TTL impulse outputs refer to a digital signal that operates at 5 volts when active and 0 volts when inactive. The term "impulse" indicates that the signal briefly goes high before returning low, rather than remaining high continuously. This type of output is commonly used in encoders to convey information in a binary format. Understanding these characteristics is essential for effectively working with devices that utilize TTL outputs. Overall, TTL impulse outputs are straightforward digital signals that convey information through brief voltage changes.