A controlled lighting system includes an encoding device and a lamp. The encoding device includes a rectifier for rectifying an AC voltage input to result in a rectified signal, and an encoder for generating an encoded signal from the rectified signal and display data. The encoded signal has consecutive signal regions with a waveform of a positive half-cycle of an AC sinusoidal wave or a low potential. The lamp includes a LED unit and a decoding device. The decoding device includes a direct current converter for extracting a direct current voltage from the encoded signal, a detecting circuit for extracting a wave signal from the encoded signal, a processor for generating decoded data related to a light-emitting operation according to the wave signal, and a driver for driving the LED unit according to the direct current voltage from the direct current converter and the decoded data from the processor.