An ultrasonic transmission system in which, for the purpose of transmission, a signal is used which generates a broadband signal by means of code spreading and is capable of eliminating any echoes by means of correlation. The transmission system exhibits a transmitter and a receiver. In this configuration, digital information is spread to a great bandwidth in accordance with a CDMA technique, D/A converted and then transmitted by means of ultrasound via an air Preferred applications of the present invention are air interfaces having a length of a few meters. One field of application is, for example, the connection of cordless handsets or hands-free telephones to telephones.