Abstract:
The present invention is directed to a remotely actuated splitter bypass function (RASB) working in conjunction with a test head at the central office for testing and maintaining copper loops in the digital subscriber line environment. The RASB allows a competitive local exchange carrier to test and maintain the xDSL portion of the copper loop with minimal interference and disturbance to/from the plain old telephone system (POTS) service by bypassing the central office splitter. The splitter bypass operation includes the steps of selecting a copper loop pair for testing, actuating a first relay for monitor mode, actuating a second relay for bypass mode, testing the selected copper loop, and resetting the first and second relays back to normal mode. By applying positive and negative voltages from the tip and ring with respect to ground, various relays can be set (actuated) and reset to provide multiple modes of operations. In this manner, relays can be designed to respond in certain voltage levels and polarities.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a remotely actuated splitter bypass system and method for testing and maintaining a copper loop. More particularly, the present invention is directed to a system and method for remotely actuating a bypass function in a splitter such that testing and maintenance can be performed by a local exchange carrier without interference to/from the plain old telephone system (POTS) service. In particular, the present invention discloses systems and methods allowing a competitive local exchange carrier (CLEC) to access the copper loop for testing and maintenance with minimal interference to/from the POTS service.  
         BACKGROUND OF THE INVENTION  
         [0002]    In 1999, the Federal Communications Commission (FCC) adopted rules to promote competition between local telephone companies and providers of high speed Internet access and other data services by directing the telephone companies to share their telephone lines with such providers. With these rules, many companies can deploy new technologies on a faster, more cost-effective basis, thereby allowing residential and business customers to access broadband and POTS services from a choice of different providers.  
           [0003]    Digital Subscriber Line or xDSL is one of the most promising new technologies for delivering superior service and higher speed connections over existing infrastructure. Recent changes in the telecommunications industry such as the deregulation of local markets have brought on the emergence of new technologies such as xDSL. In addition, the growing demand for faster, more reliable Internet access has increased the demand for technologies that deliver higher speed connections over existing infrastructure.  
           [0004]    As known, different competing forms of digital subscriber line technologies are collectively designated as XDSL technologies with the “x” representing various one or more letter combinations, which are used in front of the “DSL” acronym to designate the type of technology being used. Some of the more prevalent xDSL technologies include HDSL, ADSL, SDSL, RADSL, VADSL, and VDSL.  
           [0005]    xDSL uses the existing copper loop that is traditionally used for conventional telephony to deliver data at high bandwidth. Currently, the transmission rates for xDSL technologies are dependent on the distance between a central office and a particular customer. Depending on the type of xDSL technology, the transmission rate downstream to the customer and upstream to the central office may vary. Also, xDSL uses packet switching technology that operates independently of the voice telephone system, allowing telephone companies to provide Internet service and not lock up circuits for telephone calls. xDSL can carry both voice and data signals simultaneously, in both directions, allowing the customer to log onto the Internet and make a telephone call at the same time. Thus, it is easy to understand why XDSL is becoming the preferred system and method for sending/receiving analog and digital data/signals in the telecommunications industry.  
           [0006]    Traditionally, incumbent local exchange carriers (ILECs) used the existing copper loop for voice telephone and data services. With the adoption of the new FCC rules, competitive local exchange carriers (CLECs) can obtain access to the high-frequency portions of the local loop from the ILECs. This enables the CLECs to provide xDSL services over the same telephone lines simultaneously used by the ILECs, which technique is know as “line sharing.” 
           [0007]    Line sharing allows customers to obtain data service from either the ILEC or CLEC without having to forego the traditional voice service from their current provider. Line sharing also allows customers to receive both voice and data services on the same line; thus, eliminating the need for customers to procure a second line. In other words, line sharing involves the CLEC providing xDSL service on the same copper loop on which the ILEC provides POTS service. As a result, this allows for a more efficient use of the existing telephone infrastructure by allowing CLECs to take advantage of the large installation base that already exists.  
           [0008]    One major shortcoming of the current line sharing system and method is the testing and maintenance of the copper loop for the CLECs. This problem is better understood by describing the current line sharing system and method, which is described in greater detail with reference to FIGS.  1 - 2 .  
           [0009]    [0009]FIG. 1 illustrates a simplified diagram of a conventional line sharing system. In the conventional system, a central office (CO) is connected to a customer&#39;s telephone  16  and an ATU-R (ADSL transceiver remote unit)  18  or similar end unit at the customer&#39;s premise (home, office, etc.) using a copper loop  14  (pair of copper wires). In the CO, a voice switch  2 , which is generally owned by the ILEC, and a DSLAM (DSL Access Multiplexers)  4 , which in this case is owned by the CLEC, are connected to a CO splitter  6 . As known, the voice switch  2  includes circuitry for providing POTS (voice) service and the DSLAM  4  includes circuitry for providing xDSL service to the customer. The DSLAM  4  generally receives incoming xDSL lines and aggregates the traffic onto highspeed uplink trunks such as ATM or Frame Relay. The CO splitter  6  is typically found in a main distribution frame and is generally a passive unit (i.e., no power).  
