Method and Apparatus for Scrambling a High Speed Data Transmission

摘要

A method of transmitting high speed serial data with reduced levels of radiated emissions is disclosed. A transmitting device scrambles data utilizing a pseudo-random number sequence generator. Scrambling the data eliminates transmission of repeated data sequences. The transmitting device similarly scrambles idle pairs of data between data transmissions to eliminate an additional source of repeated data sequences. The scrambled and encoded data is transmitted to a receiving device. The receiving device also includes a pseudo-random number sequence generator. Synchronization of the two pseudo-random number sequence generators occurs by utilizing control characters of the data frame being transmitted. Each of the pseudo-random number sequence generators is configured to generate the same sequence of numbers and is initialized to start with a first number in the sequence of numbers corresponding to the first byte of data being transmitted or received.

主权项

1. A system to reduce emissions from a communication bus in an industrial controller, the system comprising:
a transmitting device including a first scrambling element, the transmitting device configured to:
generate a plurality of data packets for transmission via the communication bus,scramble the plurality of data packets with the first scrambling element prior to transmission,insert a plurality of idle pairs between sequential data packets selected from the plurality of data packets, andscramble at least a portion of the plurality of idle pairs inserted between sequential data packets with the first scrambling element prior to transmission; and a receiving device configured to receive the of data packets transmitted via the communication bus, the receiving device including a second scrambling element operative to unscramble the received data packets, wherein the second scrambling element is synchronized with the received data packets.