Abstract:
A telematics unit is provided for a vehicle having a power unit, along with a method for controlling a telematics unit for a vehicle. The telematics unit includes a voltage sensor, a global positioning system unit, and a processor. The voltage sensor senses a measure of a voltage of the power unit. The global positioning system unit obtains position data as to a position of the vehicle. The processor is coupled to the voltage sensor and the global positioning system unit. The processor is configured to determine whether the voltage for the power unit has decreased using the sensed measure of the voltage, determine whether the vehicle is moving using the position data, and command the telematics unit to an off mode if the voltage has decreased and the vehicle is not moving.

Description:
TECHNICAL FIELD 
     The technical field generally relates to vehicles, and, more particularly, to telematics units and methods for controlling telematics units for a vehicle. 
     BACKGROUND 
     Many vehicles in the marketplace are equipped with telematics units. Certain telematics units are designed, constructed, and programmed to enable a user of the vehicle (hereinafter “user”) to interact with a communications network. The communication network includes a remotely located call center (hereinafter “call center”) staffed with live advisors (hereinafter “advisors”) who are trained to provide assistance to the user. Through the communication network, a user may utilize a wide variety of telematics services that are designed to facilitate and/or enhance the user&#39;s driving and/or vehicle ownership experience. Such services may include, but are not limited to, navigation assistance, vehicle monitoring, and telecommunication services. These telematics services may be provided by a manufacturer of the vehicle, by a manufacturer of the telematics units, or by some other telematics service provider. 
     For many telematics units, it is desirable to have the units remain powered on only when the vehicle is in an operational state in which the vehicle may be operated by a user. However, in certain circumstances, for example in which the telematics unit is not connected to a communications bus of the vehicle, it may be difficult for the telematics unit to determine the operational state of the vehicle. 
     Accordingly, it is desirable to provide an improved method for controlling a telematics unit for a vehicle that commands the telematics unit between power on and power off operating modes, for example in situations in which the telematics unit is not connected to a communications bus of the vehicle. It is further desirable to provide an improved telematics unit that is commanded between power on and power off operating modes, for example in situations in which the telematics unit is not connected to a communications bus of the vehicle. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     SUMMARY 
     In accordance with one example, a method for controlling a telematics unit for a vehicle having a power unit is provided. The method comprises the steps of determining whether a voltage for the power unit has decreased, determining whether the vehicle is moving, and commanding the telematics unit to an off mode if the voltage has decreased and the vehicle is not moving. 
     In accordance with another example, a method for controlling a telematics unit for a vehicle having a power unit is provided. The method comprises the steps of sensing a measure of a voltage of the power unit, detecting a measure of movement of the vehicle, commanding the telematics unit to an off mode if the voltage has decreased by at least a first predetermined voltage amount and the vehicle is moving at least at a predetermined velocity for at least a predetermined amount of time as determined using the sensed measure of the voltage and the detected measure of movement, and commanding the telematics unit to an on mode if the voltage has increased by at least a second predetermined voltage amount as determined using the sensed measure of the voltage. 
     In accordance with a further example, a telematics unit is provided for a vehicle having a power unit. The telematics unit comprises a voltage sensor, a global positioning system unit, and a processor. The voltage sensor is configured to sense a measure of a voltage of the power unit. The global positioning system unit is configured to detect a measure of movement of the vehicle. The processor is coupled to the voltage sensor and the global positioning system unit. The processor is configured to determine whether the voltage for the power unit has decreased using the sensed measure of the voltage, determine whether the vehicle is moving using the detected measure of movement, and command the telematics unit to an off mode if the voltage has decreased and the vehicle is not moving. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain examples of the present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is an exemplary schematic illustration of a non-limiting example of a communication system and a telematics unit having a power on and off feature that may be used together with the communication system; 
         FIG. 2  is a flowchart of an exemplary process for powering a telematics unit on and off, and that can be implemented in connection with the telematics unit of  FIG. 1 ; 
         FIG. 3  is a flowchart of an exemplary sub-process for the process of  FIG. 1 , namely the sub-process of determining whether a vehicle is moving; and 
         FIG. 4  is an exemplary flowchart of various stages of the process of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature, and is not intended to limit the disclosure or the application and uses thereof. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, or the following detailed description. 