           [0010]    In greater detail, the CO splitter  6  is used to isolate the voice service from the XDSL service. The isolation generated by the CO splitter  6  is important for minimizing interference between the two types of services and removing transients. The CO splitter  6  separates voice and data band signals received from the copper loop  14  and provides the respective signals to the voice switch  2  and the DSLAM  4 . The CO splitter  6  also combines the voice and data band signals received from the voice switch  2  and the DSLAM  4  and provides the combined signals to the copper loop  14 .  
           [0011]    The CO splitter  6  includes a low pass filter (LPF)  8  connected to the voice switch  2  and a high pass filter (HPF)  10  (or DC clocking capacitors) connected to the DSLAM  4 . The LPF  8  filters out higher band xDSL signals and prevents such signals from interfering with the voice switch  2 . Likewise, the HPF  10  filters out low band voice signals and prevents such signals from interfering with the DSLAM  4 . In other words, the high frequency signals generated by the DSLAM  4  will not interfere with the voice switch  2  because of the LPF  8 , and the low frequency signals generated by the voice switch  2  will not interfere with the DSLAM  4  because of the HPF  10 . The voice service typically occupies the band between 0 KHz (DC) to 4 KHz, and the XDSL service occupies some predetermined band above the voice service such as from 25.9 KHz to 1.1 MHz.  
           [0012]    A signature S 1   12  is also connected to the voice portion of the CO splitter  6 . As known, the signature can be used in conjunction with a CO test system for fault identification and localization. The signature S 1   12  is preferably a passive network such as a resistance, capacitor, zeners and diodes combined to from a unique network, which is used to assist in detecting fault conditions, loop length measurements, and the like. The signature S 1   12  can also be active circuit elements that perform a specific function, as known in the art.  
           [0013]    A second remote (RT) splitter  20  having a LPF  22 , HPF  24 , and signature SR  26  can be optionally installed in the customer&#39;s premise. The LPF  22  is connected to the telephone  16  for filtering out high band signals, while the HPF  24  is connected to the ATU-R  18  for filtering out low band signals.  
           [0014]    [0014]FIG. 2 illustrates a diagram of an existing circuit used in the conventional line sharing system as shown in FIG. 1. The LPF  8  generally includes series inductors  30 - 35  and capacitors  42 ,  44 , while the HPF  10  generally includes series capacitors  50 - 53  and inductors  60 ,  62 .  
           [0015]    The voice switch  2  typically includes circuitry for interfacing with a pair of wires, tip and ring, from the outside plant. As is well known, tip and ring are terms used to describe the two wires that are used to set up a telephony/xDSL connection. The voice switch  2  includes amplifiers  73 ,  74 , connected in series to resistors  71 ,  72 , respectively. The amplifiers  73 ,  74 , and resistors  71 ,  72 , form a balance drive interface circuit to the tip and ring wires. As known, the voice switch  2  can be implemented with transformers instead of amplifiers  73 ,  74 . The DSLAM  4  includes a pair of capacitors  81 ,  82  connected in parallel.  
           [0016]    With the conventional line sharing system and CO splitter  6  as shown in FIGS.  1 - 2 , the ILEC using the voice switch  2  can continue to test and maintain the copper loop in the traditional manner, typically using mechanized loop testing via a Class  5  switch. The LPF  8  in the CO splitter  6  does not significantly interfere with this process. However, it is well known that the CLEC&#39;s ability to test and maintain the copper loop for xDSL service is greatly handicapped using the conventional CO splitter  6  because of the HPF  10  and the POTS service. Thus, it is very difficult for the CLEC to access the copper loop for independent testing and maintenance.  
           [0017]    Another disadvantage using the conventional system and method is that the CO splitter  6  is typically implemented in a manner that benefits the ILECs, which utilize their customized test systems to test and maintain the POTS portion of the copper loop. The CLECs, which are typically in direct competition with the ILECs for xDSL service, currently do not have a system and method for independent testing/maintenance of the copper loop. For example, when the ILEC uses the copper loop for voice service, the CLEC is generally prohibited from testing the copper loop in fear of disturbing or interfering with the voice service. If the copper loop is busy or off-hook (i.e., customer using the telephone), the CLEC will be very hesitant to test the copper loop because such testing may terminate the telephone call.  
           [0018]    As described above, the conventional CO splitter is generally acceptable for the ILECs for testing the copper loop for voice service, but it is inadequate for the CLECs for testing the same loop for xDSL service. Accordingly, there is a need for a system and method for providing a reliable and effective manner of testing and maintaining the copper loop in the xDSL environment for CLECs. Thus, there is a need for a remotely actuated splitter bypass system and method for improved testing and maintenance of the copper loop for the CLECs without interference or disturbance to/from the POTS service.  
         SUMMARY OF THE INVENTION  
         [0019]    In view of the above-described problems of the prior art, it is an object of the present invention to provide a remotely actuated splitter bypass system and method.  
           [0020]    It is another object of the present invention to provide a system and method for implementing a remotely actuated splitter bypass function in the existing line sharing infrastructure for improved testing and maintenance for a CLEC.  
