| 摘要 |
PURPOSE:To convert a linear PCM code which is displayed with a complement of 2 into a nonlinear PCM code of a mu law including the bit steal with use of three ROMs of 256 words X4 bits. CONSTITUTION:The lower 13 bits (b'2, b'3-b'14) of 14 bits of a linear PCM code displayed with a complement of 2 of an input are connected to the input of one side of EX-OR1-13 respectively. The highest bit b'1 is fed to the other input. An adder 14 of 13 bits adds ''33'' in the normal mode and then adds ''34'' in the bit steal mode. The addition of ''33'' or ''34'' is selected by a 2-1 selector 15. The output of the adder 14 is applied to ROMs 17, 18 and 19 of 256 words X4 bits except the lowest bit b'14. In such way, a linear PCM code is converted into a nonlinear PCM code. |
