low band excitation signal to derive the high band excitation signal.

16. The apparatus of claim 1, wherein the apparatus is selected from a mobile station and a base station.

17. The apparatus of claim 1, wherein the instructions are comprised within an implementation of a component that is selected from a wideband encoder and a wideband decoder.

18. A method for dynamic normalization to reduce loss in precision for low-level signals, comprising:

determining a normalization factor for a current frame of a signal, wherein the normalization factor depends on an amplitude of the current frame of the signal, and wherein the normalization factor also depends on values of states after one or more operations were performed on a previous frame of a normalized signal;

normalizing the current frame of the signal based on the normalization factor that is determined; and

adjusting the states'"'"' normalization factor based on the normalization factor that is determined.

19. An apparatus that is configured for dynamic normalization to reduce loss in precision for low-level signals, comprising:

means for determining a normalization factor for a current frame of a signal, wherein the normalization factor depends on an amplitude of the current frame of the signal, and wherein the normalization factor also depends on values of states after one or more operations were performed on a previous frame of a normalized signal;

means for normalizing the current frame of the signal based on the normalization factor that is determined; and

means for adjusting the states'"'"' normalization factor based on the normalization factor that is determined.

20. A computer-readable medium configured to store a set of instructions executable to:

determine a normalization factor for a current frame of a signal, wherein the normalization factor depends on an amplitude of the current frame of the signal, and wherein the normalization factor also depends on values of states after one or more operations were performed on a previous frame of a normalized signal;

normalize the current frame of the signal based on the normalization factor that is determined; and

adjust the states'"'"' normalization factor based on the normalization factor that is determined.

21. A system for dynamic normalization to reduce loss in precision for low-level signals, comprising:

a factor determination component that is configured to determine a normalization factor for a current frame of a signal, wherein the normalization factor depends on an amplitude of the current frame of the signal, and wherein the normalization factor also depends on values of states after one or more operations were performed on a previous frame of a normalized signal;

a signal normalizer that is configured to normalize the current frame of the signal based on the normalization factor that is determined; and

a states normalization factor adjuster that is configured to adjust the states'"'"' normalization factor based on the normalization factor that is determined.