Abstract:
A combination of algorithms and circuits are used to combine POTS, high-speed bi-directional data, and back-powering onto the drop connection for fiber to the distribution point architectures. A telephone adapter device can be utilized to prevent damage from back-powering occurring at POTS telephones connected to the drop connection. In addition, circuits are used to prevent damage from back-powering occurring at POTS telephones directly connected to the drop connection. A circuit is used to provide more consistent power to the electronics at the distribution point even when the input back-power to the distribution point may fluctuate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/953,211, entitled “Combining POTS, High-speed Data, and Back-Powering on a Single Pair of Wires for Fiber to the Distribution Point (FTTdp) Architectures,” filed Mar. 14, 2014, which application is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Network service providers want to cost effectively satisfy customer demand for high-speed data. One way to provide customers with high-speed data is through the use of a fiber optic connection. A Fiber to the Distribution Point (FTTDP) connection can provide a more cost effective alternative for providing high-speed data services to customers than a Fiber to the Home (FTTH) connection. In an FTTDP architecture, an optical termination unit is placed close to the customer, e.g., at a distribution point, and then one or more existing very short metallic drop wires to the customer are reused. Reuse of the existing drop wires eliminates a significant component of fiber optic cable and fiber installation cost that would be present with an FTTH connection. As the connection between the optical termination unit and the customer premises is short, very high-speed data can be carried with inexpensive, low power hardware. 
     For example, in DSL (digital subscriber line) systems, it is generally desirable for the DSL connection to be as short as possible in order to enhance speed and performance. One option for obtaining a short DSL connection involves placing the DSL modems connected to the network at distribution points. A distribution point might typically be located at the top of a telephone pole or at a pedestal located on the ground within a few hundred feet of the customer premises. A number of drop connections, e.g., telephone lines, can fan out from the distribution point with each drop connection heading towards a different customer premises. 
     One problem with placing the DSL modem at the distribution point is that the DSL modem and the other components at the distribution point may have difficulty obtaining a reliable power supply from the immediate vicinity of the distribution point. One solution to this problem involves supplying power to the distribution point from equipment at the customer premises using the drop connection that carries the DSL signals. 
     However, there can be problems with providing power from customer premises equipment to the components located at the distribution point. The customer premises equipment has to provide a significant amount of power to adequately power all of the components at the distribution point. The large amount of power provided by the customer premises equipment to the distribution point can damage other equipment connected to the drop connection. In addition, the power provided to the distribution point by the customer premises equipment is DC power and can be affected by other low frequency signals, e.g., a ringing signal, on the drop connection. The other low frequency signals on the drop connection can significantly impact the DC power from the customer premises equipment such that the components at the distribution point do not receive enough power to ensure proper operation of the components. 
     Therefore, what is needed are systems and methods to consistently provide power from customer premises equipment to components at the distribution point over the drop connection without damaging other components that may be connected to the drop connection. 
     SUMMARY 
     The present application generally pertains to systems and methods for providing high-speed (e.g., near-gigabit) data service (HSDS) with compatible POTS (plain old telephone service) utilizing back powering from the equipment at the customer premises to supply equipment at a distribution point located outside of the customer premises. The high-speed data service operates over a high-speed data connection, such as a digital subscriber line (DSL) connection operating in accordance with one of the very high-speed DSL (VDSL) standards, including G.fast technology. 
     One advantage of the present application is that telephones directly connected to the drop connection are not damaged by back power provided on the drop connection for the distribution point. 
     Another advantage of the present application is that the distribution point can remain powered even during fluctuations in the back power voltage caused by a ringing signal on the drop connection. 
     Other features and advantages of the present application will be apparent from the following more detailed description of the identified embodiments, taken in conjunction with the accompanying drawings which show, by way of example, the principles of the application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing an embodiment of a telecommunication system. 
         FIG. 2  is a schematic diagram of an embodiment of a telephone adapter device from the telecommunication system of  FIG. 1 . 
         FIG. 3  is a block diagram showing an embodiment of an HSDU from the telecommunication system of  FIG. 1 . 
         FIG. 4  is a block diagram showing an embodiment of the distribution point from the telecommunication system of  FIG. 1 . 
         FIG. 5  is a schematic diagram showing an embodiment of the switch module from the distribution point of  FIG. 4 . 
