Verfahren und Schaltungsanordnung zur Verbindung von Teilnehmerstationen mit deren Handapparaten in Fernsprechanlagen

1,098,729. Radio and inductive signalling; substation equipment. INTERNATIONAL STANDARD ELECTRIC CORPORATION. Aug. 27, 1965 [Sept. 1, 1964], No. 36911/65. Headings H4K, H4L and H4U. The cord from a telephone subscriber's handset to the instrument body is replaced by a radio link. As described, using different carrier frequencies for each direction of transmission, the handset and the instrument body each contain two aerials and a radio transmitter and a receiver. Power for the handset equipment is supplied by a primary or secondary battery contained therein. Charging of a secondary battery may be by direct current via plug-and-socket connections which engage when the handset is replaced on its cradle, or by alternating current induced by a winding in the instrument body into a winding in the handset and rectified therein, contacts being provided to break the circuit from the battery to the handset equipment and make the circuit from the alternating current source to the winding in the instrument body when the handset is replaced. Different values of carrier frequencies may be used for different subscribers.