SE440304B - PHONE CONNECTOR SWITCH FOR CONNECTING TO A PUPINIZED CABLE - Google Patents

Description

15 20 25 30 35 i y9 @ 5g; a2-e 2 but the design and dimensionalisation of a suitable barrier filter has given major problems. Such a blocking filter must firstly block the tariff pulse frequency as far as possible and, on the other hand, ensure an error-free and, as far as possible, frequency-independent transmission of the frequencies on the telephony band in both directions. Since the cut-off frequency of 4 kHz is very close to the upper limit of the telephony band, these requirements have so far not been technically achievable. It has been found that, for example, simply constructed filters, which have good properties in high-frequency counting, are not useful. Nor has it been possible so far to find any relatively simple, symmetrical circuit circuits with real terminations, which circuits satisfy the two mentioned requirements. The object of the present invention is to provide a blocking filter with a simple construction suitable for tariff pulse frequencies in the vicinity of the upper speech band limit, especially for 4-kHz counting, which prevents feeding of taxi pulses to the telephone set or feeding of arising in the telephone set. interference signals to the taxi impulse receiver, but still enables at least approximately frequency-independent transmission of the speech frequencies in both directions, and in addition provides a good impedance transformer which is tuned to an average cable impedance for a normal, non-pupinized telephone line.

This object is achieved according to the invention with a telephone subscriber exchange, the features of which appear from the characterizing part of claim 1.

It has surprisingly been found that it is possible to dimension a blocking filter which is symmetrical, relatively simple in shape, with a complex termination of the type specified on the telephone side in such a way that it has a wide, mainly te. - the telephone band corresponding to the passband and an immediate attenuation of the taxi impulses immediately connected to the passband. For optimal wave transmission, such a blocking filter at the same time has the properties of an optimal impedance transformer, so that ordinary telephone sets adapted to normal telephone lines can be connected to pupinized lines without any disadvantages by pre-connection of a subscriber exchange according to the present invention.

In particular, it has been found that a blocking filter according to the invention also gives a good rectangular equivalent.

Preferably, the blocking filter according to the invention may be arranged to block a rate pulse frequency of approximately 4 kHz. Detailed, preferred embodiments appear from claims 2-5, while claims 6-8 describe a preferred embodiment of the invention, which allows the use of commercially available charge calculators or devices for call data measurement, which are arranged to receive 12- or 16-kHz rate pulses and designed as a four-pole for connection to the two speech wires.

Such toll counters and devices can be conveniently easily connected between the subscriber exchange according to the invention and the telephone set.

The invention will be described in more detail below with exemplary embodiments with reference to the accompanying drawings. Fig. 1 shows a block diagram of a central line with a station exchange and a subscriber station, which is provided with a subscriber exchange and a toll counter. Fig. 2 shows an equivalent diagram for the blocking filter terminations in the case when the station is transmitting. Fig. 3 corresponds to Fig. 1 but applies to the case when the telephone set is transmitting.

Fig. 4 shows a typical attenuation curve provided with a blocking filter for a subscriber exchange according to the invention, which illustrates the attenuation A as a function of the frequency (in Hz) during voltage transmission from the subscriber to the station (according to Fig. 3). Fig. 5 shows a first embodiment of a blocking filter in its soil asymmetrical version. Fig. 6 shows a second embodiment of a blocking filter in its soil asymmetrical version. Figures 7 and 8 show the earth-symmetrical version of the barrier filter according to Figures 5 and 6, respectively.

Fig. 9 shows a block diagram of a central line with a station exchange and a subscriber station, which is provided with a subscriber exchange, a frequency transformer and one between the subscriber exchange and the telephone set of the voice wires. coupled device for billing and possible call measurement.

