Patent Publication Number: US-11647165-B1

Title: Audio/video recording and communication doorbell devices including transistor assemblies, and associated systems and methods

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/138,841, filed on Sep. 21, 2018, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present embodiments relate to audio/video (A/V) recording and communication devices, including A/V recording and communication doorbells, security cameras, and floodlight controllers. In particular, the present embodiments relate to improvements in the functionality of A/V recording and communication devices that strengthen the ability of such devices to reduce crime and enhance public safety. 
     BACKGROUND 
     Home security is a concern for many homeowners and renters. Those seeking to protect or monitor their homes often wish to have video and audio communications with visitors, for example, those visiting an external door or entryway. A/V recording and communication devices, such as doorbells, provide this functionality, and can also aid in crime detection and prevention. For example, audio and/or video captured by an A/V recording and communication device can be uploaded to the cloud and recorded on a remote server. Subsequent review of the A/V footage can aid law enforcement in capturing perpetrators of home burglaries and other crimes. Further, the presence of one or more A/V recording and communication devices on the exterior of a home, such as a doorbell unit at the entrance to the home, acts as a powerful deterrent against would-be burglars. 
     SUMMARY 
     The various embodiments of the present audio/video (A/V) recording and communicating doorbell devices including transistor assemblies have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of the present embodiments as expressed by the claims that follow, their more prominent features now will be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description,” one will understand how the features of the present embodiments provide the advantages described herein. 
     One aspect of the present embodiments includes the realization that significant power may be dissipated in a full-wave rectifier circuit of an A/V recording and communication doorbell device. In particular, an A/V recording and communication doorbell device typically includes a full-wave rectifier circuit as part of a power supply of the doorbell device. In applications where the A/V recording and communication doorbell device is powered from an alternating current (AC) electrical power source, e.g., a transformer external to the A/V recording and communication doorbell device, the full-wave rectifier circuit converts AC input power from an input power bus to a direct current (DC) output power into an output power bus, to power the A/V recording and communication doorbell device. In applications where the A/V recording and communication doorbell device is powered from a DC electrical power source, e.g., a photovoltaic device or a battery, the full-wave rectifier circuit provides a DC path between the input power bus and the output power bus, to power the A/V recording and communication doorbell device. 
     An example full-wave rectifier circuit includes four diodes, and each of the four diodes has a forward voltage drop of approximately 0.6 volt when current is flowing through the diode. This voltage drop can cause significant power loss. For example, consider a hypothetical scenario where the full-wave rectifier circuit converts AC input power from an input power bus to a DC output power, where current flowing through the full-wave rectifier circuit has a root-mean-square (RMS) magnitude of one ampere. Current will flow through all four of the diodes in this example, and approximately 2.4 watts (W) of power will be dissipated in the full-wave rectifier circuit, due to the diode forward voltage drop. This power dissipation may necessitate that the A/V recording and communication doorbell device include one or more cooling devices, such as heatsink(s). The cooling devices may increase cost and/or size of the A/V recording and communication doorbell device. Additionally, power dissipation in the full-wave rectifier circuit may leave insufficient power for the A/V recording and communication doorbell device to operate under certain conditions, particularly in cases where the doorbell device is powered from an electrical power source of limited capacity, e.g., from a photovoltaic device or a battery. 
     Furthermore, the voltage drop across each diode may result in insufficient power supply voltage on the output power bus when an input electrical power source has a small voltage magnitude, e.g., when the input electrical power source is a photovoltaic device or a battery. For example, consider a hypothetical scenario where the full-wave rectifier circuit converts AC input power from the input power bus to a DC output power. The forward voltage drop across the full-wave rectifier circuit will reduce peak voltage on the output power bus by approximately 1.2 volts, which may result in insufficient power supply voltage for the A/V recording and communication doorbell device under some conditions. 
     The present embodiments solve these problems, for example, by providing A/V recording and communication doorbell devices including a transistor assembly. In some embodiments, the transistor assembly replaces a full-wave rectifier circuit, while in some other embodiments, the transistor assembly supplements a full-wave rectifier circuit. The transistor assembly is configured, for example, to emulate a full-wave rectifier circuit, and/or to provide a DC path between an input power bus and an output power bus. The transistor assembly includes transistors, e.g., field effect transistors, which may have significantly lower forward voltage drop than diodes. Consequently, the A/V recording and communication doorbell devices including a transistor assembly may dissipate significantly less power than conventional A/V recording and communication doorbell devices. Additionally, the A/V recording and communication doorbell devices including a transistor assembly may operate with lower input voltages than conventional A/V recording and communication doorbell devices. 
     In a first aspect, an A/V recording and communication doorbell device includes a transistor assembly electrically coupled between an input power bus that distributes at least one of an alternating current (AC) input power and a direct current (DC) input power, and an output power bus that provides a DC output power for the A/V recording and communication doorbell device. The A/V recording and communication doorbell device further includes control circuitry configured to cause the transistor assembly to convert the at least one of the AC input power and the DC input power from the input power bus to the DC output power into the output power bus, to provide the DC output power for the A/V recording and communication doorbell device. 
     In an embodiment of the first aspect, the control circuitry is further configured to detect a presence of AC voltage on the input power bus, and in response to detecting the presence of the AC voltage on the input power bus, cause the transistor assembly to emulate a bridge rectifier to convert the AC input power from the input power bus to the DC output power into the output power bus. 
     In another embodiment of the first aspect, the control circuitry is further configured to cause the transistor assembly to emulate a diode electrically coupled across the input power bus to rectify the AC input power into a rectified DC output power to a signaling device. 
     In another embodiment of the first aspect, the A/V recording and communication doorbell device further includes a button configured to be pressed to cause a signaling device to activate, wherein the control circuitry is further configured to cause the transistor assembly to short-circuit the input power bus, in response to the button being pressed, to cause the signaling device to activate. 
     In another embodiment of the first aspect, the control circuitry is further configured to detect a presence of DC voltage on the input power bus, and in response to detection of the DC voltage on the input power bus, cause the transistor assembly to provide a DC path between the input power bus and the output power bus. 
     In another embodiment of the first aspect, the input power bus includes a first node and a second node, and the output power bus includes a third node and a fourth node. The transistor assembly includes a first transistor electrically coupled between the first node and the third node, a second transistor electrically coupled between the second node and the third node, a third transistor electrically coupled between the first node and the fourth node, and a fourth transistor electrically coupled between the second node and the fourth node. 
     In another embodiment of the first aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective on-states, and cause the second transistor and the third transistor to operate in their respective off-states, in response to a first DC voltage at the first node being greater than a second DC voltage at the second node. 