         FIG. 6  is a block diagram showing an embodiment of the power source from the distribution point of  FIG. 4 . 
         FIG. 7  is a schematic diagram of an embodiment of the non-linear inductor of the power source of  FIG. 6 . 
     
    
    
     Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. 
     DETAILED DESCRIPTION 
       FIG. 1  shows a system  10  for communicating data and voice between several customer premises  12  and at least one network  16 . The network  16  can include any of various types of telecommunication networks, such as the public switched telephone network (PSTN). The at least one network  16  can be connected to a network facility  14 , such as a central office, by one or more connections  15 . The network facility  14  can be connected to a distribution point (DP)  18  by at least one high-speed data connection  20 , e.g., an optical fiber, and multiple POTS (plain old telephone service) lines  22 . The high-speed data connection  20  provides a high-speed channel that carries a data stream between the DP  18  and the network facility  14 . The POTS lines  22  provide voice channels between the DP  18  and the network facility  14 . In one embodiment, there can be a POTS line  22  for each customer premise  12  connected to the DP  18 . However, in other embodiments, the number of POTS lines  22  and the number of customer premises  12  connected to the DP  18  may be different. Further, while the embodiment in  FIG. 1  shows one DP  18  connected to the network facility  14  and two customer premises  12  connected to the DP  18 , more than one DP  18  can be connected to the network facility  14  and more or less than two customer premises  12  can be connected to a DP  18 . 
     The DP  18  is connected to one or more customer premises  12  via at least one conductive connection  24 , such as a twisted-wire pair. The physical or conductive connection  24  from the DP  18  to a customer premise  12  is referred to as a “drop connection.” The drop connection  24  at the customer premises  12  can be connected to one or more customer premises equipment (CPE), such as a telephone  26 , a high-speed data unit (HSDU)  28 , a fax machine, etc., located at the customer premise  12 . 
     When a customer wants to obtain high-speed data service (HSDS), which may or may not include voice service, a user, e.g., a customer or a technician, connects the HSDU  28  to the drop connection  24 . In addition, if the customer is receiving voice service with HSDS, a telephone adapter device (TAD)  30  is connected by the user between each telephone  26  (or any other device, e.g., a fax machine, expecting a POTS signal on the drop connection  24 ) at the customer premises  12  and the drop connection  24 . The TAD  30  is a passive device that permits a standard POTS telephone or other POTS device to work in conjunction with the HSDU  28 . If a customer is not using a HSDU  28  then a TAD  30  does not have to be connected between the telephone  26  and the drop connection  24  since only a POTS signal is provided on the drop connection  24 . 
     The TAD  30  is used to prevent damage to the telephone  26  that may occur as a result of an excessive current being received by the telephone  26  during operation of the HSDU  28 , more specifically, the providing of back power by the HSDU  28 . The TAD  30  can have a passive splitter or filter to separate the POTS voice signal from the HSDS signal and current limiters (that may or may not contain voice-band bypasses) to limit the current provided to the telephone  26 . The TAD  30  can include resistors to limit the current to the telephone  26  to about 25 mA (milliAmperes) when the telephone  26  is in the off-hook state even though the open circuit line voltage at the telephone  26  can be more than 50 V (volts). The TAD  30  can have low-pass filters to minimize the interference of signaling transients into the data path and isolate the telephone  26  from the high-speed data being sent and received by the HSDU  28 . 
       FIG. 2  shows a schematic diagram of a TAD  30 . The TAD  30  has connection ports coupled to the drop connection  24  and a POTS telephone  26 . In one embodiment, the connection ports for the TAD can be receptacles to receive corresponding plugs connected to wiring for the drop connection  24  and wiring for the telephone  26 . The TAD  30  has input wires IWA and IWB connected to the port for the drop connection  24  and output wires TELA and TELB connected to the port for the telephone  26 . IWA can be connected to TELA by a series connected inductor L 1  and resistor R 1  and IWB can be connected to TELB by a series connected inductor L 2  and resistor R 2 . A capacitor C 1  can be connected in parallel between L 1  and R 1  and between L 2  and R 2 , as shown in  FIG. 2 . The inductors L 1  and L 2 , the resistors R 1  and R 2  and the capacitor C 1  can be appropriately sized to provide the desired current limiting and filtering functions of the TAD  30 . In one embodiment, inductors L 1  and L 2  can be 0.5 milliHenries (mH), the resistors R 1  and R 2  can be 850 ohms ( 0 ) and the capacitor C 1  can be 22 nanoFarads (nF). 