     With reference to  FIG. 1 , there is shown a non-limiting example of a communication system  10  that may be used together with examples of the apparatus disclosed herein and to implement examples of the methods disclosed herein. The communication system generally includes a vehicle  12 , a wireless carrier system  14 , a land network  16 , and a call center  18 . It should be appreciated that the overall architecture, setup and operation, as well as the individual components of the illustrated system are merely exemplary and that differently configured communication systems may also be utilized to implement the examples of the method disclosed herein. Thus, the following paragraphs, which provide a brief overview of the illustrated communication system  10 , are not intended to be limiting. 
     Vehicle  12  may be any type of mobile vehicle such as a motorcycle, car, truck, recreational vehicle (RV), boat, plane, and the like, and is equipped with suitable hardware and software that enables it to communicate over communication system  10 . Some of the vehicle hardware  20  is shown generally in  FIG. 1  including a telematics unit  24 , a microphone  26 , a speaker  28 , and buttons and/or controls  30  connected to the telematics unit  24 . Operatively coupled to the telematics unit  24  is a network connection or vehicle bus  32 . Examples of suitable network connections include a controller area network (CAN), a media oriented system transfer (MOST), a local interconnection network (LIN), an Ethernet, and other appropriate connections such as those that conform with known ISO (International Organization for Standardization), SAE (Society of Automotive Engineers), and/or IEEE (Institute of Electrical and Electronics Engineers) standards and specifications, to name a few. 
     The telematics unit  24  is an onboard device that provides information or other functions, such as those described further below. In the depicted example, the telematics unit  24  is an onboard device that provides a variety of services through its communication with the call center  18 . In certain other examples, the telematics unit  24  may comprise a stand-alone navigation device and/or another type of telematics unit that may not require the call center and/or certain other features of the communication system  10 . 
     In the depicted example, the telematics unit  24  generally includes a housing  25 , an electronic processing device  38 , one or more types of electronic memory  40 , a cellular chipset/component  34 , a wireless modem  36 , a dual mode antenna  70 , a navigation unit containing a GPS chipset/component  42 , and one or more voltage sensors  82 . The electronic processing device  38 , the one or more types of electronic memory  40 , the cellular chipset/component  34 , the wireless modem  36 , the navigation unit containing the GPS chipset/component  42 , and the one or more voltage sensors  82  are preferably disposed within the housing  25 . In one example, the wireless modem  36  includes a computer program and/or set of software routines adapted to be executed within the electronic processing device  38 . 
     The telematics unit  24  may provide various services including: turn-by-turn directions and other navigation-related services provided in conjunction with the GPS chipset/component  42 ; airbag deployment notification and other emergency or roadside assistance-related services provided in connection with various crash and/or collision sensor interface modules  66  and collision sensors  68  located throughout the vehicle; and/or infotainment-related services where music, internet web pages, movies, television programs, videogames, and/or other content are downloaded by an infotainment center  46  operatively connected to the telematics unit  24  via vehicle bus  32  and audio bus  22 . In one example, downloaded content is stored for current or later playback. The above-listed services are by no means an exhaustive list of all the capabilities of telematics unit  24 , but are simply an illustration of some of the services that the telematics unit  24  may be capable of offering. It is anticipated that telematics unit  24  may include a number of additional components in addition to and/or different components from those listed above. 
     In the depicted example, the telematics unit  24  also includes a first connector  84  and a second connector  88 . The first connector  84  comprises a connector (for example, a cable or wire) configured to be electrically connected to a vehicle power unit  86 . In one example, the vehicle power unit  86  comprises a vehicle battery, such as a twelve volt vehicle battery. The second connector  88  comprises a connector (for example, a cable or wire) configured to be electrically connected to a vehicle ground unit  90 . In certain examples, the telematics unit  24  may be connected or coupled to the vehicle only via the first and second connectors  84 ,  88 . For example, the telematics unit  24  may not be coupled to the vehicle bus  32 . 
