EP1142294A1 - Circuit et procede de telealimentation - Google Patents

Circuit et procede de telealimentation

Info

Publication number
EP1142294A1
EP1142294A1 EP99960705A EP99960705A EP1142294A1 EP 1142294 A1 EP1142294 A1 EP 1142294A1 EP 99960705 A EP99960705 A EP 99960705A EP 99960705 A EP99960705 A EP 99960705A EP 1142294 A1 EP1142294 A1 EP 1142294A1
Authority
EP
European Patent Office
Prior art keywords
remote
voltage
subscriber
supply voltage
fed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99960705A
Other languages
German (de)
English (en)
Inventor
Peter Kovarik
Günther STADLBAUER
Franz Haselsteiner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Flextronics International GmbH and Co Nfg KG
Original Assignee
Ahead Communications Systems AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AT214698A external-priority patent/AT409909B/de
Priority claimed from AT219098A external-priority patent/AT408597B/de
Priority claimed from AT0058399A external-priority patent/AT410877B/de
Application filed by Ahead Communications Systems AG filed Critical Ahead Communications Systems AG
Publication of EP1142294A1 publication Critical patent/EP1142294A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/001—Current supply source at the exchanger providing current to substations
    • H04M19/008—Using DC/DC converters

Definitions

  • the invention relates to a circuit arrangement for the remote supply of a local part connected via a transmission line to the office part of a front-end device of a communication transmission system, with a DC voltage converter, preferably comprising a converter transformer, which converts the voltage of a remote supply voltage source switchable in the office part and thus to the local part connected subscriber terminals.
  • a DC voltage converter preferably comprising a converter transformer, which converts the voltage of a remote supply voltage source switchable in the office part and thus to the local part connected subscriber terminals.
  • the remote feeding of subscribers has been a technique that has been known for a long time in order to enable a supply of telephone terminal equipment that is independent of the local conditions.
  • a local part is supplied with a constant remote supply voltage from the office part, which is dimensioned such that, with maximum line length and maximum local part load by participants, the local part has sufficient power to be able to supply all participants simultaneously.
  • the apron devices that can be used in the context of the invention are not limited to voice transmission applications but can also be designed for data transmissions of any kind.
  • the remote supply voltage in current pair gain systems is in the range of approximately 120 V (DC) upwards.
  • the lowest possible remote supply voltage in the order of approximately 60 V (DC) is aimed for. With these voltage values, the participants cannot be adequately supplied during peak load times.
  • the object of the invention is therefore to provide a circuit arrangement of the type mentioned at the beginning, with which, on the one hand, the supply with a low remote supply voltage is ensured and, on the other hand, sufficient power can be quickly provided for all participants even during peak load times.
  • a voltage change is usually carried out, which is designed over time so that it has few harmonics, e.g. a sine-like transition function is selected, which takes a correspondingly long time. During this transition period, the district may be under-supplied.
  • Another object of the invention is therefore to make a constant adaptation of the remote feed voltage to the current power requirement, during the transition times that occur between two different ones Voltage values of the remote supply voltage supply should always be guaranteed without interruptions.
  • this is achieved in that a monitoring device is provided in the district, with which the current power requirement of the district and the subscriber terminals connected to it can be determined, and that the remote supply voltage source in the office part via the monitoring device depending on the determined power requirement by means of a Transmission line connected transmission device is controllable.
  • the remote supply voltage can be adapted to the current power requirement, as a result of which it can be kept at relatively low values during an average operating state. If there is strong subscriber activity, the remote feed voltage must be increased accordingly, which is caused by feedback from the transmission device.
  • a buffer capacitor can be switched via a controllable switch to the supply input of the DC-DC converter, at least one of the connections of the buffer capacitor via a charging branch containing a rectifier element, if appropriate with the interposition of a further rectifier element, is connected to one of the wires of the transmission line, and that a control output of the monitoring device is connected to the control input of the controllable switch.
  • the required power can therefore be applied during the adaptation of the remote supply voltage to the current power requirement by the charge stored in the buffer capacitor.
  • the supply input of the DC-DC converter is connected to the wires of the transmission line via at least one rectifier element. This prevents the buffer capacitor from being discharged by other circuit parts of the circuit arrangement according to the invention when the buffer capacitor is applied to the supply input of the DC / DC converter.
  • the charging branch is preferably formed from a series connection of a rectifier element and a resistor, so that only a charging current can flow into the buffer capacitor via this branch.
  • the controllable switch for connecting the buffer capacitor to the supply input of the converter transformer can be formed by an FET, as a result of which very efficient control of the buffer capacitor can be achieved.
  • the connections of the buffer capacitor can be connected to the inputs of a voltage comparator, the output of which is connected to the transmission unit, by means of which the voltage of the supply voltage source in the office part can be set to a higher charging voltage lower comparator voltage threshold is set by the buffer capacitor voltage, the supply voltage source to the higher charging voltage and then is reset to its previously set value when an upper comparator voltage threshold is exceeded.
  • the power requirement of the subscriber terminals connected to the local part is constantly determined, and that the supply voltage required for the current power requirement in the office part is set, the supply voltage required in each case being determined beforehand in accordance with the typical operating cases. In this way, the remote supply voltage suitable for each operating case can be set.
  • the voltage at the buffer capacitor is continuously monitored and the buffer capacitor is charged in the event of a charge loss via the remote supply voltage source in the office part until the higher charging voltage at the buffer capacitor is reached and when the higher one is reached Charging voltage, the remote supply voltage is reset to its previously set value, and that the power requirement of the subscriber terminals fed by the local part is continuously measured and, if there is insufficient power supply by the local part, the controllable switches are closed and the buffer capacitor is connected to the supply input of the direct voltage converter is, so that this releases a large part of its charge to the DC-DC converter, at the same time causing an increase in the supply voltage as it corresponds to the current power requirement.
  • the invention also relates to a method for remote feeding of a local part connected via a transmission line to the office part of a front-end device of a message transmission system, to which several subscriber lines are connected, the local part being remotely fed with a remote supply voltage source provided in the office part.
  • the current flow over the transmission line is limited to 60 mA. This corresponds to the value that a person in good health can tolerate without permanent damage.
  • the supply voltage is applied regardless of the current power consumption of the district, which is essentially due to the operating state of the subscriber line, e.g. on-hook status, off-hook status and call status.
  • a disadvantage of this tendency towards increasingly higher supply voltages lies in the lack of insulation dielectric strength of the line pairs concerned. While due to the long history of telephony over the lifespan of telephone lines when operating with standard official supply voltages of typically 48 V to 60 V, long-term experience is already available, these are still pending for the more than four times higher remote supply voltages. Due to the low insulation thickness of the wire academy, insulation problems can arise which can damage the cables.
  • the high supply voltages endanger the assembly personnel, who are directly exposed to them when, for example, they connect the local part to the transmission line or carry out shunting work.