           [0021]    It is yet another object of the present invention to provide circuitry allowing a CLEC to access the copper loop for testing and maintenance with minimal interference and disturbance to/from the POTS service.  
           [0022]    It is a further object of the present invention to provide a system and method for providing a reliable and effective manner for testing and maintaining a copper loop in the xDSL environment for a CLEC.  
           [0023]    It is still a further object of the present invention to provide a system and method for remotely actuating a bypass function in a splitter such that testing and maintenance can be performed by a CLEC without interference or disturbance to/from the POTS service.  
           [0024]    It is another object of the present invention to provide controls signals that are carried by the same copper loop pair during testing.  
           [0025]    It is yet another object of the present invention to provide an enable signal to enable multiple pairs of copper loops and when the enable signal is absent, all splitters automatically revert to the normal mode of operation.. It is a further object of the present invention for providing a method for remotely actuating a bypass function in a splitter using a direct control approach.  
           [0026]    It is yet another object of the present invention for providing a method for remotely actuating a bypass function in a splitter using a state machine control approach.  
           [0027]    These and other objects of the present invention are obtained by providing a remotely actuated splitter bypass (RASB) function that can be used with a conventional splitter in the current line sharing system. The RASB includes circuitry, working in conjunction with an off-the-shelf splitter, for testing and maintaining a copper loop by a CLEC with minimal interference and disturbance to/from the POTS service. The splitter bypass operation includes the steps of selecting a copper loop pair for testing, actuating a first relay for monitor mode, actuating a second relay for bypass mode, testing the selected copper loop, and resetting the first and second relays back to normal mode. The RASB can be implemented using direct control or state machine control. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    These and other objects and advantages of the present invention will become apparent and more readily appreciated from the following detailed description of the presently preferred exemplary embodiments of the invention taken in conjunction with the accompanying drawings, of which:  
         [0029]    [0029]FIG. 1 illustrates a simplified block diagram of a conventional line sharing system having a splitter;  
         [0030]    [0030]FIG. 2 illustrates a diagram of an existing circuit used in the conventional line sharing system as shown in FIG. 1;  
         [0031]    [0031]FIG. 3A illustrates a block diagram of a line sharing system having a splitter with a remotely actuated splitter bypass function in accordance with the preferred embodiments of the present invention;  
         [0032]    [0032]FIG. 3B illustrates a flow diagram showing the splitter bypass operation in accordance with the preferred embodiments of the present invention;  
         [0033]    [0033]FIG. 3C illustrates a simplified block diagram representing the normal mode in accordance with the preferred embodiments of the present invention;  
         [0034]    [0034]FIG. 3D illustrates a simplified block diagram representing the monitor mode in accordance with the preferred embodiments of the present invention;  
         [0035]    [0035]FIG. 3E illustrates a simplified block diagram representing the bypass mode in accordance with the preferred embodiments of the present invention;  
         [0036]    [0036]FIG. 4 illustrates an enable/powering system diagram in accordance with the preferred embodiments of the present invention;  
         [0037]    [0037]FIG. 5A illustrates a specific example of the remotely actuated splitter bypass signaling definition in accordance with the first preferred embodiment of the present invention;  
         [0038]    [0038]FIG. 5B illustrates a signaling sequence of FIG. 5A in accordance with the first preferred embodiment of the present invention;  
         [0039]    [0039]FIG. 5C illustrates a functional block diagram of the remote relay control in accordance with the first preferred embodiment of the present invention;  
         [0040]    [0040]FIG. 5D illustrates an example of a detailed circuit diagram of the remote relay control in accordance with the first preferred embodiment of the present invention;  
         [0041]    [0041]FIG. 6A illustrates a specific example of the remotely actuated splitter bypass signaling definition in accordance with the second preferred embodiment of the present invention;  
         [0042]    [0042]FIG. 6B illustrates a signaling sequence of FIG. 6A in accordance with the second preferred embodiment of the present invention;  
         [0043]    [0043]FIG. 6C illustrates a functional block diagram of the remote relay control in accordance with the second preferred embodiment Qf the present invention;  
         [0044]    [0044]FIG. 6D illustrates a more detailed block diagram of the state machine in accordance with the second preferred embodiment of the present invention;  
         [0045]    [0045]FIG. 6E illustrates a state table in accordance with the second preferred embodiment of the present invention; and  
         [0046]    [0046]FIG. 6F illustrates an example of a detailed circuit diagram of the remote relay control in accordance with the second preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0047]    The present invention will now be described in greater detail, which will serve to further the understanding of the preferred embodiments of the present invention. As described elsewhere herein, various refinements and substitutions of the various embodiments are possible based on the principles and teachings herein.  
         [0048]    The preferred embodiments of the present invention will be described with reference to FIGS.  3 - 6 , wherein like components and steps are designated by like reference numerals throughout the various figures. Further, specific parameters such as potential differences, voltage values, circuit layouts, and the like are provided herein, and are intended to be explanatory rather than limiting.  