     In another embodiment of the first aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective off-states, and cause the second transistor and the third transistor to operate in their respective on-states, in response to the first DC voltage at the first node being less than the second DC voltage at the second node. 
     In another embodiment of the first aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective on-states, and cause the second transistor and the third transistor to operate in their respective off-states, in response to a first AC voltage at the first node being greater than a DC voltage at the third node. 
     In another embodiment of the first aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective off-states, and cause the second transistor and the third transistor to operate in their respective on-states, in response to a second AC voltage at the second node being greater than the DC voltage at the third node. 
     In another embodiment of the first aspect, the A/V recording and communication doorbell device further includes a button configured to be pressed to cause a signaling device to activate, wherein the control circuitry is further configured to cause the transistor assembly to short-circuit the input power bus, in response to the button being pressed, to cause the signaling device to activate. 
     In another embodiment of the first aspect, the signaling device is at least one of a mechanical signaling device and a digital signaling device. 
     In another embodiment of the first aspect, the control circuitry is configured to cause the transistor assembly to short-circuit the input power bus by causing the first transistor and the second transistor to operate in their respective on-states. 
     In another embodiment of the first aspect, the control circuitry is configured to cause the transistor assembly to short-circuit the input power bus by causing the third transistor and the fourth transistor to operate in their respective on-states. 
     In another embodiment of the first aspect, each of the first transistor and the second transistor includes a p-channel metal oxide semiconductor field effect transistor (MOSFET), and each of the third transistor and the fourth transistor includes an n-channel MOSFET. 
     In another embodiment of the first aspect, the A/V recording and communication doorbell device further includes a respective diode device electrically coupled in parallel with each of the first transistor, the second transistor, the third transistor, and the fourth transistor. 
     In a second aspect, a method is performed by an A/V recording and communication doorbell device to transfer electrical power from an input power bus to an output power bus, and the method includes detecting a voltage at a node of the input power bus, and based on the voltage, controlling a transistor assembly to transfer electrical power between the input power bus and the output power bus to power circuitry of the A/V recording and communication doorbell device. 
     In an embodiment of the second aspect, the voltage is an alternating current (AC) voltage at the node, and controlling a transistor assembly to transfer electrical power between the input power bus and the output power bus includes causing the transistor assembly to emulate a bridge rectifier to convert an AC input power from the input power bus to a direct current (DC) output power into the output power bus. 
     In another embodiment of the second aspect, the method further includes controlling the transistor assembly to emulate a diode electrically coupled across the input power bus to rectify the AC input power into a rectified DC output power to a signaling device. 
     In another embodiment of the second aspect, the method further includes receiving an input to cause the signaling device to activate and in response to receiving the input to cause the signaling device to activate, causing the transistor assembly to short-circuit the input power bus to provide the AC input power to the signaling device. 
     In another embodiment of the second aspect, the voltage is a DC voltage at the node, and controlling a transistor assembly to transfer electrical power between the input power bus and the output power bus includes causing the transistor assembly to provide a DC path between the input power bus to the output power bus, based on the DC voltage. 
     In another embodiment of the second aspect, the node is a first node of the input power bus, the DC voltage is a first DC voltage, and the DC path is a first DC path, and the method further includes detecting a second DC voltage at a second node of the input power bus and determining whether the first DC voltage is greater than the second DC voltage. When the first DC voltage is greater than the second DC voltage, the transistor assembly provides the first DC path, and when the first DC voltage is not greater than the second DC voltage, the transistor assembly provides a second DC path. 
     In another embodiment of the second aspect, the first DC path and the second DC path are electrically coupled to the output electrical power bus in a same polarity. 
     In another embodiment of the second aspect, the voltage is an AC voltage, and the method further includes detecting a DC voltage at a node of the output power bus and determining that the AC voltage at the node of the input power bus is greater than the DC voltage at the node of the output power bus. Upon the determining that the AC voltage at the node of the input power bus is greater than the DC voltage at the node of the output power bus, controlling a transistor assembly to transfer electrical power between the input power bus and the output power bus includes converting an AC input power from the input power bus to a DC output power into the output power bus. 
     In another embodiment of the second aspect, the AC voltage is a first AC voltage and the node of the input power bus is a first node of the input power bus, and the method further includes detecting a second AC voltage at a second node of the input power bus, where the first AC voltage is an opposite polarity of the second AC voltage, and determining that the second AC voltage at the second node of the input power bus is greater than the DC voltage at the node of the output power bus. Upon the determining that the second AC voltage at the second node of the input power bus is greater than the DC voltage at the node of the output power bus, controlling a transistor assembly to transfer electrical power between the input power bus and the output power bus includes converting the AC input power from the input power bus to the DC output power into the output power bus. 
     In a third aspect, an A/V recording and communication doorbell device includes a full-wave rectifier circuit which includes a first two series-connected diodes in parallel with a second two series-connected diodes, where the full-wave rectifier circuit is electrically coupled between an input power bus and an output power bus. The full-wave rectifier circuit is configured to convert an alternating current (AC) input power from the input power bus to a direct current (DC) output power into the output power bus to power the A/V recording and communication doorbell device. The A/V recording and communication doorbell device further includes control circuitry and a transistor assembly. The transistor assembly includes four transistors, each of the four transistors being connected in parallel with a respective one of the diodes of the full-wave rectifier circuit. The control circuit is configured to detect a voltage at a node of the input power bus, and based on the voltage, cause the transistor assembly to convert the AC input power from the input power bus to the DC output power into the output power bus in lieu of the full-wave rectifier circuit. 
     In an embodiment of the third aspect, the control circuitry is further configured to cause the transistor assembly to emulate a diode electrically coupled across the input power bus to rectify the AC input power into a rectified DC output power to a signaling device. 
     In another embodiment of the third aspect, the A/V recording and communication doorbell device further includes a button configured to be pressed to cause a signaling device to activate, and the control circuitry is further configured to cause the transistor assembly to short-circuit the input power bus, in response to the button being pressed, to cause the signaling device to activate. 
     In another embodiment of the third aspect, the control circuitry is further configured to detect a presence of DC voltage on the input power bus, and in response to detection of the DC voltage on the input power bus, cause the transistor assembly to provide a DC path between the input power bus and the output power bus. 
     In another embodiment of the third aspect, the input power bus includes a first node and a second node, the output power bus includes a third node and a fourth node, and the transistor assembly includes a first transistor electrically coupled between the first node and the third node, a second transistor electrically coupled between the second node and the third node, a third transistor electrically coupled between the first node and the fourth node, and a fourth transistor electrically coupled between the second node and the fourth node. 
