DIGITAL TELEPHONE SET Russian patent published in 2000 - IPC

FIELD: electronic communication. SUBSTANCE: in preferable embodiment, device has control unit, which has unit for switching encoder-decoder on and off, and analysis unit, which has first, second and third comparison circuits with respective first, second and third memory units, which store information signal feature code, test feature code and call feature code, respectively. Input signal shift register has 24 bits. First to eighth of its outputs are connected to corresponding first inputs of first and second comparison circuits, which second inputs are connected to respective outputs of first and second memory units. First to twenty fourth bit outputs of register are connected to respective first inputs of third comparison circuit, which second inputs are connected to respective outputs of third memory unit. Outputs of first, second and third comparison circuits are connected to encoder-decoder control unit, test response generator and calling device control signal generator. Device provides separate comparison of information signal, test and call feature codes. In addition, control unit of device may be designed as microcontroller. Device provides possibility to switch on encoder-decoder and respectively scrambler and descrambler, only when information signal is present. At the same time, encoder-decoder and respectively scrambler and descrambler are switched off, when no information signal is present. This also protects circuits of digital telephone set from fault triggering, thus decreasing amount of power consumed by encoder-decoder and scrambler and descrambler. In addition, this provides protection against fault device triggering, when test and call signals are received. EFFECT: increased functional capabilities. 15 cl, 3 dwg