     In certain examples, the first connector  84  comprises a voltage supply line that is powered by a vehicle battery when the vehicle is off and by an alternator when the vehicle is on. Such a voltage supply line is sometimes referred to in the industry as a twelve volt supply bus. In this example, the vehicle power unit  86  may include both a battery and an alternator. When the vehicle is in an off state, the voltage supply line voltage is less than thirteen volts. Conversely, when the vehicle is in an on state, the voltage supply line voltage is greater than thirteen volts. 
     The voltage sensors  82  are configured to sense a voltage of the vehicle power unit  86  of the vehicle at various points in time (for example, as provided over the first connection  84 ). In certain examples, the voltage sensors  82  may be part of and/or disposed within the electronic processing device  38 . In certain other examples, the voltage sensors  82  provide signals and/or information to the electronic processing device  38  representative of the voltage of the vehicle power unit  86 . 
     The electronic processing device  38  processes the voltage signals and/or information pertaining thereto for use in determining whether a voltage drop or a voltage increase has occurred. The electronic processing device  38  also uses information or signals obtained from the GPS chipset/component  42  for use in determining whether the vehicle is currently moving, a velocity of the vehicle movement, durations of time for such movement, and related determinations. The electronic processing device  38  uses these various determinations regarding the vehicle power unit voltage and the vehicle movement in optimally commanding the telematics unit  24  between on and off operating modes based on whether the vehicle is in an operational state in which the vehicle may be operated by a user, for example in accordance with the steps of the process  200  described further below in connection with  FIGS. 2-4 . 
     Vehicle communications may use radio transmissions to establish a voice channel with wireless carrier system  14  so that both voice and data transmissions can be sent and received over the voice channel. Vehicle communications are enabled via the cellular chipset/component  34  for voice communications and the wireless modem  36  for data transmission. In order to enable successful data transmission over the voice channel, wireless modem  36  applies some type of encoding or modulation to convert the digital data so that it can be communicated through a vocoder or speech codec incorporated in the cellular chipset/component  34 . Any suitable encoding or modulation technique that provides an acceptable data rate and bit error can be used with the present examples. Dual mode antenna  70  services the GPS chipset/component  42  and the cellular chipset/component  34 . 
     Microphone  26  provides the user or other vehicle occupant with a means for inputting verbal or other auditory commands, and can be equipped with an embedded voice processing unit utilizing a human/machine interface (HMI) technology known in the art. Conversely, speaker  28  provides audible output to the vehicle occupants and can be either a stand-alone speaker specifically dedicated for use with the telematics unit  24  or can be part of a vehicle audio component  64 . In either event, microphone  26  and speaker  28  enable vehicle hardware  20  and call center  18  to communicate with the occupants through audible speech. The vehicle hardware also includes one or more buttons and/or controls  30  for enabling a vehicle occupant to activate or engage one or more of the vehicle hardware  20  components. For example, one of the buttons and/or controls  30  can be an electronic pushbutton used to initiate voice communication with call center  18  (whether it be a human such as advisor  58  or an automated call response system). In another example, one of the buttons and/or controls  30  can be used to initiate emergency services. 
     The audio component  64  is operatively connected to the vehicle bus  32  and the audio bus  22 . The audio component  64  receives analog information, rendering it as sound, via the audio bus  22 . Digital information is received via the vehicle bus  32 . The audio component  64  provides amplitude modulated (AM) and frequency modulated (FM) radio, compact disc (CD), digital video disc (DVD), and multimedia functionality independent of the infotainment center  46 . Audio component  64  may contain a speaker system, or may utilize speaker  28  via arbitration on vehicle bus  32  and/or audio bus  22 . 
     The vehicle crash and/or collision detection sensor interface  66  is operatively connected to the vehicle bus  32  or directly connected to the telematics unit  24 . The collision sensors  68  provide information to the telematics unit  24  via the crash and/or collision detection sensor interface  66  regarding the severity of a vehicle collision, such as the angle of impact and the amount of force sustained. 
     Vehicle sensors  72 , connected to various sensor interface modules  44  are operatively connected to the vehicle bus  32 . Example vehicle sensors include but are not limited to gyroscopes, accelerometers, magnetometers, emission detection, and/or control sensors, and the like. Example sensor interface modules  44  include powertrain control, climate control, and body control, to name but a few. 
