DE2162964B2 - Circuit arrangement for determining the operating status of subscriber lines in telephone systems - Google Patents

Description

The invention relates to a circuit arrangement for determining the operating state of subscribers services in telephone systems, in which the two Aden each subscriber line in the associated subscriber circuit via feed resistors and via in Idle state of the subscriber line closed unc in the call state of the subscriber line open Switches with two poles of a supply voltage source can be connected and each with a resistor Connections of a capacitor are connected to the one capacitor connection via a < Diode a query pulse delivering query device and practice on the other capacitor terminal another diode evaluates the state of charge of the capacitor when it is queried facility is connected.

Such a circuit arrangement is known from de German Auslegeschrift 12 18 535. With this Circuit arrangement it is possible to determine three operational states of the subscriber line:

1. can the "idle state" of the subscriber line can be determined, which is characterized in that the supply voltage is determined by means of the said! Switch is constantly placed on the subscriber line and the handset of the subscriber station is in place (open loop);

2. the line status 'outgoing call' can be determined for which the switch mentioned are also closed and the handset is lifted (closed loop);

3. the “call status” of the subscriber line can be derived from the specified) Switches are open and thus the supply voltage ii of the subscriber circuit is not connected to the line wheels and in which the handset is lifted.

The object of the invention is to provide a circuit arrangement of the type mentioned at the outset, mi which in addition to the three operating states mentioned, two more can be determined in a simple manner: can. For it is desirable

4. the »false call status« and

5. the "false call end status" of the subscriber line when the relevant subscriber key is queried tion to sign.

The "false call status" occurs when a triggering connection is present, i. n. if between the called subscriber, but not the calling subscriber has hung up his handset, ode if the calling subscriber tries to connect to the called subscriber or a Found Koppelnetzgasse occupied. The »Miss

calling status "is present when after a Wrong call the calling subscriber has just put on his handset, the switching facility but has not yet returned to sleep.

By the German Auslegeschnit 11 37 085 is a Telephone system with a subscriber memory known, with the help of which now also the determination further operating states is made possible. For example, the operating states »has hung up «and» is in the release state «ι ο record. A toroidal core memory is used for the subscriber memory suggested. Such a toroidal core memory, however, has a complicated structure and is expensive; one is endeavors to use integrated circuits to make telephone systems cheaper to a wider extent; the use of toroidal core storage is contrary to this.

Furthermore, the German Auslegeschrift 10 84 770 a device for checking a line on its current occupancy is known, in addition to a toroidal core memory also the use of transistors to determine the conduction state is suggested. The transistors are inserted into the line wires due to the voltage drops Resistances controlled and give the states »Line feed wires available« and »Line feed current not available «on to evaluation equipment.

The stated object is achieved according to the invention in that when there is a false call, the Switches are open and further switches a supply voltage characterizing the false call across the Put feed resistors on the two wires and that on the common connection point of the the switch that applies the false call potential and the associated feed resistance test device recognizing the query is connected.

Another embodiment of the invention is characterized in that one is permeable to the feed stream polarized diode in the line core connected to the test device between the access point of the line selector and the associated feed resistor is inserted that the test device a between said connection pin and the one pole of a bias voltage source inserted series resistor and a test circuit composed of a resistor, a capacitor and a diode having, these test circuit members being connected together in a star shape and the one remote from the star point so Resistance connection with the mentioned connection point, the capacitor connection distant from the star point with the interrogation device and the star point remote diode connection connected to the evaluation device is, and that the diodes are polarized and the polarity ss of the bias source pole and the size of the Bias voltage are chosen such that these diodes are independent of the interrogation potential when the switches are open are lockable. In the call state of the subscriber line, there is therefore no evaluable signal at the output ho generated by the test facility. The supply voltage applied to the subscriber line by the line selector cannot have a negative influence on the test facility.

According to a further advantageous embodiment of the 6s According to the invention, the evaluation device has two threshold value circuits connected in parallel on the input side with different input thresholds; the feed potential at the mentioned connection point, the False call potential and the query potential are dimensioned in such a way that the resulting from the query Input voltage of the evaluation device with closed supply voltage switches above the highest Schwellwen and when false call voltage switches are closed between the threshold values Such an arrangement enables increased reliability of the information about the operating states of the Participant management.

The interrogation device is particularly simple when it is connected to a voltage source with a single pole has switchable voltage divider with two different taps, one of which with the Loop testing circuit and the other is connected to the testing device.

