Definition
Electronic systems that represent information using continuously varying physical signals, such as a voltage that rises and falls smoothly to mirror the quantity it is measuring. In VOR navigation receivers, analog systems process the radio signal as a continuous waveform to determine the aircraft's bearing relative to the station.
Plain English
Equipment that handles information as a smoothly changing signal, rather than as a stream of discrete numbers. The signal flows up and down in step with whatever it is measuring.
Context Anchor
Seen in VOR navigation discussions when describing older receivers and cockpit indicators that use moving needles or pointers to show navigation information.
Derivation
From the Greek 'analogos,' meaning 'proportionate' or 'corresponding.' An analog signal corresponds directly and continuously to the thing it represents, which is why the term fits so well: the signal is an analog of reality.
Why Pilots Care
Many legacy aircraft still use analog VOR receivers and analog instruments. Knowing the difference between analog and digital systems helps pilots understand why some indicators respond smoothly while others update in steps, and why troubleshooting procedures differ between older and newer avionics.
Analogy
Think of a dimmer switch on a light. It slides smoothly through every brightness level. That smooth, continuous control is analog. A regular on/off switch, by contrast, is digital -- only two states.
Intuition Check
Analog does not simply mean old or outdated. In this context, it means the information is represented by smooth, continuous changes.
Example Sentence 1
The aircraft's analog VOR receiver drives a needle that swings smoothly as the bearing changes.
Example Sentence 2
Many training aircraft still use analog systems for attitude and heading so students learn to interpret traditional instrument presentations.