       FIG. 3  is a block diagram showing an embodiment of the HSDU  28 . The HSDU  28  is connected to the drop connection  24  and to an AC (alternating current) power source by the user installing the HSDU  28  at the customer premises  12 . A power supply  32  receives an AC voltage from the AC power source and converts the AC voltage to a DC (direct current) voltage. In other embodiments, the power supply may be coupled to a DC power source (not shown). The power supply  32  provides a power signal (e.g., a DC voltage) to the drop connection  24  to power the components of the distribution point  18 , which process is referred to as “back powering.” In one embodiment, the DC voltage provided by the power supply  32  can range between 50 V (volts) and 55 V and is limited to a maximum of 60 V to comply with safety extra low voltage (SELV) requirements. 
     The HSDU  28  also includes a control unit  40  connected to the drop connection  24  to manage the high-speed data and the voice data (if the customer is receiving voice service) provided over the drop connection  24  to the HSDU  28 . The control unit  40  can include a modem  42  to send and receive the high-speed data and voice data using the drop connection  24 . The voice data can be processed by a VOIP (voice over IP (internet protocol)) unit  44  that converts the digital voice data from the modem  42  to analog voice data that is sent to the telephones  26  over the drop connection  24 . The VOIP unit  44  can also receive analog voice data from the telephones  26  over the drop connection  24  and convert the analog voice data to digital voice data that is provided to the modem  42  for inclusion in the data stream. The VOIP unit  44  can also be used to activate the ring unit  34  when a ringing activation signal is included in the voice data. The ring unit  34  can place a 55 V RMS (root mean square), 20 Hz (hertz) ringing signal on the drop connection  24  to initiate the ringing process in the telephone(s)  26 . 
     The HSDU  28  includes a control element  46  that can be used to filter or separate the high-speed data from the voice data. In one embodiment, the voice data can be provided in the data stream at a frequency of about 3 or 4 kHz or less and the high-speed data can be provided in the data stream at a frequency of about 1 MHz or greater. The high-speed data can be provided to a data port in the HSDU  28  and the voice data can be provided to the VOIP unit  44 . In one embodiment, the data port can include an Ethernet connection. The HSDU  28  can also include a current detector  36  to measure the current being drawn on the power supply  32  (referred to as the IDU) or another parameter equivalent to the current drawn on the power supply  32 . 
       FIG. 4  shows an embodiment of the DP  18  that is used to provide voice (telephone) and/or high-speed data to customer premises  12 . The DP  18  does not have a dedicated connection to a power supply located in the vicinity of the DP  18 , such as a battery or a line connection to an electric utility. The DP  18  can include a service unit  50  that is connected to the high-speed data connection  20 . The service unit  50  can process data in both the downstream and upstream directions. In the downstream direction, the service unit  50  receives a high-speed data signal from the network  16  and de-multiplexes the data for transmission across a plurality of drop connections. In the upstream direction, the service unit  50  receives a plurality of data streams from a plurality of drop connections and multiplexes the data into a high-speed data signal for transmission to network  16 . 
     The service unit  50  can include an optical network unit (ONU)  52  that can receive at least one packet flow from the high-speed data connection  20  and convert the received packet flow(s) from the optical domain to the electrical domain. The converted packet flow(s) can then be forwarded to control unit  54  and then sent to the customer premises  12  using a transceiver (XCVR)  56 . The transceiver  56  can communicate using DSL (digital subscriber line) protocols, e.g., asymmetric DSL (ADSL), high-bit-rate DSL (HDSL), very-high-bit-rate DSL (VDSL), VDSL2, or G.fast, or other known protocols. The control unit  54  can include a control element  62  that is configured to forward the data packets of the high-speed data stream from the ONU  52  to the transceiver  56  based on the destination addresses in the data packets such that each data packet is ultimately received by the HSDU  28  corresponding to the packet&#39;s destination address. 
