For MIL-STD-1553, the definition of the word “channel” depends on the context. Sometimes it refers to a dual redundant data bus. Other times, it refers to the fact that a dual redundant bus includes two “channels”. These two channels are sometimes referred to as “Channel A” and Channel B”.

In other contexts, they’re referred to as the “primary channel” and the “secondary channel” or “backup channel”. In either context, the requirements for a MIL-STD-1553 channel include the electrical, mechanical, and operating characteristics of a serial data communication bus defined by the 1553 channel.