  • the object of the invention is therefore to provide a method of the type mentioned at the outset with which the supply can be adapted to the current conditions Remote supply voltage is guaranteed and with which sufficient power can be provided for all participants even during peak load times.
  • Another object of the invention is to enable careful use of the available resources, for example existing two-wire lines, which can be described as "change copper to gold”.
  • this is achieved in that the current operating state of the subscriber lines in the office part or in the local part is continuously detected and a remote feed voltage is assigned to the detected operating state, which corresponds to the current power requirement of the remote-fed local part and the connected subscriber lines, and that the remote feed voltage source is assigned to the assigned Voltage value is set.
  • the power consumption of the district is largely determined by the operating state, ie the states "on-hook”, “off-hook” and “call, of the subscriber lines. Due to the occupancy probability of subscriber lines, only a subset of the number in the remote-powered systems
  • the method according to the invention enables the supply voltage to be reduced over long periods of time, for example during the night, in these operating states. It can be assumed that the full supply voltage is used only in rare cases. This results in a reduction when the method according to the invention is used
  • the electrical supply voltage of the cable insulation is only applied when this is necessary, so there is less corrosion on uninsulated parts of the installation, and it also provides better protection for the maintenance and installation personnel than attainable against electric shock.
  • the remote supply voltage is reduced accordingly in order to avoid any risk to the assembly personnel.
  • Another advantage is that a lower susceptibility to faults can be reached, since the gas-filled surge arresters used in conventional telephone exchanges have the property of igniting below the static ignition voltage at fast transients. The more the spark gap is biased by a DC voltage, the more so. In practical operation, this behavior leads to a brief failure of the transmission link, since the synchronization has to be set up again without this being necessary for reasons of overvoltage protection.
  • the remote feed voltage can be switched over by means of a transition function when changing from one operating state to the next one.
  • a voltage change is usually carried out, which is designed over time so that it is subject to few harmonics, e.g. a transition function is selected that takes a correspondingly long time.
  • the remote feed voltage can be increased or decreased depending on the number of subscribers in the same voltage levels, a higher voltage level than the same voltage levels being provided during the transition from the idle state to a subscriber or vice versa.
  • the higher voltage level occurs because various circuit parts of the remote supply are deactivated in the idle state or stand-by mode.
  • the invention relates to a message transmission system with an office part, with a remote supply voltage source, with a local part remote-fed via a transmission line, the office part or the local part each having at least one detector for detecting the operating state of the subscriber lines and the office part with the local part via a data transmission unit in connection stands.
  • the task is to specify such a transmission system with which adequate personal protection and a low, average voltage load on the transmission line can be achieved.
  • the output voltage source can be remotely controlled in its output voltage, the remote supply voltage source being connected to the control input of a control unit, which control unit is connected to the output of the at least one detector for detecting the operating state in the office part and to the data transmission unit.
  • detectors already present in the district or in the district can be used for the detection of the various operating states, the operating states determined in the district being transmitted to the district via the data transmission unit. Due to the controllability of the remote supply voltage source, it can be adapted to the respective power requirement. Average participant activities therefore result in a far lower remote supply voltage than is required to feed top participant activities.
  • the invention also relates to a method for the remote supply of a via a transmission line to the office part of an apron device
  • the local part of the communication system connected to which several subscriber lines are connected, the local part being remotely supplied with a remote supply voltage source provided in the office part, via which the subscriber terminals connected to the subscriber lines, preferably via subscriber interfaces, are supplied.
  • Remote feeding is used e.g. in pair gain systems which provide two or more subscriber channels on a single two-wire transmission line via signal multiplexing devices, as a result of which multiplication of the subscriber connections can be achieved.
  • the connection between the individual subscribers and the transmission line takes place in each case via a local part of a front-end facility set up for this purpose, which provides the ringing voltage and the loop current for different activity states of the individual subscribers.
  • a front-end facility set up for this purpose, which provides the ringing voltage and the loop current for different activity states of the individual subscribers.
  • the type of activity status of the subscriber terminal e.g. on-hook status, off-hook status, call status or similar there is a different need for power.
  • the district is usually supplied from the office part of the apron facility with a constant remote supply voltage, which is dimensioned so that with maximum line length of the transmission line and the subscriber lines as well as maximum district load by participants, the district provides sufficient power to be able to supply all participants at the same time.
  • the apron devices that can be used in the context of the invention are not limited to voice transmission applications but can also be designed for data transmissions of any kind.
  • the current supply voltage in current pair gain systems is in the range between approximately 120 V (DC) and approximately 360 V (DC). As already mentioned, the current flow over the transmission line is limited to 60 mA for safety reasons.
  • the remote supply voltage is kept constant regardless of the operating state and the load states on the subscriber lines. It must therefore also be selected so that the device is fully functional at maximum power consumption by all participants connected to the district. For this reason, the remote feed voltage often reaches very high values.
  • the object of the invention is therefore to provide a method of the type mentioned at the outset, with which a reduction in the remote feed voltage and nevertheless a constant, uninterrupted supply of the participants is ensured.
  • this is achieved in that the power consumption of the district is continuously measured and, when a predeterminable limit value of the power consumption is exceeded, the power which is remotely fed via the subscriber lines is reduced at least for some of the activated or active subscriber terminals.
  • the state of the individual subscriber terminals is strongly determined by the speaking habits of the individual subscribers, but cannot in any way are predicted, so that for a large part of the operating time there is an average load which is far below a theoretical maximum load which would result from the maximum transmission line length, maximum subscriber line length for all participants and simultaneous activation of all participants.
  • the remote feed voltage can be designed for an average load on the district by participants and, according to the invention, when an increase in activity occurs, which becomes apparent through an increase in the power consumption of the district, the remote power for the activated or active subscriber terminals is reduced. This is supported by the fact that a large number of functions of modern subscriber terminals can also be operated with significantly lower outputs than those specified by the network operators, since the latter have to comply with the details of the few old devices that are still in use are.
  • the power consumption of the district can be measured continuously by means of the remote feed current flowing through this transmission line, so that the power consumption can be determined exactly by means of this current measurement, provided that the remote supply voltage is kept constant.
  • the voltage or impressed current applied to the subscriber terminals for maintaining these states can be reduced by a predeterminable value. If this reduction takes place for each activated or active subscriber by a relatively small amount, this reduction does not hinder the functionality of the individual subscriber terminals, but overall enables a reduction in the power required for the remote-powered subscribers.
