Accuracy

The physics of baseball

A ball is moving at its fastest when it leaves the pitcher's hand. The ball loses velocity as it moves away from the pitcher due to air resistance. Generally speaking, a baseball's velocity will drop by approximately 1 MPH for every 7 feet that it travels away from the pitcher's hand.

Radar speed

Radars usually measure the ball's speed just a few feet after it is released from the pitcher's hand. The accuracy of the speed measurement is typically within ± 1 MPH (± 2 KPH).

It is worth noting that ball speed measured by any radar is that of the ball velocity vector directly toward the radar. If the radar is not aligned with the actual flight path of the ball from thrower to receiver, the radar speed-reading will be reduced by the cosine of the angle by which the radar is displaced from the ball travel path. As a rule of thumb, a 10° angle will incurr a 2% speed error.

SPEEDUP Baseball Speed

The SPEEDUP Baseball app measures the speed of the ball as it travels across the camera's horizontal field of view. More precisely, it is the speed of the ball when it is approximately halfway through the camera's horizontal field of view. The accuracy of the speed measurement is typically within ± 2 MPH (± 3 KPH).

Please note that, unlike a radar, the actual flight path of the ball from thrower to receiver does not have a significant impact on the speed measurement accuracy.

speedup Vs radar

If you plan to evaluate the SPEEDUP technology by comparing the speed returned by the SPEEDUP Baseball app versus that estimated by a radar, please beware that on some measurements a speed difference of up to 5 MPH (7 KPH) may be observed due to the following factors :

The speed measured by a radar contains errors : accuracy is typically within ± 1 MPH (± 2 KPH),
The speed measured by the SPEEDUP Baseball app also contains errors : accuracy is typically within ± 2 MPH (± 3 KPH),
The measurement points are not the same : a radar measures the speed of the ball close to release point while the SPEEDUP Baseball app measures the speed of the ball when it is approximately halfway through the camera's horizontal field of view, located about 7 feet (2 meters) ahead of the release point. The contribution of this factor in the speed difference is about 1 MPH (2 KPH).
If the radar is not aligned with the actual flight path of the ball from thrower to receiver, the radar speed-reading will be reduced by the cosine of the angle by which the radar is displaced from the ball travel path. As a rule of thumb, a 10° angle will incurr a 2% speed error.

Example 1 :

True speed at release point : 75 MPH (120 KPH)
True speed at SPEEDUP measurement point : 74 MPH (118 KPH)
The radar overestimates the speed by 1 MPH (2 KPH); The speed returned by the radar will be 75 + 1 = 76 MPH (122 KPH)
The SPEEDUP Baseball app underestimates the speed by 2 MPH (3 KPH); The speed returned by the SPEEDUP Baseball app will be 74 - 2 = 72 MPH (115 KPH), which is 5 MPH (7 KPH) lower than that estimated by the radar.

Example 2 :

True speed at release point : 75 MPH (120 KPH)
True speed at SPEEDUP measurement point : 74 MPH (118 KPH)
The angle by which the radar is displaced from the ball travel path is about 12° leading to an error of about 1 MPH (2 KPH) in the speed estimated by the radar
The radar underestimates the speed by 1 MPH (2 KPH); The speed returned by the radar will be 75 - 1 - 1 = 73 MPH (120 - 2 - 2 = 116 KPH)
The SPEEDUP Baseball app overestimates the speed by 2 MPH (3 KPH); The speed returned by the SPEEDUP Baseball app will be 74 + 2 = 76 MPH (121 KPH), which is 3 MPH (5 KPH) higher than that estimated by the radar.

Please note that the speed difference increases significantly as the angle by which the radar is displaced from the ball travel path increases. This factor may become the primary contributor in the speed difference if it is not carefully adjusted.

field tests

A typical test session consists in throwing balls towards a baseball net and comparing the speed returned by a radar with that measured by the SPEEDUP Baseball app.

As explained above, if the radar is not aligned with the actual flight path of the ball, the radar speed-reading will be reduced by the cosine of the angle by which the radar is displaced from the ball travel path. In order to minimize this effect, the pitcher will try his best to throw the ball towards the radar located behind the net.

Page updated

Google Sites

Report abuse