Spectrogram mask trigger

• US 20060025947A1
• Filed: 07/29/2004
• Published: 02/02/2006
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Earls, Jeffrey D.
• Granted Patent: US 7,873,486 B2
• Time in Patent Office: Days
• US Class Current: 702/76
• CPC Class Codes: G01R 13/0254 for triggering, synchronisation
• CPC Class Codes: G01R 23/16 Spectrum analysis; Fourier analysis

Abstract

A spectrogram mask trigger is generated in response to multiple or complex frequency events within a signal being monitored. A sequence of frequency masks over a period of time is generated according to a frequency trajectory, frequency hops or other complex frequency events expected in the signal to form a spectrogram mask. The spectrogram mask is then applied to multiple spectra or spectrogram of the signal to determine whether an anomalous frequency event has occurred within the time period or to identify a particular frequency pattern within the signal. Depending upon the results of the spectrogram mask application, the spectrogram mask trigger is generated for storing a block of data from the signal surrounding the triggering event for further analysis.

Claims

1. An apparatus for generating a spectrogram mask trigger comprising:

means for generating a spectrogram of an input signal having a plurality of spectra; and

means for comparing the spectrogram with a spectrogram mask having a sequence of frequency masks over a specified time period to generate the spectrogram mask trigger.

2. The apparatus as recited in claim 1 wherein the generating means comprises means for updating the spectrogram when a new spectrum is received for the input signal.

3. The apparatus as recited in claim 1 wherein the spectrogram mask trigger is generated when the spectrogram violates the spectrogram mask in the comparing means.

4. The apparatus as recited in claim 1 wherein the spectrogram mask trigger is generated when the spectrogram satisfies the spectrogram mask in the comparing means.

5. A method of generating a spectrogram mask trigger comprising the steps of:

building a spectrogram having multiple spectra for an input signal; and

comparing the spectrogram with a spectrogram mask having a sequence of frequency masks over a specified time period to generate the spectrogram mask trigger.

6. The method as recited in claim 5 wherein the building step comprises the step of updating the spectrogram when a new spectrum for the input signal is received.

7. The method as recited in claim 5 wherein the spectrogram mask trigger is generated in the comparing step when the spectrogram violates the spectrogram mask.

8. The method as recited in claim 5 wherein the spectrogram mask trigger is generated in the comparing step when the spectrogram satisfies the spectrogram mask.

9. The method as recited in claim 5 wherein the spectrogram mask comprises a sequence of frequency masks that define a specific sequence of frequency hops in a frequency hopping signal.

10. The method as recited in claim 5 wherein the spectrogram mask comprises a sequence of frequency masks that provide for expected spectral splatter at the beginning and end of a pulse signal caused by turn-on and turn-off transients in an amplifier.

11. The method as recited in claim 5 wherein the spectrogram mask comprises a sequence of frequency masks that define an expected frequency trajectory of a carrier in the input signal.

12. A spectrogram mask for use in a spectrogram mask trigger generator comprising a sequence of frequency masks defining amplitude and frequency boundaries for comparing with a spectral representation of an input signal over a period of time.