# US 8,432,438 B2 · Device for dimming a beacon light source used in a light based positioning system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,432,438 B2 - Document ID: US8432438B2 - Status: Granted - Kind: B2 - Application number: 13/526,812 - Filed: 2012-06-19 - Published: 2013-01-31 - Granted: 2013-04-30 - Earliest claimed: 2011-07-26 - Assignees: Bytelight, Inc. - Applicants: Daniel Ryan; Aaron Ganick - Inventors: Daniel Ryan; Aaron Ganick - Web page: https://patentgrep.com/patent/US8432438B2 ## CPC - H05B 47/195: the transmission using visible or infrared light - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract In one aspect, the present disclosure relates to a dimmable beacon light source for a light based positioning system. In some embodiments, the light source includes a dimmer control switch configured to generate a dimmer signal having a desired light output level, a dimmable driver for controlling the light output of the light source, and a modulator for receiving the dimmer signal from the dimmer control switch, generating a digital pulse recognition signal by controlling the frequency of the dimmer signal to a desired frequency value, and transmitting the digital pulse recognition signal to the dimmable driver to drive the light output of the light source. In some embodiments, the digital pulse recognition signal is a pulse width modulated signal. In some embodiments, the digital pulse recognition signal has a duty cycle based on the dimmer signal. ## Claims ### Claim 1 A dimmable beacon light source for a light based positioning system comprising: a dimmer control switch configured to generate a dimmer signal having a desired light output level; a dimmable driver for controlling the light output of the light source; and a modulator for receiving the dimmer signal from the dimmer control switch, generating a digital pulse recognition signal by controlling the frequency of the dimmer signal to a desired frequency value, and transmitting the digital pulse recognition signal to the dimmable driver to drive the light output of the light source, wherein the modulator comprises: a digital pulse recognition tone generator for receiving binary data from an information source and converting the binary data into one or more digital pulse recognition tones representing the desired frequency value; and a waveform generator for using the one or more digital pulse recognition tones and the dimmer signal to generate the digital pulse recognition signal. ### Claim 2 (depends on 1) The light source of claim 1, wherein the digital pulse recognition signal comprises a pulse width modulated signal. ### Claim 3 (depends on 1) The light source of claim 1, wherein the digital pulse recognition signal has a duty cycle based on the dimmer signal. ### Claim 4 (depends on 1) The light source of claim 1, wherein the frequency of the digital pulse recognition signal is based on the one or more digital pulse recognition tones. ### Claim 5 (depends on 1) The light source of claim 1, wherein the one or more digital pulse recognition tones are chosen from a set of possible digital pulse recognition tones and the set of possible digital pulse recognition tones comprises a minimum frequency, a maximum frequency, and are separated by a minimum frequency step interval. ### Claim 6 (depends on 5) The light source of claim 5 wherein the minimum frequency, the maximum frequency, and the minimum frequency step interval are chosen based on the frequency response of the light source and the sampling time of a target imaging sensor. ### Claim 7 (depends on 1) The light source of claim 1, wherein the digital pulse recognition tone generator comprises an encoder for mapping the binary data to one or more digital pulse recognition tones. ### Claim 8 (depends on 1) The light source of claim 1, wherein the one or more digital pulse recognition tones are chosen based on pre-computed mappings between the binary data and the digital pulse recognition tones. ### Claim 9 (depends on 1) The light source of claim 1, wherein the one or more digital pulse recognition tones are computed based on the binary data after receipt of the binary data from the information source. ### Claim 10 (depends on 1) The light source of claim 1 wherein the waveform generator combines the one or more digital pulse recognition tones with a periodic symbol created by a symbol creator to generate the digital pulse recognition signal. ### Claim 11 (depends on 10) The light source of claim 10, wherein the symbol created by the symbol creator is selected from a set of symbols by a symbol selector. ### Claim 12 (depends on 11) The light source of claim 11, wherein the set of symbols comprises a saw tooth wave, a sine wave, a square wave, and a square wave with a DC offset. ### Claim 13 (depends on 1) The light source of claim 1, wherein the digital pulse recognition signal has an average output determined by the dimmer signal. ### Claim 14 (depends on 1) The light source of claim 1, wherein the digital pulse recognition signal comprises a hard-coded average output. ### Claim 15 (depends on 1) The light source of claim 1, wherein the dimmable driver comprises the modulator. ### Claim 16 (depends on 1) The light source of claim 1, wherein the dimmable driver converts the digital pulse recognition signal to a pulse width modulated signal to control the output of the light source. ### Claim 17 (depends on 1) The light source of claim 1, wherein the digital pulse recognition signal has a pulse width causing the light output to be substantially the same as the desired light output of the dimmer signal. ### Claim 18 (depends on 1) The light source of claim 1, wherein the dimmer signal is generated by a triac dimmer. ### Claim 19 (depends on 1) The light source of claim 1, wherein the binary data comprises an arbitrary identifier for the light source. ### Claim 20 (depends on 1) The light source of claim 1, wherein the modulator sends the digital pulse recognition signal to the dimmable driver using an override input of the dimmable driver. ### Claim 21 (depends on 20) The light source of claim 20, wherein the dimmable driver receives and ignores the dimmer signal based on receiving the digital pulse recognition signal using the override input of the dimmable driver. ### Claim 22 (depends on 1) The light source of claim 1, wherein the light output of the light source is emitted by a light-emitting diode (LED).