Calculate your serve speed

Discussion in 'Other Equipment' started by tennisplayer_85, Nov 12, 2012.

  1. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    hey, you can sign up now also at www.tennisservespeed.com
    and watch a video explaining the whole thing.

    as people might have noticed, its also possible from within the App. :)
     
    #51
  2. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    #52
  3. mxmx

    mxmx Semi-Pro

    Joined:
    Feb 14, 2011
    Messages:
    680
    so....was this app legit/accurate, or not?
     
    #53
  4. sansaephanh

    sansaephanh Professional

    Joined:
    Apr 13, 2009
    Messages:
    1,166
    Location:
    Oakland
    ^+1. Comments nao
     
    #54
  5. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    I am interested in the program. However, the above statement has me a little concerned.

    As others have noted, I am interested in the speed at impact only, not an average.

    Based on the following website, http://advancedtennis.com/results/speedloss.htm, the ball loses an average of 27% in speed just before the bounce. Have you taken something like that into account?

    Harry
     
    #55
  6. tyu1314

    tyu1314 Semi-Pro

    Joined:
    Oct 31, 2011
    Messages:
    476
    Location:
    Stony Brook,NY
    Did anyone compare it to a real speed radar and see how accurate it is??
     
    #56
  7. Chas Tennis

    Chas Tennis Hall of Fame

    Joined:
    Feb 17, 2011
    Messages:
    4,276
    Location:
    Baltimore, MD
    tennisplayer_85 said that, was it?, over 750 TW readers responded to his survey on interest.

    Didn't anyone buy the application and can give some feedback?

    With all that interest why isn't there some feedback from users?
     
    #57
  8. LeeD

    LeeD Bionic Poster

    Joined:
    Dec 28, 2008
    Messages:
    36,403
    Location:
    East side of San Francisco Bay
    They lost interest after watching their and my pitifully slow serves.
     
    #58
  9. omega4

    omega4 Rookie

    Joined:
    Jan 31, 2013
    Messages:
    274
    Location:
    Atlanta GA
    I have a nice chronometer watch that times at .20 seconds.

    I just need to find a way to serve a tennis ball that travels for 1 mile. Once I do, I'll be all set in calculating my service speed.
     
    #59
  10. BHiC

    BHiC Rookie

    Joined:
    May 7, 2012
    Messages:
    308
    Location:
    USA
    I have the same question, has anyone actually tried this app?
     
    #60
  11. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    #61
  12. axel89

    axel89 Banned

    Joined:
    Feb 13, 2012
    Messages:
    1,161
    bought app wil test out sewrve later
     
    #62
  13. Chas Tennis

    Chas Tennis Hall of Fame

    Joined:
    Feb 17, 2011
    Messages:
    4,276
    Location:
    Baltimore, MD
    Are there any of the 750 mentioned above who bought the application?

    Any of the 750 reading this?
     
    #63
  14. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    I sent a couple of email questions to the OP and he responded.

    The first question I asked him was whether the app calculates an average speed. He said that the current version is only calculating the average speed, which is not good. Assuming that the difference between the initial speed and speed at landing is about 27%, the average speed due to air resistance should be about 16-17% off the initial speed. So, he is risking getting bad reviews due to "inaccurate" serve speed.

    The second question I asked him was whether the app is doing 60 fps or 30 fps for my Iphone 4S. He said he programmed the phone to use 60 fps, rather than its default 30 fps rate. This means the resolution should be plus or minus about 5 mph (different between two adjacent frames) at high speed (i.e., over 110 mph).

    My conclusion: His use of 60 fps is really great, but until the app calculates the initial serve speed, it's not ready for purchase IMO.

    If you want to purchase the app, I think you should use the app for counting the frames and use the chart (see link below) to convert it to the initial speed.

    http://tt.tennis-warehouse.com/showt...=1#post7190514

    Harry
     
    #64
  15. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    Oops, bad link above. Use this one below.

    http://tt.tennis-warehouse.com/showthread.php?p=7190514&posted=1#post7190514

    Harry
     
    #65
  16. mongting

    mongting Rookie

    Joined:
    Mar 29, 2011
    Messages:
    149
    Location:
    TX
    I hope he can use the sound first and if it doesn't work, make the user pick the moment from the video.
     
    #66
  17. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    A few more days and version 1.2 will be available!
    ServeSpeed version 1.2 is committed to the App Store! Just waiting for Apple to accept.

    Most important updates:
    - Uses algorithms to calculate your initial serve speed (ISS), which corresponds to the speed shown on TV (previous version only calculated the average speed).
    - Calculates the speed at bounce and fall of the ball due to gravity.

