Siemens Aktiengesellschaft

Siemens Aktiengesell Schaft

Klaus Wintzer

Ernst Hofer

Robert Lechner

Frithjof Von Sichart

Josef Zemanek

Peter Hirschmann

Friedemann Vollnhals

Peter Picard

An analog-to-digital converter for converting analog signals received in parallel on a plurality of incoming lines into digital signals comprises a selector unit having a plurality of signal inputs. Each input is connected to an incoming line via a filter capacitor. A grounded network connected to an output of the selector unit has a storage capacitor and a switch arranged in parallel for short-circuiting the capacitor temporarily. The network simulates a common resistor for establishing a filter section together with the presently through-connected filter capacitor. One input of a comparator is connected to the selector output. The second input is supplied by an analog reference voltage source which may comprise a digital-to-analog converter for supplying an analog reference voltage adjustable under control of the current condition of the comparator output signal. The reference voltage thus is iteratively approximated to the current analog value of the stored sampling probe.

Digital-to-analog converter

A digital-analog converter functioning according to the .mu.-law wherein a sequence control receives an input digital signal and controls the position of a plurality of switches so as to selectively apply positive or negative voltages to a main resistor network and an auxiliary resistor network and further controls the plurality of switches in such networks for either grounding or connecting to an operational amplifier the outputs of said main and auxiliary resistor networks so as to produce an analog output signal. The invention is useful in time division multiplex telephone systems with digital subscriber stations, for example.

Digital to analog converter which uses main and auxiliary resistor

Circuit arrangement for synchronizing a subordinate system, in particular a digital subscriber station, by a superordinate system, in particular a digital exchange, in a PCM time-multiplex telecommunication network. The circuit arrangement operates to evaluate only those synchronization bit combinations which lie at the beginning of a message signal block, thereby avoiding initiation of a re-synchronization during transmission of a block.

Circuit arrangement for the synchronization of a digital subscriber

In a PCM time multiplex telecommunications network the digital signal input of the coder/decoder of each subscriber station has an individually controllable receiving memory connected to the input of the coder/decoder, and the digital signal output of the respective coder/decoder has an individually controllable transmitting memory connected thereto. The control of the signal receipt and transmission by the coder/decoder takes place at different points in time than the receipt of PCM signals by the receiving memory, and the transmission of PCM signals by the transmitting memory.

Circuit arrangement for the transmission of digital signals between

Apparatus for a telecommunication system having subscriber stations constructed to send and receive analog signals which are communicated from one station to the other by means of digital signals is described. Each subscriber station is equipped with a converter for converting received digital signals into analog signals and analog signals into digital signals for transmission. The converter circuit employs an analog to digital converter constructed to work according to the iterative principle and including a binary counter and a buffer register, the stages of which are enabled, respectively, by predetermined counter stage outputs. A digital to analog converter is connected to receive the outputs of the bistable stages forming the buffer register. The counter is connected to trigger the conversion of a received digital signal into an analog signal and subsequently to initiate the conversion of an analog signal into a digital signal; this occurs only after a specified calling bit sequence is received by the converter.

Apparatus for converting analog signals into digital signals and digital

A method and apparatus for a telecommunication installation is disclosed for converting PAM analog signals into PCM digital signals and vice versa. A conversion circuit which is connected to a telephone station comprises an input register for temporarily storing the incoming PCM digital signals and an output register for temporarily storing the outgoing PCM digital signals. This conversion circuit includes a clock pulse generator which enables a counter to count through all its counter positions upon the appearance of each channel time slot pulse of the incoming PCM channel time slot pulse train. The input register and counter are connected to an intermediate register which in turn is connected to a digital-to-analog converter for converting the incoming PCM digital signal into an analog signal. This analog signal is sent to the receiving unit of the telephone station in a first time interval of the counter. The conversion circuit also comprises an analog comparator which is connected to the transmitting unit of the telephone station for receiving PAM analog signals. This PAM analog signal is converted into a digital signal in the intermediate register during a second time interval of the counter. The converted analog signal is then fed to the output register to be sent to the PCM switching center. Thus, the conversion circuit of this invention is time shared for use in converting both digital and analog signals.

Reversible analog-to-digital converter

Power saving means is shown for use with a converter circuit in a telephone switching installation. The converter circuit comprises an analog-to-digital converter and a digital-to-analog converter. The voltage supply for the converter circuit is switched on only upon the appearance of analog signals to be converted into digital signals or digital signals to be converted into analog signals.

Power saving circuit for use with a converter circuit in a telephone

A method and apparatus are described for transmitting, over switching apparatus, digital information signals, together with a preceding address signal, wherein the address signal indicates a signal receiver capable of receiving the information signals in any time sequence. The information signals emanating from a given signal transmitter, prior to being transmitted to the switching apparatus, are individually stored, and only after a predetermined number of information signals are present are the information signals and related address signals transmitted. In the switching apparatus the address signal is used to establish a connection between the switching apparatus input and the switching apparatus output connected to the addressed signal receiver only for the period during which the information signals are transmitted.

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Munich, Germany

Klaus Wintzer