  • the subscriber supply voltage and / or the subscriber supply current can be reduced in the off-hook state of the respective subscriber terminal or the call voltage and / or the call current can be reduced in a further embodiment of the invention in the call state of the respective subscriber terminal.
  • the reduction of the remote power can take place in stages, the power consumption of the local part being compared with the predeterminable limit value after each stage of the reduction in power and the reduction being terminated when the limit is undershot. Due to the gradual reduction in the distance-fed power, which can be carried out either in analog or digital form, the power consumption of the district can be reliably adjusted to the limit value required for a stable supply.
  • the continuous reduction of the remote power can take place via a self-contained analog control loop. This can be achieved with relatively low expenditure on circuitry.
  • the invention relates to a message transmission system with an office part, with a remote supply voltage source, with a local part that is fed via a transmission line and to the local part via subscriber lines and with the interposition of subscriber interfaces.
  • the task consists in specifying a aforementioned message transmission system which can be operated with a relatively low remote supply voltage, but which nevertheless ensures that all participants are supplied when a very high or maximum level of activity occurs.
  • a device for determining the power consumption and a device for reducing the remote power of the subscriber terminals are provided in the local part, and in that the device for reduction is controllable via a control unit connected to the device for determining the power consumption.
  • the power consumed by the district and passed on to the subscriber terminals is continuously determined via the device provided for determining the power consumption.
  • the measured values are compared with a predetermined limit value and as soon as this is exceeded, the device for reducing the remote power output reduces the power available for the subscriber terminals, so that despite a very high level of activity, all subscribers can still be operated without hindrance.
  • the device for determining the power consumption can be formed by a current measuring device for measuring the remote feed current.
  • the power consumption can be measured in an accurate and reliable manner by measuring the remote feed current.
  • the device for reducing the remote power of the subscriber terminals can be formed by a device for reducing the subscriber supply voltage and / or the subscriber current.
  • the device for reducing the remote power of the subscriber terminals can be formed by a device for reducing the ringing voltage and / or the ringing current.
  • the remote-powered power is reduced by a ringing alarm operated with reduced voltage or current, which in most cases results in only a slight change in the ringing signal, since lower limit values for ringing voltage or ringing current are provided in the usual types of devices of this type are, which are in some cases considerably below the nominal values, so that these lower limit values enable reliable operation with lower power consumption.
  • the device for reducing the remote-powered power comprises a digital control loop.
  • a digital control loop Such has the advantage that it can be implemented in an integrated design.
  • the device for reducing the remote power can also comprise an analog control loop, with which the remote power can be regulated continuously, with little circuit complexity.
  • the invention also relates to a method for remote feeding a local part connected via a transmission line to the office part of a front-end device of a communication system, to which e.g. One or more subscriber terminals are connected via subscriber lines, the local part or the official part being either the feeding sub-device or the sub-device to be fed and vice versa, and wherein the sub-device to be fed is remotely fed with a remote supply voltage source provided in the feeding sub-device.
  • the object of the invention is therefore to provide a method of the type mentioned at the outset, with which the supply with a current supply which can be adapted to the current conditions is ensured, and with which, even during peak load times, sufficient power for all participants in the district or when fed by the district in Office part can be provided.
  • Another object of the invention is to enable careful use of the available resources, for example existing two-wire lines.
  • this is achieved in that the power consumption of the sub-device to be fed and the power loss of the transmission line are determined in a test step in the feeding sub-device and, if the power requirement of the sub-device to be fed is known, that of the between the feeding Sub-device and the sub-device to be fed existing line resistance is calculated, and that depending on the calculated line resistance and the operating state of the sub-device to be fed, the required remote feed voltage is determined and the remote feed voltage source is set to the appropriate value.
  • the remote feed voltage can be matched to the actual distance between the feed device and the feed device to be fed and the operating state of the feed device to be fed, so that there is a significant reduction in the feed voltage to the average load of the feed device to be fed.
  • What is essential here is the direct measurement of the actual power consumption, which provides relatively good accuracy for determining the line resistance.
  • the line resistance is the essential quantity to be recorded in order to be able to determine the required remote supply voltage.
  • the sub-device to be fed may be the local part and the sub-device may be the official part, the power consumption of the local part to be fed being determined by determining the number of active subscribers. With knowledge of the power consumption of the participants, a statement can be made about the operating status of the district by counting the active participants.
  • the remote feed voltage is adapted to the current subscriber activity by increasing or decreasing the determined and set remote feed voltage as a function of the operating states of the subscriber lines.
  • the remote feed voltage can be increased or decreased in stages depending on the number of participants, with a higher voltage stage than the preferably identical voltage stages being provided during the transition from an idle state to a state with an active participant or vice versa .
  • the voltage levels can also have different levels.
  • Each increase or decrease in the number of participants thus corresponds to a voltage level by which the remote feed voltage is increased or decreased.
  • the higher voltage level during the transition from the idle state to the active operation of a subscriber terminal occurs because additional circuit parts are deactivated in the idle or standby mode.
  • the increase or decrease in the number of active subscribers by one or a few subscribers has only a minor effect on the power requirement.
  • the increase or decrease by a voltage level can therefore take place when the number of active participants increases or decreases by a predeterminable number of participants.
  • the voltage is only increased when, for example, three other participants become active.
  • the subdevice to be fed can be the office part and the subdevice can be the local part, the operating state of the office part to be fed being determined and transmitted via the transmission line to the dining part.
  • the office part can be remotely fed, so that it is only supplied when the district is also in operation. This can e.g. be of advantage in data transmission facilities that are located in the district and if they fail, the office part no longer has to be operated.
  • the remote feed voltage determined and set by the test step can be increased or decreased depending on the operating state of the office part, whereby the latter is supplied with the appropriate remote feed voltage regardless of whether it is in an idle state or in an active state.
  • the remote feed voltage is increased or decreased in stages depending on the operating state of the office part.
  • a precisely defined voltage level is assigned to each operating state.
  • the determined value of the remote feed voltage is fed to a control amplifier as a setpoint, with which the remote feed voltage source is controlled. This means that the remote supply voltage is exactly matched to the determined target value.
  • the remote feed voltage is switched by means of a transition function when changing from one operating state to the next.
  • a voltage change is usually carried out, which is designed over time so that it has few harmonics in the transmission frequency range, e.g. a suitable transition function is selected, which takes a correspondingly long time.
  • An adjustment of the remote feed voltage to the respective line resistance between the district and the official district can then be carried out particularly advantageously if, according to a development of the invention, the test step is carried out at the start of operation while the remote feed voltage is started up.
