Patent ID: 7456589

Claim:
A method of operating a light source ( 100 ) including a ballast ( 110 ) in electrical communication with a lamp ( 120 ), said method comprising: operating the ballast ( 110 ) to determine ( 920 ) a first average lamp power to be applied to the lamp ( 120 ) during a first data period; operating the ballast ( 110 ) to generate and communicate ( 930 ) a first pulse width modulated drive signal to the lamp ( 120 ) during the first data period, the first pulse width modulated drive signal having one of a first waveform and a second waveform for applying the first average lamp power to the lamp ( 120 ), the first waveform including at least one pulse representative of a first data bit, the second waveform including at least one pulse representative of a second data bit; and operating the lamp ( 120 ) to emit a first modulated light output in response to a reception of the first pulse width modulated drive signal during the first data period, the first modulated light output being representative of the first data bit in response to the first pulse width modulated drive signal having the first waveform, the first modulated light output being representative of the second data bit in response to the first pulse width modulated drive signal having the second waveform.