     In another embodiment of the third aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective on-states, and cause the second transistor and the third transistor to operate in their respective off-states, in response to a first DC voltage at the first node being greater than a second DC voltage at the second node. 
     In another embodiment of the third aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective off-states, and cause the second transistor and the third transistor to operate in their respective on-states, in response to the first DC voltage at the first node being less than the second DC voltage at the second node. 
     In another embodiment of the third aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective on-states, and cause the second transistor and the third transistor to operate in their respective off-states, in response to a first AC voltage at the first node being greater than a DC voltage at the third node. 
     In another embodiment of the third aspect, the control circuitry is further configured to cause the first transistor and the fourth transistor to operate in their respective off-states, and cause the second transistor and the third transistor to operate in their respective on-states, in response to a second AC voltage at the second node being greater than the DC voltage at the third node. 
     In another embodiment of the third aspect, the A/V recording and communication doorbell device further includes a button configured to be pressed to cause a signaling device to activate, and the control circuitry is further configured to cause the transistor assembly to short-circuit the input power bus, in response to the button being pressed, to cause the signaling device to activate. 
     In another embodiment of the third aspect, the signaling device is at least one of a mechanical signaling device and a digital signaling device. 
     In another embodiment of the third aspect, the control circuitry is configured to cause the transistor assembly to short-circuit the input power bus by causing the first transistor and the second transistor to operate in their respective on-states. 
     In another embodiment of the third aspect, the control circuitry is configured to cause the transistor assembly to short-circuit the input power bus by causing the third transistor and the fourth transistor to operate in their respective on-states. 
     In another embodiment of the third aspect, each of the first transistor and the second transistor includes a p-channel metal oxide semiconductor field effect transistor (MOSFET), and each of the third transistor and the fourth transistor includes an n-channel MOSFET. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments of the present A/V recording and communication doorbell devices including a transistor assembly now will be discussed in detail with an emphasis on highlighting the advantageous features. These embodiments depict the novel and non-obvious A/V recording and communication doorbell devices shown in the accompanying drawings, which are for illustrative purposes only. These drawings include the following figures, in which like numerals indicate like parts: 
         FIG.  1    is a schematic diagram illustrating an example of an A/V recording and communication doorbell device including a transistor assembly that is electrically coupled to an alternating current power source and a signaling device, according to various aspects of the present disclosure; 
         FIG.  2    is a schematic diagram illustrating an example of an A/V recording and communication doorbell device including a transistor assembly that is electrically coupled to a direct current power source, according to various aspects of the present disclosure; 
         FIG.  3    is a schematic diagram illustrating an example of an A/V recording and communication doorbell device including a transistor assembly that is electrically coupled to an alternating current power source, a signaling device, and a doorbell circuit device, according to various aspects of the present disclosure; 
         FIG.  4    is a schematic diagram illustrating an example of an A/V recording and communication doorbell device including a transistor assembly and a full-wave rectifier circuit, according to various aspects of the present disclosure; 
         FIG.  5    is a functional block diagram illustrating a system for communicating in a network according to various aspects of the present disclosure; 
         FIG.  6    is a functional block diagram for an A/V recording and communication doorbell device according to various aspects of the present disclosure; 
         FIG.  7    is a flowchart illustrating an example process for transferring electrical power from an input power bus to an output power bus, according to various aspects of the present disclosure; and 
         FIG.  8    is a flowchart illustrating another example process for transferring electrical power from an input power bus to an output power bus, according to various aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As discussed above, a full-wave rectifier circuit of an A/V recording and communication doorbell device may dissipate significant power under certain circumstances. Additionally, voltage drop across diodes of a full-wave rectifier circuit may result in insufficient power supply voltage on the output power bus under some conditions. The present embodiments solve these problems, for example, by providing A/V recording and communication doorbell devices including a transistor assembly. The transistor assembly is electrically coupled between an input power bus and an output power bus. The input power bus may be, for example, electrically coupled with an AC or DC power source, and in some embodiments the input power bus is electrically coupled in series with a signaling device and an AC or DC power source. The output power bus provides DC output power for the A/V recording and communication doorbell device. 
     The input power bus includes a first node and a second node, and the output power bus includes a third node and a fourth node. The transistor assembly includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The first transistor is electrically coupled between the first node and the third node, and the second transistor is electrically coupled between the second node and the third node. The third transistor is electrically coupled between the first node and the fourth node, and the fourth transistor is electrically coupled between the second node and the fourth node. The control circuitry is configured to generate a first control signal ϕ 1 , a second control signal ϕ 2 , a third control signal ϕ 3 , and a fourth control signal ϕ 4 , which control the first transistor, the second transistor, the third transistor, and the fourth transistor, respectively. The control circuitry is configured to generate the first control signal ϕ 1 , the second control signal ϕ 2 , the third control signal ϕ 3 , and the fourth control signal ϕ 4  to cause the transistor assembly to convert an AC input power and/or a DC input power from the input power bus to DC output power into the output power bus. 
     The A/V recording and communication doorbell devices further include a button that is configured to be pressed by a user to cause a signaling device to activate. In certain embodiments, the control circuitry is configured to cause the transistor assembly to short-circuit the input power bus, in response to the button being pressed or in response to receiving another input, to cause the signaling device to activate. Additionally, in some embodiments, the control circuitry is configured to detect a presence of AC voltage on the input power bus, and in response to detecting the presence of the AC voltage on the input power bus, cause the transistor assembly to emulate a bridge rectifier to convert the AC input power from the input power bus to the DC output power into the output power bus. Furthermore, in particular embodiments, the control circuitry is configured to detect a presence of DC voltage on the input power bus, and in response to detection of the DC voltage on the input power bus, cause the transistor assembly to provide a DC path between the input power bus and the output power bus. Moreover, in some embodiments, the control circuitry is configured to cause the transistor assembly to emulate a diode electrically coupled across the input power bus to rectify the AC input power into a rectified output power to a signaling device. 
     The remaining detailed description describes the present embodiments with reference to the drawings. In the drawings, reference numbers label elements of the present embodiments. These reference numbers are reproduced below in connection with the discussion of the corresponding drawing features. 
       FIG.  1    is a schematic diagram illustrating an A/V recording and communication doorbell device  102  including a transistor assembly that is electrically coupled to an alternating current (AC) power source  104  and a signaling device  106  via wiring  108 . The A/V recording and communication doorbell device  102  is configured to activate the signaling device  106 , e.g., to cause the signaling device  106  to output sound, when a user presses a button  116  of the A/V recording and communication doorbell device  102 , as discussed below. In some embodiments, the A/V recording and communication doorbell device  102  is located at a premises (e.g., a home), with the A/V recording and communication doorbell device  102  being located outside the home (e.g., next to a front door). In some other embodiments, the A/V recording and communication doorbell device  102  may be inside the home. 
