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ReopeningWed
06-23-2010, 09:58 PM
Hello TW.
My circle of hitting partners and JoeyG recently purchased a radar gun to measure the speed of our shots with.
We de-virginized the radar gun on our serves, and much to my surprise, the first serve I hit was clocked at 102mph.

The fastest serve hit that day was 108, by myself, which surprised me a lot. Until then, I had always believed my fastest serves hovered around 80mph, which leads me to believe that our method of clocking the ball is not accurate.

We had a volunteer stand against the fence, about where a returner would stand had they been on the baseline. From there, 10 feet behind the baseline, the volunteer(today it was JoeyG, sorry about hitting you) would aim the radar gun at the incoming ball, and track it with the gun until the ball would stop moving.

Two things things struck me as odd today. Among us is a teenager about 6'3, who we had considered to possess the biggest serve amongst us(we believed his serve to have gone at least 115 one day where he played particularly well). When his serves were recorded, his serves were only clocked in the upper 80s at best.
The other thing was that some guys would dump the ball into the net or the tape, and the readout would still go in the upper 80s to low 90s.

So my questions would be:

1. What would be the best (most accurate) way to set up the radar gun to measure shot speed?
2. How is the radar gun set up for pro events?
3. What do you think happened with taller teenager and the guys who dumped the ball into the net?

Thanks TW community,
ReopeningWed

spaceman_spiff
06-24-2010, 01:03 AM
Basic radar guns only measure speed in one dimension. So, if you hit the ball straight at the gun at the same angle the gun is aimed, then it will read the correct speed (higher numbers).

However, if you hit at a different angle (the tall guy serving more downward or a wide serve going across the face of the gun), the gun will register a lower number. That's because the gun is only measuring the speed the ball is going relative to the angle of the gun. (Imagine a right triangle where the hypotenuse is your serve; the gun is only measuring the side of the triangle running towards the gun, which is smaller than the hypotenuse.)

So, if you put the gun on the center of the net and hit a 100mph serve straight at it, it should register 100 mph. But, if you hit a 100mph serve out wide, it will register something lower.

That said, most big tournaments use phase-array guns nowadays. They are designed to measure the true speed of a serve no matter the angle it is travelling relative to the gun.

Dave M
06-24-2010, 10:39 AM
you hit a 100mph serve out wide, it will register something lower.

That said, most big tournaments use phase-array guns nowadays. They are designed to measure the true speed of a serve no matter the angle it is travelling relative to the gun.

Thats part of the reason why serve speeds a fair few years ago no suddenly got a lot higher.
Le us know i if you make changes and what difference if any it makes.

spaceman_spiff
06-25-2010, 12:53 AM
Thats part of the reason why serve speeds a fair few years ago no suddenly got a lot higher.

Exactly. If you could go back in time and measure the serves from the past with a phase-array gun, you'd find the guys back then were hitting harder than we all thought.

They weren't really hitting 80-mph slice serves. Their slice serves were simply measuring 80 mph on the old, one-dimensional radar guns.

Geezer Guy
06-25-2010, 01:04 PM
So my questions would be:

1. What would be the best (most accurate) way to set up the radar gun to measure shot speed?
2. How is the radar gun set up for pro events?
3. What do you think happened with taller teenager and the guys who dumped the ball into the net?

1) Position the gun near the center strap (behind the net for safety, if it can shoot through the net) and aim serves down the T.
2) I believe it's placed on the rear wall, behind the center hash mark.
3) You can hit the ball just as hard into the net as you can over the net. I've heard the serve speed is measured in the first 10 feet after the ball is struck.