Fig. 1 shows a central line with the two between a telephone station 1, in which a taxi pulse sensor 3 and a telephone station exchange 4 are installed, and a subscriber station with a telephone set 2, a subscriber exchange provided with a blocking filter - a stand 5 and a taxi pulse receiver 6, taxi pulse amplifier 7 and a charge counter 8 connected the speech wires a and b. The station exchange 4 prevents a transmission of the taxi pulses generated during a call from the taxi pulse generator 3 to the other station equipment. The blocking filter 5 of the subscriber exchange blocks the taxi pulses supplied via the speech wires a, b, which are fed to the amplifier 7 via the taxi pulse receiver 6 for controlling the toll counter 8, so that these pulses do not reach the telephone H 2 and interference signals are generated in the telephone. the taxi pulse frequency does not reach the receiver 6 for controlling the charge counter 8. In the embodiment shown, the blocking filter 5 is arranged to block taxi pulses with a frequency of approximately 4 kHz and equipped with terminations, which according to Figs. 2 and 3 are complex on the telephone side and real on the station side. It has been found that a complex termination in the form of a parallel connection consisting of a resistor R2 with a resistance t of approximately 860 och and a capacitor C2 with a capacitance of approximately 40 nF well corresponds to the input impedance which telephone lines generally have. and that a real termination consisting of a resistor R1 with a resistance of approximately l1010 9 on the station side is very well adapted to the impedance of a pupinized line and of the station switch. When the station switch transmits, ie a voltage transfer from the station to the subscriber, there is a source voltage U0 at the station and a voltage U2 at the output of the blocking filter 5 on the subscriber side (Fig. 2). When the subscriber transmits, i.e. a voltage transfer from the subscriber to the station, the voltage U0 is present at the subscriber side, the parallel connection R2 and C2 being connected in series with this voltage source (Fig. 3), and at the output of the cut-off filter 5 on the station side is the voltage U2.

For the construction of a blocking filter 5 with such terminations and the property that the speech frequency is transmitted error-free and practically frequency-independent in both directions on the telephony band, known technology hardly gives any suggestion, since so far only synthesis of filters for real terminations has been known. da. It can be expected that a filter with different terminations, one of which is also complex, will result in a rather complicated circuit.

However, it has surprisingly been found that a relatively simple built-in reactance filter, which has the shape of an impedance symmetrical filter, meets the mentioned requirements in an excellent manner. Fig. 5 shows a first embodiment of such a reactance filter 5 in its earth asymmetrical shape. The following description is limited to this shape, as it is simpler than the earth-symmetrical shape used in practice with equal longitudinal stresses. The conversion of this earth symmetrical shape is shown in Fig. 7 and can be accomplished by any person skilled in the art. Fig. 5 shows that the blocking filter 5 has a series circuit connected in a speech wire a consisting of two parallel oscillation circuits L3, C3 and L4, C4 and on the station side a coil L5 and further capacitors C6, C7 and C8, which are arranged between the two the parallel oscillating circuits and on both sides of the coil L5 and connecting the two speech wires a and b. A preferred component list for the filter element is as follows; L3 14.5 mH L5 64.3 mH C3 109.5 nF C6 51 nF L4 43.6 mH C7 41 nF C4 36.3 nF C8 17 nF These values can of course vary a few percent.

With such a blocking filter 5, in the case of a voltage transfer from the subscriber to the station according to Fig. 3, an ÜwA-.l Ûf-'TFT 'TFT ._ a =' - 'iMÅlm-É 6 attenuation A = 20 lg Rl U' _ * - UZ / -ïllïz-, (varvia 1: 1 = 1100 sz and o R2 = 860 0), this attenuation being shown in Fig. 4 as a function of the frequency in Hz. According to this function, the attenuation on the telephony band between 0 and about 3600 Hz is very small and rises steeply immediately above the telephony band, with two narrow, adjacent attenuation peaks appearing at about 4000 Hz, since the blocking filter S has two parallel oscillation circuits. .

The corresponding curve for attenuation during a voltage transmission from the station to the subscriber has in principle the same shape but is in a known manner superimposed with a frequency-dependent additional attenuation.

The described blocking filter 5 is not only a frequency filter which meets the desired requirements, but also forms a practical, optimal impedance transformer, so that a good tuning to the average value of the cable impedance for a normal, ie non-pupinized line is achieved. This means that in principle the ordinary telephone sets intended for normal telephone lines can be used without further ado at the subscriber's location for connection to pupinised lines, which are provided with a subscriber exchange according to the invention, without any deteriorations regarding the signal transmission or the hearing equivalent. occurs.

