UltraEdge and Snickometer Explained: How Cricket Detects Bat Edges

UltraEdge (also known as Snickometer in its earlier form) is the technology used in the Decision Review System (DRS) to determine whether a cricket ball has made contact with the bat or not — specifically for caught-behind and LBW decisions where an edge may or may not have occurred. It is a sound-wave analysis tool: microphones embedded in the stumps or near the pitch pick up the sound of the ball; this sound is displayed as a waveform on a TV monitor; when the waveform shows a 'spike' (a sharp increase in audio amplitude) at the exact moment the ball passes the bat, it indicates contact.

How UltraEdge Works: The Waveform

UltraEdge technology: (1) Audio microphones are installed in the stumps (stump microphones) — these pick up sounds from the immediate playing environment including bat-on-ball contact; (2) The audio signal is displayed as a waveform in real time — a flat line indicates silence; peaks indicate sounds; (3) The time of ball delivery (from the bowler's release) is tracked via ball-tracking software; when the ball reaches the bat's zone (identified via the ball-tracking path), the waveform at that precise time is examined; (4) A 'spike' on the waveform at the exact moment the ball passes the edge of the bat indicates an edge; a flat line at that moment indicates no contact. Third umpire process: the third umpire watches the ball-tracking replay with the UltraEdge waveform overlay; if there is a clear spike at the moment of bat-passage, the edge is confirmed; if flat, no edge is confirmed; if ambiguous, the on-field decision stands.

UltraEdge vs Hot Spot vs the Original Snickometer

Three generation of edge-detection tools: (1) Snickometer (1999-2009, broadcast-only): the original waveform tool, invented by Allan Plaskett. Used only for broadcast replays — not connected to on-field decisions. The Snickometer was often reviewed after the match to determine if decisions were correct, but could not affect the match outcome. (2) Hot Spot (thermal imaging, 2009-2015): an infrared camera system that showed heat generated by friction between ball and bat/pad. An edge created a heat signature on the bat face or edge. Limitation: Hot Spot required significant friction to generate a detectable heat mark — thin edges or glancing contact sometimes left no mark despite an edge. 2015 controversy: multiple decisions in the 2015 Ashes showed Hot Spot missing thin edges (particularly Stuart Broad being given not out in the 1st Test — he had edged the ball but Hot Spot showed no mark). (3) UltraEdge (2015-present): replaced Hot Spot as the primary edge-detection tool; audio waveform analysis is more sensitive than thermal imaging for thin edges. Limitation: UltraEdge can pick up pad sounds (ball hitting pad without bat contact) that can be confused with edge spikes if the ball-bat proximity is very close.

UltraEdge Limitations

UltraEdge is not infallible — known limitations: (1) Pad sound confusion: when the ball strikes the pad very close to the bat, the pad-impact sound can create a waveform spike that coincides with the ball-bat proximity window — appearing to show an edge when there was none. Third umpires are trained to distinguish pad spikes (typically broader, lower frequency) from bat spikes (sharper, higher frequency), but ambiguous cases remain difficult; (2) Environmental noise: if a stump microphone picks up crowd noise, wind, or other environmental sounds at the precise moment of ball passage, the waveform can be misleading; (3) Stump microphone positioning: a ball that passes the bat several centimetres from the stump microphone generates a weaker signal than a ball passing the bat when the stump microphone is closer — the distance of the edge from the microphone affects signal strength and waveform clarity. Despite these limitations, UltraEdge is considered the most reliable edge-detection tool available in 2024.