Siemens Corporation

Deepak R Muzumdar

Rolf E Schneider

Donald A Foggia

Gerhart F Klaiber

Theodore W Wagner

William A Levine

Richard Sanders

Orrie J Van Der Meiden

Sam Liang

George A Mierzwa

Gerry Suarez

Large telephone keyset

A frame format for PCM speech data in a telphone transmission system and a digital telephone apparatus for use with this frame format are disclosed. The frame format includes a superframe formed of 32 data frames, each comprising three 8 bit data words (bytes). The first data word of a frame includes a synchronization code and a signalling code; the second and third data words include PCM speech samples or other digital data. A transmission rate of 192 kilobits/second is chosen so as to match the PCM sampling rate of 8 KHz.

Frame format for PCM speech data in a telephone transmission system and

Telephone busy lamp field console with display

Telephone busy lamp field console

Large telephone keyset with display

Telephone with function keys

Digital telephone apparatus suitable for use as a subscriber station as well as for an attendant console. The telephone apparatus is connectable for full duplex communication with a four wire telephone transmission line. The telephone apparatus is capable of transmitting PCM speech data and/or digital data from a digital data interface to a peripheral data system. The telephone apparatus comprises an internal data bus to which are connected a digital transceiver, a sync/signalling generator, a serial frame synchronizer and at least one codec/PCM filter. The transceiver transmits and receives digital data to and from the telephone transmission line. The sync/signalling generator repeatedly supplies an 8 bit first data word to the internal data bus containing a binary synchronizing code and a signalling code. Simultaneously, the serial frame synchronizer repeatedly receives from the data bus and decodes an 8 bit first data word containing a synchronizing code and a signalling code. The codec/PCM filter repeatedly receives from and transmits to said internal data bus 8 bit PCM voice samples as additional data words immediately following the first data word. A microcomputer, including a number of input/output devices, receives successive signalling codes from the serial frame synchronizer and repeatedly transmits signalling codes to the sync/signalling generator for communicating with the telephone exchange to which the apparatus is connected.

Digital telephone apparatus

Small telephone keyset

Telephone with display

Small telephone keyset with display

A modular telephone keyset instrument is arranged within a rectangular casing having indentations in the top for receiving a telephone handset. Electrical (electronic) circuits are provided on a mother PC board, a daughter PC board and a key switch PC board, stacked within the housing from bottom to top, respectively. The daughter and keyset PC boards are connected to the mother PC board by ribbon cables. A hook switch, mounted on and attached to the daughter PC board extends through one of the indentations in the top to sense whether the telephone handset is placed in the indentations.

Modular telephone keyset structure

Growing community of inventors

Boca Raton, FL, United States of America

Deepak R Muzumdar