    I guess there was some confusion about if version 1.0 could already calculate the initial speed. Unfortunately this led to one guy leaving a bad comment in the App Store thinking he could serve harder than 56 miles per hour initial speed while the 56 miles per hour was in fact the average speed, so he did serve a lot harder. I would really appreciate it if some of you guys could mention this in another review in the App Store.

    Quite some people asked for reviews, unfortunately not all the people who upvoted the App actually spend a few dollars on buying it.

    Thanks to the dedicated player who wrote this in the Finnish App Store:
    Kätevä ja toimii paremmin kuin odotin ★★★★

    Via google translate I found that it means “Convenient and works better than I expected”!

    I assure you, you wont regret your purchase. I would give a 60 day money back guarantee. But apple unfortunately doest offer this.

    All I can ask is if you buy it please leave a review here and in the App Store.

    In the mean time I’ll keep on working on the SOUND DETECTION functionality! So with a single click you can go the point of contact (racquet hitting the ball). Which will not only save lots of time but also improve the accuracy / human error because of the high sample rate.
     
    #67
  18. Chas Tennis

    Chas Tennis Hall of Fame

    Joined:
    Feb 17, 2011
    Messages:
    4,276
    Location:
    Baltimore, MD
    Accuracy tests

    This should not take very long to answer.

    Normally, in doing scientific or engineering work the measurement equipment used for calibration, model number, etc. are known and can be referred to.

    Specifically, what instruments did you use to verify the accuracy of your smartphone serve measuring application?

    Could you show a series of your test results?

    What is the accuracy?
     
    #68
  19. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    The instruments i use for testing the accuracy are videos from the australian open where the professional radar gun shows the speed in the end. I currently only tested 9 videos and these are the test results:

    The results are from ServeSpeed V1.2 (in a few days available in the App Store)

    Serves from the Australian open 2013
    Video quality 1280x720, 59.94fps:
    1st serve David Ferrer, Professional radar gun 197Km/h, ServeSpeed App 197Km/h (+/- 0)
    1st serve David Ferrer, Professional radar gun 183Km/h, ServeSpeed App 182Km/h (+/- 1)
    1st serve David Ferrer, Professional radar gun 190Km/h, ServeSpeed App 186Km/h (+/- 4)
    2nd serve Novak Djokovic, Professional radar gun 156Km/h, ServeSpeed App 158Km/h (+/- 2)
    2nd serve David Ferrer, Professional radar gun 149Km/h, ServeSpeed App 147Km/h (+/- 2)
    Video quality 1280x720, 50fps:
    1st serve Victoria Azarenka, Professional radar gun 152Km/h, ServeSpeed App 149Km/h (+/- 3)
    1st serve Victoria Azarenka, Professional radar gun 159Km/h, ServeSpeed App 156Km/h (+/- 3)
    1st serve Li Na, Professional radar gun 164Km/h, ServeSpeed App 160Km/h (+/- 4)
    1st serve Li Na, Professional radar gun 161Km/h, ServeSpeed App 153Km/h (+/- 8)

    Average precision +/- = (27/9) = 3 Km/h = 1.86 miles

    Hold in account that the last 4 videos are only 50fps.

    Some videos are harder to calculate than others depending on the frame right at the point of contact. This is why the slider bar in the app comes in handy. This way its possible to say that the serve is in between 2 frames (making it more precise). At the beginning this might be a bit difficult but once you get the hang of it, it becomes easier.

    That's why i made an extra video explaining how to get the best precision (so you get all the ins and outs). If you sign up for the mailinglist (through the website or from within the app) you will receive it right away. Also i'll keep you updated on upcoming updates like the sound detection etc!

    These are real test results, people can try it themselves.

    PS: I am planning to test many more videos and based on these statistic try to improve the accuracy in upcoming updates.
     
    #69
  20. Chas Tennis

    Chas Tennis Hall of Fame

    Joined:
    Feb 17, 2011
    Messages:
    4,276
    Location:
    Baltimore, MD
    You went to the Australian Open and recorded videos with an iphone? Then compared the iphone measurement to the displayed radar measurement?
     
    #70
  21. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    Yes!, all correct except for me not taking the videos, wish I could have been there (hopefully next year though!) . I got the videos through someone that I know.

    Apple is taking its time :S , bit more patience and 1.2 should be there...

    b.t.w. if people get a chance to records some more videos, you can always send them to me. I am planning on gathering more myself, but to more the better!
    I guess I don’t necessarily have to mention this but if you do, make sure you record the moment the racquet hit the ball + its landing location and afterwards the speed that the professional radar gun will show.
     
