blip

A blip is a transient luminous dot or trace that appears on the display of radar, sonar, or oscilloscope equipment, caused by a signal return from a detected object or electrical event. In radar operation, the blip represents the echo of a transmitted pulse bouncing back from a target, with its position on the screen indicating bearing and range. The term has become generic across electronics, used whenever a brief, localized brightening occurs on a phosphor or LED display in response to an incoming signal.

In power systems and electrical utilities, technicians use blips to identify transient disturbances on oscilloscope traces: voltage spikes, induction events, or switching artifacts that last only microseconds to milliseconds. A blip on a waveform capture may be the only evidence of a fault condition that occurred during a grid event or equipment malfunction. The brevity and small scale of the blip make it easy to miss in live observation, which is why permanent recording and later analysis of stored traces are essential for diagnosing intermittent problems.

Variants and visibility

The visibility of a blip depends entirely on the phosphor persistence of the display tube and the gain settings of the receiver. A fast-decay phosphor, typical of modern CRTs and digital screens, renders blips crisp but transient; older long-persistence tubes would show a fading afterimage that could accumulate across multiple sweeps. In digital systems, blips are captured as data samples and rendered post-acquisition, allowing brightness and duration to be adjusted during review without loss of information.

Confusing a blip with genuine signal is a common source of false alarms in radar, sonar, and condition monitoring. Electromagnetic noise, thermal effects, cable reflections, and photomultiplier tube noise can all produce spurious blips. Filters, signal averaging, and threshold settings help distinguish real targets from electronic artifacts, but sensitivity tuning is always a tradeoff: raise the threshold too high and you miss weak signals; lower it and clutter proliferates. The word itself, probably onomatopoetic in origin, has stuck because it conveys the sudden, punctual character of the phenomenon.