The invention will now be explained in more detail using an exemplary embodiment. It shows

F i g. 1 shows a circuit arrangement according to the invention and

Fig. 2 is a brief summary of the mode of operation in tabular form.

Fig. 1 essentially comprises a Teilnehmeranschlußle-tung with two line conductors L 1 and L 2, an input connected to the line conductors Ll, L2 Station Set Pt, an input connected to the line wires LI, L2 line selector RC, one with the line conductors Ll, L2 connected subscriber line circuit EQ, an interrogation device DT and an evaluation device made up of circuits DLl, DL 2 and DL 3. The coupling arrangement containing the line selector RC enables the subscriber line Ll, L 2 to be connected to a suitable central switching device to establish a connection.

If the subscriber line L 1, L 2 is not connected to the central switching device via the line selector RC , it is fed by the subscriber line circuit (subscriber circuit). For this purpose, switching means (not shown) close their KorUakie A 1, A 2; this means that the line is free. In this case, earth is applied to a common connection point 51 of the line wires Ll and a potential - U to a connection point B 2 of the line wire L 2. If the subscriber line is in the "false call state", contacts PX and P2 are closed by switching means, not shown , instead of contacts Ai, A2. A potential -u is applied to the connection point B 1 and the potential -t / to the connection point B2 . If the subscriber line is connected to the central switching device via the line selector RCmh, then this central switching device feeds the subscriber line, with ground potential on one line wire (L 1 or L 2) and negative potential, for example the potential - U, on the other line wire (L 2 or L 1) appears.

The test of the operating states of the subscriber line is carried out with the loop test circuit CTX and false call test circuit CT2 arranged in the subscriber circuit EQ . The loop closure test circuit Cn is described in the above-mentioned patent application and has two resistors R3, R 4, a capacitor CX and two diodes D1, D4. The resistor R3 is connected to the line conductor L 2. In contrast to what is known, the resistor /? 4 is connected to the line core L 1 via a diode D5, which is polarized so that it is permeable to the supply current

connected. The capacitor C1, which is connected with its one connection L via the diode D 4 to the interrogation device DT and with its other connection M via the diode D1 to the evaluation circuit DL 1, is located between the remote connections of the resistors R 3, R 4. A feed resistor R 1 is inserted between the diode D 5 and the connection point BX , while a further feed resistor R 2 is located between the line core L2 and the connection point B2. Furthermore, a series resistor R 5 is inserted between the connection point BX and the one pole -U of a bias voltage source, the function of which will be explained in more detail. The test circuit CT2 consists of a resistor R 6, a capacitor C 2 and a diode D 6. These test circuit elements are connected together in a star shape. The terminal of the resistor R 6 remote from the star point is connected to the connection point A1, the terminal remote from the capacitor C2 is connected to the interrogation device DT and the terminal remote from the diode D 6 is connected to the evaluation circuits DL 2, DL 3. The test circuit CT1 is in a state that is dependent on the fact whether the subscriber line loop is closed or not. In the same way, the test circuit CT2 is in a state which corresponds to the subscriber line state (idle state, false call state, conversation state).

The interrogation device DT consists of a voltage divider which can be switched single-pole to a voltage source by means of a transistor TX and has two different taps, of which a tap £ 1 connected directly to the emitter of the transistor TX with the test circuit CTl and the tap E 2 connected to the emitter via a resistor is connected to the test circuit CT2. The interrogation device DT applies positive interrogation pulses to the taps EX and E 2 at regular time intervals. Because of this, a positive potential appears at the output Sl of the test circuit CTl when the subscriber line loop is not closed, while the output SX is floating when the loop is closed. The evaluation circuit DL X evaluates every positive potential generated by the test circuit CTl as a logical one. In the same way, on the basis of an interrogation pulse, a potential appears at the output S2 of the test circuit CT2, which potential depends on the state of the test circuit CT2 and thus on the state of the subscriber line. The evaluation circuits DL 2 and DL 3 recognize these potentials. If the subscriber line is free (idle state), a potential occurs at the star point N of the test circuit CT2 which is higher than a certain value + v, the input threshold value of the evaluation circuit DL 2. This potential is recognized by both evaluation circuits DL2, DL3 . If the subscriber line is in the false call state, a positive potential appears at the neutral point No , which is between the threshold value + ν and the lower threshold value earth of the evaluation circuit DL 3. This potential is only recognized by the evaluation circuit DL 3. If the subscriber line is in the call state, a negative potential occurs at the star point N and the evaluation circuits DL 2, DL3 do not respond, ie they output a logical 0. The query result at the outputs of the evaluation circuit DL2, DL3 identifies the subscriber line status and enables the information supplied by the evaluation circuit DL1 to be evaluated as the operating status of the subscriber line.

