Lighting system having a remotely controlled electric lamp and an infrared remote controller with improved infrared filter

DETAILED DESCRIPTION Accordingly, it is desirable to provide a remotely controlled lighting system which incorporates a commercially available transmitter and receiver and which reliably functions in the presence of infrared noise having frequencies at and near the carrier frequency, and, in particular, in the presence of a fluorescent lamp driven by a high frequency ballast.
According to the invention, a lighting system including a remote control system is provided, wherein the remote control system includes a receiver which is receptive of a transmission signal having a carrier frequency and receptive of infrared noise from an electric lamp having a frequency at and about the carrier frequency.
The receiver demodulates the transmission signal and a filter acts on the demodulated signal to remove noise therein caused by the infrared light from the electric lamp.
Since the filter acts on the demodulated signal, commercially available IR receivers may be used, which lowers system cost.
In another embodiment of the invention, the filter operates on a demodulated signal wherein noise appearing as leading and trailing edges in the demodulated signal is filtered from transmitted information in the transmission signal which comprises data elements also formed of leading and trailing edges.
The filtering is performed by measuring the duration of time between detection of a leading edge and detection of a trailing edge and comparing the duration of time to a predetermined time range defining a data element.
If the measured time range is outside the predetermined time range, the trailing edge will be rejected as noise and scanning will continue until another trailing edge is detected.
In a yet another embodiment of the invention, the demodulated transmission signal includes a first set of data elements and a second, inverted set of data elements in which each data element is the inverted logical equivalent of a respective data element in the first set of data elements and the filter inverts the second inverted set and compares it to the first set