         [0049]    The present invention is directed to a remotely actuated splitter bypass (RASB) function/unit for testing and maintaining copper loops in an xDSL environment. In the context of this invention, the term “remotely” is defined to be anywhere outside the central office splitter. In other words, the present invention allows a CLEC to remotely actuating a bypass function in the CO splitter such that testing and maintenance can be performed with minimal interference and disturbance to/from the POTS service. Alternatively, the CLEC can actuate the bypass function within the CO splitter on-site. The RASB can be implemented in two preferred embodiments, direct control and state machine control.  
         [0050]    [0050]FIG. 3A illustrates a block diagram of a line sharing system having a CO splitter with a RASB function in accordance with the preferred embodiments of the present invention. In this system, the CO is connected to the customer&#39;s telephone  16  and the ATU-R  18  or similar end unit at the customer&#39;s premise using the copper loop  14 . In the CO, the voice switch  2  and the DSLAM  4  are connected to a CO splitter  100 .  
         [0051]    Positioned in between the DSLAM  4  and the CO splitter  100  at the CO is a cross connect unit  110  such as the CX100 Copper CrossConnect System from Turnstone Systems, Inc. The CX100 Copper CrossConnect System is a platform that automates the physical layer infrastructure in the CO, enabling ILECs and CLECs to remotely control, test, and manage the copper loop  14 . Additional information regarding Turnstone System&#39;s CX100 Copper CrossConnect System can be found at the web site trunstone.com, which contents are herein incorporated by reference. It is also noted that other units providing similar finctionalities as the CX100 Copper CrossConnect System can be implemented in the present invention. The cross connect  110  includes a test head  112  with a conventional processor board such as a P 150  processor (e.g., CX100 Copper CrossConnect System of Turnstone Systems, Inc.). A relay K 0  or equivalent functional element can be used to connect the test head  112  to the copper loop  14 , as described in greater detail later herein. The CO splitter  100  of the present invention includes the LPF  8 , HPF  10 , and first signature S 1   12 , similar to that of the prior art CO splitter  6 . In addition, the CO splitter  100  includes a first relay K 1  or equivalent element, second relay K 2  or equivalent element, resistor R, and second signature S 2   32 . Further included in the CO splitter  100  in between the relay K 0  of the cross connect  110  and the first relay K 1  is a remote relay control (RRC)  102 . The RRC  102  is connected to the xDSL portion of the loop at point A (part of the tip and ring wires) and controls the first and second relays K 1 , K 2 . A more detailed description and circuit diagrams of the RRC  102  are provided later herein.  
         [0052]    The LPF  8  is connected to the voice switch  2 , and the HPF  10  is connected to the DSLAM  4  via relays K 0 , K 1 . The first signature S 1   12  and the second signature S 2   32  are also connected to the voice and xDSL portions of the copper loop, respectively. During operation, an enable signal (ENABLE), which preferably carries very low power and is common to n number of splitters, from the cross connect  110  or similar device is sent to the CO splitter  100  and n number (i.e.,  50 ,  100 , etc.) of splitters (OTHERS). In the context of the Turnstone System&#39;s CX100 Copper CrossConnect System, n is preferably  550 , but other arbitrary number of copper loops can be used depending on the type of cross connect used. The RRC  102  is implemented per each copper loop.  
         [0053]    [0053]FIG. 3B illustrates a flow diagram showing the splitter bypass operation in accordance with the preferred embodiments of the present invention. Reference will be made to both FIGS. 3A and 3B concurrently for a more complete understanding of the present system and method.  
         [0054]    The steps described in FIG. 3B illustrate the method of testing the copper loop  14  for the CLEC using the RASB of the present invention. Although other modes of operation are possible using the present invention, for simplicity, three modes are described: normal, monitor, and bypass. These three modes are described in greater detail with reference to FIGS.  3 C- 3 E. For example, FIG. 3C illustrates a simplified block diagram of FIG. 3A representing the normal or default mode. The LPF  8  and HPF  10  are connected to the copper loop in the traditional splitter arrangement, similar to that described in the background section.  
         [0055]    Referring back to FIG. 3B, the CLEC uses the test head  112  to select a copper loop  14  pair from n number of copper loop pairs for testing in step  302 . When the CLEC has selected the copper loop  14 , xDSL service is temporarily shut off, and the test head  112  is cormected to the copper loop  14  via the relay KO in step  304 , thereby disconnecting the copper loop  14  from the DSLAM  4 . The relays described herein can be switched via software, hardware, or combinations thereof, but in certain embodiments as described later herein, the relays are controlled via hardware functions.  
         [0056]    In step  306 , the first relay K 1  is actuated (set) via RRC  102  for monitoring the voice path to determine whether the bypass function should be activated. This is accomplished by measuring the voltage on the copper loop  14  in a non-intrusive manner. As known, different voltage values across the copper loop  14  indicate whether the loop is off-hook (busy) or on-hook. The resistor R in the CO splitter  100  minimizes interference to the copper loop  14  during this process. The resistance value is selected such that the generated noise from actuating the first relay K 1  is acceptable. Generally, the resistor R has a high ohm value (&gt;100 k ohms) to allow monitoring without any material disturbance to the copper loop  14  (i.e., provides stability). The first relay K 1  can be either a latching or non-latching relay, depending on the specific preferred embodiment.  
