Apparatus and method for discriminating between voice and data by using a frequency estimate representing both a central frequency and an energy of an input signal

• US 6,718,297 B1
• Filed: 02/15/2000
• Issued: 04/06/2004
• Est. Priority Date: 02/15/2000
• Status: Expired due to Fees

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Franklin, Cheryl Jean, Carroll, Edward James, Pride, Joseph Peebles III
• Primary Examiner(s): Dorvil, Richemond
• Assistant Examiner(s): Storm, Donald L.
• Application Number:
  US09/504,784
• Time in Patent Office: 1,512 Days
• Field of Search: 704/206, 704/205, 704/201, 704/203, 379/93.09, 379/93.01, 379/93.06
• US Class Current: 704/206
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10

Abstract

The present invention classifies an input signal as either voice or data with reduced energy consumption. The present invention includes a frequency estimator and an energy estimator for processing an input signal and a classification unit connected to both the frequency and energy estimators for classifying the input signal. The frequency estimator includes a delay and difference integrator. In operation, the delay receives the input signal and generates a delayed input signal and the difference integrator receives the delayed and input signals and generates a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of the input signal. The energy estimator generates an estimate of the energy level of the input signal. The classification unit classifies the input as either voice or data based on a comparison of the frequency and energy estimate values and a data threshold value.

Claims

1. An apparatus for classifying an input signal as either a voice or data signal in a communication system, wherein said apparatus comprises:

a frequency estimator that receives the input signal and generates a frequency estimate value representing both an estimated central frequency of the input signal and an estimated energy level of input signal;

an energy estimator that receives the input signal and generates an energy estimate value representing an estimate of the energy level of the input signal; and

a classification unit in electrical communication with both said frequency and energy estimators, wherein said classification unit receives the frequency and energy estimate values and classifies the input signal as either a voice or data signal based on the frequency and energy estimate values and a data threshold value.

2. An apparatus according to claim 1, wherein said classification unit further comprises a normalizer in electrical communication with both said frequency and energy estimators, and wherein said normalizer generates a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

3. An apparatus according to claim 2, wherein said normalizer divides the frequency estimate value by the energy estimate value and generates a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

4. An apparatus according to claim 2, wherein the data threshold value defines a frequency value, wherein said classification unit further comprises a frequency detector in electrical communication with said normalizer, and wherein said frequency detector compares the normalized frequency estimate value to the data threshold value and classifies the input signal as a data signal if the normalized frequency estimate value is at least as great as the data threshold value.

5. An apparatus according to claim 2, wherein said classification unit further comprises:

a frequency detector in electrical communication with said normalizer;

a switch in electrical communication with both said normalizer and said frequency detector for selectively connecting the normalizer and the frequency detector; and

an energy detector in electrical communication with said energy estimator and said switch, wherein said energy detector initially compares the energy estimate value to an energy threshold value defining a minimum energy level, wherein if the energy estimate value is at least as great as the energy threshold value, said energy detector controls said switch to connect said normalizer and said frequency detector, such that the frequency detector may classify the input signal as either voice or data.

6. An apparatus according to claim 1, wherein said classification unit further comprises an energy detector in electrical communication with said energy estimator, wherein said energy detector initially compares the energy estimate value to an energy threshold value defining a minimum energy level, and wherein said energy detector classifies the input signal as a voice signal if the energy estimate value is no greater than the energy threshold value.

7. An apparatus according to claim 1, wherein said classification unit comprises:

a frequency detector in electrical communication with said frequency estimator;

an energy detector in electrical communication with both said energy estimator and said frequency detector; and

a memory device in electrical communication with said energy detector, said memory device storing a table that includes a plurality of differing data threshold values, wherein said energy detector receives the energy estimate value and selects a data threshold value from the plurality of differing threshold values in said table based on the amplitude of the energy estimation value, and wherein said frequency detector receives the data threshold value from said energy detector and classifies the input signal as a data signal if the frequency estimate value is at least as great as the selected data threshold value.

8. An apparatus according to claim 1, wherein said frequency estimator comprises:

a delay that receives the input signal and generates a delayed input signal;

a difference integrator in electrical communication with said delay and the input signal, wherein said difference integrator receives the delayed and input signals and generates a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of the input signal.

9. An apparatus according to claim 8, wherein said frequency estimator further comprises an absolute value device in electrical communication with said delay, wherein said absolute value device receives the frequency estimate value and generates an absolute value of the frequency estimate value.

10. An apparatus according to claim 8, wherein said frequency estimator further comprises an accumulator device in electrical communication with said delay, wherein said accumulator device receives the frequency estimate value and generates a frequency estimate value.

11. An apparatus according to claim 1, wherein said energy estimator comprises:

an absolute value device that receives the input signal and generates an absolute value of the input signal; and

an accumulator device in electrical communication with said absolute value device, wherein said accumulator device generates an energy estimate value representing the amplitude of the input signal.

