# How to record speed and distance of a ball?

#### Mr.Feelgood

Joined Nov 29, 2023
3
I want to be able to shoot a ball and then record the distance it travelled and the speed, the ball can have circuitry placed inside. I know very little about electronics however my research has led me to believe that, the best option would be to use RF 433 Mhz or 868 Mhz as they are- *Sufficient to be able to supply the 2 pieces of information required. *Can work on low battery voltage. *Cover the desired line-of-sight distance at around 500 meters. *Minimal components/cost. *Transmitter PCB can be designed at less than 15mm². It would be desirable if the speed and distance measured can be seen on a basic app. As a starting point, is using RF the way to go or is there other options? How do I find someone that could help with the design?

#### MrChips

Joined Oct 2, 2009
30,469
Welcome to AAC!

The first thing is we need to change the title of your thread so that it reflects the nature of the thread.
For example, a title such as "How to record speed and distance of a ball?"

Secondly, you need to provide as much information as possible.
1) What is the size and weight of the ball?
2) What is the ball made of?
3) Is the ball hollow?
4) What is shooting the ball?
5) What is the angle of the initial trajectory?

Is this possible? Yes.
But what do you mean by speed? The ball will have an initial speed at launch and the speed will decrease to zero.

You could probably do it with a 3-axis accelerometer. You can compute the velocity and distance based on the information from the accelerometer.

#### WBahn

Joined Mar 31, 2012
29,857
Is this some kind of school project? If so, it belongs in Homework Help.

What is "low battery voltage"? 9 V? 1.5 V? 0.8 V?

A PCB that is less than 15 mm²?

Are you really talking about designing a transmitter in which the board is less than 4 mm on a side?

Consider that a U.S. dollar coin is 2 mm thick.

#### Mr.Feelgood

Joined Nov 29, 2023
3
Your thread title suggestion makes sense, i'll change it when I find out how.
The "ball" hasn't been designed yet as it would depend on what it must incase within. I anticipate that shock/impact absorption should be incorporated within the ball to protect electronics.
1) Depends on electronics but, if it could fit within a Chicken Egg or smaller would achieve the desired size.
2) Potential materials could be- foam/sponge, rubber/silicon, plastic or a combination of.
3) Only to allow for the electronics and suspension/dampening.
4) An air cannon. Potential of +300 mph.
5) I believe that an angle of around 45 deg is best to gain the most distance, measuring the distance is priority over speed.
6) The fastest speed to be registered somewhere near the start of launch.

I'll need to look in to the 3-axis accelerometer as I currently have no clue.

Thank you for replying to my question/s. I hope my answers offer some help.

#### Mr.Feelgood

Joined Nov 29, 2023
3
Is this some kind of school project? If so, it belongs in Homework Help.

What is "low battery voltage"? 9 V? 1.5 V? 0.8 V?

A PCB that is less than 15 mm²?

Are you really talking about designing a transmitter in which the board is less than 4 mm on a side?

Consider that a U.S. dollar coin is 2 mm thick.
It's an old man hobbyist project.
I don't know what voltage a micro transmitter would need but the replaceable or rechargeable power supply must be capable of working for 2-3 hours. Throw ball, go pick it up and throw again. So once the distance has been measured and sent, it can power down.
15mm by 15mm board.
According to what I've seen online, it might be 10-15mm depth.

#### MisterBill2

Joined Jan 23, 2018
17,797
I designed, and our company sold, a system to measure speed based on the time measured for an object to break two laser beams 4 inches apart. So laser beams and fast sensors would be a simple way to generate the signals to accurately measure the object velocity without affecting it. Measuring the distance is a bigger challenge indeed. A transmitter of any kind will have some latency in detecting an impact, and before the package can transmit a signal the ball will travel a greater distance. Measuring the time to impact will require knowing the velocity of the ball constantly as it is in flight. So it would not be very accurate, except for relative distances between identical objects.
So a radar or similar system that records the distance and velocity should be able to also detect the sudden change in velocity as it impacts, if the surface provides any friction. So it would not see the distance to landing on wet smooth ice. So a radar or light reflective ball seems like a reasonable option. Radar coupled with a modulated transmitter that will signal the instant of impact could deliver a very accurate measurement if accurately calibrated.
Based on my experimenting many years ago with items about 2 inches in diameter and air pressures about 100PSI, ranges for 300 to 500 feet can be expected.