  • the various voltage levels can be set by an analog or digital control method, as a result of which the remote supply voltage can be set precisely or in stages.
  • the various voltage levels can be set using a digital potentiometer.
  • a further variant of the invention can consist in the fact that the calculated values of the line resistance are temporarily stored and can be queried via a maintenance device. Changes in the line resistance that occur over longer periods of time can thus be recorded and statistically processed.
  • the invention relates to a communication system with a feeding sub-device, which comprises a remote supply voltage source, and with a sub-device to be fed via a transmission line.
  • the task is to carry out an adaptation of the remote feed voltage that is as simple as possible to the actually existing length of the transmission line and the operating state.
  • the output voltage source can be controlled via a control device in its output voltage, a measuring device, preferably a current measuring device, being provided for determining the power consumption of the sub-device to be fed and the transmission line, and the output of the measuring device being connected to the control device.
  • the measuring device for determining the power consumption With the aid of the measuring device for determining the power consumption, a reliable statement can be made about the power loss occurring on the transmission line and from this about the line resistance, which enables a suitable control of the remote supply voltage source.
  • the current flowing into the sub-device to be fed is measured via the current measuring device and the total applied power is determined with the aid of the applied value of the remote supply voltage, from which the power dissipated on the line can in turn be calculated if the power of the sub-device to be fed is known.
  • the feeding sub-device can be the office part and the sub-device to be fed can be the local part, which configuration e.g. is common for a pair gain system.
  • Another variant according to the invention can consist in that the feeding device is the local part and the feeding device is the office part.
  • This supply coming from the district can be advantageous for data transmission devices, the most important component of which is located in the district, as a result of which the official part only has to be fed when the district is in operation.
  • the feeding sub-device or the sub-device to be fed can each have at least one detector for detection, for example the operating state of the subscriber lines or the subscriber terminals, and the feeding sub-device with the one to be fed Partial device are connected via a data transmission unit, wherein preferably the output of the at least one detector or the data transmission unit is connected to the control device. It is thus possible to fully grasp the changes in activity of the sub-device to be fed, from which changes a corresponding setting of the remote feed voltage can be derived.
  • control device is connected to a maintenance device in which the calculated values of the line resistance can be buffered and queried.
  • Fig.l is a block diagram of a communication system with an embodiment of the circuit arrangement according to the invention.
  • FIG. 2 shows a circuit diagram of a further embodiment of the circuit arrangement according to the invention.
  • FIG. 3 shows a diagram of the remote supply voltage changed according to the invention as a function of the number of active participants
  • FIG. 4 shows a block diagram of an embodiment of the message transmission system according to the invention with remote feeding
  • FIG. 5 shows a block diagram of a further embodiment of the message transmission system according to the invention.
  • FIG. 6 shows a block diagram of a further embodiment of the message transmission system according to the invention.
  • FIG. 7 shows a diagram of the remote feed voltage changed according to the invention as a function of the number of active subscribers
  • FIG. 8 shows an equivalent circuit diagram of the message transmission system according to FIG. 6;
  • FIG. 9 shows a further diagram of the remote feed voltage changed according to the invention as a function of the operating state of the sub-device to be fed.
  • Fig. 1 shows part of a remote communication system, e.g. of a pair gain system, an office part 20 and a local part 21 of a front-end facility being connected via a transmission line 1 ', 2'.
  • the local part is to be understood in a completely generalized form as the part fed by distance, which contains an analog or digital interface between the transmission line and the subscriber lines.
  • a local part of this form can therefore be implemented not only in pair gain systems but also in xDSL or comparable systems within the scope of the invention.
  • the office part is the remote part, which in each case contains an analog or digital office interface between the telephone or data switching system and the transmission line.
  • the invention can be implemented for all forms of known analog or digital office parts.
  • N 4 subscriber interfaces are remotely fed from the district 21, but the number of subscribers N is not subject to any Restriction.
  • the power requirement fluctuates depending on the number of currently active participants.
  • the district 21 is supplied via the office section 20 with a remote supply voltage, via which the subscriber terminals connected to the district are fed after conversion.
  • a monitoring device 23 is provided according to the invention in the district 21, with which the current power requirement of the district 21 with the subscriber terminals connected to it can be determined.
  • the remote supply voltage source located in the office section 20, which is not shown in FIG. 1 can be controlled via the monitoring device 23 as a function of the determined power requirement by means of a transmission device 24, which in turn is connected to the transmission line 1 ', 2' via a separating device 25.
  • the control data can e.g. are transmitted via a control channel on the transmission line 1 ', 2'.
  • the power requirement of the subscriber terminals connected to the local section 21 is continuously determined and the supply voltage required for the current power requirement is set accordingly in the office section 20, the supply voltage required in each case having been preferably empirically determined beforehand for all operating cases.
  • a known resistor Rx is connected to the DSL district part input and the loop resistance, which is composed of the line resistance of the transmission line 1, 2 and the known resistor Rx, is measured while the remote supply voltage is switched on.
  • the optimal remote supply voltage for all operating cases can be calculated from the measurement result.
  • the current power requirement is now transmitted to the office part 20 via the monitoring device 23 and the transmission device 24 and the remote feed voltage is changed there accordingly.
  • a relatively low remote supply voltage can be set during normal operating times, which is advantageous both in terms of safety technology and with regard to the cable load.
  • circuit arrangement shown in FIG. 2 can be used which, in addition to the known direct voltage converter 14, 15, contains circuit parts which briefly provide electrical energy during the time period required for readjusting the remote supply voltage.
  • the remote supply voltage can thus be polarity-independent on the transmission line 1, 2 Bmmm voltages that may occur are smoothed by the charging capacitor 10. Capacitor 11 prevents high-frequency interference.
  • the DC voltage converter fed by the remote supply voltage is formed in the exemplary embodiment according to FIG. 2 by a converter transformer 14, of which only the primary side is shown, and a clocked switch 15 which chops the DC voltage in accordance with its activation.
  • the converter transformer 14 converts the voltage of the remote feed voltage source which can be switched to the transmission line 1, 2 in the office section 20 and thus feeds the subscriber terminals connected to the local section 21.
  • a buffer capacitor 12 can be switched via a controllable switch 13 to the supply input of the DC / DC converter 14, one of the connections of the buffer capacitor 12 being connected to one of the wires of the transmission line 1, 2 via a charging branch 7, 8 containing a rectifier element 7 is.
  • a control output of the monitoring device 23 is connected to the control input of the controllable switch 13.
  • the energy required for a short time is taken from the buffer capacitor 12 by appropriate control of the switch 13, which at predetermined times, e.g. charged after a participant ends the call or as needed.
  • the switch 13 which is preferably formed by an FET (field effect transistor)
  • the switch 13 is closed, the amount of charge stored in the buffer capacitor 12 can flow into the DC / DC converter 14, 15 and thereby fill the temporary power gap.
