Abstract:
Optical network terminal (ONT) power failure management. A system for permitting a customer of a telecommunication company, for whom fiber to the premises (FTTP) has been installed, to control operating features associated with operation of a battery backup unit (BBU) which is used, during power failure, for powering the ONT associated with the FTTP installation and the customer&#39;s telephone(s). The controlling of these features includes utilization of signal-controlled switches, which are manually over-rideable by the customer, thereby providing the desired operating feature control.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to usage of a telecommunication company&#39;s fiber to the premises (FTTP) installation at customer premises and, more particularly, relates to the customer&#39;s controlling of features associated with a battery backup unit (BBU) used for powering an optical network terminal (ONT) associated with the FTTP installation during power failures. 
         [0003]    2. Description of Prior Art 
         [0004]    Fiber optic infrastructure is currently being deployed by certain telecommunication companies, including the assignee of the present invention, and being operatively connected to their respective customer bases. Fiber optic telecommunication infrastructure offers many advantages over the old standard copper wire cabling, not the least of which is vastly increased bandwidth. The plain old telephone system (POTS) had operated, and still operates, with copper wiring. POTS is now being made compatible with fiber optic cabling. 
         [0005]    However, a POTS telephone system in combination with this new fiber optic infrastructure involves certain optically-related and/or other functionality not previously needed in the copper wire cabling world. For example, an optical line terminal (OLT) is needed which may be located in the central office of the relevant telecommunications company or at some other regional location (but not on customer premises). The OLT is communicatively coupled via fiber optic cable to the ONT which is normally located immediately outside of a customer&#39;s premises (typically mounted on an outside wall some four-five feet above ground). 
         [0006]    The ONT is powered by a power supply such as, for example, a power supply similar, or related, to that described in patent application Ser. No. 11/144,566 filed Jun. 3, 2005, claiming benefit of provisional application Ser. No. 60/576,675 filed Jun. 3, 2004, its assignee, and inventor being, in common with those of this instant application entitled: “Multi-Component ONT Power Supply” and incorporated by reference herein in its entirety. That power supply is, in turn, powered by typical electric utility company power which is subject to power failure for reasons including, without limitation, natural disasters and terrorist attacks. During a utility company power failure, traditional POTS telephone service over copper wiring is ordinarily able to continue because of POTS battery back-up infrastructure which is in place at telecommunication company central offices. This battery backup system is designed to maintain POTS telephone service for an entire community. But, that otherwise-available emergency POTS telephone service shall not be available to a telephone customer using a FTTP system, if the ONT cannot communicate with the OLT over the fiber optic cable because the ONT lacks power due to that power failure. 
         [0007]    To this end, battery backup has also been provided within the FTTP environment for the ONT and for customer telephone instruments connected to that ONT. But, in contrast with the central office location of POTS battery backup, ONT battery backup is located proximate its associated ONT, generally within, or near, the telephone customer&#39;s premises. This ONT battery backup unit (BBU) can be designed to include certain customer-useful features. One example is an alarm which sounds when the battery voltage level is low. However, an incessant sounding alarm can be an annoyance and, to compound the annoyance, the alarm is itself using battery energy when emitting sound. These features, under certain circumstances, can therefore be a detriment instead of a benefit to the customer. There is, therefore, a need for managing these features in a manner that reduces or eliminates any customer annoyance otherwise generated by these features. The present invention provides a solution to this shortcoming of the prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the present invention include methodology and apparatus for managing an optical network terminal under conditions of a general power failure. More specifically, the present invention relates to managing certain automatic indicators of battery-backup voltage level for the optical network terminal in a manner to allow the customer a measure of control over these indicators. 
         [0009]    In a particular embodiment, the present invention relates to a residential fiber optic communication system powered by electricity from a utility company. The system permits communication via customer premises equipment (CPE) including a telephone in a normal mode of operation. An OLT is located remotely from the customer premises, and can be located in a central office of the telephone company associated with the customer&#39;s telephone. An ONT is located at the customer premises and is in communication over a fiber optic cable with the OLT. A DC power supply is located at the customer premises for purpose of supplying electrical power to the customer&#39;s ONT and to the customer&#39;s telephone(s) via the ONT. A rechargeable battery backup unit (BBU) is located at the customer premises and is rechargeable by the power supply. The BBU is operatively coupled to the ONT and to the customer&#39;s telephone(s) via the ONT for the purpose of supplying substitute electrical power to the ONT and to the telephone(s) if and when the utility company electric power fails. 
