During a tennis rally, there are many interesting data and stats that could be stored for a player to look at later on (e.g. swing speed, shot type, ball contact location, racket vibration, etc.). Current racket sensors are expensive, and provide excessive information. We want to use what we’ve learned about Arduinos and Arduino sensors to build a basic tennis racket sensor. The accelerometer is mounted on the tip of the racket head. The accelerometer will be wired along the frame to an Arduino in the throat of the racket. The Arduino will communicate with another Arduino that is hooked up to a computer through XBee serial communication. Using material from the pedometer lab (thresholds, calibration, incremental counting), we will use the accelerometer data to record the number of times the ball impacts the racket during a point (rally counting). We also use the accelerometer data, along with our own integration method, to compute an approximation for the plow-through velocity during the timeframe of the impact.