    #71
  22. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    #72
  23. ArthurX

    ArthurX New User

    Joined:
    Jan 22, 2013
    Messages:
    12
    Would this also work for a sport such as cricket?
     
    #73
  24. ArthurX

    ArthurX New User

    Joined:
    Jan 22, 2013
    Messages:
    12
    Hi, I just bought the app, after I have recorded the serve and press keep and calculate it just crashes! This is on the iPad.
     
    #74
  25. v-verb

    v-verb Hall of Fame

    Joined:
    Nov 9, 2012
    Messages:
    2,077
    Location:
    Toronto
    Looking forward to updates - want to buy this but not if there's a legit crash problem...
     
    #75
  26. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    I just checked out the new version's screen shots at the app store. Apparently, he is using the serve speed formula at http://www.donthireddy.us/tennis/speed.html which I told him about. The numbers all check out. This means the serve speed estimate should be very accurate.

    The OP has finally turned the app into a useful tool by calculating the initial serve speed. I will be buying the app soon.

    If you are just curious about your serve speed and are not interested in doing so on a regular basis, you can just record the serve and plug in the numbers into the website link above. That will do roughly the same thing with less accuracy.

    Harry
     
    #76
  27. Chas Tennis

    Chas Tennis Hall of Fame

    Joined:
    Feb 17, 2011
    Messages:
    4,276
    Location:
    Baltimore, MD
    Last edited: Feb 21, 2013
    #77
  28. Chas Tennis

    Chas Tennis Hall of Fame

    Joined:
    Feb 17, 2011
    Messages:
    4,276
    Location:
    Baltimore, MD
    Does the application use both the frame at racket impact and the frame when the ball bounces to get the initial velocity? Or other information?
     
    #78
  29. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    Hi ArthurX, great you bought the App! I have to admit that I haven’t tested the app on ipads, just iphones. On the iPhone everything works fine.
    In the next update I’ll try to test it on the ipad and fix the error.

    To your question about cricked. No this App is just for tennis! The distance measurements I do are for tenniscourts only.
     
    #79
  30. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    I think the App on first startup asks for permission to your ‘Photo library’. This is only because it wants to save the recorded videos there. If you pressed [don’t allow] it might crash trying to access a video that was not saved to your library (i'll make sure i'll check that in the next version).

    So if you did press [don’t allow] , you can simply solve this by going to your iphone ‘Settings’ -> ‘Privacy’ -> ‘Photo’s’ -> allow the ServeSpeed App here to use it.

    Let me know if this solved your problem? If this was not the problem you might wanna update your ios version. I would very much like to hear from you :) !
     
    #80
  31. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    Thanks Harry! Yes I am using almost the same math as shown on that website.
    It’s a great explanation if you wanna know more about how it’s calculated!

    And yes you can calculate it all yourself but for 3 dollars really? It’s quite a lot of work to do it yourself. And if you’re like me you don’t wanna know it just once ;)

    Though I think the average speed of version 1.0 was very useful too for measuring improvements, ServeSpeed 1.2 of course is a lot cooler since with the initial speed you can compare yourself to the pro’s!
     
    #81
  32. JPW

    JPW Rookie

    Joined:
    Dec 15, 2007
    Messages:
    106
    Very cool! I've done these calculations the hard way for a while now. Now I just need an iPhone to try this out :).
     
    #82
  33. v-verb

    v-verb Hall of Fame

    Joined:
    Nov 9, 2012
    Messages:
    2,077
    Location:
    Toronto
    a newer iPod will work too i think
     
    #83
  34. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    I bought the app today and tried it out. It works great! Love the 60 fps on my iphone 4s.

    I also love how you can toggle back and forth between two adjacent frames and select any point between the two frames using a slide bar, not just a midpoint between the frames.

    Great job!

    Harry
     
    #84
  35. v-verb

    v-verb Hall of Fame

    Joined:
    Nov 9, 2012
    Messages:
    2,077
    Location:
    Toronto

    So how fast did you serve?
     
    #85
  36. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    Well, I tested the app on my 13 year old son who has been playing for about 2 years. His first serve was around 95 and second serve (kick serve) was around 60-65.

    Next time, I will have my son film me so I can check my own speed. My feeling is it will probably be about the same as my son's:).

    Harry
     
    #86
  37. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    Harry, great to hear you like it so much! You would do me a huge favor if you could post this review in the App Store. If you get a chance of course :)
     
    #87
  38. v-verb

    v-verb Hall of Fame

    Joined:
    Nov 9, 2012
    Messages:
    2,077
    Location:
    Toronto

    That's EXTREMELY respectable! Very nice - I'm not sure I can match that.

    Thanks for the feedback - will buy the app this weekend

    Cheers!
     
