The basic operation of a laser tag system can be found on Wikipedia.

“Laser tag is a team or individual sport or recreational activity where players attempt to score points by tagging targets, typically with a hand-held infrared-emitting targeting device.”

The two basic parts of a laser tag system are (1) a shooting element and (2) a target.

With our system the shooting element is a red LED. We are using a red LED because it makes it easier to see and align than using an infrared LED. For the target we are using a photodetector that integrated into the front of the gun.

The laser tag system is a simple optical communications link. When the shooting element is aligned with the target it sends the player number. This is such a low data rate that the system can be much simpler than most optical communications systems. The communication protocol is simply each player is assigned a frequency. We are arbitrarily choosing to have 10 players. This means that there are 10 different frequencies that are used

Basic operation of shooting element:

• Turn the LED on and off at the rate assigned

Basic operation of the target:

• Convert the received signal into a digital signal
• Pass the digital signal through 10 bandpass filters with center frequencies of the 10 players
• Determine if the target was hit by a shooting element (i.e. the signal is not just noise)
• Determine the player by finding the largest output of the 10 bandpass filters

Now that we know the basic way that the system works we can look at some different aspects of the design in more details.

1. Determine the frequency of each player
2. Low pass filtering
3. System Flow Diagram