System and method of signal processing for use in reading data

• US 6,956,962 B1
• Filed: 05/07/2002
• Issued: 10/18/2005
• Est. Priority Date: 05/07/2002
• Status: Expired due to Fees

• Current Assignee: Digital Check Corp
• Original Assignee: Unisys Corporation
• Inventors: Hayosh, Thomas D.
• Primary Examiner(s): Werner, Brian
• Assistant Examiner(s): Patel, Shefali
• Application Number:
  US10/140,587
• Time in Patent Office: 1,260 Days
• Field of Search: 382137-140, 382/278, 382/265, 382/182, 382/207
• US Class Current: 382/139
• CPC Class Codes: G06V 30/2253 Recognition of characters printed with magnetic ink G06V30/2247 takes precedence

Abstract

A method of signal processing for use in reading data includes determining first and second waveforms, determining a cross-correlation of the first waveform with the second waveform, and determining a specific time delay corresponding to a maximum peak in the cross-correlation function. A filter is then applied based on the specific time value. The filter combines the first waveform and the second waveform so as to generate a filter output waveform including coherent information representing the data and including reduced incoherent noise.

Claims

1. A method of signal processing for use in reading data, the method comprising:

determining a first waveform by reading the data, the first waveform including coherent information representing the data and including incoherent noise;

determining a second waveform by reading the data at a different time than the first reading, the second waveform including coherent information representing the data and including incoherent noise;

determining a cross-correlation of the first waveform with the second waveform as a function of time delay;

determining a specific time delay corresponding to a maximum peak in the cross-correlation function; and

applying a filter based on the specific time delay, the filter combining the first waveform and the second waveform so as to generate a filter output waveform including coherent information representing the data and including reduced incoherent noise.

2. The method of claim 1 wherein the first and second waveforms are determined by reading the data with a dual head magnetic ink character recognition reader having a first head and a second head, the first head and the second head defining a distance therebetween.

3. The method of claim 2 further comprising:

determining a velocity based on the specific time delay and the distance between the first head and the second head; and

scaling the filter output waveform based on the velocity.

4. The method of claim 3 further comprising:

recognizing a magnetic ink character based on the scaled filter output waveform.

5. The method of claim 1 wherein the first waveform is represented by variable vector f, the second waveform is represented by variable vector g, and the cross-correlation, R, is determined substantially according to:

$R_{\mathrm{\tau <br><br>}}=\frac{1}{K}<br><br>\underset{k=0}{\overset{K-1}{\sum <br><br>}}<br><br>f_k·<br><br>g_{k+\mathrm{\tau <br><br>}}$

where K is a total number of samples, and τ

is the time delay.

6. The method of claim 5 wherein the filter output waveform is represented by variable vector c, and is determined substantially according to:

C_k=|f_k|·

g_k+τ

for τ

=the specific time delay.

7. The method of claim 6 wherein the first and second waveforms are determined by reading the data with a dual head magnetic ink character recognition reader having a first head and a second head, the first head and the second head defining a distance therebetween.

8. The method of claim 7 further comprising:

determining a velocity based on the specific time delay and the distance between the first head and the second head; and

scaling the filter output waveform based on the velocity.

9. The method of claim 8 further comprising:

recognizing a magnetic ink character based on the scaled filter output waveform.

10. A system for use in reading character data printed in magnetic ink, the system comprising:

a dual head magnetic ink character recognition reader having a first head and a second head, the first head and the second head defining a distance therebetween;

a circuit for determining a first waveform when the first head reads the data, the first waveform including coherent information representing the data and including incoherent noise, and for determining a second waveform when the second head reads the data at a different time than the first reading, the second waveform including coherent information representing the data and including incoherent noise;

correlation computation logic for determining a cross-correlation of the first waveform with the second waveform as a function of time delay, and for determining a specific time delay corresponding to a maximum peak in the cross-correlation function; and

a filter based on the specific time delay, the filter combining the first waveform and the second waveform so as to generate a filter output waveform including coherent information representing the data and including reduced incoherent noise.

11. The system of claim 10 further comprising:

processing logic for determining a velocity based on the specific time delay and the distance between the first head and the second head, and for scaling the filter output waveform based on the velocity.

12. The system of claim 11 further comprising:

recognition logic for recognizing a magnetic ink character based on the scaled filter output waveform.

13. The system of claim 10 wherein the first waveform is represented by variable vector f, the second waveform is represented by variable vector g, and the cross-correlation, R, is determined substantially according to:

$R_{\mathrm{\tau <br><br>}}=\frac{1}{K}<br><br>\underset{k=0}{\overset{K-1}{\sum <br><br>}}<br><br>f_k·<br><br>g_{k+\mathrm{\tau <br><br>}}$

where K is a total number of samples, and τ

is the time delay.

14. The system of claim 13 wherein the filter output waveform is represented by variable vector c, and is determined substantially according to:

C_k=|f_k|·

g_k+τ

for τ

=the specific time delay.

15. The system of claim 14 further comprising:

processing logic for determining a velocity based on the specific time delay and the distance between the first head and the second head, and for scaling the filter output waveform based on the velocity.

16. The system of claim 15 further comprising:

recognition logic for recognizing a magnetic ink character based on the scaled filter output waveform.