What is the oldest format used for alarm transmission?

• A. Wired signaling
• B. Digital signaling
• C. Radio frequency signaling
• D. Pulse signaling

Answer: (D)

The oldest way alarms were transmitted is through pulse signaling. This method uses basic on/off electrical pulses to convey an alarm event over a line. It’s the simplest form of signaling, relying on a sequence of pulses rather than any digital encoding or wireless transmission. Because it predates digital coding and radio transmissions, pulse signaling represents the earliest approach to sending alarm information from the site to a monitoring center. Over time, systems evolved to more complex wired signaling with coded patterns, then to digital signaling, and finally to wireless options like radio frequency signaling. So pulse signaling is the foundational, earliest format among these methods.