  • the supply input of the DC / DC converter 14 is connected to the wires of the transmission line 1, 2 via at least one rectifier element 9.
  • the charging branch is formed from a series connection of a rectifier element 7 and a resistor 8, which enables a charging current only in one direction.
  • the cargo can be loaded at predetermined times, e.g. in each case after the end of a participant's conversation or as required.
  • connections of the buffer capacitor 12 are connected to the inputs of a voltage comparator, not shown in FIG. 2, the output of which is connected to the transmission unit 24, via which the voltage of the supply voltage source in the office section can be set to a higher charging voltage, via which the buffer capacitor 12 can be charged.
  • the supply voltage source is set to the higher charging voltage when the comparator voltage drops below a lower comparator voltage threshold and is then reset to its previously set value when an upper comparator voltage threshold is exceeded.
  • the voltage is thus constantly monitored at the buffer capacitor 12 and the buffer capacitor 12 is charged in the event of a loss of charge via the remote supply voltage source in the office part, the voltage of the Supply voltage source is increased in the office part until the higher charging voltage at the buffer capacitor 12 is reached and when the higher charging voltage is reached, the remote supply voltage is reset to its previously set value.
  • the buffer capacitor 12 is constantly charged to a sufficiently high voltage in order to be able to cope with performance bottlenecks at short notice if required.
  • the feedback to the office section is used to set the remote feed voltage that is suitable for this operating state. If there is now a considerable increase in subscriber connections within a short period of time, there is an increased power requirement that the set feed voltage cannot cope with. However, readjustment of the remote feed voltage in the office part can only take place within a certain period of time in order to avoid the generation of harmonics, which would have a disruptive influence on the data transmission over the transmission line.
  • the controllable switch 13 is closed and the buffer capacitor 12 is connected to the supply input of the DC / DC converter 14, so that it charges its charge to the Outputs DC converter 14, which also causes an increase in the supply voltage, as it corresponds to the current power requirement.
  • the buffer capacitor 12 thus covers the additional power requirement during the time in which the remote supply voltage is increased. After that, the meanwhile correspondingly increased supply voltage takes over the full power supply of all participants.
  • the remote supply voltage is therefore in the reduced state, in which an average subscriber activity can be managed, between approximately 94 V and approximately 100 V compared to the currently conventional remote supply voltage of typically 166 V to 176 V.
  • Converter transformer 14 must therefore be defined for a larger input voltage range, e.g. 60V to 180V.
  • the buffer capacitor 12 is charged to a charging voltage which corresponds to an open circuit value of the remote supply voltage required for the respective operating state without the load caused by the subscriber who has just gone into the inactive state.
  • the reset of the remote supply voltage can be time-controlled or controlled by a comparator.
  • Reloading with the above-mentioned predeterminable period of time has the disadvantage that old-age effects of the capacitor capacity are not taken into account. This can be remedied by the existing comparator monitoring the charging and the recharging process only being ended when the predetermined voltage value at the buffer capacitor 12 is exceeded.
  • Figure 4 shows part of a remote communication system, e.g. of a pair gain system, an office part 200 and a local part 210 of a front-end facility being connected via a transmission line 71 ', 72'.
  • a local part is to be understood in generalized form as the part fed by distance, which contains an analog or digital interface between the transmission line and the subscriber lines.
  • a local part of this form can therefore be implemented not only in pair gain systems but also in xDSL or comparable systems within the scope of the invention.
  • the office part is the remote part, in which there is an analog or digital office interface between the telephone or data exchange system and the transmission line.
  • an analog or digital office interface between the telephone or data exchange system and the transmission line.
  • FIG. 4 e.g. A total of M exchange interfaces are provided.
  • the invention can also be implemented for all forms of known analog or digital office parts.
  • N 4 subscriber interfaces are fed remotely from the district 210, but the number of subscribers N is not subject to any restriction. The power requirement fluctuates depending on the number of currently active participants.
  • the district 210 is supplied with a remote supply voltage via the office section 200, via which the subscriber terminals connected to the district 210 are fed after conversion.
  • the remote supply voltage source located in the office part 200 which is not shown in FIG. 4, is connected to the local part 210 via the transmission line 71 ', 72'.
  • the separation of data traffic and supply voltage takes place via a separation device 250.
  • the supply separated from the data transmission via a transmission line 71, 72 branches off from the separation device 250.
  • the current operating state of the subscriber lines 220 is continuously detected in the office part 200 or in the local part 210 according to the invention, and a respective remote supply voltage is assigned to the detected operating state, which voltage corresponds to the current power requirement of the remote supply District 210 and the subscriber lines 220 connected to it. Accordingly, the remote supply voltage is set to the assigned value.
  • the office part 200 is connected to the district 210 via a data transmission unit, not shown, via which data can be exchanged between the district 210 and the office part 200.
  • a data transmission unit not shown
  • At least one detector for detecting the operating state of the subscriber lines 220, which are used for the method according to the invention.
  • the remote supply voltage source can be controlled in terms of its output voltage, the remote supply voltage source being connected to the control input (not shown) of a control unit, which control unit is connected to the output of the at least one detector for detecting the operating state in the office part and to the data transmission unit.
  • the individual operating states can thus be detected by the detectors already present and the data transmission unit.
  • an idle remote supply voltage UQ is set, which ensures that the district is supplied with the longest possible distance from the office part 200.
  • the quiescent current consumption of the district 210 is approximately constant.
  • a specific remote supply voltage is assigned, which corresponds to the respective power requirement of the subscriber line 220.
  • the increase in the remote feed voltage is associated with a certain delay time, in particular if, in order to avoid disturbances in the data transmission during the transition from one operating state to the next, the remote feed voltage by means of a transition function, e.g. Roll-off sine, is switched.
  • the remote feed voltage can thus be increased to a value which corresponds to this operating state before the actual call begins. This prevents a performance bottleneck from occurring.
  • the withdrawal of a subscriber can be registered in the office section 200 by detecting this change in state via detectors provided in the district 210 and transmitting it to the office section 200 via the data transmission unit, the supply current required for the subscriber being made available only after a delay time. This is determined by the fact that the full supply voltage assigned to the respective operating state must already be present in full in the district, and only then is the supply provided to the subscriber device, delays of up to 1 l being permitted, for example, in some countries. However, this procedure represents only one of the many ways in which the current operating state can be detected and the remote feed voltage can be set accordingly. Just as there is an increase in the remote feed voltage when there is an increase in activity, the remote feed voltage is reduced when the participants reduce activity, resulting in a downward movement along the voltage gradation shown in FIG. 3.
  • the remote feed voltage can be controlled in accordance with a step characteristic as a function of the number of active participants, as is shown by way of example in FIG.
  • Each operating state with 0.1.2 ... 8 active participants is a precisely defined one
  • the grading of the remote supply voltage can be carried out in any manner, so that only two or three remote supply voltage values can be provided in simple systems, a first value e.g. for an average load and a second value for a peak load.
