Interference Detector and Methods

• US 20110060554A1
• Filed: 11/17/2010
• Published: 03/10/2011
• Est. Priority Date: 09/22/2003
• Status: Abandoned Application

• Current Assignee: Alcotek, Inc., Intoximeters, Inc.
• Original Assignee: Alcotek, Inc., Intoximeters, Inc.
• Inventors: Sibley, Gary L., Forrester, M. Rankine, Lueck, Keith W., Mitchell, John
• Application Number:
  US12/948,261
• Publication Number:
  US 20110060554A1
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: G01D 3/032 affecting incoming signal, e.g. by averaging; gating undesired signals
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown
• CPC Class Codes: G01N 33/007 Arrangements to check the analyser calibrating G01N33/0006
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06
• CPC Class Codes: Y10S 436/90 Breath testing
• CPC Class Codes: Y10T 436/204165 Ethanol

Abstract

Interference detector and methods for detecting interference in a signal are described. More specifically, in one aspect, a method for detecting interference in a signal is provided. The method comprises determining whether the signal has at least one of a time and a frequency characteristic that is outside a predefined range, and determining that an interference event has been detected if the signal has at least one of such characteristics.

Claims

1. An interference detector for detecting electro-magnetic interference corrupting a signal from a breath alcohol sensor, the detector comprising a processor programmed to:

receive the signal from the breath alcohol sensor;

differentiate the signal to generate a differentiated signal;

compare the differentiated signal to a predefined threshold for a time rate of change range; and

determine that an interference corrupting event is detected if the time rate of change is outside the respective predetermined range.

2. The detector of claim 1 wherein the processor is further programmed to discard the signal if the interference corrupting event is detected.

3. The detector of claim 1 wherein the processor is further programmed to determine a second order or higher order derivative of the signal.

4. The detector of claim 1 further comprising an analog-to-digital converter for converting the signal into a digital signal.

5. The detector of claim 1 wherein the differentiated signal has a slope and wherein the processor is programmed to compare the slope of the differentiated signal to a maximum allowable slope.

6. The detector of claim 5 wherein the interference corrupting event is detected if the slope is greater than the maximum allowable slope.

7. The detector of claim 6 wherein the processor is further programmed to discard the signal if the interference corrupting event is detected.

8. An interference detector for detecting electro-magnetic interference corrupting a signal received from a breath alcohol sensor including a fuel cell, the detector comprising a processor programmed to:

receive the signal from the breath alcohol sensor;

transform the signal from a time domain signal to a frequency domain signal; and

process the frequency domain signal to determine whether any frequency component present is outside a predefined range; and

determine that an interference corrupting event is detected if the frequency component present is outside the predefined range.

9. The detector of claim 8 wherein the processor is further programmed to discard the signal if the interference corrupting event is detected.

10. The detector of claim 8 wherein the processor is further programmed to determine a second order or higher order derivative of the signal.

11. The detector of claim 8 further comprising an analog-to-digital converter for converting the signal into a digital signal.

12. The detector of claim 8 wherein the frequency domain signal has a slope and wherein the processor is further programmed to compare the slope of the signal to a maximum allowable slope.

13. The detector of claim 12 wherein an interference event is detected if the slope is greater than the maximum allowable slope.

14. The detector of claim 13 wherein the processor is further programmed to discard the signal if the interference event is detected.