         [0010]    A battery output sensor and controller are located at the customer premises for monitoring output level, such as output voltage, of the battery being used for backup. The controller includes means for automatically signaling the ONT to go into a sleep mode to conserve power when the utility company electric power fails and the battery output level is reduced to a first level. The ONT includes means responsive to an off hook telephone signal for over-riding operation of the automatically signaling means and thereby reverting the sleep mode back to the normal mode of operation to permit the customer to place a call from the telephone over the system. After the call is completed, the system may automatically go back to the sleep mode. 
         [0011]    However, during a utility company power failure where the output level has been reduced to an emergency level lower than the first level but greater than zero, the controller automatically signals the ONT to power-down completely. An emergency switch is connected between the output of the BBU and the ONT and is operable by the controller to disconnect the output of the BBU from the ONT. But, before that disconnection occurs, the ONI notifies the OLT over the fiber optic cable of the power-down signal. That disconnection stops all further power dissipation from the BBU through the ONT. However that emergency switch is also manually-operable by the customer to permit power to be re-supplied to the ONT from the BBU to allow the customer to make an emergency telephone call over the fiber optic cable. Typically, the customer would make that emergency call and then open the emergency switch to continue to conserve BBU energy or power. 
         [0012]    In yet an additional feature of the present invention, an audio alarm provides an audible warning under conditions of a failure of electrical power from the utility company. Typically, this may occur when the BBU output voltage is at a low level approximately equivalent to the emergency mode level, although this level may fall within a range of levels running from a non-zero level below the emergency level up to the fully charged battery output level. This audible alarm battery voltage level is selected by the telecommunications company which is supplying this system. But the customer also has a measure of control. An audio alarm switch, operable by the customer, is provided which shuts-off the audio alarm for a predetermined time selectable by the customer when the BBU output level is at or below this audible alarm battery voltage level, and after which time the audio alarm automatically sounds again. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  depicts a FTTP communication system showing the locations of various system components consistent with principles of the present invention; 
           [0014]      FIG. 2  is a schematic block diagram showing signal paths and power paths between various system components including those of  FIG. 1  consistent with principles of the present invention; and 
           [0015]      FIG. 3  is a graph of voltage versus time showing the various levels where various events may take place consistent with the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    Referring to  FIG. 1 , fiber to the premises (FTTP) system  100  is depicted. A telecommunication company&#39;s central office is shown at the left-hand side of the drawing, housing optical line terminal (OLT)  101 . Other equipment such as switches, routers, server computers, back-up batteries and other functionality (not shown) may be found in a central office. 
         [0017]    On the right hand side of the drawing a schematic profile of a customer&#39;s premises is provided with optical network terminal (ONT)  102  which may be mounted on the exterior wall of the customer&#39;s premises as shown. A typical mounting would put ONT  102  at about four-five feet above ground. ONT  102  may be a standard fiber optical terminal which provides a suitable terminus for fiber optic cable  103 . Other system components included within or at the customer premises include ONT power supply 105 , BBU  106  as battery backup for ONT  102 , and customer premises equipment (CPE)  107  which includes any residential-styled communication equipment such as telephones, facsimile devices, televisions, computer systems, etc. Either power supply  105  or BBU  106  or both may be physically located within the housing for ONT  102 , or may be located inside the customer premises. It should be understood that electrical power is brought to the customer premises by an electrical utility company (not shown). 
         [0018]    Signals received by OLT  101  over fiber optic cable  103  from ONT  102  may be processed in OLT  101  and may be forwarded to other equipment (not shown) located within the central office for further processing before routing those signals to their ultimate destination outside of the central office. In the opposite direction, signals to be forwarded from OLT  101  over fiber optic cable  103  to ONT  102  had previously been received by the central office from a source or sources located outside of the central office, may have been processed by the other equipment (not shown) located within the central office and may be further processed by OLT  101  before being forwarded from OLT  101  over cable  103 . 
