Digital chirp waveform generator and method

• US 7,482,965 B1
• Filed: 12/16/2005
• Issued: 01/27/2009
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Original Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Inventors: Kertis, Robert A., Coker, Jonathan D.
• Primary Examiner(s): Mai; Lam T
• Application Number:
  US11/305,819
• Time in Patent Office: 1,138 Days
• Field of Search: 341144-170
• US Class Current: 341/156
• CPC Class Codes: G06G 7/26 Arbitrary function generators using Fourier series or other orthogonal functions G06G7/19; using curve followers G06K11/02

Abstract

A chirp waveform generator for producing a chirp waveform ƒ(t)=sin (t² modulus m) where modulus m is represented by n submoduli and/or factored submoduli m₁-m_n. Sequence generators generate digital sequence values representative of sequences of quadratic residues for each submoduli and/or factored submoduli m₁-m_n. Sine and cosine digital-to-analog converters (DACs) connected to the sequence generators receive the digital sequence values for each submoduli and/or factored submoduli m₁-m_n and produce sequences of corresponding analog sine and cosine signals. An analog processor including adders and multipliers connected to the DACs combines the sine and cosine signals to produce the chirp waveform. The argument (t² modulus m) is an implemented phase argument that approximates a desired phase argument (πrt²). Programmable inputs on the sequence generators enable control over waveform parameters including starting phase, ramp rate and frequency.

Claims

1. A chirp waveform generator for producing a chirp waveform ƒ

(t)=sin (t² modulus m) where modulus m is represented by n submoduli and/or factored submoduli m₁-m_n, including;

sequence generators for generating digital sequence values representative of sequences of quadratic residues for each submoduli and/or factored submoduli m₁-m_n;

sine and cosine digital-to-analog converters (DACs) connected to the sequence generators, for receiving the digital sequence values for each submoduli and/or factored submoduli m₁-m_n and for producing sequences of corresponding analog sine and cosine signals; and

an analog processor connected to the DACs for combining the sine and cosine signals to produce the chirp waveform.

2. The chirp waveform generator of claim 1 wherein the analog processor includes adders and multipliers.

3. The chirp waveform generator of claim 1 wherein (t² modulus m) is an implemented phase argument that approximates a desired phase argument (π

rt²).

4. The chirp waveform generator of claim 3 wherein the submoduli and/or factored submoduli are relatively small integers.

5. The chirp waveform generator of claim 1 wherein the sequence generators include programmable inputs for controlling the chirp waveform.

6. The chirp waveform generator of claim 5 wherein the programmable inputs enable control over waveform parameters including starting phase, ramp rate and frequency.

7. A sinusoid waveform generator for producing a sinusoid waveform ƒ

(t)=sin (t modulus m) where modulus m is represented by n submoduli and/or factored submoduli m₁-m_n, including;

sequence generators for generating digital sequence values representative of sequences of linear residues for each submoduli and/or factored submoduli m₁-m_n;

sine and cosine digital-to-analog converters (DACs) connected to the sequence generators, for receiving the digital sequence values for each submoduli and/or factored submoduli m₁-m_n and for producing sequences of corresponding analog sine and cosine signals; and

an analog processor connected to the DACs for combining the sine and cosine signals to produce the sinusoid waveform.

8. The sinusoid waveform generator of claim 7 wherein the analog processor includes adders and multipliers.

9. The sinusoid waveform generator of claim 7 wherein (t modulus m) is an implemented phase argument that approximates a desired phase argument (π

rt).

10. The sinusoid waveform generator of claim 9 wherein the submoduli and/or factored submoduli are relatively small integers.

11. The sinusoid waveform generator of claim 7 wherein the sequence generators include programmable inputs for controlling the sinusoid waveform.

12. The sinusoid waveform generator of claim 11 wherein the programmable inputs enable control over waveform parameters including starting phase and frequency.

13. The invention of claim 7 and further including:

a plurality of the sinusoid waveform generators for providing a plurality of sinusoid waveforms; and

a second analog processor for combining the plurality of sinusoid waveforms to produce a non-sinusoidal waveform.