It should be noted that the interrogation device DT can interrogate several subscriber circuits at the same time, as indicated by the arrows at the taps El, £ 2. The evaluation circuits DL1, DL 2 and DL 3 can also be connected to several subscriber circuits, as is also indicated by arrows. The interrogation device DT and the evaluation device DL form a matrix-shaped subscriber line scanner.

The operation of the circuit arrangement in FIG. I. will now be described in detail. The different, successive operating states that a telephone line would normally pick up during the establishment of a call can. These operating states are: The subscriber line is in the idle state (before production of a connection), the subscriber line is in the "outgoing call" state (if the subscriber calls), the subscriber line is in the call state (if the calling line with a called Line is connected), the subscriber line is in the false call state (if for example a Conversation not possible), and the subscriber line is in the status »failed caller« (it is in Term to go from the false call state to the idle state).

In Fig. 2 shows these states and their meaning. In Fig. 2 also shows exemplary potentials at points L, M, N before the occurrence of an interrogation pulse, while columns M ' and N' show the potentials at points M, N at the beginning of an interrogation pulse. Finally, in the columns DL 1, DL 2, DL 3, the logical states of the corresponding evaluation circuits are mentioned. For the evaluation circuits DL 1 and DL 3, a logical one means that the evaluation circuit in question has received a positive potential at its input (SX, S 2) during an interrogation pulse.

For the evaluation circuit DL 2, a logical one means that this circuit has an input pulse received whose amplitude is greater than + ν.

A logical one means that the evaluation circuits have not received any input potential.

To make the description easier, it is assumed that the potential - L / = 48 V, the potential -u = -6 V and that the supply resistances RX and R 2 and the resistance of the line loop are equal to one another. It should also be assumed that during the test a positive pulse is applied to the base of the transistor TX which controls this transistor in the conductive state, the potential at the tap EX from Wen - £ / = - 48 V to the value -19 V increases so that an interrogation pulse with an amplitude of 29 V occurs.Be the interrogation, the potential of the tap El also rises from the value - U = - 48 V to the value - 30 V, so that an interrogation pulse with an amplitude of 18 V occurs Finally, the potential -I- v of the emitter of the transistor TA in the evaluation circuit DL 2 is assumed to be approximately +15 λ.

_6s 1. Idle state

The potentials earth and - U are connected to the terminals de via di <contacts AX, A 2, the supply resistors RX, R 2 around the resistors RA, R 3

Condenser Cl supplied. The connection L has the potential -17 = 48 V and the connection M has ground potential. The capacitor CX is charged. An interrogation pulse with a positive edge (29 V) applied by the interrogator DTan the tap E 1 passes through the diode D4 to the capacitor CX, so that a positive potential occurs at the point Mein, which is the sum of the emitter voltage of -19 V of the transistor TX and corresponds to the voltage of 48 V on the capacitor CX and is thus 29 V. This potential reaches the input Sl of the evaluation circuit DL X via the diode DX and there makes the transistor Γ3 conductive. The interrogation circuit DL X responds, which indicates that the subscriber line loop is open.

Earth potential is applied to the star point N via the contact AX and the resistor /? 6, while the potential - U is applied to the other connection of this capacitor. The capacitor C2 is thus charged. An interrogation pulse with a positive edge (18 V) applied by the test circuit DT to the tap £ 2 arrives at the capacitor C 2, so that a positive potential occurs at the star point N , which is the sum of the voltage of -30 V at the tap E 2 and corresponds to the voltage of 48 V on capacitor C2 and is therefore 18 V. This potential reaches the input 52 of the evaluation circuits DL 2, DL 3 via the diode D 6. This potential is higher than the potentials of the emitters of the transistors Γ4, T5 of these evaluation circuits. These transistors thus become conductive. The Au-evaluation circuits DL 2, DL 3 respond and thus indicate that the connection point BX is connected to ground potential and that accordingly the contacts AX, A1, which apply the supply voltage to the subscriber line, are closed.

The response of the evaluation circuits DL 2, DL3 indicates that the subscriber line is free. The response of the evaluation circuit DL X indicates that the subscriber line loop is open. This is in the first line of the table in FIG. 2 marked.

Outgoing call status

In this state, the subscriber line is fed via the contacts AX, A 2 , but the subscriber line loop is closed. It should be remembered that the resistance of the subscriber line loop has the same value as the feed resistors A1, R2 .