     Wireless carrier system  14  may be a cellular telephone system or any other suitable wireless system that transmits signals between the vehicle hardware  20  and land network  16 . According to an example, wireless carrier system  14  includes one or more cell towers  48 , base stations and/or mobile switching centers (MSCs)  50 , as well as any other networking components required to connect the wireless carrier system  14  with land network  16 . As appreciated by those skilled in the art, various cell tower/base station/MSC arrangements are possible and could be used with wireless carrier system  14 . For example, a base station and a cell tower could be co-located at the same site or they could be remotely located, and a single base station could be coupled to various cell towers or various base stations could be coupled with a single MSC, to list but a few of the possible arrangements. A speech codec or vocoder may be incorporated in one or more of the base stations, but depending on the particular architecture of the wireless network, it could be incorporated within a Mobile Switching Center or some other network components as well. 
     Land network  16  can be a conventional land-based telecommunications network that is connected to one or more landline telephones, and that connects wireless carrier system  14  to call center  18 . For example, land network  16  can include a public switched telephone network (PSTN) and/or an Internet protocol (IP) network, as is appreciated by those skilled in the art. Of course, one or more segments of the land network  16  can be implemented in the form of a standard wired network, a fiber or other optical network, a cable network, other wireless networks such as wireless local networks (WLANs) or networks providing broadband wireless access (BWA), or any combination thereof. 
     Call center  18  is designed to provide the vehicle hardware  20  with a number of different system back-end functions and, according to the example shown here, generally includes one or more switches  52 , servers  54 , databases  56 , advisors  58 , as well as a variety of other telecommunication/computer equipment  60 . These various call center components are suitably coupled to one another via a network connection or bus  62 , such as the one previously described in connection with the vehicle hardware  20 . Switch  52 , which can be a private branch exchange (PBX) switch, routes incoming signals so that voice transmissions are usually sent to either the live advisor  58  or an automated response system, and data transmissions are passed on to a modem or other piece of telecommunication/computer equipment  60  for demodulation and further signal processing. The modem or other telecommunication/computer equipment  60  may include an encoder, as previously explained, and can be connected to various devices such as a server  54  and database  56 . For example, database  56  could be designed to store subscriber profile records, subscriber behavioral patterns, or any other pertinent subscriber information. Although the illustrated example has been described as it would be used in conjunction with a manned call center  18 , it will be appreciated that the call center  18  can be any central or remote facility, manned or unmanned, mobile or fixed, to or from which it is desirable to exchange voice and data. In addition, in certain examples, the telematics unit  24  may not use or require a call center and/or various other features set forth in  FIG. 1  or described above. 
       FIG. 2  is a flowchart of an exemplary process  200  for controlling a power mode of a telematics unit of a vehicle. The process  200  may be implemented in connection with the telematics unit  24  of  FIG. 1  and/or in connection with other telematics units. The process  200  will be described below with reference to  FIG. 2  as well as  FIGS. 3 and 4 .  FIG. 3  provides a flowchart of an exemplary sub-process of certain steps of the process  200  (namely, determining whether the vehicle is moving, as described below in connection with steps  216  and  224  of  FIG. 2 ).  FIG. 4  provides an exemplary flowchart  400  of various stages of the process  200 . 
     As depicted in  FIG. 2 , the process  200  includes the step of sensing a voltage of a power source of the vehicle (step  202 ). In one example, during step  202 , the one or more voltage sensors  82  of  FIG. 1  sense voltage of the vehicle power unit  86  (for example, a twelve volt battery) of  FIG. 1  along the first connector  84  of  FIG. 1 . The voltage readings (and/or signals or other information pertaining thereto) are processed by the electronic processing device  38  of  FIG. 1 . 
     A determination is made as to whether the telematics unit is currently in an off mode (step  204 ). The off mode, as used throughout this application, preferably represents an operating mode in which most or all of the features of the telematics unit are not operating or have been disabled or powered off. In certain examples, the off mode may signify a sleep mode or a reduced power consumption mode, in which certain functions may be powered off or temporarily disabled, while other functions may be operating or powered on. For example, in certain examples, the telematics unit may still be able to receive calls or await instructions and/or provide certain other functions even though the telematics unit may be deemed to be in an off mode because other functions (such as those used by the user while driving, by way of example) are powered off or temporarily disabled. By contrast, an on mode preferably represents an operating mode in which most or all of the features of the telematics unit are operating or have been enabled or powered on. With reference to  FIG. 4 , the on mode is represented by stage  402 , and the off mode is represented by stage  404 . 