    #88
  39. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    Thanks Harry! really appreciate such a positive review! I am sure lots of people will find it very useful :)

    https://itunes.apple.com/app/servespeed/id581908085
     
    #89
  40. iradical18

    iradical18 Professional

    Joined:
    Mar 16, 2004
    Messages:
    1,095
    Location:
    Lorton, VA
    Any plans on an Android version?? Please say yes!
     
    #90
  41. tennisplayer_85

    tennisplayer_85 New User

    Joined:
    Apr 2, 2012
    Messages:
    37
    Great you are asking! i have looked into it already, though there are some struggles with android like the support for 60fps camera and so on. My first plans are to make the iPhone App even better with sound detection and some other great updates. So after that hopefully i can look into android.
     
    #91
  42. iradical18

    iradical18 Professional

    Joined:
    Mar 16, 2004
    Messages:
    1,095
    Location:
    Lorton, VA
    I'll be looking forward to it, thanks for answering my question! In the mean time, I'm giving my buddy 3 bucks to buy it and we'll be testing it out this weekend.
     
    #92
  43. Avles

    Avles Hall of Fame

    Joined:
    Oct 14, 2009
    Messages:
    1,505
    Location:
    The Peak of Good Living
    I was skeptical about the app but it sounds like you've done some good things with it--calculating the initial speed instead of the average speed is a big improvement.

    I have a stupidphone and get by with http://www.donthireddy.us/tennis/speed.html, but if I ever get a smartphone I might give this a try.
     
    #93
  44. Tight Lines

    Tight Lines Semi-Pro

    Joined:
    Jan 14, 2013
    Messages:
    764
    Location:
    Sparkill, NY
    In my opinion, I think you should do the Android version first as I don't think adding sound would be a substantial improvement. Even with sound detection, you would still have to review the video to select the frame showing the ball landing. Moreover, sound travels relatively slowly which means you need to ask how far the phone is from the server. In other words, you are not saving any steps in doing the calculation.

    Even with only a 30 fps camera, the calculation would be reasonably accurate since you can select a point in between two frames.

    JMHO.

    Harry
     
    #94
  45. JPW

    JPW Rookie

    Joined:
    Dec 15, 2007
    Messages:
    106
    I've been pretty excited to get an iPhone 5, first, because I just had bad luck with AT&T, and second, to get this app :) I've done these calculations with a digital camera many times. This app certainly makes it much MUCH easier.

    One question I do have for the developer is, would recording someone serving on TV be a good way to test the accuracy of this app? It seems like the timing would be the same and you could easily determine the other needed data. This just seems like a good way to check against an actual speed gun at a tennis tourney.
     
    #95
  46. Nostradamus

    Nostradamus G.O.A.T.

    Joined:
    Nov 30, 2011
    Messages:
    13,059
    Location:
    In the future
    Awsome. Mine is like 98 MPH. is this correct ? I did it with Android phone, I hope it is just as accurate.
     
    #96
  47. LeeD

    LeeD Bionic Poster

    Joined:
    Dec 28, 2008
    Messages:
    36,403
    Location:
    East side of San Francisco Bay
    98 mph flat first serve.
    In 60 degree temps, Dunlop heavy balls, IN serves, should hit the backboard about just under 3' high, 21' behind the baseline on center serves.
    Out wide, it can still go 100 if it barely hits the backwall after the initial IN bounce, because a wide serve travels up to 8' farther in distance.
     
    #97
  48. Nostradamus

    Nostradamus G.O.A.T.

    Joined:
    Nov 30, 2011
    Messages:
    13,059
    Location:
    In the future
    ??????? 100mph serve wide will hit the fence ?
     
    #98
  49. LeeD

    LeeD Bionic Poster

    Joined:
    Dec 28, 2008
    Messages:
    36,403
    Location:
    East side of San Francisco Bay
    You saw the vid of me serving when I was 62, couldn't run one step, first tennis day of the year, at night, in 60 degree heat.
    The IN serves out wide, duece court, all hit about 24-36" high at the backfence. The camera was placed on a 48" tripod. Those weren't the best serves, just the first six I tried. Only TWO went IN.
    If I served up the center, the bounce would be quite a bit higher, as you can see the ball dropping by the time it hit the backfencing on those wide serves.
    I claim 100mph, which is about the fastest on rec courts at a 4.0 level of tennis.
     
    #99
  50. spinorama

    spinorama Rookie

    Joined:
    Mar 8, 2013
    Messages:
    153
    Too many variables to calculate like that (wind, placement in relation to the distance measured perpendicular to the net, spin on the ball, weather, etc etc)....just get it clocked.
     

Share This Page