     The AC power source  104  is configured to provide power into the A/V recording and communication doorbell device  102  and the signaling device  106 . For example, the AC power source  104  may be a (e.g., step-down) transformer, having a primary winding that is electrically coupled to an external AC power source (e.g., AC mains power supply), and a secondary winding that is electrically coupled in series with the A/V recording and communication doorbell device  102  and the signaling device  106 , via the wiring  108 . The transformer may step down the voltage from the external AC power source from, for example, from a high voltage (e.g., 120 volts) to a lower voltage, typically 16 to 24 volts. In some embodiments, the AC power source  104  may be the AC mains power supply. In other embodiments, the power source  104  may be a direct current (DC) power source, e.g., as discussed below with respect to  FIG.  2   , instead of an AC power source. 
     The signaling device  106  is symbolically depicted herein as a solenoid coil. In particular embodiments, the signaling device  106  is configured to output sound and/or light, when activated. In some embodiments, the signaling device  106  may be, for example, a mechanical signaling device or an electronic signaling device. 
     The A/V recording and communication doorbell device  102  includes a transistor assembly  110 , control circuitry  112 , a camera  114 , and the button  116 . Additionally, the A/V recording and communication doorbell device  102  may include power management circuitry  118 . The camera  114  is configured to capture (e.g., generate) image data (e.g., still images, video images, etc.) representing an image of a scene proximate to the A/V recording and communication device  102 . 
     The transistor assembly  110  is electrically coupled between an input power bus  120  and an output power bus  122 . In the example of  FIG.  1   , the input power bus  120  distributes AC input power from the AC power source  104 . However, in some other embodiments, the input power bus  120  distributes DC input power, and in yet some other embodiments, the input power bus  120  distributes either AC input power or DC input power, depending on whether an AC electrical power source or a DC power electrical source is electrically coupled to the input power bus  120 . For example,  FIG.  2    is a schematic diagram illustrating an example where the input power bus  120  distributes DC input power. The example of  FIG.  2    is similar to the example of  FIG.  1   , except that the AC power source  104  is replaced with a DC power source  204 , and the signaling device  106  is omitted. The DC power source  204  may be, for example, a photovoltaic device and/or a battery device. 
     Referring again to  FIG.  1   , the output power bus  122  provides DC output power for the A/V recording and communication doorbell device  102 . In some embodiments, the output power bus  122  is electrically coupled to the power management circuitry  118 , as illustrated in  FIG.  1   . The power management circuitry  118 , for example, converts DC output power from the output power bus  122  to a form suitable for use by one or more elements of the A/V recording and communication doorbell device  102 , such as to a form suitable for use by one or more of the button  106 , the control circuitry  112 , and the camera  114 . Connections between the power management circuitry  118  and electrical loads within the A/V recording and communication doorbell device  102 , e.g., connections between the power management circuitry  118  and the control circuitry  112 , are not shown in  FIG.  1    to promote illustrative clarity. In certain embodiments, the power management circuitry  118  generates one or more regulated power supply voltages from the DC output power from the output power bus  122 . For example, in particular embodiments, the power management circuitry  118  includes one or more DC-to-DC converters. In some other embodiments, the power management circuitry  118  is omitted, and the elements of the A/V recording and communication doorbell device  102  are powered directly from the output power bus  122 . 
     As discussed below, in certain embodiments, the control circuitry  112  is configured to cause the transistor assembly  110  to short-circuit the input power bus  120  in response to a user pressing the button  116 , to activate the signaling device  106 . Short circuiting the input power bus  120  may interrupt flow of electrical power to the power management circuitry  118 . Therefore, certain embodiments of the A/V recording and communication doorbell device  102  further include an energy storage device(s) (not shown), such as a battery or a capacitor, to provide power to the power management circuitry  118  when the transistor assembly  110  short-circuits the input power bus  120 . Inclusion of the energy storage device(s) enables the A/V recording and communication doorbell device  102  to remain powered when power flow is interrupted by short-circuiting the input power bus  120 . 
     The input power bus  120  includes a first node  124  and a second node  126 , and the output power bus  122  includes a third node  128  and a fourth node  130 . The input power bus  120  may be, for example, electrically coupled in series with the AC power source  104  and the signaling device  106 . The transistor assembly  110  includes a first transistor  132 , a second transistor  134 , a third transistor  136 , and a fourth transistor  138 . The fourth node  130  may be, for example, a reference node or a ground node. The first transistor  132  is electrically coupled between the first node  124  and the third node  128 , and the second transistor  134  is electrically coupled between the second node  126  and the third node  128 . The third transistor  136  is electrically coupled between the first node  124  and the fourth node  130 , and the fourth transistor  138  is electrically coupled between the second node  126  and the fourth node  130 . 
     In the illustrated embodiment of  FIG.  1   , each of the first transistor  132  and the second transistor  134  is a p-channel, enhancement-mode, metal oxide semiconductor field-effect transistor (MOSFET), while each of the third transistor  136  and the fourth transistor  138  is an n-channel, enhancement-mode MOSFET. Use of p-channel MOSFETs as the first transistor  132  and the second transistor  134  may advantageously promote ease of driving the first and second transistors by eliminating the need to drive the transistors&#39; gates to a voltage higher than that of the third node  128 . Additionally, use of n-channel MOSFETs as the third transistor  136  and the fourth transistor  138  may advantageously promote low forward voltage drop because an n-channel MOSFET typically has a lower on-resistance than a p-channel MOSFET of similar size and technology. Consequently, the combination of p-channel and n-channel MOSFETs in transistors assembly  110  helps achieve a balance between transistor driving circuitry simplicity and low on-resistance. However, one or more of the first transistor  132 , the second transistor  134 , the third transistor  136 , and the fourth transistor  138  could be replaced with a different type of transistor, e.g., with a different type of MOSFET or with a bipolar junction transistor (BJT), without departing from the scope hereof. 
     The control circuitry  112  is configured to generate a first control signal ϕ 1 , a second control signal ϕ 2 , a third control signal ϕ 3 , and a fourth control signal ϕ 4 , which control the first transistor  132 , the second transistor  134 , the third transistor  136 , and the fourth transistor  138 , respectively. Connections between the control circuitry  112  and the transistors assembly  110  are not shown in  FIG.  1    to promote illustrative clarity. The control circuitry  112  is configured to generate the first control signal ϕ 1 , the second control signal ϕ 2 , the third control signal ϕ 3 , and the fourth control signal ϕ 4  to cause the transistor assembly  110  to convert at least one of an AC input power and a DC input power from the input power bus  120  to DC output power into the output power bus  122 . 