The potentials of the connection points of the test circuit CTX with the lines LX and L 2 are

= -16 V

for the LX and

- ² ^ = -32V

for the line core L 2. The diodes DX and D 4 are blocked, and the potential of the point L is -32 V, while the potential of the point M has the value -16 V. An interrogation pulse applied to the tap EX makes the diode D 4 conductive only for the part of the pulse that extends from the value -32 V to the value -19 V. The potential occurring at point M is therefore only

-19V + 16V = -3V.

The diode DX is blocked by this potential at point M , so that the evaluation device DLX does not respond. This indicates that the subscriber line loop is closed.

The earth potential fed in via contact A 1 reaches the learning point N via resistor Λ 6, which is therefore at earth potential. During the interrogation, the test circuit CT2 behaves as described above. The evaluation circuits

ίο DL2 and DL 3 respond and indicate the fact that the subscriber line is supplied with the potentials - U and earth.

The response of the evaluation circuits DL 2 and DL 3 indicates the free state of the subscriber line. The non-response of the evaluation circuit DL 1 marks the participant loop closure. As a result, the subscriber has just picked up his handset, and the information given by the evaluation circuits DLX, DL 2 and DL 3 leads to the detection of an outgoing call, as is also shown in the 2nd line of the table in FIG. 2 is shown.

3. Call status

In the call state, the subscriber line is connected through the coupling network containing the line selector RC to a central switching device which feeds this subscriber line. The contacts AX, A 2 and Pl, P2 are open in this case.

In the case in which the subscriber line has a negative potential of -48 V on the line core LX and earth potential on the line core L 2 , the point L is at earth potential, whereby the diode D 4 is blocked. An interrogation pulse occurring at tap El is therefore ineffective. The evaluation circuit DL X cannot respond.

In the test circuit CT2, the star point / V is at the -48 V potential, which comes from the line core LX. An interrogation pulse with a positive edge of 18 V at tap E2 causes the potential at star point N to rise to a value of -30 V. The diode D 6 is blocked, the evaluation circuits DL 2 and DL 3 cannot respond.

In the case in which the supply takes place with reverse polarity, that is, in which the line wire LX has ground potential and the line wire L 2 has the negative potential -48 V, the diode D 5 is due to the ground potential applied to the line wire LX and the Negative potential applied by the bias voltage source via the series resistor R 5 to the connection point BX - U blocked. The points LM, N then have the potential - U = -48 V. In the test circuit CTX , a potential of -19 V appears at point M owing to an interrogation pulse with a positive edge of 29 V. The evaluation circuit DL X therefore cannot respond. In the same way, an interrogation pulse with a positive edge of 18 V in the test circuit CT2 causes the potential at the neutral point N to rise to a value of voi - 30 V. The evaluation circuits DL 2 and DL 3 can therefore both not respond.

It follows from this that in the call state of the subscriber line, regardless of the feed direction, the evaluation circuits DLX, DL2, DL3 do not respond. This call status is shown in the 3rd line of the table in FIG. 2 marked.

509 581/21

Λ Q71

4. False call condition

In this state, the subscriber line is fed via the contacts Pl and P2. The potential of the connection point of the test circuit CT \ with the line conductor L 1 is

- U -I ι / - 4X V t 6 V

- - 14 V,

while the potential of the connection point of the test circuit CT 1 with the conductor L 3

"- ■""- ■ ⁺ -" 1 - -2HV

amounts to. The diodes D 1 and D4 are blocked; the potential of point L is -28 V, while the potential of point M is -14 V. An interrogation pulse at tap Ei makes diode D 4 conductive only during that part of the pulse which extends from -28 V to 19 V. A potential of -19V + 14V = -5V therefore appears at point M. The evaluation circuit DL i does not respond, which indicates that the line loop is closed.

In the test circuit CT2, the star point N is provided with the potential -u = -6V. An interrogation pulse occurring at tap £ 2 with a positive edge of 18 V is fed to capacitor C2 so that a potential of -30 V + 42 V = 12 V occurs at the star point No This potential is lower than the potential + v = + 15, so that the evaluation circuit DL 2 does not respond, while the evaluation circuit DL 3 is actuated, which indicates that the subscriber line is fed via the contacts PI and P 2.

The non- actuation of the evaluation circuits DL 1 and DL 2 and the actuation of the evaluation circuit DL 3 thus indicate the fact that the subscriber line is in the false call state, as shown in the 4th line of the table in FIG. 2 is shown.