     The determination of step  202  is preferably made by the electronic processing device  38  of  FIG. 1 . The electronic processing device  38  may make this determination based on information stored in the electronic memory  40  of  FIG. 1  as to a prior iteration of the process  200 . Alternatively, the electronic processing device  38  may make this determination based on other information pertaining to the operation of the telematics unit  24 . 
     If it is determined that the telematics unit is currently in an off mode, then a determination is made as to whether there has been a recent voltage fluctuation (step  206 ). Preferably this comprises a determination as to whether there has been a voltage fluctuation since the most previous iteration. This determination is preferably made by the electronic processing device  38  of  FIG. 1  using information or signals as to the voltage sensed in step  202 . In one example, a voltage fluctuation is determined to occur if the voltage sensed in step  202  represents a change in voltage that is greater than a predetermined amount in absolute magnitude, such as one volt, by way of example only. In another example, a voltage fluctuation is determined to occur if the voltage sensed in step  202  represents a change in voltage that is greater than a predetermined percentage, such as twenty percent, by way of example only. 
     If it is determined that a voltage fluctuation has not occurred, then the telematics unit remains in the off mode (step  208 ). Specifically, the electronic processing device  38  of  FIG. 1  preferably does not issue any commands for the telematics unit to change to the on mode if there is no voltage fluctuation. The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Conversely, if it is determined that a voltage fluctuation has occurred, then a determination is made as to whether there has been a recent voltage elevation (step  210 ). Preferably this comprises a determination as to whether there has been a voltage elevation since the most previous iteration. This determination is preferably made by the electronic processing device  38  of  FIG. 1  using information or signals as to the voltage sensed in step  202 . In one example, a voltage elevation is determined to occur if the voltage sensed in step  202  represents an increase in voltage that is greater than a predetermined amount in absolute magnitude, such as one volt, by way of example only. In another example, a voltage elevation is determined to occur if the voltage sensed in step  202  represents an increase in voltage that is greater than a predetermined percentage, such as twenty percent, by way of example only. 
     If it is determined that a voltage elevation has occurred, then the telematics unit is commanded to the on mode of operation (step  212 ). The telematics unit is preferably commanded to the on mode of operation by the electronic processing device  38  of  FIG. 1 . With reference to  FIG. 4 , this command is provided in accordance with stage  406 , in commanding the telematics unit to the on mode of stage  402 . The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Conversely, if it is determined that a voltage elevation has not occurred, then the process enters a power checking mode (step  214 ). The power checking mode yields a determination as to whether the vehicle is in an on operational state in which the vehicle may be being operated by a user. With reference to  FIG. 4 , the power checking mode is denoted as stage  410 , and the power checking mode is denoted as being entered due to the voltage fluctuation denoted in stage  408 . 
     During the power checking mode, a determination is made as to whether the vehicle is moving (step  216 ). This preferably comprises a determination as to whether the vehicle has been moving at least at a predetermined velocity for at least a predetermined amount of time. This determination is preferably made by the electronic processing device  38  of  FIG. 1 . 
     With reference to  FIG. 3 , an exemplary flowchart of a sub-process is provided for the determination of step  216  of  FIG. 2 . The sub-process begins with the step of retrieving a velocity threshold (step  302 ). The velocity threshold preferably corresponds to a minimum velocity at which the vehicle can travel while moving. In one example, the velocity threshold is approximately five miles per hour. The velocity threshold is preferably stored in the electronic memory  40  of  FIG. 1  for use by the electronic processing device  38  of  FIG. 1 . 
     A time threshold is also retrieved (step  304 ). The time threshold preferably corresponds to a minimum amount of time that the vehicle would need to be moving for a determination to be made that the vehicle is in an on operating mode. In one example, the time threshold is five seconds. The time threshold is preferably stored in the electronic memory  40  of  FIG. 1  for use by the electronic processing device  38  of  FIG. 1 . 
