FI102934B - Procedure and arrangement for raising onhook voltage - Google Patents

Description

102934

Method and arrangement for increasing the onhook voltage

The invention relates to a method for increasing the onhook voltage acting on a subscriber loop, which method is used in connection with a subscriber interface unit having wires and at least one terminal, and including subscriber interface means for adapting said wires to a subscriber interface. voltage.

The solution of the invention can be used in telecommunication devices, especially subscriber switching devices, which in some cases require increasing the onhook voltage in the subscriber loop. Onhook voltage 15 refers to the voltage that is applied between the subscriber lines when the terminal, for example, has a handset in place. Again, the offhook voltage refers to the voltage acting between the subscriber lines when the handset of the terminal, for example, a telephone, is lifted. When the offhook voltage is applied, the system has an offhook situation. Normally, the subscriber-switching devices are connected to, for example, a -48 volt operating voltage, i.e. a battery voltage. However, the battery voltage used is not always high enough to provide protection; This would generate a large enough onhook voltage to the subscriber loop. In addition, there are telephone exchanges, for example, which require a voltage higher than the onhook voltage generated by the normal battery voltage to the subscriber loop. It is therefore an object of the invention to provide a raised onhook voltage.

A solution for increasing the onhook voltage is known in the art, in which two separate battery voltages are used. Since the known solution required two separate battery voltages, the solution was 35 complex. As a result of the above, the known solution has become economically expensive. The solution has taken up a lot of space and the components used in the solution have consumed a lot of power.

It is therefore an object of the present invention to provide a new type of solution for increasing the onhook voltage in an onhook situation which avoids the problems associated with the known solution.

This is achieved by a method of the type described in the introduction, which is characterized in that an additional voltage generated from the same patte-10 bias voltage source increases the onhook voltage output from the matching means to the terminal.

The invention further relates to an arrangement for increasing an onhook voltage acting on a subscriber loop which is used in connection with a subscriber interface unit, which subscriber loop comprises wires and at least one terminal, and which subscriber interface unit comprises mating means for .

The arrangement according to the invention is characterized in that the arrangement comprises an auxiliary voltage source connected to a battery voltage source for adding an additional voltage to the battery voltage in an onhook situation.

. Several advantages are achieved by the method and arrangement of the invention. With the solution according to the invention, the onhook voltage of the subscriber loop can be increased by using only one battery voltage. In addition, the solution provides a stable and correct voltage to the onhook space-30 in the subscriber loop. The solution according to the invention is simple and consumes -: · low power. The solution becomes economically advantageous due to the small number of components. Further, the solution of the invention takes up less space than the prior art solution.

3, 102934

The invention will now be explained in more detail with reference to the examples in the accompanying drawings, in which Figure 1 shows one preferred wiring diagram of the arrangement according to the invention and Figure 2 shows another preferred wiring diagram of the arrangement according to the invention.

Figure 1 shows an arrangement according to the invention for raising the onhook voltage Von in the onhook situation. The arrangement comprises matching means 1, a battery voltage source 4 and a subscriber loop B. The subscriber loop B comprises wires a and b and a terminal 3 connected to wires a and b. The matching means l adapts the wires a and b to the subscriber interface unit. Preferably, the matching means 1 is implemented by a subscriber line matching circuit, or SLIC (Subscriber Line Interface Circuit). For example, the commercial circuit Am79M574 can be used as a SLIC. The arrangement further comprises an auxiliary voltage source 2. In the embodiment shown in the figure, the auxiliary voltage source 2 is implemented with a commercial DC / DC converter or a switching power supply. The additional voltage source 2 comprises a primary 2a and secondary 2b. The auxiliary voltage source 2 is connected from the primary side 2a to the coil voltage source 4 and the secondary side 2b to the matching means 1.

25, the radiator voltage Vbat, typically between -44 V and -54 V. The magnitude of the radiator voltage Vbat influences the magnitude of the onhook voltage Von in the subscriber loop B. The auxiliary voltage source 2 connected to the battery voltage source 4 yh-30 forms the battery voltage. of tea Vbat extra voltage Vad. The generated auxiliary voltage '· Vad is added to the radiator voltage Vbat provided by the radiator voltage source 4, whereby the onhook voltage Von acting in the subscriber loop B through the matching means 1 is increased in the same proportion. In the solution shown in the figure, a subscriber terminal 3, which is practically a telephone machine, is connected between the wires 4 102934 a and b.

In the solution of Figure 1, the pat-5 voltage Vbat of the pat-5 from the battery voltage source 4 to the primary side 2a of the auxiliary voltage source 2 is negative. The radiator voltage Vbat generated by the battery voltage source 4c may also be positive.

In this case, the connection must be changed to match the polarity of the battery voltage Vbat. The additional voltage source 2 to convert from one to the battery voltage source 4 of the patio ester negative voltage V bat so that the additional voltage source 2 and the secondary side 2b and one point between the matching means A in the -60 V to equal kriteeriojännite VKR.

Fig. 2 shows an arrangement comprising matching means 1, auxiliary voltage source 2, criterion voltage source 4 and subscriber loop B. Subscriber loop B comprises wires a and b and terminal 3 connected to wires a and b. In addition, the arrangement comprises current limiting means 5 and diodes 6, 7. The current limiting means 5 is fitted by means of diode 6 to the matching means 1 so that the anode 20 of the diode 6 is connected to the matching means 1 and the cathode of diode 6 is connected to current limiting means 5. The current limiting means 5 are practically implemented by a constant current generator. Further, in the figure, the anodes of the diodes 6, 7 are connected together. The cathode of diode 7 is connected to battery voltage source 4 and auxiliary voltage source 2. Diode 6,7 is selected to withstand a current of about 50 mA and a voltage of more than 60 V. A subscriber terminal 3, which in this case is a telephone machine, is connected between the lines a and b leaving the matching means 1.

