Building an electronic starting device

This is the ”nerdiest” entry in the blog so far 🙂 But if you are prepared to do some basic electronics wiring and maybe some very simple programming, you will be rewarded by being able to start SprintTimer with high accuracy by any mean imaginable (light, IR, pressure, switches, etc). It also allows you to add other start signals like strong sound, light flashes etc. If you do not feel up to it yourself, you might have a friend, student or athlete who thinks it is fun to tinker with a project like this.

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A battery powered router for Start Sender

Start Sender is a convenient way to send the starting time from the start to Photo Finish at the finish line. The problem is that the direct communication between two devices has a limited range (30m-40m) and to cover, e.g. a 100 m race you need an external WiFi network. And that is not always available outdoors in a stadium. A solution could be to set up a temporary router, and since there might not be a power plug nearby, it should preferably be a battery powered one.

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Making a long sound cable

Using the sound from e.g. a starting gun is the most accurate way to start the clock in SprintTimer. A problem, however, is that the start often is so far away that the sound drowns in the background noise. To transfer the sound to SprintTimer at the finish you can use a microphone with an extension cable or a Walkie Talkie. If you have two devices and access to a network you can also use Start Sender. But a stable and accurate solution for distances up to 100-150 m is a sound cable.

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SprintTimer accuracy

With SprintTimer I claim that the accuracy is almost as good as a high end professional fully automatic timing equipment. This article presents some measurement I made to test this claim. Since the most accurate method to measure a race is to start the clock with a sound and the finish with Photo Finish, I have focused on that setup, but also tested some other variations.

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Improving Photo Finish images with zoom and add on lenses.

All iPhone and iPad cameras have fairly wide angle lenses. This means that you must stand pretty close to the participants to fill out the image when recording a Photo or Video Finish. Sometimes this is an advantage (e.g. indoors), but in most cases, it is the opposite. In many water sports like rowing and kayaking, it can be difficult to get close to the finish line. And if the participants have different lanes, like in a 100 m sprint, standing close makes it impossible to set a slice width that fits all runners. This because the runners move with very different speed as seen by the camera.

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