     For example, in some embodiments, the control circuitry  112  is configured to detect a presence of AC voltage on the input power bus  120 , and in response to detecting the presence of the AC voltage on the input power bus  120 , cause the transistor assembly  110  to emulate a bridge rectifier to convert the AC input power from the input power bus  120  to the DC output power into the output power bus  122 . The control circuitry  112  is configured to cause the transistor assembly  110  to emulate a bridge rectifier, for example, by (a) detecting a DC voltage at the third node  128 , (b) determining that the AC voltage at the first node  124  is greater than the DC voltage at the third node  128 , and (c) in response to determining that the AC voltage at the first node  124  is greater than the DC voltage at the third node  128 , generating the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the fourth transistor  138  operate in their respective on-states, and the second transistor  134  and third transistor  136  operate in their respective off-states. Consequently, power is transferred between the input power bus  120  and the output power bus  122  via the first transistor  132  and the fourth transistor  138 , when the AC voltage at the first node  124  is greater than the DC voltage at the third node  128 , in these embodiments. 
     The control circuitry  112  is further configured to emulate a bridge rectifier, for example, by (a) detecting a DC voltage at the third node  128 , (b) determining that the AC voltage at the second node  126  is greater than the DC voltage at the third node  128 , and (c) in response to determining that the AC voltage at the second node  126  is greater than the DC voltage at the third node  128 , generating the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the second transistor  134  and the third transistor  136  operate in their respective on-states, and the first transistor  132  and fourth transistor  138  operate in their respective off-states. Consequently, power is transferred between the input power bus  120  and the output power bus  122  via the second transistor  134  and the third transistor  136 , when the AC voltage at the second node  126  is greater than the DC voltage at the third node  128 , in these embodiments. 
     In some embodiments, the control circuitry  112  is configured to detect a presence of DC voltage on the input power bus  120 , and in response to detection of the DC voltage on the input power bus  120 , cause the transistor assembly  110  to provide a DC path between the input power bus  120  and the output power bus  122 . The control circuitry  112  is configured to cause the transistor assembly  110  to provide a DC path between the input power bus  120  and the output power bus  122 , for example, by (a) detecting a first DC voltage at the first node  124 , (b) detecting a second DC voltage at the second node  126 , (c) determining whether the first DC voltage is greater than the second DC voltage, (d) when the first DC voltage is greater than the second DC voltage, causing the transistor assembly  110  to provide a first DC path between the input power bus  120  and the output power bus  122 , and (e) when the first DC voltage is not greater than the second DC voltage, the transistor assembly  110  provides a second DC path between the input power bus  120  and the output power bus  122 . The first and second DC paths are electrically coupled to the output electrical power bus in a same polarity, e.g., the third node  128  is positive and the fourth node  130  is negative, or vice-versa, in both of the first and second DC paths. 
     The control circuitry  112  is configured to cause the transistor assembly  110  to provide the first DC path between the input power bus  120  and the output power bus  122 , for example, by generating the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the fourth transistor  138  operate in their respective on-states, and the second transistor  134  and the third transistor  136  operate in their respective off-states. Consequently, current flows between the input power bus  120  and the output power bus  122  via the first transistor  132  and the fourth transistor  138 , in the first DC path. The control circuitry  112  is configured to cause the transistor assembly  110  to provide the second DC path between the input power bus  120  to the output power bus  122 , for example, by generating the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the fourth transistor  138  operate in their respective off-states, and such that the second transistor  134  and the third transistor  136  operate in their respective on-states. Consequently, current flows between the input power bus  120  and the output power bus  122  via the second transistor  134  and the third transistor  136 , in the second DC path. 
     Certain embodiments of the signaling device  106  may require a constant DC power supply for proper operation. Accordingly, in some embodiments, the control circuitry  112  is further configured to cause the transistor assembly  110  to emulate a diode electrically coupled across the input power bus  120  to rectify the AC input power into a rectified DC output power to the signaling device  106 . The control circuitry  112  is configured to cause the transistor assembly  110  to emulate a diode electrically coupled across the input power bus  120 , for example, by either (1) generating the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the second transistor  134  emulate a diode, or (2) generating the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the third transistor  136  and the fourth transistor  138  emulate a diode. In some embodiments, the control circuitry  112  is configured to generate the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the second transistor  134  emulate a diode by (1) causing the first transistor  132  and the second transistor  134  to operate in their on-states when voltage magnitude at the first node  124  is greater than voltage magnitude at the second node  126 , and (2) causing the first transistor  132  and the second transistor  134  to operate in their off-states when voltage magnitude at the first node  124  is less than or equal to voltage magnitude at the second node  126 . In some embodiments, the control circuitry  112  is configured to generate the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the third transistor  136  and the fourth transistor  138  emulate a diode by (1) causing the third transistor  136  and the fourth transistor  138  to operate in their on-states when voltage magnitude at the second node  126  is greater than voltage magnitude at the first node  124 , and (2) causing the third transistor  136  and the fourth transistor  138  to operate in their off-states when voltage magnitude at the second node  126  is less than or equal to voltage magnitude at the first node  124 . 
     The button  116  is configured to be pressed by a user to cause a signaling device, e.g., the signaling device  106  and/or a wireless signaling device (not shown) in wireless communication with the A/V recording and communication doorbell device  102 , to activate. In certain embodiments, the control circuitry  112  is configured to cause the transistor assembly  110  to short-circuit the input power bus  120 , in response to the button  116  being pressed or in response to receiving another input, to cause the signaling device  106  to activate. Short-circuiting the input power bus  122  results in power from the input power bus  120 , e.g., from the AC power source  104  or the DC power source  204 , being diverted through the signaling device  106 , thereby activating the signaling device  106 . The signaling device  106 , e.g., generates sound, such as a “ding-dong” sound or a melody, in response to being activated by the A/V recording and communication doorbell device  102 . In particular embodiments, the control circuitry  112  causes the transistor assembly  110  to short-circuit the input power bus  120  by either (a) generating first and second control signals ϕ 1  and ϕ 2  such that the first transistor  132  and the second transistor  134  simultaneously operate in their respective on-states, or (b) generating third and fourth control signals ϕ 3  and ϕ 4  such that the third transistor  136  and the fourth transistor  138  simultaneously operate in their respective on-states. 
     In certain embodiments, the control circuitry  112  is configured to perform additional functions, e.g., the control circuitry  112  may control the camera  114 . The control circuit  112  may be implemented, for example, by digital electronic circuitry and/or analog electronic circuitry. The A/V recording and communication doorbell device  102  can include additional elements without departing from the scope hereof. 