  • the level of the individual voltage levels can be determined mathematically or empirically. When choosing the remote supply voltage values, consideration must be given to the length of the transmission line.
  • the remote feed voltage is increased or decreased depending on the number of participants in the same voltage levels, in accordance with the same power requirement of the participants, with the transition from the idle state (stand-by) to a participant or vice versa, compared to the same voltage levels higher voltage level is provided since various circuit parts of the remote supply are deactivated in the idle state.
  • a message transmission system with an apron device formed from an office part 110 and a local part 120 is shown.
  • N exchange interfaces 130 are formed, the number of which can vary in any way.
  • a total of four exchange interfaces are formed.
  • the district 120 is connected to the public office 110 via a transmission line 101, 102, via which the district 120 is also supplied remotely, as is customary, for example, in pair gain systems.
  • a transmission line 101, 102 via which the district 120 is also supplied remotely, as is customary, for example, in pair gain systems.
  • Remote supply voltage source is provided, which has a constant remote supply voltage and is equipped with a current limitation, via which the maximum value of the current emitted by the remote supply voltage source is fixed, for example, at 60 mA.
  • arrangements of this type can be used not only for voice but also for data transmissions, for example in xDSL or comparable similar systems.
  • the local part is to be understood in a general manner as the part fed from each distance, which contains an analog or digital interface between the transmission line and the subscriber lines.
  • the office part is the remote part, in which there is an analog or digital office interface between a telephone or data exchange system and the transmission line 101, 102.
  • N subscriber lines in the exemplary embodiment according to FIG. 5 a total of four subscriber lines 131, depart from the district 120, which are connected via subscriber interfaces 114, 115, 116, 117 to subscriber terminals 104, 105, 106, 107, which are fed remotely via the district 120.
  • the number N of subscriber lines 131 is in each case greater than 2, but is not subject to any restriction and can be chosen as desired within the scope of the invention.
  • control logic in the district 120 switches the call voltage to the subscriber line 131 concerned, which generates a call signal for the subscriber addressed.
  • the call signal generation is interrupted and a subscriber feed current or loop current is impressed, which enables the subscriber terminal to be supplied.
  • the power consumption of the district must also be sufficient if all subscriber terminals are in the off-hook state or all subscribers receive a call at the same time or a combination of these states, the maximum length of the transmission line or subscriber lines in each case Is accepted.
  • the power consumption of the local part 120 is measured continuously and, if a predeterminable limit value of the power consumption is exceeded, for at least some of the activated or active subscriber terminals 104, 105, 106, 107 via the subscriber lines 131 remote power is reduced.
  • a device 123 for determining the power consumption and a device 122 for reducing the remote power of the subscriber terminals 104, 105, 106, 107 are provided in the local part, the device 122 for reducing the remote power via a device 123 for determining the control unit 124 connected to the power consumption is controllable.
  • a current measuring device 123 for measuring the remote feed current I is provided as the device for determining the power consumption, in which the power consumption takes place through the ongoing measurement of the remote feed current I flowing into the district 120 via the transmission line 101, 102.
  • the determination of the power consumption can also be carried out in another common way.
  • the voltage or voltage applied to the subscriber terminals 104, 105, 106, 107 for maintaining this state is reduced or impressed Current around a predeterminable value.
  • the subscriber supply voltage or the subscriber supply current (loop current) is reduced and the ringing voltage is reduced in the call state of the respective subscriber terminal 104, 105, 106, 107.
  • loop current the subscriber supply voltage or the subscriber supply current (loop current) is reduced and the ringing voltage is reduced in the call state of the respective subscriber terminal 104, 105, 106, 107.
  • only one of the latter measures can be implemented alone, e.g. just reducing the loop current.
  • the device for reducing the remote power of the subscriber terminals 104, 105, 106, 107 can be formed by a device for reducing the subscriber supply voltage and / or the subscriber current or can be formed by a device for reducing the ringing voltage and / or the ringing current. Any combination of the aforementioned devices is conceivable.
  • a value of the ringing voltage specified for a ringing alarm of a subscriber terminal can be changed by Be reduced by 10%.
  • the call function is not affected or only slightly affected. This may result in the alarm clock ringing a little more quietly during this phase of power reduction, but the full alarm clock voltage is applied for the majority of the operating time, during which there is only average activity, despite the relatively low remote supply voltage.
  • the remote-fed power can be reduced with the aid of an analog control loop to a predeterminable value which corresponds to the limit value of the power consumption of the district 120.
  • the power supplied via the subscriber lines 131 can also be reduced step by step in digital or analog form, with the power consumption of the district 120 being compared with the predeterminable limit value after each step of the power reduction and the reduction being terminated when the limit value is undershot.
  • the predetermined limit value can be determined, for example, by means of a comparator, which monitors a voltage drop proportional to the remote feed current and reports that a corresponding threshold has been exceeded as the limit value of the power consumption being exceeded.
  • the device for reducing the remote power can therefore comprise a digital control loop or an analog control loop, depending on the existing circuitry environment.
  • Message transmission system with an office part 206 designed as a feeding sub-device with a number M greater than or equal to 1 (1, 2, 3, ...) at exchange interfaces and a local part 201 designed as a feeding device with a number N greater than or equal to 1 (1, 2, 3, ...) shown on subscriber interfaces N to which subscriber terminals, not shown, are connected.
  • the maximum number of active subscriber terminals is therefore N.
  • M N for non-concentrated devices and N greater than M for concentrated devices.
  • the office part 206 and the district 201 belong to a common apron facility.
  • the local part is to be understood as the part fed by distance, which contains an analog or digital interface between the transmission line and the subscriber lines.
  • Such a district can therefore be realized not only in pair gain systems but also in xDSL or comparable systems within the scope of the invention.
  • the office part according to FIG. 6 is the remote part, in which there is an analog or digital office interface between the telephone or data exchange system and the transmission line.
  • the power requirement fluctuates depending on the number of participants N and the number of active participants.
  • the local part 201 fed via the remote supply voltage source 205 in turn feeds the subscriber terminals connected to it, which are not shown in FIG. 6.
  • the output voltage of the remote supply voltage source 205 can be controlled via a control device 207, a measuring device, preferably a current measuring device 208, is provided for determining the power consumption of the district 201 and the transmission line 202 and the output of the measuring device 208 is connected to the control device 207.
  • a measuring device preferably a current measuring device 208
  • the current I caused by the remote supply voltage source 205 is measured and evaluated.
  • the power consumption of the district 201 to be fed and the power loss in the transmission line 202 are determined in a test step in the office section 206 to be fed, and the line resistance existing between the district office 206 and the district 201 to be fed is calculated therefrom if the power requirement of the district 201 to be fed is known .
  • the test step is preferably carried out at the start of operation while the remote supply voltage is ramping up, but can also be carried out at other times if the need for readjustment arises.
  • the district belonging to an official part may have been measured precisely after it was manufactured or for another reason, so that its power requirement can be assumed to be known. Using the known power requirement, the actual line resistance can be calculated from the measurement results, which in many cases will be below the intended maximum resistance.
