| 摘要 |
<p>In a mainsborne control system, part of the electrical mains supply 1 services individual consumers in separate houses 2, 3 and 4 (shown by broken lines). The mains circuit 5, within each house, in connected to a number of electrical appliances, e.g. lights 6, 7, 8, thermostats 9, 10 and electric fire 11. Each appliance has an associated interface unit 6 min etc (but only shown for 6). Each house has a controller 12 13 and 14 respectively, to generate and send selectively control signals to any appliance in that house by suitable coding of the signal. The code signal is a stream of digits divided into elements forming pairs of digits, each digit having one of three carrier states. Each digit pair is permitted to have only some of the possible permutations such that the existence of any other permutation in a signal indicates that that signal has been corrupted.</p> |