     The A/V recording and communication device  102  may be electrically coupled to external circuitry in a different manner than that illustrated in  FIGS.  1  and  2    without departing from the scope hereof. For example,  FIG.  3    illustrates an alternate embodiment where a doorbell circuit device  306  is electrically coupled in parallel with the signaling device  106 . The doorbell circuit device  306  diverts power around the signaling device  106  when the transistor assembly  110  is not short-circuiting the input power bus  120 , e.g., when the button  116  is not being pressed. For instance, the doorbell circuit device  306  may create a path of low impedance, allowing current drawn by the A/V recording and communication device  102  to flow through the doorbell circuit device  306 , rather than flow through the signaling device  106 . In response to a user pressing the button  116  and the transistor assembly  110  short-circuiting the input power bus  120 , the doorbell circuit device  306  may sense an increase in voltage across the doorbell circuit device  306  (since there is a reduced voltage across the input power bus  120 ), and in response impress power onto the signaling device  106  by creating a path of high impedance, thereby diverting current into the signaling device  106  in order to activate it. 
     In some embodiments, transistor assembly  110  could be configured to work in conjunction with a full-wave rectifier circuit. For example,  FIG.  4    is a schematic diagram illustrating an A/V recording and communication doorbell device  402  that is similar to the A/V recording and communication doorbell device  102 , but further including a full-wave rectifier circuit  410 . The full-wave rectifier circuit  410  is electrically coupled between the input power bus  120  and the output power bus  122 , and the full-wave rectifier circuit  410  is configured to convert AC input power from the input power bus  120  to a DC output power into the output power bus  122  to power the A/V recording and communication doorbell device  402 . The full-wave rectifier circuit  410  includes a first two series-connected diodes  432  and  434  in parallel with a second two series-connected diodes  436  and  438 . The diode  432  is electrically coupled in parallel with the first transistor  132 , and the diode  434  is electrically coupled in parallel with the second transistor  134 . The diode  436  is electrically coupled in parallel with the third transistor  136 , and the diode  438  is electrically coupled in parallel with the fourth transistor  138 . 
     In some embodiments of the A/V recording and communication doorbell device  402 , the control circuitry  112  is configured to operate the transistor assembly  110  in a manner similar to that discussed above with respect to the A/V recording and communication doorbell device  102 . In some other embodiments of the A/V recording and communication doorbell device  402 , the control circuitry  112  is configured to cause the transistors  132 ,  134 ,  136 , and  138  of the transistor assembly  110  to operate in their on-states only under certain operating conditions of the A/V recording and communication doorbell device  402 . 
     For example, in a particular embodiment, the control circuitry  112  is configured to cause the transistor assembly  110  to operate only when the input power bus  120  distributes DC input power. In this embodiment, the control circuitry  112  is configured to cause the transistor assembly  110  to provide a first or a second DC path between the input power bus  120  and the output power bus  122  in response to detecting presence of DC voltage on the input power bus  120 , in a manner similar to that discussed above with respect to the A/V recording and communication doorbell device  102 . However, in this embodiment, the control circuitry  112  is configured to disable operation of the transistor assembly  110  when an AC voltage is detected on the input power bus  120 , and the full-wave rectifier circuit  410  transfers AC power from the input power bus  120  to the output power bus  122  in this embodiment. 
     As another example, in an embodiment, the control circuitry  112  is configured to cause the transistor assembly  110  to provide an AC power path between the input power bus  120  and the output power bus  122  in response to detecting presence of an AC voltage on the input power bus  120 , in a manner similar to that discussed above with respect to the A/V recording and communication doorbell device  102 . However, in this embodiment, the control circuitry  112  is configured to disable operation of the transistor assembly  110  when a DC voltage is detected on the input power bus  120 , and the full-wave rectifier circuit  410  transfers DC power from the input power bus  120  to the output power bus  122  in this embodiment. The control circuitry  112  is configured to disable operation of the transistor assembly  110 , for example, by causing each of the transistors  132 ,  134 ,  136 , and  138  to operate in their respective off-states. 
       FIG.  5    is a functional block diagram illustrating a system  500  for communicating in a network according to various aspects of the present disclosure. Home automation, or smart home, is building automation for the home. Home automation enable users (e.g., home owners and authorized individuals) to control and/or automate various devices and/or systems, such as lighting, heating (e.g., smart thermostats), ventilation, home entertainment, air conditioning (HVAC), blinds/shades, security devices (e.g., contact sensors, smoke/CO detectors, motion sensors, etc.), washers/dryers, ovens, refrigerators/freezers, and/or other network connected devices suitable for use in the home. In various embodiments, Wi-Fi is used for remote monitoring and control of such devices and/or systems. Smart home devices (e.g., hub devices  502 , sensors  504 , automation devices  506 , a virtual assistant (VA) device  508 , Audio/Video (A/V) recording and communication devices  510 , etc.), when remotely monitored and controlled via a network (Internet/a public switched telephone network (PSTN))  512 , may be considered to be components of the “Internet of Things.” Smart home systems may include switches and/or sensors (e.g., the sensors  504 ) connected to a central hub such as the smart-home hub device  502  and/or the VA device  508  (the hub device  502  and/or the VA device  508  may alternatively be referred to as a gateway, a controller, a home-automation hub, or an intelligent personal assistance device) from which the system may be controlled through various user interfaces, such as voice commands and/or a touchscreen. Various examples, of user interfaces may include any or all of a wall-mounted terminal (e.g., a keypad, a touchscreen, etc.), software installed on the client devices  514 ,  516  (e.g., a mobile application), a tablet computer, or a web interface. Furthermore, these user interfaces are often but not always supported by Internet cloud services. In one example, the Internet cloud services are responsible for obtaining user input via the user interfaces (e.g., a user interface of the hub device  502  and/or the VA device  508 ) and causing the smart home devices (e.g., the sensors  504 , the automation devices  506 , etc.) to perform an operation in response to the user input. 
     The hub device  502 , the VA device  508 , the sensors  504 , the automation devices  506 , the A/V recording and communication devices  510 , and/or client devices  514 ,  516  may use one or more wired and/or wireless communication protocols to communicate, including, for example and without limitation, Wi-Fi (e.g., the user&#39;s network  518 ), X10, Ethernet, RS-485, 6LoWPAN, Bluetooth LE (BLE), ZigBee, Z-Wave, and/or a low power wide-area networks (LPWAN), such as a chirp spread spectrum (CSS) modulation technology network (e.g., LoRaWAN), an Ultra Narrow Band modulation technology network (e.g., Sigfox, Telensa, NB-IoT, etc.), RingNet, and/or the like. 