         [0057]    [0057]FIG. 3D illustrates a simplified block diagram representing the monitor mode of the present invention. During the monitor mode (step  306 ), the POTS service is unaffected, and the XDSL circuit is connected to the copper loop  14  while isolating the HPF  10 . As discussed above, the xDSL circuit is bridged through the resistor R to assure minimal interference to the POTS service. In the monitor mode, the CLEC can check the DC and voice band frequencies for an off-hook or on-hook condition so that testing can be performed on the copper loop without interfering with an active POTS telephone call.  
         [0058]    In step  308 , if the voice path is determined to be off-hook, then testing is avoided in step  310 . On the other hand, if the voice path is on-hook in step  308 , then the second relay K 2  is actuated (set) via RRC  102  to enable the bypass function for testing in step  312 .  
         [0059]    [0059]FIG. 3E illustrates a simplified block diagram representing the bypass mode of the present invention. In the bypass mode (step  312 ), the POTS service is disconnected from the copper loop, and the xDSL service is reconnected directly to the copper loop. As illustrated, the LPF  8 , HPF  10 , signatures S 1   12 , S 2   32  are isolated from the rest of the circuit during the bypass mode. In this manner, the CLEC can obtain full access to the copper loop  14  in the outside plant for testing without interference to/from the LPF  8 , HPF  10 , and/or the voice switch  2 . When the second relay K 2  is actuated, testing is performed for a predetermined period (i.e., 30 seconds) via the test head  112  in step  314 . The resistor R is shorted out during the bypass mode, and testing is performed during the bypass mode.  
         [0060]    Preferably, the second relay K 2  is a non-latching type relay. It is important that the second relay K 2  is non-latching because this provides a fail-safe design in case power is lost as the system automatically resets back to the normal mode. This aspect of the invention is described in more detail later herein. Once testing is completed, the first and second relays K 1 , K 2  are reset in step  316  via RRC  102  to normal mode and the signature S 2   32  is checked in step  316 . The signature S 2  could also be checked before step  306 ; however, this may cause noise interference during a busy POTS call.  
         [0061]    [0061]FIG. 4 illustrates an enable/powering system diagram in accordance with the preferred embodiments of the present invention. In the CO, one copper loop pair from n pairs (where n is some arbitrary number) is used to transmit enable signals from the test head to the RRC and n number of CO splitters. Preferably, only one of n splitters is allowed to be in active bypass mode per test head. In this specific example, it is assumed that one copper loop pair is  26  gauge and that the distance from the cross connect  110  to a splitter shelf is a maximum of 1000 feet. It is also assumed that a standard CO battery voltage of 50±6 is used in this implementation.  
         [0062]    A signature S is used to assure that the correct copper loop pair is hooked up before switching on the power source. The cross connect  110  will check the signature S before the enable signal is generated. The enabled copper loop terminates with a 5W,±5 V DC/DC, and the average power per splitter allocation is approximately 24 mV (2.4 mA for ±5V). The ±5V could be used to power the circuitry for the n number of splitters.  
         [0063]    As described above, the RASB method and system of the present invention can be implemented in two preferred embodiments, using a direct control approach and a state machine approach. FIGS.  5 A- 5 D illustrate the first preferred embodiment, and FIGS. 6A  6 F illustrate the second preferred embodiment of the present invention. Referring back to FIG. 3A, these two preferred embodiments relate to the design and the implementation of the control signals to the first and second relays K 1 , K 2  using the RRC (remote relay control)  102 . Thus, design implementation of the LPF  8 , HPF  10 , signature S 1   12 , and signature S 2   32  will not be discussed in great detail hereinafter, as these components are known in the prior art. Further, although the CO splitter described herein is implemented with two relays, it is understood that more or less than two relays in the CO splitter can be used herein and is within the scope of the present invention.  
         [0064]    [0064]FIG. 5A illustrates a specific example of the RASB signaling definition in accordance with the first preferred embodiment of the present invention. As known, a power source in the CO can be connected to the tip, ring, and/or ground wires. In the present invention, voltages are applied to the tip and ring wires with respect to the ground wire.  
         [0065]    In the first preferred embodiment, relays are “set” or actuated when an appropriate positive voltage magnitude is applied from tip and ring wires with respect to the ground wire. Conversely, relays are “reset” when an appropriate negative voltage magnitude is applied from tip and ring wires with respect to the ground wire. The polarity of the voltages for set and reset conditions can be interchangeable by a person skill in this art (i.e., set having negative polarities and reset having positive polarities).  
