METHOD AND DEVICE FOR OPTICALLY TRANSMITTING DATA

• US 20120045221A1
• Filed: 04/28/2010
• Published: 02/23/2012
• Est. Priority Date: 04/28/2009
• Status: Active Grant

• Current Assignee: IP Edge LLC
• Original Assignee: Siemens AG
• Inventors: Walewski, Joachim
• Granted Patent: US 9,319,134 B2
• Time in Patent Office: Days
• US Class Current: 398/191
• CPC Class Codes: H04B 10/1141 One-way transmission

Abstract

In a method for optically transmitting data by means of a pulse-width-modulated light source (LED), a pulse duty factor (N) of a pulse width modulation is specified to set the brightness of the light source (LED). A bright time (T) is divided into at least a first and second partial bright time using at least one blanking so that the data (DATA) to be transmitted are encoded by the start and time length of the at least one blanking. The sum of the partial bright times within the pulse width modulation cycle substantially corresponds to the bright time according to the specified pulse duty factor.

Claims

1. A method for optically transmitting data by means of a pulse-width-modulated light source, comprising:

specifying a pulse duty factor of a pulse width modulation to set the brightness of the light source as a ratio between a blanking time of the light source and a period of a pulse width modulation cycle, wherein a difference between the period and the blanking time corresponds to a bright-up time of the light source within one pulse width modulation cycle, and

with at least one blanking, dividing the bright-up time into at least one first and second partial bright-up time so that the data to be transmitted is encoded by means of the start and time period of the at least one respective blanking,

wherein the sum of the partial bright-up times within the pulse width modulation cycle essentially corresponds to the bright-up time according to the specified pulse duty factor.

2. The method according to claim 1, wherein the light source is a light-emitting diode.

3. The method according to claim 1, wherein the data is exchanged wirelessly with a mobile terminal.

4. The method according to claim 1, wherein the data is transmitted in at least one symbol, and wherein a symbol is defined by at least one binary bit.

5. The method according to claim 1, wherein a value of a symbol is encoded at least partially by an arrangement of the blanking within the pulse width modulation cycle.

6. The method according to claim 1, wherein training sequences containing training symbols are provided at the start of a data transmission.

7. The method according to claim 6, wherein a training symbol is formed by a minimum distance between at least two blankings.

8. The method according to claim 6, wherein a training symbol is formed by a maximum distance between the first and the last blanking.

9. The method according to claim 8, wherein with a pulse duty factor set to zero, an optical power of the light source is increased by a factor which corresponds to a quotient of a time period of the pulse width modulation cycle and of a value of the time period of the pulse width modulation cycle reduced by a time period of the blankings.

10. A device for optically transmitting data by means of a pulse-width-modulated light source comprising:

a data modulation module for receiving data to be transmitted and a settable pulse duty factor of a pulse width modulation as a ratio between a blanking time of the light source and a period of a pulse width modulation cycle, wherein a difference between the period and a blanking time corresponds to a bright-up time of the light source within one pulse width modulation cycle;

wherein, the data modulation module is set up for the definition of at least one blanking by which the bright-up time is divided into at least one first and second partial bright-up time, so that the data to be transmitted is encoded by means of at least one of the start and time period of the at least one respective blanking, so that the sum of the partial bright-up times within the pulse width modulation cycle essentially corresponds to the bright-up time according to the specified pulse duty factor.

11. The device according to claim 10, wherein the light source is a light-emitting diode.

12. The device according to claim 10, wherein the data is exchanged wirelessly with a mobile terminal.

13. The device according to claim 10, wherein the data is transmitted in at least one symbol, and wherein a symbol is defined by at least one binary bit.

14. The device according to claim 10, wherein a value of a symbol is encoded at least partially by an arrangement of the blanking within the pulse width modulation cycle.

15. The device according to claim 10, wherein training sequences containing training symbols are provided at the start of a data transmission.

16. The device according to claim 15, wherein a training symbol is formed by a minimum distance between at least two blankings.

17. The device according to claim 15, wherein a training symbol is formed by a maximum distance between the first and the last blanking.

18. The device according to claim 17, wherein with a pulse duty factor set to zero, an optical power of the light source is increased by a factor which corresponds to a quotient of a time period of the pulse width modulation cycle and of a value of the time period of the pulse width modulation cycle reduced by a time period of the blankings.