5. Wrong call termination state

In the false call state, the subscriber has just hung up his handset after a false call. the Subscriber line loop is then no longer closed, although it still has contacts PI and P 2 is fed.

In the test circuit CTi , point L has the potential -U = -48 V, while point M has the potential -u = -6V. An interrogation pulse with a positive edge of 29 V, which occurs at tap £ 1, reaches capacitor CI via diode D4, so that a potential of -19 V + 42 V = 23 V occurs at point Mein. The interrogation circuit DL 1 responds, which indicates that the subscriber line loop is not closed.

In the test circuit CT2, the star point N is at the potential -u = -6V. The test circuit CT2 operates in the same way as in the case of the false call condition. The evaluation circuit DL 2 does not respond while the evaluation circuit DL 3 is actuated, which indicates that the subscriber line is fed via the contacts P1 and P 2.

The actuation of the evaluation circuit DL 1 means that the subscriber line loop is not closed. The non- actuation of the evaluation circuit DL 2 and the actuation of the evaluation circuit DL 3 mean that the subscriber line is in the false call state (fed via the contacts PI and P2). Since the subscriber line was previously in the false call state, the subscriber has just hung up his handset. The information supplied by the evaluation circuits DLi, DL 2, DL 3 therefore corresponds to a subscriber line that has given up the false call status, as shown in the 5th line of the table in FIG. 2 is shown.

The identification of the subscriber line status in connection with the loop closure detection according to The invention therefore enables the determination of the various operating states in which a Subscriber line can be located.

1 sheet of drawings

Q

Claims (4)

Patent claims: 1. Circuit arrangement for determining the operating state of subscriber lines in remote intercom systems, in which the two wires of each subscriber line in the associated subscriber circuit can be connected via feed resistors and via switches that are closed when the subscriber line is idle and open switches with two poles of a supply voltage source when the subscriber line is in a call state are connected via a resistor to the terminals of a capacitor and in which an interrogation device providing interrogation pulses is connected via a diode and an evaluation device evaluating the state of charge of the capacitor upon interrogation is connected to the other capacitor connection via a further diode , characterized in that when there is a false call the switches (A 1, A 2) are open and further switches (TJ, P2) a supply voltage characterizing the false call (- u, -LJ) via the supply resistors (R t, R 2) at Lay the two wires (L 1, L 2) and that at the common connection point (B 1) of the switch (Pi) applying the false call potential and the associated supply resistor (R 1) a test device (CT2, R 5 ) that recognizes the false call potential when interrogated , DL 2, DL 3) is connected, which, in conjunction with the device (DL \) evaluating the state of the subscriber loop, identify the states of the false call state or the false call end state. 2. Circuit arrangement according to claim 1, characterized in that a polarized diode (D 5) which is permeable to the feed current is inserted into the line core (L 1) connected to the test device between the access point of the line selector (RC) and the associated feed resistor (Ri) that the test device comprises a between said connection point (B 1) and the one pole (- U) a bias interposed series resistor (R 5) and a test circuit (CT2) comprises a resistor (R6), a capacitor (C2) and a Diode (D 6), these test circuit elements being connected together in a star shape and the resistor connection distant from the star point with the mentioned connection point (B \), the capacitor connection distant from the star point with the interrogation device (DT) and the diode connection distant from the star point with the evaluation device (DL2, DL 3) is connected, and that the diodes (D 5, D 6) are polarized in such a way and the polarity of the bias source pole and the size of the Vo The voltage is chosen so that these diodes can be blocked when the switches (A 1, A 2, Pi, P2) are open, regardless of the interrogation potential (-30 V). 3. Circuit arrangement according to claim 2, characterized in that the evaluation device has two threshold value circuits (DL 2, DL 3) connected in parallel on the input side with different input threshold values (+ 15V; OV) and that the supply potential (earth) at said connection point (B 1), the false call potential (-6V) and the interrogation potential (-30V) are dimensioned in such a way that the input voltage of the evaluation device resulting from the interrogation is above the highest when the supply voltage switches (A 1, A 2) are closed! Threshold value (+ 15 V) and with closed false call voltage switches (P 1, P2) lies between the threshold values. 4. Circuit arrangement according to one of claims 1 to 3, characterized in that di (interrogation device (DT) has a single-pole switchable voltage divider to eini voltage source with two different taps, of which one with the loop testing circuit (CTi) and the other is connected to the test facility (CT2 ...) .