SIGNAL SEARCH IN THREE DIMENSIONAL BITMAPS

• US 20090290793A1
• Filed: 05/22/2009
• Published: 11/26/2009
• Est. Priority Date: 05/22/2008
• Status: Abandoned Application

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Tracy, Robert E., Engholm, Kathryn A.
• Application Number:
  US12/471,126
• Publication Number:
  US 20090290793A1
• Time in Patent Office: Days
• US Class Current: 382/171
• CPC Class Codes: G01R 13/0227 Controlling the intensity or colour of the display
• CPC Class Codes: G01R 13/029 Software therefor
• CPC Class Codes: G06F 2218/10 by analysing the shape of a waveform, e.g. extracting parameters relating to peaks

Abstract

A method for automated searching of signal characteristics represented in a bitmap of an RF test and measurement device is provided. The bitmap is populated via sampling of a time-varying signal, where a first signal characteristic is reflected by an X-axis of the bitmap, a second signal characteristic is reflected by a Y-axis of the bitmap, and a third signal characteristic is reflected by a Z-axis of the bitmap. The method includes: selecting a region of the bitmap. The method further includes generating, for the region, a histogram of Z-values of the bitmap versus Y-values of the bitmap, searching the histogram for any portion in the histogram that meets a predetermined search criteria, and identifying a location of the bitmap corresponding to each portion of the histogram that meets the predetermined search criteria.

Claims

1. A method for automated searching of signal characteristics represented in a bitmap which is populated via sampling of a time-varying signal, where a first signal characteristic is reflected by an X-axis of the bitmap, a second signal characteristic is reflected by a Y-axis of the bitmap, and a third signal characteristic is reflected by a Z-axis of the bitmap, the method comprising:

selecting a region of the bitmap, the region having a plurality of rows and one or more columns;

generating a histogram of Z-values of the bitmap versus Y-values of the bitmap;

searching the histogram for any portion in the histogram that meets a predetermined search criteria; and

identifying a location of the bitmap corresponding to each portion of the histogram that meets the predetermined search criteria.

2. The method of claim 1, further comprising:

displaying the bitmap on a display device.

3. The method of claim 2, further comprising:

displaying a marker at the location of the bitmap corresponding to a selected portion of the histogram that meets the predetermined search criteria.

4. The method of claim 2, further comprising:

displaying a marker at the location of the bitmap corresponding to each portion of the histogram that meets the predetermined search criteria.

5. The method of claim 2, further comprising:

displaying one or more of a first signal characteristic value, a second signal characteristic value, and third characteristic value of the location of the bitmap corresponding to the selected portion of the histogram that meets the predetermined search criteria.

6. The method of claim 1, wherein the predetermined search criteria includes local vertical peaks of the histogram, above a minimum vertical threshold and a minimum horizontal threshold, which pass an excursion test.

7. The method of claim 6, wherein the location of the bitmap corresponding to each of the local vertical peaks in the histogram is positioned at a highest Z-value associated with that local vertical peak.

8. The method of claim 6, wherein the location of the bitmap corresponding to each of the local vertical peaks in the histogram is positioned at a highest Y-value associated with that local vertical peak.

9. The method of claim 1, wherein the first signal characteristic is selected from the group consisting of time and frequency.

10. The method of claim 1, wherein the second signal characteristic is selected from the group consisting of amplitude and phase.

11. The method of claim 1, wherein the third signal characteristic is selected from the group consisting of signal density and time since last hit.

12. The method of claim 1, wherein the first signal characteristic is frequency, the second signal characteristic is amplitude, and the third signal characteristic is density.

13. An RF test and measurement device, comprising:

a front end section for receiving a time-varying signal; and

a data-holding subsystem containing a bitmap generated via sampling of the time-varying signal, the bitmap having an X-axis reflecting a first signal characteristic, a Y-axis reflecting a second signal characteristic, and a Z-axis reflecting a third signal characteristic, the data-holding subsystem further containing executable instructions configured to;

generate, for a selected region of the bitmap, a histogram of Z-values of the bitmap versus Y-values of the bitmap;

search the histogram for any portion of the histogram that meets a predetermined search criteria; and

identify a location of the bitmap corresponding to each portion of the histogram that meets the predetermined search criteria.

14. The device of claim 13, further comprising:

a display device to display the bitmap; and

where the executable instructions in the data-holding subsystem are further configured to;

display, on the display device, a marker at the location of the bitmap corresponding to a selected portion of the histogram that meets the predetermined search criteria; and

display, on the display device, one or more of a first signal characteristic value, a second signal characteristic value, and a third characteristic value of the location of the bitmap corresponding to the selected portion of the histogram that meets the predetermined search criteria.

15. The device of claim 13, wherein the predetermined search criteria includes local vertical peaks of the histogram, above a minimum vertical threshold and a minimum horizontal threshold, which pass an excursion test.

16. The device of claim 13, wherein the first signal characteristic is selected from the group consisting of time and frequency.

17. The device of claim 13, wherein the second signal characteristic is selected from the group consisting of amplitude and phase.

18. The device of claim 13, wherein the third signal characteristic is selected from the group consisting of signal density and time since last hit.

19. A method for automated searching of signal characteristics comprising, at an RF test and measurement device:

receiving a time-varying signal;

populating, via sampling of the time-varying signal, a bitmap displayed by the RF test and measurement device, the bitmap having an X-axis that reflects frequency, a Y-axis that reflects amplitude, and a Z-axis that reflects density;

selecting a region of the bitmap, the region having a plurality of rows and one or more columns;

generating, for the region of the bitmap, a histogram of density values of the bitmap versus amplitude values of the bitmap;

searching the histogram for any local density peak in the histogram, above a minimum density threshold and a minimum amplitude threshold, which passes an excursion test; and

displaying a marker in the bitmap at a location corresponding to one or more local density peaks found in the histogram.

20. The method of claim 19, further comprising:

displaying one or more of a frequency value, an amplitude value, and a density value of the location of the bitmap corresponding to the one or more local peaks found in the histogram.