At 6 shows a second embodiment of a blocking filter G '5, the construction of which is based on a basic shape, in which two parallel oscillating circuits in series on the filter side adjacent to the station and a single coil on the apparatus side are arranged. Below, the earth-symmetrical shape will again be considered with the aid of Fig. 6, while the earth-symmetrical shape will be shown in Fig. 8.

When calculating such a filter, which must meet the given requirements, it turns out, however, that the last capacitance placed at the station side between the two speech wires a and b becomes negative and must therefore be replaced by a known, equivalent coupling. This consists in Fig. 6 of a parallel oscillation circuit placed in the speech wire aa L 155, C15, whose coil L15 on its side facing away from the station is connected to a series connection of a coil L18 and a capacitor C18, i.e. a series oscillation circuit. Coils L15 and L18 are connected and can in practice consist of a single coil, which has a socket for the speech wires a and for the capacitor C15, respectively. In series with the parallel oscillation circuit L115, C15 is a further parallel oscillation circuit L14, C14 and a coil L13 arranged on the telephone side. On both sides of this coil L13, the speech wires a and b are connected to each other by means of capacitors C16 and C17. A preferred component list for the filter 5 'in Fig. 6 is as follows: L133 70.5 mH C16 39.4 nF L14 45.3 mH C17 47.4 nF C14 35 nF L18 40.3 NH L15 6.61 mH C18 18.3 nF C15 82.8 nF These values can vary eg 5%.

In a further embodiment, not shown, of the ratchet filter, the parallel oscillating circuit of the filter in the middle can change location with the coil L13 connected on the ratchet side, while the coupling on the station side of the filter, which is an equivalent to the coupling part with negative capacitance, remains in the same place.

This changes the capacitance and inductance of the entire filter element. In principle, a blocking filter according to the invention can have more than two parallel oscillation circuits, whereby in general the number of attenuation peaks at 4 kHz increases correspondingly. However, it has been found that a cut-off filter with two parallel oscillation circuits completely meets the desired requirements, so that in general no additional multi-component circuit circuits other than those of Figs. 5 and 6 are necessary.

In order to be able to use known subscriber fee calculators or more expensive devices for call measurement, including fee billing, which are arranged to perform the usual high-frequency billing, ie for rate impulses from 12-16 kHz, one can preferably use it in fig. POOR QUALIT 79 059.112 * 8 10 15 20 25 30 '8 9 displayed the subscriber exchange. The station 1, the taxi pulse generator 3 installed therein, the station exchange 4 and the speech wires a and b are schematically shown in the figure, a _; The subscriber exchange is connected to the subscriber side of the wires and may comprise the blocking filter 5 ', as shown in Figs. 6 and 8, respectively, and the taxi impulse receiver 6'. The output of the tariff pulse receiver 6 'is connected to a frequency converter 9, which converts the 4-kHz tariff pulse into a 16-kHz pulse. The output of the frequency converter 9 is again connected on the telephone side of the blocking filter 5 'to the speech wires a and b, to which in addition a conventional, 4-pole charge counter 8' for 16-kHz is connected. In the embodiment shown, the input of the 16-kHz pulse is effected by means of an inductive transmitting means, which comprises a coil 11 placed in the output circuit of the frequency converter 9 and a coil 10 connected thereto in series with the capacitor C16 of the blocking filter 5 '. It is of course possible to use another form of feeding. For 12-kHz counting, it is natural to use a 4 kHz / 12 kHz converter.

With the subscriber exchange according to Fig. 9, all conventional fee calculators or call meters arranged for the known high-frequency bill can thus be used, which are designed as four poles and connected to the two speech wires a and b. The subscriber exchanges according to the invention can of course also have cut-off filters, which are intended for tariff pulse frequencies deviating from 4 kHz, which are in the vicinity of the upper limit frequency of the telephony band, for example for 3.8 kHz or even for 5 kHz.