     The user&#39;s network  518  may be, for example, a wired and/or wireless network. If the user&#39;s network  518  is wireless, or includes a wireless component, the user&#39;s network  518  may be a Wi-Fi network compatible with the IEEE 802.11 standard and/or other wireless communication standard(s). Furthermore, the user&#39;s network  518  may be connected to other networks such as the network  512 , which may comprise, for example, the Internet and/or PSTN. 
     The system  500  may include one or more A/V recording and communication devices  510  (alternatively be referred to herein as “A/V devices  510 ” or “A/V device  510 ”). The A/V devices  510  may include security cameras  510 ( a ), light cameras  510 ( b ) (e.g., floodlight cameras, spotlight cameras, etc.), video doorbells  510 ( c ) (e.g., wall powered and/or battery powered video doorbells), and/or other devices capable of recording audio data and/or image data. Video doorbells  510 ( c ) may represent, and/or be similar to, the A/V recording and communication doorbell devices  102  and  402  of  FIGS.  1 - 4   . The A/V devices  510  may be configured to access a user&#39;s network  518  to connect to a network (Internet/PSTN)  512  and/or may be configured to access a cellular network to connect to the network (Internet/PSTN)  512 . 
     The system  500  may further include a smart-home hub device  502  (which may alternatively be referred to herein as the “hub device  502 ”) connected to the user&#39;s network  518  and/or the network (Internet/PSTN)  512 . The smart-home hub device  502  (also known as a home automation hub, gateway device, or network device), may comprise any device that facilitates communication with and control of the sensors  504 , automation devices  506 , the VA device  508 , and/or the one or more A/V devices  510 . For example, the smart-home hub device  502  may be a component of a security system and/or a home automation system installed at a location (e.g., a property, a premise, a home, a business, etc.). In some embodiments, the A/V devices  510 , the VA device  508 , the sensors  504 , and/or the automation devices  506  communicate with the smart-home hub device  502  directly and/or indirectly using one or more wireless and/or wired communication protocols (e.g., BLE, Zigbee, Z-Wave, etc.), the user&#39;s network  518  (e.g., Wi-Fi, Ethernet, etc.), and/or the network (Internet/PSTN)  512 . In some of the present embodiments, the A/V devices  510 , the VA device  508 , the sensors  504 , and/or the automation devices  506  may, in addition to or in lieu of communicating with the smart-home hub device  502 , communicate with the client devices  514 ,  516 , the VA device  508 , and/or one or more of components of the network of servers/backend devices  520  directly and/or indirectly via the user&#39;s network  518  and/or the network (Internet/PSTN)  512 . 
     As illustrated in  FIG.  5   , the system  500  includes the VA device  508 . The VA device  508  may be connected to the user&#39;s network  518  and/or the network (Internet/PSTN)  512 . The VA device  508  may include an intelligent personal assistant, such as, without limitation, Amazon Alexa® and/or Apple Siri®. For example, the VA device  508  may be configured to receive voice commands, process the voice commands to determine one or more actions and/or responses (e.g., transmit the voice commands to the one or more components of the network of servers/backend devices  520  for processing), and perform the one or more actions and/or responses, such as to activate and/or change the status of one or more of the sensors  504 , automation devices  506 , or A/V devices  510 . In some embodiments, the VA device  508  is configured to process user inputs (e.g., voice commands) without transmitting information to the network of servers/backend devices  520  for processing. The VA device  508  may include at least one speaker (e.g., for playing music, for outputting the audio data generated by the A/V devices  510 , for outputting the voice of a digital assistant, etc.), at least one a microphone (e.g., for receiving commands, for recording audio data, etc.), and a display (e.g., for displaying a user interface, for displaying the image data generated by the A/V devices  510 , etc.). In various embodiments, the VA device  508  may include an array of speakers that are able to produce beams of sound. Although illustrated as a separate component in  FIG.  5   , in some embodiments the VA device  508  may not be a separate component from the hub device  502 . In such embodiments, the hub device  502  may include at least some of the functionality of the VA device  508  or the VA device  508  may include at least some of the functionality of the hub device  502 . 
     The one or more sensors  504  may include, for example, at least one of a door sensor, a window sensor, a contact sensor, a tilt sensor, a temperature sensor, a carbon monoxide sensor, a smoke detector, a light sensor, a glass break sensor, a freeze sensor, a flood sensor, a moisture sensor, a motion sensor, and/or other sensors that may provide the user/owner of the security system a notification of a security event at his or her property. 
     In various embodiments, a contact sensor may include any component configured to inform (e.g., via a signal) the security system whether an object (e.g., a door or a window) is open or closed. A contact sensor may include first and second components: a first component installed on the object itself (e.g., the door or the window); the second component installed next to the object (e.g., on the door jamb). The first and second components of the contact sensor, however, need not actually be in physical contact with one another in order to be in the closed (not faulted) state. For example, at least one of the first and second components may include a magnet, and the contact sensor may rely on the Hall effect for determining a proximity of the first and second pieces to one another. When the door, window, or other object, is opened, and the first and second components move apart from one another, the contact sensor may transmit an open signal to the security system (e.g., to the hub device  502 ). A similar process may be performed when the object is closed. In some examples, a signal transmitted by the security system by the contact sensor during opening and/or closing may be the same signal, and the hub device  502  may interpret the signal based on the known state of the object (e.g., when a door is closed, and the signal is received, the hub device  502  may update the status of the door to open). 
     The one or more automation devices  506  may include, for example, at least one of an outdoor lighting system, an indoor lighting system, and indoor/outdoor lighting system, a temperature control system (e.g., a thermostat), a shade/blind control system, a locking control system (e.g., door lock, window lock, etc.), a home entertainment automation system (e.g., TV control, sound system control, etc.), an irrigation control system, a wireless signal range extender (e.g., a Wi-Fi range extender, a Z-Wave range extender, etc.) a doorbell chime, a barrier control device (e.g., an automated door hinge), a smart doormat, and/or other automation devices. 
     As described herein, in some of the present embodiments, some or all of the client devices  514 ,  516 , the A/V device(s)  510 , the smart-home hub device  502 , the VA device  508 , the sensors  504 , and the automation devices  506  may be referred to as a security system and/or a home-automation system. The security system and/or home-automation system may be installed at location, such as a property, home, business, or premises for the purpose of securing and/or automating all or a portion of the location. 
