DE19606148A1 - Telephone line circuit for operating data or information communications equipment - Google Patents

Abstract

The circuit (1) has a variable resistance device (8), which is such that its impedance or resistance value can be varied by an electrical control drive. This enables switching between the different impedance states at the telephone connections (6,7), corresponding to the busy and idle states, as well as generating the selection pulses. The variable resistance device is connected in parallel with the telephone line connections. A circuit (5) between the telephone line connections and the variable resistance enables polarity independent connection of the circuit, and/or protects against an incorrect polarity connection.

Description

The invention relates to a telephone line connection. Such connections are in devices for information and data transmission, on telephone lines and operated in particular on an analog telephone line, common and necessary, on the one hand to the respective state of the connected device (occupied - not used, etc.) on the telephone line in order to set up a Connection necessary electrical signals (especially dialing pulses) as well states or signals necessary to maintain a connection the telephone line. On the other hand, these interfaces are used for data and information transfer also as a link between the respective device and the phone line.

Devices for information and data transmission for operation on telephone lines are In the sense of the present invention, all devices that can be connected to telephone lines are, namely, for example, telephones, exchanges for multi-point systems, Fax machines, answering machines, modems, etc.

Known connections are relatively complex in their construction, in particular also because they have separate functions for the different functions Components are provided.

The object of the invention is to demonstrate a telephone line connection that this Avoids disadvantages.

To solve this problem, an interface according to the characterizing part of claim 1 executed.

The telephone line connection according to the invention is a transformerless connection, d. H. it does not require any transformers that are complex to manufacture. All for the Establishing a connection and the electrical functions during a connection  required impedance states are determined by a single component, namely generates the impedance, which is variable and electrically controllable.

All for the call acceptance and the information and data transmission during the Connection state required information is provided via a single Coupling element from the telephone line to a subsequent circuit or to a subsequent device (e.g. modem).

Developments of the invention are the subject of the dependent claims.

The invention is described below with reference to the figure, which is a simplified illustration and in the block or functional diagram a telephone line connection according to the invention shows, explained in more detail.

In the figure, this telephone line connection is generally designated 1 . The connection serves to connect the further circuit (controller 4 ) of a device operated on a telephone network and, in particular, to generate the various states and signals on the telephone line 2 necessary for transmission and / or reception, for example exchange line, and for the transmission of data and information between the telephone line 2 and the subsequent circuit (controller 4 ) of the device.

The trunk, which is assumed in the figure as an example with the two wires 3 and 3 '(a wire and b wire) is connected to the input of the interface 1 . The controller 4 is connected to the output of the interface 1 and is used in particular for the detection, evaluation and / or further processing of signals present on the telephone line 2 . The incoming information signals to functional elements of the device which follow the controller 4 are also forwarded via the controller 4 , for example if the device is designed as a telephone to the handset or loudspeaker, if the device is designed as a modem to a connected computer etc. The transmitted information and data are also forwarded to the telephone line 2 via the controller 4 and the connection 1 in the opposite direction.

The input of the interface 1 is formed by a diode arrangement or a diode network 5 , which forms a polarity-independent connection, ie via the network 5 , the interface 1 with its terminals or connections 6 and 7 can be connected to the two wires 3 and 3 ', without having to pay attention to a certain or correct polarity.

In order to meet the conditions set by the operator of the telephone network, the diodes used in the network 5 are preferably those with a small forward residual voltage, e.g. B. Schottky diodes, germanium diodes etc.

Another essential part of the interface 1 is the variable resistor 8 , which is parallel to the wires 3 and 3 'in the connected state of the interface 1 and in a single component all functions for establishing a connection and for maintaining the connection (the display of the not - Occupied state and the occupied state and the generation of the dialing pulses, etc.) realized.

In the embodiment shown, this impedance variable resistor 8 is a field effect transistor, the control connection of which is controlled by a control line 9 from an output of the controller 4 , in such a way that when the telephone line 2 is occupied, the resistor 8 has a resistance value, for example of 600 ohms assumes that the wires 3 and 3 'indicates the occupied state, while in the unoccupied state the resistor 8 is high-resistance. Via the control line 9 , the control of the resistor 8 continues to generate the dialing pulses, in such a way that during each dialing pulse the resistor 8 is switched on completely and its impedance or resistance value is well below 600 ohms.

The impedance of the resistor 8 is independent of the frequency.

Also part of the interface 1 is a coupling element 10 , which forms the output of the interface 1 and enables a galvanically decoupled signal and information transmission to the controller 4 . This element 10 is designed so that it allows signal and information transmission in both directions. Furthermore, the element 10 is designed with a high resistance, at least on the side facing the variable resistor 8 , so that the internal resistance of the interface 1 that can be measured at the connections 6 and 7 actually only or essentially depends on the respective state of the variable resistor 8 .

The coupling element 10 is, for example, an opto-electrical coupler, a capacitively acting coupler or an electroacoustic or electromagnetic coupling device.

The peculiarity of the described interface 1 is that it is characterized by an extremely simple structure, in particular because it displays the busy or unoccupied state, the dialing pulses and any other signals or states the telephone line 2, as the only component, only requires the resistor 8 , which can be changed in its impedance and is electrically controllable.

With this design, it is also possible, with appropriate control of the resistor 8 by the controller 4, to adapt the connection in software and without changing the hardware to different, in particular also country-specific, standards, in particular also existing analog telephone networks.

The connection according to the invention only requires for galvanic decoupling an extremely low cost, namely, for example, only one or at most two opto-electrical coupler.  

The invention has been described above using an exemplary embodiment. It it goes without saying that numerous changes and modifications are possible without thereby leaving the inventive concept on which the invention is based.

Reference list

1 telephone line connection
2 telephone line
3 , 3 core
4 controllers
5 diode network
6 , 7 connection
8 Resistance with variable impedance
9 control line
10 coupling element

Claims (7)

1. Telephone line connection for operating devices for data or information transmission on a telephone network, in particular on an analog telephone network ( 2 ), characterized in that the connection ( 1 ) has a variable by electrical control in its impedance or resistance value resistor ( 8 ) which, as a result of this change in impedance at telephone line connections ( 6 , 7 ) of the switchover ( 1 ), generates at least the impedance states corresponding to a busy state and a non-busy state, and also the dialing pulses. 2. Interface according to claim 1, characterized in that the variable impedance ( 8 ) is parallel to the telephone line connections ( 6 , 7 ). 3. Interface according to claim 1 or 2, characterized in that a circuit ( 5 ) is provided between the telephone line connections ( 6 , 7 ) and the impedance variable in its resistance ( 8 ), which enables a polarity-independent connection of the interface ( 1 ) and / or acts as protection against incorrectly polarized connection. 4. Interface according to one of the preceding claims, characterized in that the impedance of one Semiconductor component is formed. 5. Interface according to one of the preceding claims, characterized in that the variable impedance of a resistor, preferably a transistor Field effect transistor is. 6. Interface according to one of the preceding claims, characterized by a coupling element ( 10 ) for the galvanically decoupled information or signal transmission to a circuit ( 4 ) following the interface ( 1 ). 7. Interface according to one of the preceding claims, characterized in that the coupling element ( 10 ) of at least one opto-electrical coupler and / or of at least one capacitively acting coupler and / or of at least one electrical-acoustic and / or electro-magnetic coupler is formed.