For the hackers among us, here is the X10 wireless protocol. This document should be viewed in a mono-spaced font. The carrier is at a nominal frequency of 300 Mhz. The envelope of the carrier is sketched below.
Time progresses from left to right.
A '1' is sampled when the envelope goes high for 0.4msec and then returns low for 0.7msec. 4,3,1 from byte 1, and bit 5 from byte 3 above, add '1' to this, and you will have the unit number. We consider the most significant bit to be transmitted first and on the left, thus the upper nibble is to the left of the lower nibble. Note that the upper nibble of byte 1 is the complement of byte 2, and the lower nibble is the same. This same relationship holds for byte 3 and 4.