RECONSTRUCTING LIGHT-BASED COMMUNICATION SIGNALS CAPTURED WITH A ROLLING SHUTTER IMAGE CAPTURE DEVICE

• US 20170093489A1
• Filed: 09/30/2015
• Published: 03/30/2017
• Est. Priority Date: 09/30/2015
• Status: Active Grant

• Current Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Breuer, Christian, Aggarwal, Anant, Stout, Barry
• Granted Patent: US 9,742,493 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H04B 10/54 Intensity modulation
• CPC Class Codes: H04B 10/67 Optical arrangements in the receiver
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS

Abstract

Methods and systems are described for sampling an LCOM message and accurately reconstructing the entire LCOM message using a light receiver (e.g., digital camera) of a typical mobile computing device, such as a smartphone, tablet, or other mobile computing device. These including receiving segments of an LCOM signal from at least two repetitions of the LCOM signal. The location of each segment within the LCOM signal is identified and each segment is stored in a corresponding location in a buffer configured to have a length equal to the LCOM signal. The buffer is a ring buffer, in some embodiments.

Claims

1. A method for reconstructing light-based communication signals, the method comprising:

determining a signal length of a light-based communication signal;

configuring a buffer to match the determined signal length;

capturing a plurality of segments of the light-based communication signal from at least two repetitions of the light-based communication signal;

identifying, upon capturing each segment of the plurality of segments of the light-based communication signal, a location of each segment within the signal; and

storing each captured segment of the plurality at a storage location of the buffer corresponding to the location of each segment within the signal.

2. The method of claim 1, wherein determining the signal length of a light-based communication signal comprises decoding a metadata header that includes the signal length.

3. The method of claim 1, wherein determining the signal length of a light-based communication signal comprises:

identifying a starting location and an ending location of the light-based communication signal; and

determining the message length based on the identified starting location and ending location of the light-based communication signal.

4. The method of claim 1, further comprising indexing the configured buffer to include storage locations corresponding to locations within the light-based communication signal.

5. The method of claim 1, wherein the capturing the plurality of segments further comprises:

adjusting a capture frequency to sequentially capture the light-based communication signal in a number of frames equal to a ratio of a signal length divided by a capture window length.

6. The method of claim 1, wherein capturing the plurality of segments is performed using a rolling shutter image capture device.

7. The method of claim 1, wherein the buffer is a ring buffer.

8. A computer program product wherein the computer program product is stored on at least one non-transitory computer-readable medium that includes instructions that, when loaded into memory, cause at least one processor to perform a method, the method comprising:

determining a signal length of a light-based communication signal;

configuring a buffer to match the determined signal length;

capturing a plurality of segments of the light-based communication signal from at least two repetitions of the light-based communication signal;

identifying, upon capturing each segment of the plurality of segments of the light-based communication signal, a location of each segment within the signal; and

storing each captured segment of the plurality at a storage location of the buffer corresponding to the location of each segment within the signal.

9. The method of claim 8, wherein determining the signal length of a light-based communication signal comprises decoding a metadata header that includes the signal length.

10. The method of claim 8, wherein determining the signal length of a light-based communication signal comprises:

identifying a starting location and an ending location of the light-based communication signal; and

determining the message length based on the identified starting location and ending location of the light-based communication signal.

11. The method of claim 8, further comprising indexing the configured buffer to include storage locations corresponding to locations within the light-based communication signal

12. The method of claim 8, wherein the capturing the plurality of segments further comprises:

adjusting a capture frequency to sequentially capture the light-based communication signal in a number of frames equal to a ratio of a signal length divided by a capture window length.

13. The method of claim 8, wherein capturing the plurality of segments is performed using a rolling shutter image capture device.

14. The method of claim 8, wherein the buffer is a ring buffer.