  • test voltage U p is set, which will generally be selected to be smaller than the remote feed voltage set later.
  • the equivalent circuit diagram for this process is shown in FIG. 8, by means of which this can be illustrated more clearly.
  • a test current I p is measured with the current measuring device 208 and the line resistance R L of the transmission line is calculated therefrom.
  • the known power consumption P R of the sub-device to be fed, the local part 201, is subtracted from the power fed into the transmission line 202 and the line resistance is calculated therefrom.
  • the required remote supply voltage is determined as a function of the calculated line resistance R L and the operating state of the district 201 and the remote supply voltage source 205 is set to the corresponding value U F.
  • the operating state is determined in a simple manner via the number N of active subscriber terminals, but could also be determined in another way.
  • U F U R + (Formula 2)
  • Subscriber terminals including the circuits active in the district.
  • the determined value of the remote feed voltage U F is fed as a setpoint to a control amplifier within the control device 207, with which the remote feed voltage source 205 is regulated to the determined value of the remote feed voltage.
  • a control amplifier within the control device 207, with which the remote feed voltage source 205 is regulated to the determined value of the remote feed voltage.
  • Any analog or digital control method can be used for this.
  • the different voltage levels can be set using a digital potentiometer.
  • the remote feed voltage can also be set analog.
  • the determined and set remote supply voltage is increased or decreased depending on the operating states of the subscriber lines or the subscriber terminals.
  • the office part 206 or the location part 201 each has at least one detector (not shown) for detecting the operating state of the subscriber lines, the office part 206 being connected to the location part 201 via a data transmission unit.
  • the outputs of the at least one detector or the data transmission unit are connected to the control device 207.
  • Data can be exchanged between the district and the office part via the data transmission unit.
  • a detector (not shown) for detecting the operating state of the subscriber lines, which detects a subscriber loop e.g. by lifting or hanging up a subscriber handset and notifying the status changes via a data channel to the data transmission unit of the office part 206, in particular in how many they were registered.
  • Detectors of this type already exist in existing office parts and can therefore be used for the method according to the invention.
  • the individual operating states can thus be detected by the detectors already present and the data transmission unit.
  • an open circuit voltage is set, which enables the district 201 to be supplied.
  • the quiescent current consumption of the district is almost constant.
  • this operating state is detected in the office part 206 via the detectors located there and this operating state is automatically assigned a specific increase in the remote feed voltage, so that the control device 207 generates a corresponding signal and outputs it to the remote feed voltage source 205.
  • the remote feed voltage is increased or decreased in stages depending on the number of participants, with a higher voltage stage than the same voltage stages being provided when changing from an idle state to a state with an active participant or vice versa. This results from the circuits of the district that are deactivated in the idle state, which go into operation when the first participant is activated and therefore contribute accordingly to the power consumption.
  • the remote supply voltage required for maintaining operation changes only to a very small extent when an individual subscriber terminal is additionally activated. It is therefore advantageous to increase or decrease a voltage level when the number of active participants increases or decreases by a predeterminable number of participants.
  • the remote supply voltage can e.g. only be switched up one level when three more participants have been activated.
  • the increase in the remote feed voltage is associated with a certain delay time, in particular if, in order to avoid interference in the data transmission during the transition from one operating state to the next, the remote feed voltage by means of a transition function, e.g. B. Roll-off sine is switched.
  • a transition function e.g. B. Roll-off sine
  • the remote feed-in voltage can thus be increased to a value which corresponds to this operating state before the start of an actual call. This prevents a performance bottleneck from occurring.
  • the withdrawal of a subscriber can be registered in the office part by transmitting this change of state to the office part via detectors provided in the local part and via the transmission unit, the feed current required for the subscriber being made available only after a delay time.
  • This is determined by the fact that the full supply voltage assigned to the respective operating state must already be present in its full amount in the district, and only then is the supply provided to the subscriber device.
  • this procedure is only one of the many ways in which the current operating state can be detected. Just as there is an increase in the remote feed voltage when there is an increase in activity, the remote feed voltage is reduced when the activity decreases.
  • the left-most voltage step in FIG. 7 is sufficient for a district with a short line, while the right-most voltage step has a considerably higher base voltage due to the longer line, which represents the power loss in the transmission line.
  • the idle state of the district 201 is characterized by level 0, in which various circuits of the district are deactivated. Therefore, the increase in activity to the first participant (level 1) is accompanied by an incomparably greater increase in the remote feed voltage than is the case with the other levels 2, 3, ..., X.
  • Each operating state with 0.1.2 ... N active participants is a precisely defined one
  • the voltage value U0 corresponds to the value that was set in the idle case by determining the line resistance using the method according to the invention.
  • the power consumption of the district when calling and feeding is approximately the same, the number of distinguishable cases in a system with N participants is then N + 1, as shown in FIG. 7. If the power consumption values deviate, a finer subdivision could be made using remote supply voltage levels.
  • the grading of the remote supply voltage can be carried out in any manner, so that only two or three remote supply voltage values can be provided in simple systems, a first value e.g. for an average load and a second value for a peak load.
  • a voltage comparator can be provided in the district, which monitors the lower permissible limit value of the remote feed voltage and, when the transmission unit falls below the lower limit value, causes an increase in the remote feed voltage.
  • the diagram shows the voltage values for two different distances between the district and the district to show the difference between a short and a long transmission line.
  • the local part can also be designed as the feeding sub-device and the office part of the apron device can be designed as the partial device to be fed, the operating state of the office part to be fed being determined and transmitted to the feeding local part via the transmission line.
  • the remote feed voltage can then preferably be increased or decreased in stages depending on the operating state of the office part, with a higher voltage stage than the same voltage stages being provided during the transition from an idle state to a state into an active state or vice versa.
  • a broadband data transmission unit is given as an example of a district via which the office part is fed. Without restricting the general idea of the invention, this form of remote feeding is indicated because it is used more often, while in principle pair gain systems can also be remote-fed from the district, but this is the rarer case.
  • the official part of the broadband transmission unit has e.g. an off state, an idle state and an active state.
  • the remote supply voltage is carried out in the same manner as described above. After a test step in which the power consumption of the transmission line and the office part is determined, the line resistance can be determined from the known power requirement of the office part (see formula 1). The required remote supply voltage is determined in accordance with the operating state of the office part and the remote supply voltage source of the local part is set to the corresponding value.
  • the sub-device to be fed in this example the public office, each has a detector for detecting the operating state of the public office and the dining district is connected to the public office to be fed via a data transmission unit, so that the operating state of the public office can be communicated to the district via this unit .