         [0066]    In greater detail, each relay can be set with a positive polarity, using some arbitrary voltage range, which range is pre-defined/pre-designed. Conversely, each relay can be reset with a negative polarity, using some arbitrary voltage range, which range again is pre-defined/pre-designed. In additional, a particular voltage range that sets a particular relay or relays includes a reciprocal voltage range to reset another relay or relays. For example, one can set relay K 1  in the +62 to +70 voltage range, and reset the relay K 3  using the −62 to −70 voltage range. In another example, relays K 1  and K 2  can be set using the +73 to +83 voltage range, and relays K 3  and K 2  can be reset using the − 73  to −83 voltage range, respectively. In this manner, multiple relays can be remotely actuated from the CO by providing different voltages and polarities. It is also noted that in FIG. 5A, the voltage ranges and polarities are for illustrative purposes only and other practical voltage ranges and polarities can be substituted for those illustrated.  
         [0067]    The signaling definition allows the relays to be set sequentially such that relay K 1  is set first and then relay K 2 , and so on. For example, it is important that relay K 1  is set first for monitor mode before setting relay K 2  for bypass mode. This is accomplished by setting the relay K 1  in a lower voltage range than relay K 1 . Likewise, the relays are sequentially reset such that relay K 2  is reset first and then relay K 1 , and so on. This is accomplished by resetting relay K 1  in a higher absolute magnitude voltage range than relay K 2 . This assures that the signaling path is not cut off pre-maturely during the relays&#39; setting and resetting processes. In other words, the present schema allows the first set relay K 1  to be the last reset relay K 1 , and the last set relay K 3  to be the first reset relay K 3 .  
         [0068]    [0068]FIG. 5B illustrates a signaling sequence of FIG. 5A in accordance with the first preferred embodiment of the present invention. As shown in FIG. 5B, the circuit is generally in normal mode, which mode refers to the traditional line sharing system. When copper loop testing is initiated from the xDSL circuit, the selected copper loop pair is connected to the test head. A first signal (e.g., +68 volts) is used to set relay K 1 . When the relay K 1  is set, this indicates the monitor mode. The copper loop is connected to the test head through resistor R. The test head checks for DC voltage and voice band signals for monitoring whether the copper loop is off-hook or on-hook. If off-hook, the system aborts accessing this loop for testing. If it is on-hook, a second signal (e.g., +78 volts) is used to set the second relay K 2 , which provides the test head direct access to the copper loop while bypassing the CO splitter. This puts the system in the bypass mode, which enables loop testing by the test head. When loop testing is completed, a third voltage signal (e.g., −88V) is used to reset the relays back to normal mode.  
         [0069]    [0069]FIG. 5C illustrates a functional block diagram of the RRC in accordance with the first preferred embodiment of the present invention. The RRC  102   a  includes a Signal Conditioning block (SC)  502  connected to a first Level Sense (LS 1 )  504 , second Level Sense (LS 2 )  506 , reset Level Sense (LSR)  508 , and tip and ring wires at point A. The LS 1   504  detects the presence of the first voltage signal (e.g., +68V), the LS 2   506  detects the presence of the second voltage signal (e.g., +78V), and the LSR  508  detects the presence of the third voltage signal (e.g., −88V). The LS 1   504  is further connected to and controls the first latching relay K 1   104 . V r1  is the reference voltage for LS 1   504 , V r2  is the reference voltage for LS 2   506 , and V rr  is the reference voltage for LSR  508 . The reference voltages are pre-defined and can also be adjustable depending on the type and values of the hardware components used in a particular circuitry.  
         [0070]    The relay K 1   104  is preferably a latching-type relay (includes memory), which could be either electromechanical or semiconductor solid state. The latching-type feature is essential in that once the applied voltage exceeds a pre-defined reference voltage, a constant voltage is applied to actuate the relay K 1 . The latching-type feature is also essential because it can then allow application of a voltage across the T and R to perform other functions without affecting the first relay K 1 .  
         [0071]    A latch (LH- 1 )  510  is connected to the LS 2   506  and controls the second nonlatching relay K 2   106 . A “watch-dog” timer (TMR)  512  is used in case of a system malfunction. After a timeout period (i.e., 60 seconds), the TMR  512  automatically resets the relays K 1   104 , K 2   106  back to the normal mode.  
         [0072]    During operation, the test head sends a first voltage signal to the tip and ring wires. The SC  502  conditions the signal and inputs it to the LS 1   504 , LS 2   506 , and LSR  508 . The first voltage signal is detected by LS 1   504 , which in turns sets the first relay K 1   104 . This indicates the monitor mode, and the test head monitors the copper loop.  
         [0073]    If the copper loop is on-hook, the test head generates and sends a second voltage signal to the tip and ring wires. After signal conditioning by the SC  502 , the second voltage signal is detected by the LS 2   506 . This signal is then outputted by the LS 2   506  and sent to the input S of the flip flop LH- 1   510 . The LH- 1   510  then outputs a logical  1  via output Q to the AND gate  514  and TMR  512 , producing a second logical  1  at the TMR&#39;s output Q. The logical  1  outputs from both the LH- 1   510  and TMR  512  are sent to the AND gate  514  to produce a logical  1  at the AND gate&#39;s output to set the second relay K 2   106 . The system is now in the bypass mode and loop testing can be performed.  
