5 results about "500 kHz" patented technology

The radio frequency of 500 kilohertz (500 kHz) has been an international calling and distress frequency for Morse code maritime communication since early in the 20th century. The unit kilohertz was not introduced until the 1960s. For most of its history, the international distress frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles (per second) or 500 kc.