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Devices For Supply Of Signal Current (AREA)
  • Telephonic Communication Services (AREA)
  • Direct Current Feeding And Distribution (AREA)

Abstract

L'invention concerne un circuit de téléalimentation d'une partie locale (21) reliée, par l'intermédiaire d'une ligne de transmission (1, 2), à la partie principale (20) d'un dispositif préliminaire d'un système de transmission de messages, comportant un convertisseur continu-continu (14, 15), pourvu de préférence d'un convertisseur-transformateur (14), qui convertit la tension d'une source de tension de téléalimentation pouvant être raccordée, dans la partie principale (20), à la ligne de transmission et alimente ainsi des terminaux d'abonnés raccordés à la partie locale (21). Dans la partie locale (21) se trouve un dispositif de surveillance (23), avec lequel les besoins en énergie du moment de la partie locale (21) et des terminaux d'abonnés raccordés à celle-ci peuvent être constatés. La source de tension d'alimentation peut être commandée par l'intermédiaire du dispositif de surveillance (23), en fonction des besoins en énergie constatés, au moyen d'un dispositif de transmission relié à la ligne de transmission (1, 2).
EP99960705A 1998-12-22 1999-12-21 Circuit et procede de telealimentation Withdrawn EP1142294A1 (fr)

Applications Claiming Priority (9)

Application Number Priority Date Filing Date Title
AT214698 1998-12-22
AT214698A AT409909B (de) 1998-12-22 1998-12-22 Schaltungsanordnung zur fernspeisung
AT219098A AT408597B (de) 1998-12-30 1998-12-30 Verfahren zur fernspeisung eines nachrichtenübertragungssystems
AT219098 1998-12-30
AT58399 1999-03-31
AT0058399A AT410877B (de) 1999-03-31 1999-03-31 Verfahren zur fernspeisung eines nachrichtenübertragungssystems
AT123899 1999-07-16
AT123899 1999-07-16
PCT/AT1999/000312 WO2000038404A1 (fr) 1998-12-22 1999-12-21 Circuit et procede de telealimentation

Publications (1)

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EP1142294A1 true EP1142294A1 (fr) 2001-10-10

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Application Number Title Priority Date Filing Date
EP99960705A Withdrawn EP1142294A1 (fr) 1998-12-22 1999-12-21 Circuit et procede de telealimentation

Country Status (6)

Country Link
EP (1) EP1142294A1 (fr)
AU (1) AU1761000A (fr)
BR (1) BR9916492A (fr)
IL (1) IL143876A0 (fr)
MX (1) MXPA01006434A (fr)
WO (1) WO2000038404A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4254305A (en) * 1979-02-07 1981-03-03 International Telephone And Telegraph Corporation Current limited subscriber line feed circuit
DE3204429A1 (de) * 1982-02-09 1983-10-06 Siemens Ag Schaltungsanordnung zur geregelten spannungsversorgung von ferngespeisten endeinrichtungen in fernmelde-insbesondere fernsprechanlagen
US5289359A (en) * 1991-02-13 1994-02-22 Charles Industries, Limited DC-DC power converter including sensing means for providing an output when the reserve power of the converter falls below a predetermined amount for a given input voltage
US5754644A (en) * 1996-06-27 1998-05-19 Lucent Technologies Inc. Method for customizing operation of a battery feed circuit in a telecommunications network

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0038404A1 *

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WO2000038404A1 (fr) 2000-06-29
BR9916492A (pt) 2001-09-04
MXPA01006434A (es) 2002-07-22
AU1761000A (en) 2000-07-12
IL143876A0 (en) 2002-04-21

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