Method and attenuator for detection and iterative attenuation of spikes in complex signals

• US 8,868,162 B2
• Filed: 10/20/2009
• Issued: 10/21/2014
• Est. Priority Date: 10/20/2008
• Status: Expired due to Fees

• Current Assignee: Neurochip Corporation
• Original Assignee: Neurochip Corporation
• Inventors: Zalay, Osbert C., Bardakjian, Berj L.
• Primary Examiner(s): VOORHEES, CATHERINE M
• Application Number:
  US12/582,407
• Publication Number:
  US 20100113951A1
• Time in Patent Office: 1,827 Days
• Field of Search: 607/27, 607/28, 600/509, 600/544, 702/66, 324/76.12
• US Class Current: 600/509
• CPC Class Codes: G01D 3/032 affecting incoming signal, e.g. by averaging; gating undesired signals

Abstract

A method of attenuating spikes in a complex signal comprises examining the complex signal to detect spikes therein and for each detected spike, generating an estimate inverse signal and applying the estimate inverse signal to the complex signal to attenuate the spike associated with the estimate inverse signal.

Claims

1. An attenuator for attenuating spikes in a complex signal comprising:

a spike detector configured to detect spikes in the complex signal; and

a spike attenuator configured to attenuate each detected spike, said spike attenuator including an envelope detector configured to fit an envelope around each detected spike,

the spike attenuator including an inverse signal generator configured to generate, for each detected spike fitted with an envelope, an estimate inverse signal and a multiplier configured to apply the estimate inverse signal to the detected spike to attenuate the detected spike.

2. The attenuator of claim 1 wherein said spike detector is configured to compare the amplitude of the complex signal with a threshold value to detect spikes in the complex signal.

3. The attenuator of claim 2 wherein the threshold value is a function of the complex signal.

4. The attenuator of claim 3, wherein the threshold value is proportional to the root mean square of the complex signal.

5. The attenuator of claim 2 wherein,

said spike attenuator is configured to generate, for each detected spike, a scaled mirror image of the detected spike,

the spike attenuator further includes a comparator configured to compare the attenuated spike with another threshold value and a feedback path that feeds the attenuated spike back to the envelope detector when the attenuated spike exceeds the another threshold value.

6. The attenuator of claim 5 wherein said complex signal is a biological signal.

7. The attenuator of claim 6 wherein said biological signal is one of a neural signal and a cardiac signal.

8. The attenuator of claim 5, wherein the envelope detector fits a sigmoidal envelope around each detected spike.

9. The attenuator of claim 5, wherein the attenuated spike, when equal to or less than said another threshold value, has an amplitude that is equal to or less than an average complex signal baseline activity in its neighborhood.

10. The attenuator of claim 1 further comprising:

a memory array configured to digitally store the values of said complex signal, said spike detector, for each value of said complex signal, configured to compare the value to a plurality of preceding and subsequent values of said complex signal to determine if said value represents a peak and if so, compare the value of the complex signal with a threshold value to determine if said value represents a spike.

11. The attenuator of claim 10 wherein the threshold value is a function of the complex signal.

12. The attenuator of claim 11, wherein the threshold value is proportional to the root mean square of the complex signal.

13. The attenuator of claim 1 wherein,

the inverse signal generator is configured to generate, for each detected spike, a scaled mirror image of the detected spike

the spike attenuator further includes a comparator configured to compare the attenuated spike with a threshold value and a feedback path that feeds the attenuated spike back to the envelope detector when the attenuated spike exceeds the threshold value.

14. The attenuator of claim 13, wherein the envelope detector fits a sigmoidal envelope around each detected spike.

15. The attenuator of claim 13, wherein the attenuated spike, when equal to or less than said threshold value, has an amplitude that is equal to or less than the average complex signal baseline activity in its neighborhood.

16. The attenuator of claim 1 wherein said complex signal is a biological signal.

17. The attenuator of claim 16 wherein said biological signal is one of a neural signal and a cardiac signal.

18. The attenuator of claim 2 further comprising:

a memory array configured to digitally store the values of said complex signal, said spike detector, for each value of said complex signal, configured to compare the value to a plurality of preceding and subsequent values of said complex signal to determine if said value represents a peak and if so, compare the value of the complex signal with the threshold value to determine if said value represents a spike.

19. The attenuator of claim 18 wherein said complex signal is a biological signal.

20. The attenuator of claim 19 wherein said biological signal is one of a neural signal and a cardiac signal.

21. The attenuator of claim 1, wherein the envelope detector fits a sigmoidal envelope around each detected spike.

22. An attenuator for attenuating spikes in a complex signal comprising:

a spike detector configured to detect spikes in the complex signal by comparing the amplitude of the complex signal with a first threshold value; and

a spike attenuator configured to attenuate detected spikes in said complex signal, for each spike to be attenuated, said spike attenuator configured to generate and iteratively apply scaled inverse signals to the complex signal to attenuate the spike,

wherein the spike attenuator includes,

an envelope detector configured to fit an envelope around each spike to be attenuated,

an inverse signal generator configured to generate a scaled inverse signal of each spike,

a multiplier configured to combine each spike to be attenuated with an associated scaled inverse signal to generate an attenuated spike,

a comparator configured to compare the attenuated spike with a second threshold value and

a feedback path configured to feed the attenuated spike back to the envelope detector when the attenuated spike exceeds the second threshold value.

23. The attenuator of claim 22 wherein the first threshold value is a function of the complex signal.

24. The attenuator of claim 23, wherein the first threshold value is proportional to the root mean square of the complex signal.

25. The attenuator of claim 22 further comprising:

a memory array configured to digitally store the values of said complex signal, said spike detector, for each value of said complex signal, configured to compare the value to a plurality of preceding and subsequent values of said complex signal to determine if said value represents a peak and if so, compare the value of the complex signal with the threshold value to determine if said first value represents a spike.

26. The attenuator of claim 22, wherein the envelope detector fits a sigmoidal envelope around each spike to be attenuated.

27. The attenuator of claim 22, wherein the attenuated spike, when equal to or less than said second threshold value, has an amplitude that is equal to or less than an average complex signal baseline activity in its neighborhood.

28. The attenuator of claim 22, wherein said complex signal is a biological signal.

29. The attenuator of claim 28, wherein said biological signal is one of a neural signal and a cardiac signal.