         [0074]    When loop testing is completed, the test head sends a third voltage signal to the tip and ring wires. This signal is detected by the LSR  508  after signal conditioning via the SC  502 . The LSR  508  in turn sends the third voltage signal to reset relay K 1   104  and to the LH- 1   510 , which in turn resets relays K 2   106 , K 1   104  in a sequential or simultaneous manner for this particular case. The system is now back in the normal mode. In the event that the third reset voltage signal is not received by or sent to the LH- 1   510  due to some malfunction, the relay K 2   106  automatically resets itself back to the normal mode via the TMR  512 , thereby providing a fail-safe bypass function and POTS service is connected back to the splitter in the normal mode.  
         [0075]    [0075]FIG. 5D illustrates an example of a detailed circuit diagram of the RRC  102   a  in accordance with the first preferred embodiment of the present invention. Reference will be made concurrently to FIGS. 5C and 5D for a more complete understanding of the detailed circuit diagram.  
         [0076]    Functionally, the LS 1   504  includes transistors Q 1 , Q 2 , Q 5 , Q 6 , and resistors R 4 , R 5 . The LS 2   506  is represented by transistors Q 9 -Q 11 , and resistors R 12 , R 13 , and the LSR  508  is represented by transistors Q 3 , Q 4 , Q 7 , Q 8 , and resistors R 6 , R 7 , R 11 . Next, the LH- 1   510  circuitry consists of transistors Q 12 -Q 14 , resistors R 14 -R 20 , and diodes D 3 , D 4 . The TMR  512  includes transistors Q 15 -Q 17 , resistors R 21 -R 24 , R 27 -R 28 , and capacitor C 2  (used for switching as it is charged up). The AND gate  514  includes transistors Q 18 -Q 21 , resistors R 25 -R 26 , R 29 -R 31 , and diode D 5 . The SC  502  consists of resistors R 1 -R 3  and capacitor C 1 .  
         [0077]    [0077]FIG. 6A illustrates a specific example of the RASB signaling definition in accordance with the second preferred embodiment of the present invention. The second preferred embodiment is directed to the state machine control. Similar to the first preferred embodiment, voltages are applied to the tip and ring wires with respect to the ground wire.  
         [0078]    The RASB signaling definition of the second preferred embodiment is similar to the first preferred embodiment in that the relays are “set” or actuated when an appropriate voltage magnitude and polarity is applied from tip and ring wires with respect to the ground wire, and relays are “reset” when an appropriate voltage magnitude and polarity is applied from tip and ring wires with respect to the ground wire. The polarity of the voltages for set and reset conditions can be interchangeable by a person skill in this art by appropriately designing the circuit (i.e., set having negative polarities and reset having positive polarities).  
         [0079]    In greater detail, each relay can be set with a positive polarity, using some arbitrary voltage range, which range is pre-defined/pre-designed. Conversely, each relay can be reset with a negative polarity, using some arbitrary voltage range, which range again is pre-defined/pre-designed. In the state machine approach, the first and second relays K 1  and K 2  can be set sequentially using the +62 to +70 voltage range. Likewise, these relays can be reset sequentially or simultaneously for this particular embodiment from the second relay K 2  to the first relay K 1  in the −73 to −83 voltage range. In this manner, multiple relays can be remotely actuated from the CO by providing different voltages and polarities. It is further noted that in FIG. 6A, the voltage ranges are for illustrative purposes only and other practical voltage ranges can be substituted for those illustrated.  
         [0080]    The signaling definition allows the relays to be set sequentially such that relay K 1  is set first and then relay K 2 , and so on. For example, it is important that the relay K 1  is set first for monitor mode before setting relay K 2  for bypass mode. This is accomplished by sequentially setting the relay K 1  first and then the relay K 2 . Likewise, the relays are sequentially reset such that relay K 2  is reset first and then relay K 1 , and so on. This assures that the signaling path is not cut off pre-maturely during the relays&#39; setting and resetting processes. For this particular case, sequential reset is not necessary.  
         [0081]    [0081]FIG. 6B illustrates a signaling sequence of FIG. 6A in accordance with the second preferred embodiment of the present invention. As shown in FIG. 6B, the circuit is generally in normal mode, which mode refers to the traditional line sharing system.  
         [0082]    When copper loop testing is initiated from the xDSL circuit, the selected copper loop pair is connected to the test head. A first signal (e.g., +68 volts) is generated to set relay K 1 , which indicates the monitor mode. The loop is then connected to the test head through resistor R. The test head checks for DC voltage and voice band signals for monitoring whether the copper loop is off-hook or on-hook. If off-hook, the system aborts accessing this copper loop for testing. If it is on-hook, a second voltage signal (e.g., +68 volts) is sent to set second relay K 2 , which provides the test head direct access to the copper loop while bypassing the CO splitter. Thus, two sequential voltage signals of equal value are used to set the relays K 1 , K 2 . This puts the system in the bypass mode, which enables loop testing by the test head. When loop testing is completed, a third voltage signal (e.g., −88V) is used to reset the relays back to normal mode.  
