Modulation signature trigger

• US 7,816,904 B2
• Filed: 10/09/2007
• Issued: 10/19/2010
• Est. Priority Date: 10/09/2007
• Status: Active Grant

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Torin, Shigetsune
• Primary Examiner(s): VALONE, THOMAS F
• Application Number:
  US11/869,637
• Publication Number:
  US 20090094495A1
• Time in Patent Office: 1,106 Days
• Field of Search: 324/76.12
• US Class Current: 324/76.12
• CPC Class Codes: G01R 13/0254 for triggering, synchronisation
• CPC Class Codes: G01R 23/16 Spectrum analysis; Fourier analysis

Abstract

A trigger generator and trigger method are provided for determining whether or not a signal under test matches a modulation signature. The modulation signature may be provided as a magnitude signature, a phase signature or both. When the magnitude values, phase values, or both of a signal under test are the same as their respective modulation signature, an error computation will be close to zero. If this value is within a threshold value, a trigger signal or other indication of a match is produced.

Claims

1. A test and measurement instrument comprising:

a signal input to obtain magnitude values or phase values corresponding to a signal under test;

a detector to compare the magnitude values, or the phase values against a modulation signature; and

a comparator to generate a trigger signal when a portion of the signal under test matches the modulation signature;

wherein the modulation signature is a phase signature; and

wherein the detector compares the difference between the phase values of the signal under test and the phase signature.

2. The test and measurement instrument of claim 1, wherein the detector applies weighting based upon a magnitude signature corresponding to the phase signature.

3. A method comprising the steps of:

obtaining magnitude values or phase values for a signal under test;

comparing the magnitude values or phase values against a modulation signature; and

indicating that a portion of the signal under test matches the modulation signature;

wherein the step of comparing phase values against a modulation signature further comprises subtracting a phase signature from the phase values to obtain a phase differences signal.

4. The method of claim 3, further comprising calculating a straight line fit to the phase differences.

5. The method of claim 4, further comprising providing a magnitude signature along with a phase signature and applying a weighting factor based upon the magnitude signature when calculating the straight line fit.