Pocket Radar - My Ultimate tool for checking accurancy - Or how to use video to clock speed !

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Sep 29, 2015
26
3
Hello everybody, (sorry for my french English :)
Since many years I clock myself using the 240 fps video of my iPhone.
But now I'm going to get a POCKET RADAR to make it easier on me.
Since IMO this is the best forum for Softball; from which I learned a lot, I came here (and there also, I admit) to check for reviews on different Radars...
And oh my, HO MY, how many different opinions there are, some confusing and others evidently coming from people who don't get the point!
I read about exit velocitys and decrease of speed during the flight of the pitch.
I read cosine effect etc.
And this lead me to figure out how to pin point my method, and that is what I did and I'm about to share here.
This will help me, next week, to check my Pocket Radar unit (ball coach model) and I will make an attempt to check once and for all its accurancy.
I did this for ATHLA Velocity also, and somedays it is ok but some others (same light / same setting etc.) the app is everywhere in its readings !

So here is how I did proceed:
0/ Camera (iPhone 6 for me) is setted to shoot at 240 fps (you can do all that follows with a 60 fps cam also but tha margin of error will go from 0.25 miles to 1!)
1/ I place the camera in order to shoot a true profile as much as I can. I pitch against a wall at the exact distance (see 2/) since a glove catcher is proe to move on certain pitchs.
2/ First red marker (see pics and/or videos) is 10 feet away from the pitching plate so the lenght of stride and/or release point doesn't affect the maths. This leaves me 36 feet of ball flight to get the AVG speed of the pitch from release to back of home plate.
3/ Every consecutive marker is 2 meters away (6.56 feet) and the last one 0.97 meters from target wall (3.18 feet).

Once I got the video I play it on KINOVEA a great free soft for PC you might know and can find by google or whatever.
This is how I made all the time measurements and markings etc.
Then once I got the timing I used to do the maths by myself and then found this page very convenient that does it for me (and you).
Just enter the datas (feet and time) and click on the "calculate speed" button.

You can not go wrong with this formula !
So just for fun, I measured the loss of speed a ball go through during its flight !
It is impressive how the last meter is critical in speed loss (I might be a tad wrong on this since the distance is so short, a minimal error gets udge)

I am old and don't throw very fast, but I figured out that this will match with the U12/U14 arms of yours :)

Hope you will enjoy this ! I'm glad to share it here ! My girlfriend now says I'm a nerd ! ah ah ah ! I am !

I will let you know how the comparaison with the PR BC goes !
Cheers,
Play ball !

Videos of the tests :


 

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Last edited:
May 15, 2008
1,913
113
Cape Cod Mass.
Interesting concept. I am now wondering how much the true trajectory of the ball affects a velocity measurement. Your 'ruler', on the wall is horizontal, the ball trajectory is on an arc; it starts up, flattens, then goes downward. A radar measurement is most accurate when the ball-gun are perfectly aligned. When I take a ruler and plot the two points where the ball crosses the lines demarcating your first 2 meter section it points to a spot about 10 ft high when it gets to where the catcher would be. This makes me think that placing my radar gun that high would result in a more accurate velocity reading. Similarly if I was taking a reading from behind the pitcher locating the radar lower, closer to the ground, and pointing it up in line with the initial trajectory would be more accurate. How much more accurate, I don't know.
 
Apr 2, 2015
1,198
113
Woodstock, man
You are measuring the way they used to measure bullet velocity, using a chronograph - see Bob Feller.



Dont calc using the average speed. Today's radar gives you the fastest speed out of the hand. So, the comparable thing using your lines in Kinovea is to calc the speed at the first and second measurement only.
 
Feb 17, 2014
7,152
113
Orlando, FL
You are measuring the way they used to measure bullet velocity, using a chronograph - see Bob Feller.



Dont calc using the average speed. Today's radar gives you the fastest speed out of the hand. So, the comparable thing using your lines in Kinovea is to calc the speed at the first and second measurement only.