12. A method for classifying an input signal as either a voice or data signal in a communication system, wherein said method comprises the steps of:

receiving an input signal;

generating a frequency estimate value representing both an estimated central frequency of the input signal and an estimated energy of the input signal;

generating an energy estimate value representing an estimate of the energy level of the input signal; and

classifying the input signal as either a voice or data signal based on the frequency and energy estimate values and a data threshold value.

13. A method according to claim 12, wherein said classifying step further comprises the step of initially normalizing the frequency estimate value based on the energy estimate value to thereby generate a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

14. A method according to claim 13, wherein said normalizing step comprises dividing the frequency estimate value by the energy estimate value to thereby generate a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

15. A method according to claim 13, wherein the data threshold value defines a frequency value, wherein said classifying step comprises the steps of:

comparing the normalized frequency estimate value to the data threshold value; and

classifying the input signal as a data signal if the normalized frequency estimate value is at least as great as the data threshold value.

16. A method according to claim 13, wherein said classifying step further comprises initially comparing the energy estimate value to an energy threshold value defining a minimum energy level, wherein if the energy estimate value is at least as great as the energy threshold value, said classifying step comprises comparing the normalized frequency estimate value to the data threshold value, and classifying the input signal as a data signal if the normalized frequency estimate value is at least as great as the data threshold value.

17. A method according to claim 12, wherein said classifying step further comprises initially comparing the energy estimate value to an energy threshold value defining a minimum energy level, and wherein said classifying step classifies the input signal as a voice signal if the energy estimate value is no greater than the energy threshold value.

18. A method according to claim 12, wherein said classifying step comprises the steps of:

receiving the energy estimate value;

selecting a data threshold value from a plurality of differing threshold values based on the amplitude of the energy estimate value; and

classifying the input signal as a data signal if the frequency estimate value is at least as great as the selected data threshold value.

19. A method according to claim 12, wherein said generating a frequency estimate value step comprises the steps of:

delaying the input signal to thereby generate a delayed input signal;

determining a difference between the delayed input signal and the input signal; and

generating a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of the input signal.

20. A method according to claim 19, wherein said generating a frequency estimate value step further comprises the step of generating an absolute value of the frequency estimate value.

21. A method according to claim 19, wherein said generating a frequency estimate value step further comprises the step of accumulating the frequency estimate value.

22. A method according to claim 12, wherein said generating an energy estimate value step comprises the steps of:

generating an absolute value of the input signal; and

generating an energy estimate value representing the amplitude of the input signal.

23. An apparatus for classifying an input signal as either a voice or data signal in a communication system, wherein said apparatus comprises:

a delay that receives the input signal and generates a delayed input signal;

a difference integrator in electrical communication with said delay and the input signal, wherein said difference integrator receives the delayed and input signals and generates a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of the input signal; and

a classification unit in electrical communication with said difference integrator, wherein said classification unit classifies the input signal as either a voice or data signal based on the frequency estimate value and a data threshold value.

24. An apparatus according to claim 23, wherein said classification unit comprises a normalizer in electrical communication with said difference integrator, wherein said normalizer normalizes the frequency estimate value based on an energy estimate value representing the energy of the input signal and generates a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

25. An apparatus according to claim 24, wherein said normalizer divides the frequency estimate value by the energy estimate value and generates a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

26. An apparatus according to claim 24, wherein said classification unit further comprises a frequency detector in electrical communication with said normalizer, wherein said frequency detector compares the frequency estimate value with a data threshold value, and wherein said detector classifies the input signal as a data signal if the frequency estimate value is at least as great as the data threshold value.

27. An apparatus according to claim 23 further comprising:

an absolute value device in electrical communication with said difference integrator, wherein said absolute value device generates an absolute value of the input signal; and

an accumulator device in electrical communication with said absolute value device, wherein said accumulator device generates a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of input signal.

28. A method for classifying an input signal as either a voice or data signal in a communication system, wherein said method comprises the steps of:

delaying the input signal to thereby generate a delayed input signal;

generating a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of the input signal based upon the input signal and the delayed input signal; and

classifying the input signal as either a voice or data signal based on the frequency estimate value and a data threshold value.

29. A method according to claim 28 further comprising after said generating step normalizing the frequency estimate value based on an energy estimate value representing the energy of the input signal to thereby generate a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

30. A method according to claim 29, wherein said normalizing step comprises dividing the frequency estimate value by the energy estimate value to thereby generate a normalized frequency estimate value representing an estimate of the central frequency of the input signal.

31. A method according to claim 29, wherein said classifying step comprises comparing the frequency estimate value with a data threshold value and classifying the input signal as a data signal if the frequency estimate value is at least as great as the data threshold value.

32. A method according to claim 28 further comprising after said generating step:

generating an absolute value of the input signal; and

generating a frequency estimate value representing both the estimated central frequency of the input signal and the estimated energy of input signal.