What is indicated by a distinctive trouble signal in alarm systems?

A distinctive trouble signal in alarm systems serves to inform the user that a malfunction exists within the system. This signal is designed to alert technicians or users that there is an issue requiring attention, which could range from a device not functioning properly to a wiring fault. Unlike routine alarm signals that indicate a system's normal functioning or emergency conditions, a trouble signal specifically denotes that some part of the system is not operating as intended.

In contrast, signals indicating that the system is in test mode, functioning correctly, or that the power supply is fully charged do not carry the same implication of malfunction. These signals are essential in maintaining the overall reliability and effectiveness of fire alarm systems, ensuring that any potential problems can be addressed promptly to maintain safety standards.