Abstract: The present invention relates to a radio signals transmitter.The transmitter according to the invention comprises a pulse train generator including a quartz oscillator, generating a high frequency signal which is provided to a transistor 7 controlled by the charge and the discharge of a condensor 5 acting on the voltage of its base. A train of A.C. frequency pulses is thereby produced.The generator is protected by a housing which is worn around the neck of the user by means of a chain forming a quarter wavelength antenna.The present invention is used as a portable distress signals transmitter for isolated persons, such as skiers, mountaineers or other people in difficulty.