| 摘要 |
An input (1) is provided for data in clear text from the transmitter. An outlet (2) for encoded information, a mixer (3) consisting of an EXOR grid, a coder (4) for production of code bit sequences, and components (6,7,8) for selection control are also included. The coder, which has an input connected to the mixer output, comprises a 16-bit shift register (9), a memory (5), which may be a byte-organised ROM or EPROM, and a multiplexer (10). The thirteen first bits of the shift register are connected to the memory address inputs and its last three bits are coupled to the address inputs of the multiplexer. The outputs of the memory are connected to the inputs of the multiplexer. Selections may be made as to whether an incoming data bit shall be encoded or not, and whether an encoded bit shall be loaded into the register or not. Choice is controlled by a programmable control (8). For each word bit, a signal is sent to the grid inputs for appropriate choice determn. One grid (7) receives on its other input a code bit from the multiplexer, and has its outlet connected to the mixer. The other grid (6) output is connected to an activation input on the register. |