     The transceiver  56  can use output line  58  to connect to a switch module  100 . The switch module  100  can also be connected to a POTS line  22  and drop connection  24 . The switch module  100  can be configured to selectively connect the drop connection  24  to either the POTS line  22  (if the customer has requested only telephone service) or the high-speed data service (HSDS) output line  58  connected to transceiver  56  (if the customer has requested high-speed data service that may or may not include telephone service). While the switch module  100  in  FIG. 4  is shown separate from service unit  50 , the switch module  100  can be incorporated into the service unit  50  in another embodiment. 
     In one embodiment, the DP  18  can include a switch module  100  for each POTS line  22  connected to the DP  18 . When the DP  18  has more than one switch module  100 , the service unit  50  can include multiple transceivers  56  and output lines  58 . Each switch module  100  can be connected to a POTS line  22  and an output line  58  and transceiver  56 . 
     The control unit  54  can include a power source  68  that receives the DC voltage from the power supply  32  over the drop connection  24  and output line  58 . The power source  68  can use the DC voltage from the power supply  32  to provide power to the components of the service unit  50  and/or switch module  100 . In one embodiment, the power source  68  can provide 5 V, 3.3 V, 1 V, etc. to the components of the service unit  50  and/or switch module  100 . A current detector  60  can measure the current used by the service unit  50  or another parameter equivalent to the current used by the service unit  50 . The current detector  60  can provide the measured current for the service unit  50  (referred to as the ISU) or other parameter equivalent to the measured current for the service unit  50  to a control element  62  that can forward the measured current or other parameter over the output line  58  and the drop connection  24 , i.e., a powering data link (PDL), to the control unit  40  ( FIG. 3 ) in the HSDU  28 . In one embodiment, the PDL can be part of the high-speed data communicated over the drop connection  24 . The control element  62  can also be used to provide a control signal to the switch module  100  over line  64 . 
     The ISU is provided over the PDL to the control unit  40  in the HSDU  28 . The control unit  40  subtracts the ISU value from the IDU value and makes control decisions based on the difference between the IDU value and the ISU value. In other embodiments, other comparisons or analysis of the IDU value, ISU value or the other parameters equivalent to the IDU and ISU can be performed and used as the basis for making control decisions. For example, a ratio of the IDU and ISU values can be compared to a threshold ratio and control decisions based on whether the IDU and ISU ratio is greater than or less than the threshold ratio. 
     In one embodiment, the control unit  40  can determine if a telephone  26  connected through a TAD  30  is in the off-hook state by determining if the IDU-ISU difference value is greater than a predetermined current value, e.g., 10 mA. If an off-hook state for a telephone  26  using a TAD  30  is determined by the control unit  40 , a signal is provided to the VOIP unit  44  to initiate further processing by the VOIP unit  44 . In another example, if the VOIP unit  44  has instructed the ring unit  34  to place a ringing signal on the drop connection  24 , the off-hook state can be determined as described previously and the ringing signal can be terminated by the VOIP unit  44  in response to the determination of the off-hook state in the telephone  26  using the TAD  30 . 
     In another embodiment, the control unit  40  can use the IDU-ISU difference value to determine if a fault condition exists that can result in a telephone  26  receiving an excessive current that can damage the telephone  26 . One example of a fault condition is a telephone  26  being connected directly to the drop connection  24 , i.e., there is no TAD  30  connected between the telephone  26  and the drop connection  24 , and entering the off-hook state, which would result in the telephone  26  receiving an excessive current. If the IDU-ISU difference value is greater than a predetermined current value, e.g., 150 mA, then a fault condition is present and the control unit  40  can instruct the power supply  32  to stop supplying the DC voltage to the drop connection  24 . Alternatively, the control unit  40  can deactivate or disengage the power supply  32  when a fault condition is present. The predetermined current value used for fault detection can be selected such that a predetermined number of telephones  26  using TADs  30 , e.g.,  5  telephones  26  using TADs  30 , can be in the off-hook state without triggering a fault condition. In one embodiment, the current measurements (IDU and ISU) are conducted at a sufficiently high rate to detect the off-hook state even during polarity reversals in the ringing signal provided by ring unit  30 . In another embodiment, the current measurements (IDU and ISU) are filtered sufficiently, e.g., averaged, to avoid the impact of transient conditions on the current measurements. 
