Communications: electrical – Systems – Selsyn type
Reexamination Certificate
1999-06-14
2001-02-20
Crosland, Donnie L. (Department: 2736)
Communications: electrical
Systems
Selsyn type
C379S413000, C379S418000, C379S382000
Reexamination Certificate
active
06191684
ABSTRACT:
The invention relates to a circuit arrangement for remotely supplying a subscriber connection in a communications system, in particular a pair-gain system, having subscribers who can be connected via subscriber lines to a central point, for example a local section, with the supply voltage and current in each case being fed to the subscriber via at least one supply isolating element which is connected in series with the subscriber and the associated subscriber line, one connection of which at least one supply isolating element is connected to a supply voltage source assigned to the subscriber, while its other connection is connected to one wire in the subscriber line.
In known circuit arrangements of this type, the DC remote supply to the subscribers is produced by means of supply isolating elements which are provided, for example, in a local section of a remote equipment or of an exchange or the like, and which can typically be formed by resistors, inductances or current sources in order to provide a supply power level which is of the same magnitude irrespective of the distance to the subscriber, while ensuring, however, at the same time that the signal circuit and supply circuit are isolated.
The voltage drop across the supply isolating elements in conventional circuit arrangements is governed by the maximum voice level which is transmitted and can be received and by the maximum charge-pulse level. Since the charge pulses are transmitted only for a short time at specific intervals, the excess power in the supply isolating element in the remaining time intervals has to be dissipated via heat losses. Furthermore, the voice level is subject to different regulations in different countries, and the supply voltage is thus designed for the greatest of these levels, as a result of which additional power losses occur in countries with a low relative level in the circuit arrangements. This reduces the remote supply range, particularly for remotely supplied remote equipment.
A further disadvantage of the known circuit arrangements is that the amount of energy made available to each subscriber is that which allows the subscriber to still receive a regular supply when said subscriber is at the greatest possible range from the local section. The excess energy which remains for a subscriber who is located closer thus has to be destroyed, likewise in the local section, in the form of heat. In consequence, very large amounts of heat have to be dissipated in some cases, which, for example where there are a large number of subscribers in central exchanges, results in a cooling apparatus being set up which is used exclusively for this purpose. In this case, not only is energy wasted, but the necessity to constantly maintain the cooling results in a considerable cost.
The object of the invention is to avoid these disadvantages and to specify a circuit arrangement of the type mentioned initially which allows the heat losses to be reduced, as a result of which no cooling apparatus is required.
A further object of the invention is to achieve a high utilization level for the energy which is available for the subscriber supplies.
Furthermore, it is intended to allow an increase in the number of subscribers who can be supplied. A further aim of the invention is to achieve an increase in the supply range to individual subscribers.
This is achieved according to the invention by the output voltage of the supply voltage source being controllable.
The controllable output voltage of the supply voltage source allows the voltage drop across the supply isolating element to be reduced to the necessary extent as a function of a control variable via which the cause of the power losses occurring in the local sections can be identified and quantified.
A further embodiment of the invention provides for the supply voltage source to have a first control input, which is connected to the output of a control unit that produces analog or digital control signals as a function of the time profile and magnitude of the charge-pulse level and/or of the voice-signal level and/or of the maximum voice-signal level that occurs on the subscriber line.
Before the activation of a charge pulse, the output voltage of the supply voltage source, and thus the voltage drop across the supply isolating element, are increased via the first control input, and they are then reduced to the original value again after the charge pulse. With regard to the maximum voice-signal level which occurs on the subscriber line, the supply voltage can be matched via the control unit to the value agreed for a country or a region, or control can be carried out as a function of the time profile of the voice-signal level.
A development of the invention provides that the output voltage of the supply voltage source is increased or decreased in response to a rise or fall, respectively, in the control signals at one of its control inputs, preferably corresponding to a mathematical function, such that the harmonic component produced by the transition is below the lowest voice frequency that occurs on the subscriber line, preferably below 300 Hz.
This avoids any sudden transition from one voltage state to the other leading to the formation of interference frequencies which, superimposed on the voice signal, would be audible to the subscriber and would interfere with the course of the call.
According to another variant of the invention, it is possible to provide for the supply voltage source to have a second control input, which is connected to the output of a further control unit, the inputs of which further control unit pick up the voltage drop across the at least one supply isolating element, such that the output voltage of the supply voltage source is controllable as a function of the voltage drop that occurs across the supply isolating element.
This allows the power losses to be minimized by matching the supply voltage to the actually existing subscriber loop impedance, thus resulting both in optimization of the supply range for the number of subscribers and a reduction in the heat losses to be dissipated in the supply isolating elements. Greater individual subscriber ranges can thus be achieved, with the same total range.
A further feature of the invention may consist in that, in addition to the at least one supply isolating element, a further supply isolating element is provided, which is connected between the other subscriber line wire and ground.
Such a balanced supply is used to comply with national and international regulations and Standards. Furthermore, additional balancing circuits may be provided, which are not described in any more detail.
According to a further embodiment of the invention, it is possible to provide for the supply isolating element to be formed by a constant-current source, an inductance, an electronic inductor or a non-reactive resistor.
Both the constant-current source, the inductance, the electronic inductor and the non-reactive resistor allow the supply to be fed to the subscriber but, in the process, prevent any short circuit of the signal voltages transmitted on the subscriber line.
In a further embodiment of the invention, it possible to provide for the supply voltage source for supplying subscribers to be formed by a controllable switched-mode regulator. This allows any increase in the magnitude of the supply voltage to be controlled in a simple manner.
According to a further feature of the invention, the switched-mode regulator can be formed by an existing ringing-voltage generator in the local section.
In many implementations of local sections, each subscriber is assigned his or her own ringing-voltage generator, which includes a switched-mode regulator which can be used to produce the supply voltage, so that there is no need to provide a specific circuit for the subscriber.
In a further embodiment of the invention, it is possible to provide for the further control unit to be formed from a control amplifier, and for the output of the control amplifier to be connected to the second control input of the switched-mode regulator, s
Stadlbauer Günther
Steininger Robert
Burns Doane Swecker & Mathis L.L.P.
Crosland Donnie L.
Ericsson Austria AG
LandOfFree
Remote supply circuitry does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Remote supply circuitry, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Remote supply circuitry will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2615690