     In addition, global positioning system (GPS) data is obtained (step  306 ). The GPS data preferably corresponds to data as to a geographic location of the vehicle over time. The GPS data is preferably obtained continuously by the GPS chipset/component  42  of  FIG. 1  for use by the electronic processing device  38  of  FIG. 1 . 
     A vehicle velocity is calculated (step  308 ). The vehicle velocity is preferably calculated continuously by the electronic processing device  38  of  FIG. 1  using the GPS data obtained from the GPS chipset/component  42  of  FIG. 1  during step  306 . 
     In addition, a determination is made as to whether the vehicle velocity has been calculated for an amount of time that is greater than or equal to the time threshold of step  304  (step  310 ). This determination is preferably made by the electronic processing device  38  of  FIG. 1 . 
     If it is determined that the vehicle velocity has not been calculated for an amount of time that is greater than or equal to the time threshold, then the process returns to step  306 . Steps  306 - 310  then repeat, as the vehicle velocity is re-calculated using new, updated GPS data, until there is a determination in a subsequent iteration of step  310  that the vehicle velocity has been calculated for an amount of time that is greater than or equal to the time threshold. 
     Once it is determined in an iteration of step  310  that the vehicle velocity has been calculated for an amount of time that is greater than or equal to the time threshold, a determination is then made as to whether the vehicle velocity has been greater than or equal to the velocity threshold of step  302  for an amount of time that is greater than or equal to the time threshold (step  312 ). This determination is preferably made by the electronic processing device  38  of  FIG. 1 . 
     If it is determined that the vehicle velocity has been greater than or equal to the velocity threshold for an amount of time that is greater than or equal to the time threshold, then the vehicle is deemed to be moving (step  314 ). For example, in one example in which the velocity threshold is five miles per hour and the time threshold is five seconds, the vehicle will be deemed to be moving if the vehicle has been travelling with a velocity of at least five miles per hour for a duration of time of at least five seconds. With reference to  FIG. 4 , the determination that the vehicle is moving is denoted by stage  412 . 
     Conversely, if it is determined that the vehicle velocity has not been greater than or equal to the velocity threshold for an amount of time that is greater than or equal to the time threshold, then the vehicle is deemed to be not moving (step  316 ). For example, in the above-described example in which the velocity threshold is five miles per hour and the time threshold is five seconds, the vehicle will be deemed to be not moving if the vehicle has not been travelling with a velocity of at least five miles per hour for a duration of time of at least five seconds. With reference to  FIG. 4 , the determination that the vehicle is not moving is denoted by stage  414 . In addition, in certain examples in which the vehicle may be moving at one point in time and then ceases moving, the determination of the vehicle&#39;s movement may change from moving to not moving, as denoted by transition stage  422  of  FIG. 4 . 
     Returning now to  FIG. 2 , if it is determined in step  216  that the vehicle is moving, then the process proceeds to the above-referenced step  212 , as the telematics unit is commanded to the on mode of operation. With reference to  FIG. 4 , this command is provided in accordance with stages  412  and  420 , in commanding the telematics unit to the on mode of stage  402 . The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Conversely, if it is determined in step  216  that the vehicle is not moving, then the process proceeds instead to the above-referenced step  208 , as the telematics unit is commanded instead to remain in the off mode of operation. The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Returning now to step  204 , if it is determined that the telematics unit is currently in an on mode, then a determination is made as to whether there has been a recent voltage drop (step  218 ). Preferably this comprises a determination as to whether there has been a voltage drop since the most previous iteration. This determination is preferably made by the electronic processing device  38  of  FIG. 1  using information or signals as to the voltage sensed in step  202 . In one example, a voltage drop is determined to occur if the voltage sensed in step  202  represents an initial decrease in voltage that is greater than a predetermined amount in absolute magnitude, such as one volt, followed by a more relatively smaller and more gradual additional decrease in voltage, by way of example only. In another example, a voltage drop is determined to occur if the voltage sensed in step  202  represents a decrease in voltage that is greater than a predetermined percentage, such as twenty percent, followed by a more relatively smaller and more gradual additional decrease in voltage, by way of example only. 