Claims (8)

7905902-8 PATENT REQUIREMENTS 1. A telephone subscriber exchange for connection to a pupinised line, which exchange has a blocking filter for keeping taxi impulses fed via a central line separate from a telephone set, the blocking filter (5, 5 ') having a passband in the talking band area and being arranged. blocking rate pulse frequencies in the vicinity of the upper speech band boundary, partly consisting of a reactant filter, which has a series connection of at least two parallel oscillation circuits and inter-capacitors arranged therebetween (C6; C18), characterized in that the last component at the end of the series consists of a coil (LS: Ll3); that cross-capacitors (C7, C8; C16, C17) are arranged on both sides of this coil; and that the reactance filter immediately behind the passband range, at the high frequency end, has a maximum attenuation at the current rate pulse frequency of approximately 4 kHz, the filter being formed with a complex termination corresponding to a parallel circuit of ohmic and capacitive impedances (R1, C2) on the telephone side and a real termination (R1) on the station side. Subscriber switch according to Claim 1, characterized in that the complex termination on the telephone side (2) corresponds to an ohmic resistor (R2) with a resistance of 800-1000 och and a capacitance (C2) connected in parallel to this resistor. with a capacitance of 30-50 nF and that the real termination on the station side corresponds to an ohmic resistor (R1) with a resistance of 1000-1200 Q. Subscriber switch according to Claims 1 and 2, characterized in that the blocking filter (5) in its earth asymmetrical shape for achieving a termination resistance (R1) of approximately 1100 Q * on the station side and for achieving a termination with a * Enea Qaaizm n 79 Û-5-9-'Û: 2 ~ 8 10 resistors (R2) of 860 Q and a capacitance (C2) of approximately 40 nF on the telephone side have a coil (LS) placed on the station side with an inductance of 64 mH, on the one hand a parallel oscillation circuit arranged next to this coil with a coil (L4), the inductance of which is 44 mH, and a capacitor (C4) with a capacitance of 36 nF, and on the other hand a second parallel oscillation circuit with a coil (L3), having an inductance of 14 mH, and a capacitor (C3) having a capacitance of 110 nF, and furthermore, the two capacitors (a, b) connecting capacitors (C8, C7, C6) having capacitances which with from the beginning from the capacitor lying on the station side exhibits capacitances of 17 nF, 4 nF and 51 nF, respectively, whereby d all component values can vary approximately 5%. Subscriber switch according to Claim 1 or 2, characterized in that the blocking filter (5 '), in its earth-symmetrical shape on the station side, has on the one hand an equivalent capacitance with a negative capacitance consisting of a parallel oscillation circuit placed in one of the speech wires (a). L15, C15) and a series oscillating circuit (L18, C18), which connects the coil (L15) of the parallel oscillating circuit to the second speech wire (b), the coils (L15, L18) of these oscillating circuits being connected. 5. A subscriber exchange according to claim 4, characterized in that the coils (L15, L18) for the parallel and series oscillation circuit of said equivalent coupling consist of a common coil _ with a socket connectable to the first-mentioned speech wire (a). Subscriber switch according to claims 4 and 5, characterized in that the equivalent connection for providing a termination resistor (R1) of approximately 1100 Q on the station side and for providing a connection with a resistor (R2) of approximately 860 and a capacitance (C2) of approximately 40 nF on the telephone side has partly a parallel oscillation circuit with a coil (L15) of 6.6 mH and a capacitor (C15) of 83 nF and partly a series oscillation circuit with a coil (L18) of 40 mH and a capacitor (C18) of 18 nF and that a second parallel oscillation circuit is provided with a coil (L14) of 45 mH and a capacitor (C14) of 35 nF and a coil (L13) of 71 mH on the telephone side, which second parallel oscillation circuit has capacitors (C16, C17) which connect the speech wires, the capacitor (C16) placed on the telephone side having a capacitance of 39 nF and the second capacitor (C17) having a capacitance of 47 nF and whereby all the above-mentioned component values can vary by approximately 5%. Subscriber switch according to one of the preceding claims, characterized in that a frequency converter (9) is connected to a taxi pulse receiver (6 '), which converter converts the frequency of the taxi pulse coming from the station (1) into a the conventional high frequency count suitable frequency (12 and 16 kHz, respectively), and that the output of the frequency converter is connected to the speech wires on the side of the blocking filter (5 ') facing the telephone set (2). A subscriber exchange according to claim 7, characterized by an inductive transmission means (10, 11), which connects the frequency converter (9) to the subscriber side of the blocking filter (5 '). -L- '. 19111 f fi iïj fl r- ~ f ~~ 7 ~~ f * few-m us -_, =, V. = _, ¿