Static RF imaging for inside walls of a premises

• US 8,077,072 B2
• Filed: 12/29/2009
• Issued: 12/13/2011
• Est. Priority Date: 09/03/2009
• Status: Active Grant

• Current Assignee: TiaLinx, Inc.
• Original Assignee: TiaLinx, Inc.
• Inventors: Mohamadi, Farrokh, Nag, Soumya K.
• Primary Examiner(s): Brainard, Timothy A
• Application Number:
  US12/649,268
• Publication Number:
  US 20110050479A1
• Time in Patent Office: 714 Days
• Field of Search: 342/22, 342/176, 342/191
• US Class Current: 342/22
• CPC Class Codes: G01S 13/888 through wall detection
• CPC Class Codes: G01S 13/89 for mapping or imaging

Abstract

A system includes a radar unit configured to provide raw data from scanning an exterior of a structure; and a signal processing and imaging module configured to: process the raw data into markers of interior locations of the structure; and display an image of interior structural features based on the markers. A method includes: scanning a building structure from the exterior of the structure using a radar unit to provide raw data; processing the raw data into markers of interior locations of the structure; estimating locations of interior structural features of the structure from the markers; and displaying an image of the interior structural features.

Claims

1. A system comprising:

a radar unit configured to provide raw data from scanning an exterior of a structure, wherein the raw data from scanning is provided from multiple scan locations; and

a signal processing and imaging module configured to;

process the raw data into markers of interior locations of the structure;

populate an image grid having a first axis and a second axis with wall-coordinate pixels estimated from the multiple scan locations;

demarcate an interior wall of the structure from the wall-coordinate pixels by a line passing through the first axis at a fixed pixel location on the first axis and parallel to the second axis if the wall-coordinate pixels along the line satisfy a pre-determined criterion; and

display an image of interior structural features based on the markers.

2. The system of claim 1, wherein:

the signal processing and imaging module is further configured to form a 2-dimensional binary image from coordinates of the markers.

3. The system of claim 1, wherein the signal processing and imaging module is further configured to:

form a 2-dimensional binary image from coordinates of the markers; and

form an image of interior structural features based on the 2-dimensional binary image.

4. The system of claim 1, wherein:

the pre-determined condition is satisfied if the number of wall-coordinate pixels along the line that are those of marker coordinates exceeds a specified number N_p.

5. The system of claim 1, wherein:

a coordinate of the image grid is determined to be a marker coordinate based on an average waveform amplitude of the raw data that falls within a range bin exceeding a suitable threshold T₀.

6. A method comprising:

scanning a building structure from the exterior of the structure using a radar unit to provide raw data;

processing the raw data into markers of interior locations of the structure, further comprising;

summing waveforms of the raw data from multiple locations;

smoothing the summed waveforms using a moving average filter into an integrated waveform;

determining clusters of markers based on a threshold detector applied to the integrated waveform;

assigning each cluster a single marker at the center of the cluster based on a criterion that clusters of markers are separated from each other by at least a pre-chosen distance parameter R_{cluster, min};

estimating locations of interior structural features of the structure from the markers; and

displaying an image of the interior structural features.

7. The method of claim 6, wherein:

the threshold detector comprises comparing the amplitude of the integrated waveform to a suitable threshold T₀.

8. The method of claim 6, wherein:

the threshold detector comprises an adaptive threshold detector, based on a constant false alarm rate (CFAR) estimation for a given false alarm rate.