#### KeithWalker

Joined Jul 10, 2017
3,029
You don't need an accelerometer or microprocessor in the ball to measure speed. You can measure it fairly simply using the Doppler effect. The ball only needs to contain a small transmitter which has the carrier modulate by an accurate frequency signal. The receiver, located at the point where the ball is launched, would need to feed the demodulated signal into an accurate frequency measuring circuit. The received carrier frequency will vary inversely with the speed of the ball as it travals away from the source.. The distance could be calculated from the time that the received frequency is different from the transmitted frequency.

#### BobTPH

Joined Jun 5, 2013
8,662
This is not a project for someone who knows very little about electronics. I have been an electronics hobbyist for 55 years, and I would expect this project to take me about 1000 hours of research and development, i.e. a half a year of full time work.

I already know how to design microprocessor based circuits and boards and do the programming. I have used 433MHz, as well as WIFI in my projects. If you don’t have that kind of knowledge, I would expect it to take at least two years, if you learn really fast.

If you expect someone here to do the project for you, well, it has happened before, but not for anything this difficult.

So, where to start? Hire a competent EE and expect to pay him $100K if U.S. or euro based. #### Papabravo Joined Feb 24, 2006 20,994 This is not a project for someone who knows very little about electronics. I have been an electronics hobbyist for 55 years, and I would expect this project to take me about 1000 hours of research and development, i.e. a half a year of full time work. I already know how to design microprocessor based circuits and boards and do the programming. I have used 433MHz, as well as WIFI in my projects. If you don’t have that kind of knowledge, I would expect it to take at least two years, if you learn really fast. If you expect someone here to do the project for you, well, it has happened before, but not for anything this difficult. So, where to start? Hire a competent EE and expect to pay him$100K if U.S. or euro based.
I think @BobTPH has accurately forecasted the amount of time and money involved. My suggestion is to play the long game and start acquiring the skill set and the pieces parts this project requires. See what can learn along the way. Maybe you will get there and maybe you won't, but you'll sure have a good time making the effort.

#### MrChips

Joined Oct 2, 2009
30,469
Your thread title suggestion makes sense, i'll change it when I find out how.
I have changed the thread title for you.

#### MisterBill2

Joined Jan 23, 2018
17,797
To measure the initial velocity have the two light beams ten inches apart, the first beam break starts pulses from a 10 MHZ module to a counter. The second beam break stops the pulses to the counter. Then the counter will read microseconds and tenths of microseconds to go ten inched. from that number it can calculate the velocity in inches per second. That gives the speed.

#### MrChips

Joined Oct 2, 2009
30,469
And once you know the initial speed and angle, you can calculate the trajectory at a first approximation. This is basic high school physics.

#### WBahn

Joined Mar 31, 2012
29,857
And once you know the initial speed and angle, you can calculate the trajectory at a first approximation. This is basic high school physics.
Though air resistance is almost certainly going to cause major deviations. If we are talking about something the size and weight of a tennis ball, the deviation will likely be so huge that the approximation is pretty much useless. If it were fired at a muzzle velocity of just 50 m/s, the vacuum distance would be in excess of 250 m. But in air, it would be unlikely to make it more than about 70 m. This is using a quadradic drag model. Things are only going to depart more rapidly as the muzzle velocity increases toward the 300 mph mentioned. Smaller and/or denser projectile will suffer less, of course.

#### MisterBill2

Joined Jan 23, 2018
17,797
The flow restriction provided by the valve on the launcher will have a major effect on the range, as will the length of the barrel. The shape of the projectile also has a large effect. One launcher that used a large-port ball valve would deliver an object like a juice can full of water about 120 yards from a 4-foot barrel about 1.62 inches in diameter, using a whole lot of air pressure. That tank was not small, the pressure rating was 3AA1800 . A thinner tank was felt to expand when pressurized, and was abandoned. caution: a bursting pressure tank can be deadly. The distance was measured to the water splat crater.