     If it is determined that a voltage drop has not occurred, then the telematics unit remains in the on mode (step  220 ). Specifically, the electronic processing device  38  of  FIG. 1  preferably does not issue any commands for the telematics unit to change to the off mode if there is no voltage drop. The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Conversely, if it is determined that a voltage drop has occurred, then the process enters a power checking mode (step  222 ). The power checking mode yields a determination as to whether the vehicle is in an on operational state in which the vehicle may be being operated by a user. With reference to  FIG. 4 , this power checking mode, along with the power checking mode of step  214  (described above), are collectively denoted as state  410 . 
     During the power checking mode, a determination is made as to whether the vehicle is moving (step  224 ). This preferably comprises a determination as to whether the vehicle has been moving at least a predetermined velocity for at least a predetermined amount of time. This determination is preferably made by the electronic processing device  38  of  FIG. 1 . The above-referenced exemplary flowchart of  FIG. 3  also applies to the determination of step  224 . Specifically, similar to step  216 , the determination of whether the vehicle is moving in step  224  likewise is preferably determined using steps  302 - 316  of  FIG. 3  (described above). 
     If it is determined in step  224  that the vehicle is moving, then the process proceeds to the above-referenced step  220 , as the telematics unit is commanded to remain in the on mode of operation. The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Conversely, if it is determined in step  224  that the vehicle is not moving, then a timer is applied (step  226 ). The timer comprises waiting an amount of time equal to a predetermined timer threshold, and then recalculating the vehicle velocity at the expiration of the timer. Preferably the vehicle velocity is also calculated continuously during the timer period. The timer is preferably executed by the electronic processing device  38  of  FIG. 1 . The timer preferably expires after an amount of time, such that, if the vehicle is not moving throughout the duration of the timer, it would be unlikely that the vehicle is currently in an on mode. In one example, the timer is approximately five minutes. 
     A determination is then made as to whether the vehicle is moving after the initiation of the timer and before the expiration of the timer (step  228 ). This determination is preferably made by the electronic processing device  38  of  FIG. 1 . 
     If it is determined that the vehicle is moving after the initiation of the timer and before the expiration of the timer, then the process proceeds to the above-referenced step  220 , as the telematics unit is commanded to remain in the on mode of operation. With reference to  FIG. 4 , the vehicle&#39;s beginning of movement is denoted by transition stage  424 , and may occur at any time during the timer period. The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Conversely, if it is determined that the vehicle is still not moving after the initiation of the timer and before the expiration of the timer, then the telematics unit is commanded to the off mode of operation (step  230 ). The telematics unit is preferably commanded to the off mode of operation by the electronic processing device  38  of  FIG. 1 . With reference to  FIG. 4 , this command is provided in accordance with stage  418 , in commanding the telematics unit to the off mode of stage  404 . The process then returns to step  202 , as the voltage is sensed again at a new point in time for a new iteration and the process repeats. 
     Accordingly, methods and systems are disclosed for controlling operational modes of a telematics unit. The disclosed methods and systems allow for effective powering on and powering off of telematics units via the use of a sensed vehicle power unit voltage along with GPS data from the telematics unit. The disclosed methods and systems can be implemented in connection with various different types of telematics units, and can be implemented regardless of whether the telematics units are connected or otherwise coupled to a communications bus of the vehicle. 
     It will be appreciated that the disclosed systems and processes may differ from those depicted in the Figures and/or described above. For example, the communication system  10 , the telematics unit  24 , and/or various parts and/or components thereof may differ from those of  FIG. 1  and/or described above. Similarly, certain steps of the process  200  may be unnecessary and/or may vary from those depicted in  FIGS. 2-4  and described above. It will similarly be appreciated that various steps of the process  200  may occur simultaneously or in an order that is otherwise different from that depicted in  FIGS. 2-4  and/or described above. It will similarly be appreciated that, while the disclosed methods and systems are described above as being used in connection with automobiles such as sedans, trucks, vans, and sports utility vehicles, the disclosed methods and systems may also be used in connection with any number of different types of vehicles, and in connection with any number of different systems thereof and environments pertaining thereto. 
     While at least one example has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the detailed description represents only examples, and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the examples. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.