         [0083]    [0083]FIG. 6C illustrates a functional block diagram of the RRC in accordance with the second preferred embodiment of the present invention. The RRC  102   b  includes a Signal Conditioning block (SC)  602  connected to a reset Level Sense (LSR)  604 , Level Sense Set (LSS)  606 , and tip and ring wires at point A. The RRC  102   b  also includes a State Machine (SM)  608 , timer (TMR)  610 , and an AND gate  612 . First and second relays K 1   104 , K 2   106  are preferably non-latching (standard) type relays. The “watch-dog” timer (TMR)  610  is used in case of a system malfunction. After a timeout period (i.e., 60 seconds), the TMR  610  automatically resets the relays K 1   104 , K 2   106  back to the normal mode. V rr  is the reference voltage for LSR  604 , and V rs  is the reference voltage for LSS  606 .  
         [0084]    When the system is in the normal mode, the outputs B 0  and B 1  of the SM  608  are represented by logical  0 s. During operation from normal mode to monitor mode, the test head sends a first voltage signal (e.g., +68V) to the tip and ring wires at point A. The SC  602  conditions the signal inputs it to the LSR  604  and LSS  606 . The first voltage signal is detected by the LSS  606 , which in turn sends the voltage signal to the SM  608  at input CP to increment the SM  608  from normal to monitor mode. The output B 0  of the SM  608  is now represented by a logical  1  and is used to set the first relay K 1   104 , thereby actuating the monitor mode. Meanwhile, the output from B 0  of SM  608  is sent to the input S of the TMR  610  to begin the timing signal.  
         [0085]    During the monitor mode, if the copper loop is determined to be on-hook, the test head generates and sends a second voltage signal (e.g., +68) equal to the first voltage signal to the tip and ring wires. After signal conditioning by the SC  602 , the second voltage signal is detected by the LSS  606  to increment the SM  608  from monitor to bypass mode by outputting a logical  1  at the B 1  output.  
         [0086]    The logical  1  outputs from both B 0  of SM  608  and Q of TMR  610  are sent to the AND gate  612  to produce a logical  1  at the AND gate&#39;s output to set the second relay K 2   106 . The system is now in the bypass mode and loop testing can be performed. When loop testing is completed, the test head sends a third voltage signal (e.g., −88V) to the tip and ring wires. The third voltage signal is detected by the LSR  604  after signal conditioning via the SC  602 . The LSR  604  in turn sends the third voltage signal to the SM  608 , which in turn resets first and second relays K 2   106 , K 1   104  by generating logical  0 s at B 0  and B 1 . The system is now in the normal mode.  
         [0087]    In the event that the third reset voltage signal is not received by or sent to the LSR  604  or SM  608  due to some malfinction, the relay K 2   106  automatically resets itself back to the normal mode via the TMR  610 .  
         [0088]    [0088]FIG. 6D illustrates a more detailed block diagram of the state machine in accordance with the second preferred embodiment of the present invention. The state machine is represented by FF 0  (flip flop  0 )  702  and FF 1  (flip flop  1 )  704 . The voltage signals from LSR  604  and LSS  606  are sent to the FF 0   702  and FF 1   704  at inputs C (clear input) and CP (clock input), respectively. The output B 0  is generated from outputs Q 1  of FF 0   702 , and the output B 1  is generated from output Q 2  of FF 1   704 .  
         [0089]    [0089]FIG. 6E illustrates a state table in accordance with the second preferred embodiment of the present invention. As shown, the normal mode is active when the output B 0  and B 1  signals are logical  0 , which represents that the first and second relays K 1 , K 2 , are not set. The monitor mode is active when the output B 0  signal is a logical  1  and the output B 1  signal is a logical  0 , which represents that the first relay K 1  is set and the second relay K 2  is not set. The bypass mode is active when both the output B 0  and B 1  signals are logical  1 , which represents that the first and second relays K 1 , K 2  are set.  
         [0090]    [0090]FIG. 6F illustrates an example of a detailed circuit diagram of the RRC  102   b  in accordance with the second preferred embodiment of the present invention. Reference will be made concurrently to FIGS. 6C and 6D for a more complete understanding of the detailed circuit diagram of FIG. 6F.  
         [0091]    Functionally, the SM  608  includes FF 1  and FF 2 . The LSR  604  is represented operational amplifier C 2 , and the LSS  606 s is represented by operational amplifier C 1 . Next, the TMR  610  includes transistors Q 1 -Q 4 , resistors R 9 -R 14 , and capacitor C 2  (used for switching as it is charged up). The AND gate  612  includes transistors Q 6 , Q 7 , and resistor R 16 . The SC  602  consists of resistors R 1 , R 2 , R 19  and capacitor C 1 .  
         [0092]    In other embodiments, other components can be substituted for the specific components described herein so long as these components perform essentially identical functions as described herein.  
         [0093]    In the previous descriptions, numerous specific details are set forth, such as specific functions, components, etc., to provide a thorough understanding of the present invention. However, as one having ordinary skill in the art would recognize, the present invention can be practiced without resorting to the details specifically set forth.  
         [0094]    Although only the above embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications of the exemplary embodiments are possible without materially departing from the novel teachings and advantages of this invention.