         [0019]      FIG. 2  is a schematic block diagram showing signal paths and power paths between various system components, including those of  FIG. 1 . For clarity purposes, power paths are shown in wide-bus format and the signal paths are depicted as single line connectives. It should be understood that the thickness of the actual power cable and the thicknesses of the actual signal cables are not necessarily related to each other in the proportions shown in the drawing. Also, the spatial relationship shown in  FIG. 1  may not be strictly maintained in  FIG. 2 . For example, the telephone company battery backup  219  in  FIG. 2  is actually physically located within the telecommunication company&#39;s central office, and the utility company&#39;s electric power, shown within  FIG. 2  as block  200  for clarity of illustration, is actually brought to the customer&#39;s premises in accordance with typical power distribution from a utility company. 
         [0020]    Power Distribution: 
         [0021]    Continuing with  FIG. 2 , customer premises equipment CPE  107  comprises CPE 107 A (exclusively telephone or telephones) and CPE  107 B (all non-telephonic consumer premises equipment such as television, etc.). Starting with the utility company electric power functionality  200 , it can be seen that electric power is distributed to CPE  107 B on power bus  215  and to ONT power supply  105  on power bus  201 . ONT power supply  105 , in turn, distributes power to ONT  102  over power bus  206 / 205  and to BBU  106  over power bus  202 . BBU  106 , in turn, and only if utility company electric power  200  has failed, distributes power to ONT  102  through power bus  203 / 204 / 205  by way of emergency switch  210 , and distributes power to audio alarm  220  through power bus  207 / 208  by way of timer switch  211 . 
         [0022]    Power output from ONT  102  is supplied to the customer&#39;s telephone(s)  107 A over power bus  217 . This power is derived from ONT power supply  105  if there is no power failure, and is derived from ONT BBU  106  if there is a power failure. 
         [0023]    In the upper left of  FIG. 2 , other power distribution is shown as deriving from the telephone company&#39;s central office battery backup  219 , and as being distributed over power bus  218  to the central offices OLT unit  101 . Therefore, if there is a power failure affecting both the customer&#39;s premises as well as the telephone company&#39;s central office, telephone company battery backup  219  substitute-powers the equipment located within the central office such as OLT  101 , but does not supply substitute power to ONT  102  or to CPE  107 . 
         [0024]    Signal Distribution: 
         [0025]    Referring to battery level sensor and controller  209 , (hereinafter “controller  209 ”) at the lower left of  FIG. 2 , it can be seen that several signal paths emanate therefrom. Controller  209  includes functionality that senses the voltage level output of BBU  106  via power bus  203 . When there has not been a power failure for some period of time, the batteries (not shown) of BBU  106  may be fully charged by power supply  105 . When a power failure occurs, whereupon BBU  106  is pressed into service, output of the batteries of BBU  106  generally declines over time. This is illustrated in greater detail in  FIG. 3 . 
         [0026]      FIG. 3  is a graph of voltage output from the batteries of BBU  106  as a function of time. This discharge curve is merely exemplary, and curve depicted in  FIG. 3  can assume virtually any shape having a negative or zero slope. At time zero, the batteries are fully charged, as shown. At time T 1 , the batteries have discharged to a point where the discharge curve intersects, at point “A”, the sleep mode level, also referred to herein as level  1 . This level might be, for example, approximately 75%-90% of the fully charged level, but could be virtually any percentage of the fully charged level above an emergency level, defined below. 
         [0027]    At time T 2 , the battery voltage has continued to discharge to a point where the discharge curve intersects, at point “B”, with the audio alarm level. The alarm level is pre-set at the telecommunications company, and it is normally intended to signal low battery voltage, but it could be used to signal something other than low battery voltage. The settable range for the audio alarm is from just above zero to just under fully charged as shown by bracket “C”. If set at just above zero, it shall give an audio signal just as the batteries fail completely. If set at just under fully charged, it shall give an audio signal indicative of the onset of a power failure. This latter setting may be useful under the circumstances of a power failure during daytime where no electric lights or appliances are operating and where a customer may not otherwise have been aware of the power failure. Typically, the audio alarm level can be set to be at or near emergency mode level, with which the voltage discharge curve intersects at time T 3  and at point “D.” 
         [0028]    It should be understood that the system can remain in sleep mode from point A, the level at which the sleep mode was initiated, down to point D, even though the audible alarm signifying the power outage may have sounded in the interim. Also, intermittent telephone usage may have occurred in the interim, as described below. Finally, if and when the batteries become fully discharged, at time T 4 , the battery voltage discharge curve intersects, at point “E”, with a zero level of voltage. 
