How Exactly Does DRS Technology Work?

Technical explanation of how Snickometer and Ultra-Edge work during DRS.

The decision Review System (DRS) is something that always comes under the scanner in a professional match in one way or the other. Due to it being a very complex system, most people don't always get what they see on the replays. 

Warren Brennan is the founder and chief technology officer of BBG Sports where he developed the Hotspot/RTS system for spotting edges with Allan Plaskett. In a Cricketingview podcast, Brennan explained how exactly the system works and why we see what we see on the TV. 

While talking about the Snickometer, Brennan talked about the problem with only using Snickometer to find the edge. 

"In Snickometer, you don't actually know from where the noise comes from: there could be a movement of the keeper behind the stumps just as the ball is going past the bat; it becomes difficult against slow bowlers. It is very difficult to differentiate," Brennan said. 

"When the ball comes off the glove, you'll get a much smaller spike and generally a bit wider; a thuddy type noise. Whereas ball on bat if it's come off the side of the bat you'll get much more of a spike. What we've also found particularly through T20 cricket is when they play those paddle shots you almost get no noise at all even if it's off the bat because of the angle of the bat.

"We've found that using Snicko and hotspot together is the only way that we're comfortable trying to find the best decision," Brennan added. 

Brennan said that cameras need to be perfectly synchronized for the umpires to make a decision. He talked about the lightning and thunder phenomenon: light travels faster than sound. The phenomenon works in this system as well which means that if the cameras are not synced then it won't be possible to catch the sound and the spike at the same time. 

"There are a couple of things that are really paramount with the system. the first thing is the synchronization of the cameras has to be absolute and that's the most important thing. All of the cameras have to be perfectly synchronized." 

"The other part of the system that's very very important is to come up is the video and audio offset that must remain throughout the day so one of the really big things that we constantly do every ball."

He said the RTS technology calibrates due to the light and sound scenario which might not be necessary in the case of ultra-edge technology. 

"Our Snickometer operator winds back every ball and when there's a bat on the ball we check the sync. The key to our system which is different from the Ultra Edge is that we calibrate it because of the lightning and thunder scenario. 

"We calibrate the system so that the noise in the graph will not show until the ball is clearly past the bat because the sound can't appear before the bat it's just not possible. Our calibration setup is noise has to be one frame past the ball going past the bat and that's what we've told the ICC and they've told their umpires and most of the time they get that right," Brennan said. 

Real-Time Snicko During AUS vs IND Test series

Basically what this means is that when there is a case where there is the availability of RTS technology, you'll see video and Snickometer side by side which gives a better case for umpires to make a decision. The Snickometer is set one frame after the ball goes past the bat which gives a perfect sync to the noise and video.  

In IPL 2022, ultra-edge technology is being used. As per Warren Brennan, the ultra-edge have a different measurement for this scenario. This podcast was from 2021 which means if there were any technical changes post this conversation, we might not know but the basic idea of how a computer identifies an edge and the umpire sees is this.