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Modulation for coded light transmission

  • US 20130202310A1
  • Filed: 10/19/2011
  • Published: 08/08/2013
  • Est. Priority Date: 10/20/2010
  • Status: Active Grant
First Claim
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1. A light driver (18) for driving at least one light source arranged to emit coded light based on a control signal, the light driver comprising:

  • a receiver arranged to receive a sequence u=[u1, . . . , uk, . . . uK] of source symbols uk representing an information sequence of an information source;

    a processing unit arranged to determine, from the sequence of source symbols, a sequence z=[z1, . . . , zk, . . . , zK] of channel symbols zk forming the control signal;

    a transmitter arranged to provide the at least one light source with the control signal thereby driving the at least one light source;

    wherein the processing unit is arranged to determine the sequence of channel symbols z by mapping each source symbol uk at time k to a composite channel symbol zk=(zk,1, zk,2) comprising at least one first channel symbol zk,1, one of which is identical to uk, and at least one second channel symbol zk,2 having a value chosen from a set M, wherein the value of zk,2 is determined according to a weighting function having the source symbol uk and at least one future and/or past source symbol ui, i≠

    k as input arguments, the weighting function comprising at least two non-zero weighting factors, the mapping resulting in that the power spectral density at frequency zero of the sequence z of channel symbols is equal to zero, and whereinthe control signal thereby enables no visible flicker to be present in coded light emitted by the at least one light source.

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