         [0029]    Returning to  FIG. 2 , while also referring back to  FIG. 3 , when the voltage discharge curve is at point “A”, at the first level (sleep mode level) of output from BBU  106 , a sleep signal is sent over signal line  213  from controller  209  to ONT  102  requesting that ONT  102  enter a sleep or standby mode. In the sleep mode, multiple functions of ONT  102  are stopped to conserve power. For example, the video services could be shut down within 30 seconds, and the data services could be shut down within 15 minutes. ONT  102  remains in this sleep mode until one of two things happen: (1) electric power  200  is restored or (2) the customer lifts its telephone  107 A off hook, whichever occurs first. The latter event sends a signal from telephone(s)  107 A over signal line  216  to ONT  102  which, in combination with the powering of ONT  102  by battery backup  106 , returns ONT  102  to a fully functional unit for purposes of allowing this particular telephone call to be made. ONT  102  and telephone  107 A are both powered by BBU  106  having initial voltage output at sleep mode level. After the customer has completed that telephone call and hangs the phone back on the hook, the batteries of BBU  106  have further discharged somewhat and ONT  102  reverts to sleep mode if power  200  has not yet been restored. But, if power was restored during that telephone call, ONT  102  remains fully functional and does not revert to sleep mode. Additional calls can be made during power failure in sleep mode, provided that the voltage level output of BBU  106  remains above the emergency voltage level. 
         [0030]    If the voltage level output of BBU  106  drops to an emergency voltage level, then ONT  102  can be automatically and completely turned off. The emergency level, shown as intersecting the voltage discharge curve at point “D” in  FIG. 3 , is a level that is pre-determined by the telecommunications company that supplies ONT unit  102 . This emergency level provides sufficient residual energy in BBU  106  to allow, e.g., one or two phone more telephone calls of limited duration. Under these conditions, controller  209  provides a shut-off signal on signal line  212  to switch  210 , which causes it to open. The power which had been supplied over power bus  203 / 204 / 205  to ONT  102  through switch  210  is thereby interrupted, whereby ONT  102  shuts off and cuts off power to telephone  107 A. However, switch  210  is also manually operable by the customer, and if an emergency phone call must be made, that switch can be manually closed, thereby over-riding the automatic shut-down signal. There shall be sufficient energy remaining in BBU  106  to power ONT  102  and telephone  107 A to allow that emergency phone call. Under these conditions, it may take a little time, perhaps ten minutes, for ONT  102  to return to operating condition before communication over the telephone actually takes place. 
         [0031]    Referring next to audio alarm  220 , it can sound only during power failure. It can be energized by BBU  106  via power buses  207 / 208  through switch  211  only when there is power failure. But switch  211  has to be closed to allow power to be applied to alarm  220 . Switch  211  is controlled by a control signal over signal line  214  which is generated when the alarm level is triggered by the discharging battery voltage (Point B in  FIG. 3 ). This level is set by the equipment supplier. However, that audible signal, as useful as it may be to alert the telephone customer or other members of the customer premises household of the power failure, can quickly become annoying to hear. Furthermore, the audible sound itself saps electrical energy from BBU  106  thereby making the batteries deplete more quickly than otherwise. The customer has capability of avoiding these problems. 
         [0032]    Indeed, switch  211  is manually operable and it can be opened by the customer at any time which shall interrupt the application of electrical power via power bus  207 / 208  thereby cause the alarm to stop sounding if it had been on. This is an improvement provided to the customer which permits him/her to remove what might become an annoying sound not to mention saving precious battery power at the same time. 
         [0033]    In addition, switch  211  has a controllable timing feature (not shown) associated with it. Switch  211  can be set by the customer for certain periods of time, for example one hour. If set to one hour, then if switch  211  is manually opened, it shall remain open for one hour. After that hour, it automatically closes allowing BBU power to be reapplied to alarm  220 , thereby sounding the audible alarm. Thus, not only can the alarm be temporarily silenced by the customer, but the duration of the silence between alarm soundings is also under the control of the customer. 
         [0034]    While illustrative embodiments of the present invention have been shown and described, numerous variations and alternative embodiments may occur to those skilled in the art. For example, as noted, the threshold setting of the alarm is predetermined by the equipment provider. The equipment provider could offer various models with various alarm settings if that were deemed to be a useful marketing strategy. Other variations and alternative embodiments are contemplated, and can be made without departing from the spirit and scope of the present invention as defined in the appended claims.