Radar Gun Fun, Part 1

Demystifying the Radar Gun: What Exactly is a Radar Gun?

This is part one of a three-part series on radar guns. This series will start with explaining what radar is before moving on to common errors and mistakes while using with the final article being an experiment comparing multiple radar systems.

Growth & Uses

Growing up during the 90's and early 2000's, radar guns weren't as prevalent as they are now. As kids, my teammates and I were all fascinated when one would come around during summer tournaments or at the fair with all the other carnival games. Radar guns used to be for the elite talents, the rich, or the top programs in the area. Now you can find them at most events and practices. If you are looking to make scout videos to send off to college coaches, you're going to want to attach velocity readings.

Lighting the radar gun up is the easiest way to make it to the next level *Should be noted this is the WRONG angle to measure velocity*

Speaking of getting scouted, you better be able to light that gun up if you want to go anywhere. This is why they are becoming more common in practice settings. Having a radar gun allows for mechanical adjustments and training programs to be tracked to show improvement (or lack of). Besides just measuring top-end velocity, a radar gun can be used to see the difference between fastball and off-speed pitches. Different coaches will have their preference on what they want the velocity difference to be, but whether it is 8, 9, or 10 mph, you're going to need a radar gun to effectively train for it. Having a radar gun in your tool belt is great for training muscle memory and pitch design.

With radar guns becoming more common and more important, it is vital we understand them. So let’s dig in.

How Does a Radar Gun Measure Velocity?

The change in pitch you hear from a train horn as it passes by is known as the Doppler Effect

You're late for work. You have to rush out the door desperately trying to make up some time. You drive away from your house and as you get to the railroad tracks the lights start flashing and the arms come down. You start cursing because you were so close to making it, but as you sit there you can hear the train horn. As the train gets closer the pitch seems to increase, then after it passes you it decreases. The movement of the train towards (and then away from) you sitting in the car increases (then decreases) the frequency of the sound waves from the train horn. This causes the change in pitch being heard and is known as the Doppler Effect. The radar gun sends out waves at a certain frequency. When these waves come in contact with the baseball moving through the air, some of the waves are reflected back towards the radar like an echo. Due to the Doppler Effect a change in frequency occurs that is proportional to the speed of the ball. This reflected wave is then relayed back to the gun. The gun, programmed with a complex algorithm, calculates the velocity based on the occurring Doppler Effect of the baseball. This is also known as Doppler Radar. Keep in mind that a baseball is slowing down very rapidly due to air resistance. So, the exact time when the radar gets the speed measurement makes a big difference.

What Varies Between Guns?

Doppler Radar is better known for its use by meteorologists in predicting weather forecast by measuring the motion of water particles in the clouds, but this is the same system used by all radar guns. So, if they use the same system to calculate velocity then they should all have equal accuracy, right? Wrong. This will be covered more in the next article, but it all starts with the internal computer that needs to be calibrated just right to be able to calculate the changes in frequency into velocity accurately. Another variable is the frequency of which the radar emits it's radio waves. Measured in gigahertz (GHz), the higher this number is the more cycles per second it does. For reference, standard WiFi operates at 2.4 GHz which is 2.4 billion cycles per second. Some radar guns operate at ten times that amount which is 24 billion cycles per second (24 GHz)! This is one variable that can influence the accuracy along with subjecting the radar gun to interference. After all, we know how frustrating it is when you can't connect to your WiFi, imagine trying to scout the next big thing and your radar gun goes haywire from other interference rendering it useless. These topics will be covered in more detail in the next part of the series as it relates to the errors and common mistakes of radar gun use.

The "Cone"

So now we know that the radar gun "shoots" out radio waves. This makes sense since most of them come in a hand-held form resembling a gun. It is even called pistol style. However, the way the waves shoot out is far from bullet-like.

The "Frame of Capture" resembles a cone like that of a flashlight

Unlike the straight linear line of a bullet, the radio waves that a radar gun shoots out are shaped in more of a cone fashion. Think of yourself in a pitch-black room with just a flashlight on you. When you flip that flashlight on and shine it on the nearest wall, you get a circle of light. As you move closer to the wall, the circle shrinks. The opposite happens when you move away from the wall. This is because the beam from the flashlight is also a cone. So you can expect the radar gun's "frame of capture" to operate in the same fashion as the flashlight beam. The ratio of diameter to height can vary from gun to gun. For reference, the Pocket Radar has a cone ratio of about 3:1. What this really means is that at three feet away the diameter of the cone is 1 foot. If the radar gun is mounted behind home plate, 60 feet away, the radar will have a cone diameter spreading out to 20 feet. Of course, the most accurate reading will be straight in line with the radar beam, but this is just another tease for the second article.

Common Errors & Mistakes

Hopefully, this helps with understanding how radar guns work. Just because we know all about the cone, frame of capture, the frequency of the gun, and what Doppler radar is doesn't mean we know how to use it. Although everything seems straightforward, a radar gun is a piece of technology and slight flaws within each of the setup parameters can affect the radar's ability to get good readings. If these all compounded on each other, someone could end up with a reading that is not so accurate from an otherwise accurate device. It is in everyone's best interest that we go beyond just how they work and learn how to use them properly and avoid mistakes. With that, I couldn't fit everything into one post so stay tuned for our next adventure in a week!