Abstract: The invention relates to a power providing device (2) for providing power to a plurality of power receiving devices (31), a power distribution system including such power providing device (2), a method for providing power to a plurality of power receiving devices (31) and a corresponding computer program. During standby the power providing device (2) is beneficially supplied with power coming from a power source (1) dedicated or adjusted for the low energy consumption, e.g. a uplink port (23) or a shared power bus. The current drawn from such power source (1) (or the power provided to the downlink power receiving devices (31)) is measured and, for example, the derivative is used in order detecting a current increase just when it starts. This information may be used such the main power supply (29) gets started in order to be available for more power demand than available through the hierarchical powering coming from the standby power source (1).

Abstract: The invention relates to a power providing device (2) for providing power to a plurality of power receiving devices (31), a power distribution system including such power providing device (2), a method for providing power to a plurality of power receiving devices (31) and a corresponding computer program. During standby the power providing device (2) is beneficially supplied with power coming from a power source (1) dedicated or adjusted for the low energy consumption, e.g. a uplink port (23) or a shared power bus. The current drawn from such power source (1) (or the power provided to the downlink power receiving devices (31)) is measured and, for example, the derivative is used in order detecting a current increase just when it starts. This information may be used such the main power supply (29) gets started in order to be available for more power demand than available through the hierarchical powering coming from the standby power source (1).

Abstract: A method of controlling an input signal supplied from an encoder to a modulator, wherein the input signal causes modulation of a current flowing through a light source in order to embed data in light emitted by the light source. The method comprises: for each of a plurality of possible logical transitions allowed by the encoding scheme from an adjacently preceding symbol to a present symbol, determining a respective observed value for the current level of the present symbol; for each of the plurality of logical transitions, determining an associated error between the respective observed value and a corresponding one of a set of nominal values for the current levels; and based on the respective error for each of the plurality of logical transitions, applying a respective compensation to the corresponding input in order to bring the resulting current level closer to the corresponding nominal value.

Abstract: A driver circuit comprising: output circuitry for connecting the circuit to a load, the output circuitry comprising one or more energy-storing components; switching circuitry arranged to supply power from a power supply to the load by supplying a current through at least one of the energy-storing components that resists a change in current, or applying a voltage across at least one of the energy-storing components that resists a change in voltage; and control circuitry arranged to control the switching circuitry, to cause the above-mentioned current or voltage to oscillate between an upper envelope and a lower envelope. The control circuitry is configured to modulate data into this current or voltage by shifting the upper envelope between at least a first amplitude level and a second amplitude level, and by shifting the lower envelope by the same amount in the same direction at the same time.

Abstract: A drive signal is generated, describing a waveform having discrete levels used to represent packets of data interspersed with idle periods, the data being encoded according to an at least three-level code, which is DC-free in that, at least when the data is substantially random, the symbol values average to the value of the zero symbol. The drive signal is used to drive a light source, and thereby transmit the encoded signal embedded in the emitted visible light. At least when the data is substantially random, the levels of the drive signal have a predetermined average DC level during the packets; and the modulation comprises representing the idle periods using a DC-free modulation alternating between a plurality of levels comprising at least a first and a second level, such that over each idle period the levels average to said predetermined DC level of the packets.

Abstract: A driver circuit comprising: output circuitry for connecting the circuit to a load, the output circuitry comprising one or more energy-storing components; switching circuitry arranged to supply power from a power supply to the load by supplying a current through at least one of the energy-storing components that resists a change in current, or applying a voltage across at least one of the energy-storing components that resists a change in voltage; and control circuitry arranged to control the switching circuitry, to cause the above-mentioned current or voltage to oscillate between an upper envelope and a lower envelope. The control circuitry is configured to modulate data into this current or voltage by shifting the upper envelope between at least a first amplitude level and a second amplitude level, and by shifting the lower envelope by the same amount in the same direction at the same time.

Abstract: A method of controlling an input signal supplied from an encoder to a modulator, wherein the input signal causes modulation of a current flowing through a light source in order to embed data in light emitted by the light source. The method comprises: for each of a plurality of possible logical transitions allowed by the encoding scheme from an adjacently preceding symbol to a present symbol, determining a respective observed value for the current level of the present symbol; for each of the plurality of logical transitions, determining an associated error between the respective observed value and a corresponding one of a set of nominal values for the current levels; and based on the respective error for each of the plurality of logical transitions, applying a respective compensation to the corresponding input in order to bring the resulting current level closer to the corresponding nominal value.