A method and apparatus of transmitting signals for segmented access in a communication system is disclosed. The present invention also provides -1–N-methyl-N\u2014-1-phenylethylethylamine and 3–1–1-phenylethylamino)ethylphenol as intermediates of the compound represented by formula, and the use of the compound represented by formula for preparing rivastigmine used for treating Alzheimer disease. At least one of the video frames is identified as being received by each of the video devices based on the received data. The leakage test device is biased to an off state.