A socket wrench includes a handle and an actuating head connected with the handle. The generated travel trajectory is transformed to map information. The PWM driver provides a series of fan drive pulses on the output terminal, and the limiter prevents the voltage on the output terminal from falling below a predetermined voltage. The signal processing system also includes a data exchange capable of exchanging data signals modulated by a voiceband carrier on the switched circuit network with unmodulated data signal packets on the packet based network.