     After the fault condition is detected, the HSDU  28  can enter a pre-power-up state. The HSDU  28  can also be in the pre-power-up state immediately after the switch module  100  connects the drop connection  24  to the HSDS output line  58 . The pre-power-up state can be used to avoid damage to or from the HSDU  28  if there are short circuits or foreign potentials on the drop connection  24  and to avoid damaging a telephone  26  directly connected to the drop connection  24 . The output voltage from the HSDU  28  is approximately zero in the pre-power up state. If foreign potentials are at acceptable levels, then the HSDU  28  begins the power-up process. 
     In the power-up process, the HSDU  28  controls the power supply  32  to place a current limited 10 Volts (e.g., less than 40 mA) on the drop connection  24 . The service unit  50  has an under-voltage lock-out that keeps the service unit  50  from drawing more than 1 mA for input voltages from the power supply  32  of less than 18 V. If the HSDU  28  delivers less than a predetermined amount of current, e.g., 10 mA, during the power-up process, then the HSDU  28  transitions to an idle state and begins supplying the DC voltage, i.e., the back power voltage, to the drop connection  24  with the power supply  32 . If more than the predetermined amount of current is delivered by the HSDU  28 , such as by having a telephone  26  connected directly to the drop connection  24  in the off-hook state, which can draw more than 100 mA of current, the HSDU  28  detects the over-current, instructs the power supply  32  to stop supplying DC voltage to the drop connection  24 , imposes a predetermined time delay, and enters the pre-power-up state. 
       FIG. 5  shows an embodiment of a switch module  100  used to switch the connectivity of the drop connection  24  between POTS service and high-speed data service (HSDS). The switch module  100  can include a latching relay  102  to connect the drop connection  24  to either the POTS line  22  or the HSDS output line  58 . The latching relay  102  can include a first port to connect to the drop connection  24 , a second port to connect to the POTS line  22  and a third port to connect to the HSDS output line  58 . In a first state of the latching relay  102 , a first coil in the latching relay  102  can be energized to connect the drop connection  24  to the HSDS output line  58 . In a second state of the latching relay  102 , a second coil in the latching relay  102  can be energized to connect the drop connection  24  to POTS line  22 . Starting logic  104  can be connected between the wires of the drop connection  24  and used to energize the first coil or the second coil depending on the desired state for the latching relay  102 . In addition, the starting logic  104  is connected to line  64  and receives and processes the control signal sent on line  64  to the control unit  54 . In one embodiment, the control signal from the control unit  54  can be used to prevent the starting logic  104  from switching the latching relay  102  to the second state from the first state. In another embodiment, the HSDU  28  can send an activation signal to the starting logic  104 , instructing the starting logic  104  to switch the latching relay  102  from the second state to the first state to connect the drop connection  24  to the HSDS line  58  instead of the POTS line  22 . 
       FIG. 6  is a block diagram showing the power source  68 . The power source  68  can receive the DC voltage from the power supply  32  ( FIG. 3 ) over output line  58 . The power source  68  can include a POTS splitter  70  to isolate or separate the power and voice signals from the high-speed data signals. In one embodiment, the voice signals can be at a frequency as low as about 300 Hz. The power and voice signals from the POTS splitter  70  are provided to a bridge rectifier  72 . The bridge rectifier  72  outputs the absolute value of the input voltage, i.e., outputs only positive voltages. The output of the bridge rectifier  72  is provided to a non-linear inductor  74  and capacitor  76  before reaching the SMPS (switched mode power supply)  78 . The SMPS  78  can include a switching regulator to control the output voltage and current characteristics provided to loads, e.g., the components of the service unit  50  and switch module  100 , connected to the SMPS  78 . 
     In one embodiment, the bridge rectifier  72  can provide the DC voltage, e.g., 55 V, from the power supply  32  on the drop connection  24  to the non-linear inductor  74  and capacitor  76 . However, when a ringing activation signal is received by the VOIP unit  44 , the VOIP unit  44  instructs the ring unit  34  to place a sinusoidal ringing signal, e.g., a 20 Hz, 55 V RMS signal, on the drop connection  24 . The aggregate voltage of the DC voltage, e.g., 55 V, and the ringing voltage, e.g., 55 V RMS, received by the bridge rectifier  72  can vary between a maximum, e.g., 133 V, and a minimum, e.g., −23 V, generated from adding the DC voltage and the maximum and minimum ringing voltages. The variance in aggregate voltage received by the bridge rectifier  72  caused by the overlay of the ringing signal voltage on the DC voltage can result in the voltage from the bridge rectifier  72  being less than the expected DC voltage, i.e., the expected back power voltage, for a portion of the time. To prevent the SMPS  78  from not having enough power during the portion of the time that the voltage from the bridge rectifier  72  is less than the expected DC voltage, the non-linear inductor  74  changes inductance to permit more current to the capacitor  76  thereby permitting the capacitor  76  to store additional charge and voltage during high voltage periods, i.e., the portions of time where the voltage to the bridge rectifier  72  is greater than the expected DC voltage. The capacitor  76  can then discharge the additional charge and voltage acquired during the high voltage periods when the voltage to the bridge rectifier  72  is less than the expected back power voltage. In one embodiment, the non-linear inductor  74  can be used to isolate the capacitor  76  and the SMPS  78  from variances in the voltage from the bridge rectifier  72 . 
