Method of controlling and correcting an asymmetric waveform

• US 7,225,096 B2
• Filed: 09/05/2003
• Issued: 05/29/2007
• Est. Priority Date: 09/25/2002
• Status: Expired due to Fees

• Current Assignee: Thermo Finnigan LLC (Thermo Fisher Scientific Incorporated)
• Original Assignee: Thermo Finnigan LLC (Thermo Fisher Scientific Incorporated)
• Inventors: Guevremont, Roger, Potvin, Lucien
• Primary Examiner(s): Hoff; Marc S.
• Assistant Examiner(s): Charioui; Mohamed
• Application Number:
  US10/529,305
• Publication Number:
  US 20060052960A1
• Time in Patent Office: 1,362 Days
• Field of Search: 702/57, 702 64- 67, 702 70- 73, 702/75, 702/77, 702/85, 702/106, 702/189, 702/190, 702/193, 702/194, 250/282, 250/286, 250/292, 356/437, 379/24, 331/2, 331/14, 327/94, 324/138
• US Class Current: 702/106
• CPC Class Codes: G01R 19/2506 Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values G01R19/003 takes precedence; Details concerning sampling, digitizing or waveform capturing displaying waveforms G01R13/00; analog sampling G01R19/0053

Abstract

Disclosed is a method of controlling an asymmetric waveform generated as a combination of two sinusoidal waves having a frequency that differs by a factor of two. A method according to the instant invention includes a step of sampling a generated asymmetric waveform to obtain a set of data points, the set of data points being indicative of the generated asymmetric waveform. The sampled data points are arranged in an order according to magnitude, and then compared to template data relating to a desired asymmetric waveform. In dependence upon the comparison, a correction to the generated asymmetric waveform is determined.

Claims

1. A method of controlling an asymmetric waveform generated by an asymmetric waveform generator as a combination of two sinusoidal waves having respective frequencies that differ from each other by a factor of two, the method comprising the steps of:

sampling the generated asymmetric waveform to obtain a set of data points that is indicative of the generated asymmetric waveform;

arranging the sampled data points in an order according to magnitude;

comparing the arranged sampled data points to template data relating to a desired asymmetric waveform;

in dependence upon the comparison, determining a correction to the generated asymmetric waveform, the determined correction for adjusting at least one of a phase angle difference between the two sinusoidal waves and an amplitude of at least one of the two sinusoidal waves; and

,

adjusting LC tuning electronics of the asymmetric waveform generator in dependence upon the determined correction, so as to control the asymmetric waveform being generated thereby.

2. A method according to claim 1, wherein the generated asymmetric waveform has the general form V(t)=A sin (ω

t)+B sin (2ω

t−

Θ

), where V(t) is the asymmetric waveform voltage as a function of time, A is the amplitude of the first sine wave at frequency ω

, where ω

is the frequency in radians/sec, B is the amplitude of the second sine wave at a frequency 2ω

, and Θ

is a phase angle offset between the first sinusoidal wave and the second sinusoidal wave.

3. A method according to claim 2, wherein the determined correction is for satisfying the condition A+B is equal to a desired asymmetric waveform peak voltage.

4. A method according to claim 3, wherein the determined correction is for satisfying the condition Θ

=π

/2.

5. A method according to claim 4, wherein the determined correction is for satisfying the condition that A/B equals a predetermined value.

6. A method according to claim 3, wherein the determined correction is for satisfying the condition that A/B equals a predetermined value.

7. A method according to claim 2, wherein the determined correction is for satisfying the condition Θ

=π

/2.

8. A method according to claim 2, wherein the determined correction is for satisfying the condition that A/B equals a predetermined value.

9. A method according to claim 2, including the step of repeating the steps of claim 1 in an iterative fashion.

10. A method according to claim 1, comprising a step of obtaining the template data, the template data including a set of data points relating to the desired asymmetric waveform.

11. A method according to claim 10, wherein the step of comparing comprises a step of determining a difference between each arranged sampled data point and a corresponding data point of the template data.

12. A method according to claim 10, wherein the step of obtaining template data comprises the step of retrieving template data from a memory.

13. A method according to claim 10, wherein the step of obtaining template data comprises the step of evaluating V(t)=A sin(ω

t)+B sin (2ω

t−

Θ

) for each one of a plurality of t-values, for determining a first set of data points, and further comprises the step of arranging the first set of data points in an order according to magnitude.

14. A method according to claim 10, wherein the set of data points that is indicative of the generated asymmetric waveform and the template data relating to the desired asymmetric waveform include a same number of data points.

15. A method according to claim 1, wherein the step of sampling is performed as an analog-to-digital sampling for collecting data points contained within one cycle of the generated asymmetric waveform.

16. A method according to claim 1, wherein the step of sampling is performed as an analog-to-digital sampling, for collecting data points from a plurality of portions of the generated asymmetric waveform during a period of time overlapping with a plurality of different cycles of the generated asymmetric waveform.

17. A method according to claim 1, including the step of repeating the steps of claim 1 in an iterative fashion.

18. A storage medium encoded with machine-readable computer program code for controlling an asymmetric waveform generated by an asymmetric waveform generator as a combination of two sinusoidal waves having respective frequencies that differ from each other by a factor of two, the storage medium including instructions for:

obtaining a set of data points that is indicative of the generated asymmetric waveform;

arranging the data points in an order according to magnitude;

obtaining template data including a set of data points relating to a desired asymmetric waveform;

comparing values of data points within a predetermined range of the arranged data points to values of data points within a corresponding predetermined range of the template data;

in dependence upon the comparison, determining a correction to the generated asymmetric waveform, the determined correction for adjusting at least one of a phase angle difference between the two sinusoidal waves and an amplitude of at least one of the two sinusoidal waves; and

,

adjusting LC tuning electronics of the asymmetric waveform generator in dependence upon the determined correction, so as to control at least one of the phase angle difference between the two sinusoidal waves and the amplitude of at least one of the two sinusoidal waves.