Figure 2 shows that the radiator voltage Vbat generated by the battery voltage source 4 is typically between -44 V and -54 V. By connecting the auxiliary voltage source 2 and the current limiting means 5 in the figure, the voltage applied to the matching means 1 is increased by -35 t. At the same time, the subscriber loop B in the on-hook situation 5 102934 grows

the effective onhook voltage Von, which in the solution according to the invention is higher than that generated by the subscriber loop B generated solely by the battery> voltage source 4

onhook voltage Von. The auxiliary voltage Vad generated by the auxiliary voltage source 2 is switched on only in the onhook situation. The current limiting means 5 comprises a voltage regulating circuit 8 which maintains the criterion voltage V kr generated at the point A between diodes 6, 7 and the matching means 1 even though the patte-10 bias voltage Vbat generated by the battery voltage source 4 is fluctuating. By using the control circuit 8, the maximum supply voltage of the adapter means 4 acting at point A of the arrangement is avoided. If the coil voltage Vbat generated by the coil voltage source 4 has interfering voltages, for example ripple voltage, then the regulating circuit 8 maintains the voltage Vkr acting at point A of the arrangement.

In the arrangement of Fig. 2, current I passes through the matching means 1. The current limiting means 5 are dimensioned such that, in the onhook situation, I draws 20 currents, i.e., the same as that which the matching means 1 draws. Thus, at the anodes of the diodes 6, 7 shown in the figure, the acting voltage at point A of the figure is the sum of the radiator voltage Vbat generated by the battery voltage source 4 and the auxiliary voltage Vad produced by the auxiliary voltage source 2. In the off-25 hook condition, most of the current flowing through the matching means 4 passes through diode 7, whereby the auxiliary voltage Vad generated by the auxiliary voltage source 2 does not add up to the radiator voltage Vbat generated by the battery voltage source 4. Then, at point A of the arrangement, only the pat-30 blade voltage Vbat is affected.

,! If the nominal value of the radiator voltage Vbat in the solution shown in the figure is, for example, -48 V, the voltage at the point A in the figure is regulated by the regulating circuit 8 to -60 V. If the onhook voltage V is for example -44 V and the battery voltage Vbat to be used is -44 V, then point -60 V is required at point A. In this situation, the auxiliary voltage source 2 generates an auxiliary voltage Vad of about -18 V. Directly calculating the auxiliary voltage Vad and the radiator voltage Vbat is equal to -62 V. is -60V, which gives rise to an onhook .onhook voltage of -44V.

While the invention has been described above with reference to the example of the accompanying drawings, it is to be understood that the invention is not limited thereto, but can be modified in many ways within the scope of the inventive idea set forth in the appended claims.

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Claims (14)

A method for increasing the onhook voltage (Von) acting on a subscriber loop (B), which method is used in connection with a subscriber interface unit, which subscriber loop (B) includes wires (a, b) and at least one terminal (3), and which subscriber interface unit includes adapting means (1) for adapting said wires (a, b) to the subscriber interface unit, and wherein the radiator voltage source (4) 10 generates a radiator voltage (Vbat), characterized in that the auxiliary voltage (Vad ) increasing the onhook voltage (Von) from the matching means (1) to the terminal (3). Method according to claim 1, characterized in that the auxiliary voltage (Vad) is applied only in the onhook situation. Method according to claim 1, characterized in that the current provided by the auxiliary voltage (Vad) is limited. A method according to claim 3, characterized in that the current is limited to approximately the current drawn by the matching means (1) in the on-hook situation. A method according to claim 1, characterized in that the criterion voltage (Vkr) acting at the point (A) between the battery voltage source (4) and the matching means (1) is kept constant. An arrangement for increasing the active onhook voltage (Von) in a subscriber loop (B) used in connection with a subscriber interface unit, the subscriber loop (B) comprising wires (a, b) and at least one terminal (3), and the subscriber interface unit comprising matching means. (1) for connecting the wires (a, b) to the subscriber interface unit, which arrangement comprises a battery voltage (Vbat) for generating a battery voltage (Vbat) of the radiator 35, characterized in that the arrangement comprises an additional voltage (2) connected to the battery voltage source (4) Vad) to the battery voltage (Vbat) in an onhook situation. Arrangement according to Claim 6, characterized in that the auxiliary voltage source (2) is connected in series with the battery voltage source (4). Arrangement according to Claim 7, characterized in that the additional voltage source (2) is Arrangement according to claim 6, characterized in that the arrangement comprises current limiting means (5) for switching on the auxiliary voltage (Vad) in an on-hook situation. Arrangement according to Claim 9, characterized in that the current limiting means (5) are connected in series with the auxiliary voltage source (2). 10 DC / DC converter or switching power supply. Arrangement according to Claim 9, characterized in that the current limiting means (5) are implemented by a constant current generator. An arrangement according to claim 6, characterized in that the arrangement comprises only one battery voltage source (4). An arrangement according to claim 9,. 25, characterized in that the current limiting means (5) comprises an arrangement of the regulator (8) to maintain the constant criterion voltage (Vkr) acting at (A). Arrangement according to Claim 6, characterized in that the matching means (1) is implemented by a subscriber line interface circuit, for example a SLIC circuit. »102934 \