       FIG. 7  is a schematic diagram of an embodiment of the non-linear inductor  74 . In one embodiment, the non-linear inductor  74  can have an impedance of 9500Ω in the voice band, an apparent inductance of 3 H, a voltage drop across the active portion of the non-linear inductor  74  (which includes all of the components shown in  FIG. 7  but R 1 ) of 3.35 V at room temperature and 330 mA of current, an equivalent series resistance of 5Ω, and the ability to withstand 2.88 volts peak-to-peak with low distortion. In the embodiment shown in  FIG. 7 , R 1  can be 5Ω, R 2  can be 40,000Ω, R 3  can be 1,000Ω, R 4  can be 10,000Ω, R 5  can be 1,000Ω, C 1  can be 15 pF, D 1  can be a Zener diode, J 1  can be a junction field-effect transistor (JFET), Q 1  can be a PNP power transistor, Q 2  can be NPN switching transistor, and Q 3  can be a PNP switching transistor. However, in other embodiments other suitable components having different characteristics can be used. 
     In the non-linear inductor  74  shown in  FIGS. 7 , J 1  and R 3  form a current source to provide loop gain to the amplifier formed from the Q 2 , Q 3  and Q 1  transistors since R 1  has low resistance. Without the J 1  and R 3  current source, the impedance of the non-linear inductor  74  would be too low and would short out the signals in the voice band. In addition, D 1  and R 5  can be a saturation element that provides a useful saturation behavior that keeps the power source  68  powered up during ringing, i.e., a ringing signal is present on the drop connection  24 . D 1  and R 5  lower the inductance of the non-linear inductor  74  by a factor of 1+R 2 /R 5  for large voltage increases across the non-linear inductor  74 . The reduction in inductance of the non-linear inductor  74  permits the current through the non-linear inductor  74  to increase and increase the voltage on the capacitor  76 . If there is no change in the inductance, the current and the charge on the capacitor  76  would remain at the same level as when there is no ringing signal present, i.e., only the DC voltage is present. The “extra” voltage on the capacitor  76  obtained when the aggregate voltage is greater than the expected DC voltage can then be used when the aggregate voltage drops below the expected DC voltage. 
     In another embodiment, an alternate solution to the problem of the voltage being below the expected DC voltage would be to use a square wave ringing signal instead of a sinusoidal ringing signal to decrease the dwell time of the composite waveform below the expected DC voltage. 
     In one embodiment, the TAD  30  can be an active device that includes the appropriate circuitry, e.g., the VOIP unit  44 , to receive and process the voice signals included as part of the high-speed data stream on the drop connection  24 . In addition, if the TAD  30  is an active device, the ringing activation signal included as part of the voice data may be processed at the TAD  30  and the ringing signal for the telephone  26  can be sent directly to the telephone  26  from TAD  30 , i.e., there is no ringing signal on the drop connection  24 . In another embodiment, capacitors can be included to shunt R 1  and R 2  to decrease the insertion loss from the TAD  30 . 
     Although the figures herein may show a specific order of method steps, the order of the steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. Variations in step performance can depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the application. Software implementations could be accomplished with standard programming techniques, with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps. 
     In various embodiments described above, a service unit is shown as residing at a distribution point. In other embodiments, any of the service units described herein may reside at other locations. For example, a service unit may be mounted on a side of the house in which the HSDU  28  is situated. 
     It should be understood that the identified embodiments are offered by way of example only. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the embodiments without departing from the scope of the present application. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the application. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.