Higher end radar will provide more than average speed. I can get initial, terminal, or average. The difference between initial and terminal is especially useful as it relates to spin rate.
 
Sep 29, 2015
26
3
... When I take a ruler and plot the two points where the ball crosses the lines demarcating your first 2 meter section it points to a spot about 10 ft high when it gets to where the catcher would be. This makes me think that placing my radar gun that high would result in a more accurate velocity reading. Similarly if I was taking a reading from behind the pitcher locating the radar lower, closer to the ground, and pointing it up in line with the initial trajectory would be more accurate. How much more accurate, I don't know.

Hello Armwhip,
Maybe 10 ft is a bit high in number (even on the first vid "K" position) but that is a question that I asked myself also.
For thee Radar lower pointing in line with the ball is also something I'm wondering.
Maybe the "boss" from Pocket Radar will clear this out? Anyway I'm going to test many placements of the unit and compare.
I'd like to have it slightly in front of me so I can read the screen while the ball travels to the wall.
Might have some kind of "average" speed this way.
I'm more interested in consistency (to check progress) than in pure pin point exit speed even if the higher number is a big satisfaction :)
 
Sep 29, 2015
26
3
You are measuring the way they used to measure bullet velocity, using a chronograph - see Bob Feller.



Dont calc using the average speed. Today's radar gives you the fastest speed out of the hand. So, the comparable thing using your lines in Kinovea is to calc the speed at the first and second measurement only.


Nice video thanks :)
Yeah I know about radars giving speed out of the hand.
The thing is that if I calculate on ONLY the fist 2 or 4 meters the margin of error goes high!
The longer the segment is, the lower the margin.
For 36 ft it is about 0.25 mile for an image (4 milliseconds).. I guess we can divide this by 2 if we extrapollate (is that word correct ? If we guess...) the ball position.
If I go down on calculating the first 15 ft out of release, the margin goes to 1 mile which I feel is too much.
Extrapollating ball position, we can go down to 0.5 mile which, I feel, is just ok
We have to consider also that the cam lense may induce a little tad of parralax factor (cosine? in english?) but as for the arc in ball trajectory this is getting too much and beyond my maths capacity ! ;)
I rather practice ! ah ah ah
Thanks for the input !
 
Sep 29, 2015
26
3
Higher end radar will provide more than average speed. I can get initial, terminal, or average. The difference between initial and terminal is especially useful as it relates to spin rate.
Yeah,
Anf I find average speed very interesting.
And even more, milliseconds are the key. The time you give the batter to see the ball.
We see that a big and long stride can affect the speed perception for the batter, since even if slower the ball travel less.
The same idea makes me want to hide the ball as long as possible. (so no one handed backswing, specially for a slow guy like me)
 
May 15, 2008
1,913
113
Cape Cod Mass.
I don't know about anyone else but when I catch for my pitchers, which I do quite often, I typically see their fastest speeds on low pitches. I have always thought that it had something to do with gravity and a lower trajectory. I see now that the speed increase is more likely due to the fact that a low pitch has a lower trajectory out of the pitcher's hand which is more in line with the location of the Pocket Radar, which I am holding in my throwing hand as I wait for the ball.
 
Sep 29, 2015
26
3
Here are my trajectories :)
Red is fastball / Yellow for (simili but still efeective) Raise-Curve / Blue for Change Up
Yellow and green dots are for speed differencies (where the raise ball and changeup are when the Fast arrived)
My fast is no more than 53 mph
I guess that a faster pitcher might flatten the arc somehow.
 

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Feb 10, 2018
496
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NoVA
In my experience using the Pocket Radar—I also hold it in my throwing hand waiting for the pitch on the bucket—the balls that go down and in typically get the highest reading (perhaps 1-2mph greater than down the chute) and balls that sail high typically get the lowest readings (perhaps 1-3mph slower).

Not sure why...but also don’t care enough to take a DFP science class to figure it out. LOL.
 

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