| 摘要 |
PURPOSE:To obtain a mapping method and a decoding method in which quantity of stored data is reduced and to obtain an inexpensive MODEM with less memory capacity. CONSTITUTION:A received 7-bit signal is divided into high-order 4 bits and low-order 3-bits by a divider 100, and the high-order 4 bits are used to generate an address accessing a basic coordinate table by a memory address generator 101 and a basic coordinate point is read from a memory 102. The low-order 3-bits are used for discriminating to which sub-set the signal belongs. In response to the discriminated sub-set, an adder 104 and a rotation device 105 apply mapping such as rotation to the basic coordinate point to obtain the reception signal. |