     The system  500  may further include one or more client devices  514 ,  516 . The client devices  514 ,  516  may communicate with and/or be associated with (e.g., capable of access to and control of) the A/V devices  510 , a smart-home hub device  502 , the VA device  508 , sensors  504 , and/or automation devices  506 . In various embodiments, the client devices  514 ,  516  communicate with other devices using one or more wireless and/or wired communication protocols, the user&#39;s network, and/or the network (Internet/PSTN)  512 , as described herein. The client devices  514 ,  516  may comprise, for example, a mobile device such as a smartphone or a personal digital assistant (PDA), or a computing device such as a tablet computer, a laptop computer, a desktop computer, etc. In some embodiments, the client devices  514 ,  516  include a connected device, such as a smart watch, Bluetooth headphones, another wearable device, or the like. In such embodiments, the client devices  514 ,  516  may include a combination of the smartphone or other device and a connected device (e.g., a wearable device), such that alerts, data, and/or information received by the smartphone or other device are provided to the connected device, and one or more controls of the smartphone or other device may be inputted using the connected device (e.g., by touch, voice, etc.). 
     The A/V devices  510 , the hub device  502 , the VA device  508 , the automation devices  506 , the sensors  504 , and/or the client devices  514 ,  516  may also communicate, via the user&#39;s network  518  and/or the network (Internet/PSTN)  512 , with network(s) of servers and/or backend devices  520 , such as (but not limited to) one or more remote storage devices  522  (may be referred to interchangeably as “cloud storage device(s)”), one or more backend servers  524 , and one or more backend application programming interfaces (APIs)  526 . While  FIG.  5    illustrates the storage device  522 , the backend server  524 , and the backend API  526  as components separate from the network  520 , it is to be understood that the storage device  522 , the backend server  524 , and/or the backend API  526  may be considered to be components of the network  520 . For example, the network  520  may include a data center with a plurality of computing resources used to implement the storage device  522 , the backend server  524 , and the backend API  526 . 
     The backend server  524  may comprise a computer program or other computer executable code that, when executed by processor(s) of the backend server  524 , causes the backend server  524  to wait for requests from other computer systems or software (clients) and provide responses. In an embodiment, the backend server  524  shares data and/or hardware and/or software resources among the client devices  514 ,  516 . This architecture is called the client-server model. The client devices  514 ,  516  may run on the same computer or may connect to the backend server  524  over the network (Internet/PSTN)  512  and/or the network  520 . Examples of computing servers include database servers, file servers, mail servers, print servers, web servers, game servers, and application servers. The term server may be construed broadly to include any computerized process that shares a resource to one or more client processes. 
     The backend API  526  may comprise, for example, a server (e.g. a real server, or a virtual machine, or a machine running in a cloud infrastructure as a service), or multiple servers networked together, exposing at least one API to clients. In various embodiments, the backend API  526  is provided by servers including various components such as an application server (e.g. software servers), a caching layer, a database layer, or other components suitable for implementing one or more APIs. The backend API  526  may, for example, comprise a plurality of applications, each of which communicate with one another using one or more public APIs. In some embodiments, the backend API  526  maintains user data and provides user management capabilities, thereby reducing the load (e.g., memory and processor consumption) of the client devices  514 ,  516 . 
     In various embodiments, an API is a set of routines, protocols, and tools for building software and applications. Furthermore, the API may describe a software component in terms of its operations, inputs, outputs, and underlying types, defining functionalities that are independent of their respective implementations, which allows definitions and implementations to vary without compromising the interface. As such, the API may provide a programmer with access to a particular application&#39;s functionality without the need to modify the particular application. 
     The backend API  526  illustrated in  FIG.  5    may further include one or more services (also referred to as network services). A network service is an application that provides data storage, manipulation, presentation, communication, and/or other capability. Network services are often implemented using a client-server architecture based on application-layer network protocols. Each service may be provided by a server component (e.g., the backend server  524 ) running on one or more computers (such as a dedicated server computer offering multiple services) and accessed via a network by client components running on other devices (e.g., client devices  514 ,  516 ). However, the client and server components can both be run on the same machine. Clients and servers may have a user interface, and sometimes other hardware associated with them. 
     The network  520  may be any wireless network, any wired network, or a combination thereof, configured to operatively couple the above-mentioned modules, devices, components, and/or systems as illustrated in  FIG.  5   . For example, the network  520 , the user&#39;s network  518 , and/or the network (Internet PSTN)  512  may include one or more of the following: a PSTN (public switched telephone network), the Internet, a local intranet, a PAN (Personal Area Network), a LAN (Local Area Network), a WAN (Wide Area Network), a MAN (Metropolitan Area Network), a virtual private network (VPN), a storage area network (SAN), a frame relay connection, an Advanced Intelligent Network (AIN) connection, a synchronous optical network (SONET) connection, a digital T1, T3, E1 or E3 line, a Digital Data Service (DDS) connection, a DSL (Digital Subscriber Line) connection, an Ethernet connection, an ISDN (Integrated Services Digital Network) line, a dial-up port such as a V.90, V.34, or V.34bis analog modem connection, a cable modem, an ATM (Asynchronous Transfer Mode) connection, or an FDDI (Fiber Distributed Data Interface) or CDDI (Copper Distributed Data Interface) connection. Furthermore, communications may also include links to any of a variety of wireless networks, including WAP (Wireless Application Protocol), GPRS (General Packet Radio Service), GSM (Global System for Mobile Communication), LTE, VoLTE, LoRaWAN, LPWAN, RPMA, LTE Cat-“X” (e.g. LTE Cat 1, LTE Cat 0, LTE CatM1, LTE Cat NB1), CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), and/or OFDMA (Orthogonal Frequency Division Multiple Access) cellular phone networks, global navigation satellite system (GNSS), such as global positioning systems (GPS), CDPD (cellular digital packet data), RIM (Research in Motion, Limited) duplex paging network, Bluetooth radio, or an IEEE 802.11-based radio frequency network. The network can further include or interface with any one or more of the following: RS-232 serial connection, IEEE-4024 (Firewire) connection, Fibre Channel connection, IrDA (infrared) port, SCSI (Small Computer Systems Interface) connection, USB (Universal Serial Bus) connection, or other wired or wireless, digital or analog, interface or connection, mesh or Digi® networking. 
     The hub device  502 , the VA device  508 , and/or any of the components of the network(s) of servers/backend devices  520  (e.g., the backend server  524 , the backend API  526 , the storage devices  522 , etc.) may be referred to herein as a “network device” or “network devices.” 
     With further reference to  FIG.  5   , the system  500  may also include a security monitoring service  528 . The security monitoring service  528  may be operated by the same company that manufactures, sells, and/or distributes the A/V devices  510 , the hub device  502 , the VA device  508 , the sensors  504 , and/or the automation devices  506 . In other embodiments, the security monitoring service  528  may be operated by a third-party company (e.g., a different company than the one that manufactured, sold, and/or distributed the A/V devices  510 , the hub device  502 , the VA device  508 , the sensors  504 , and/or the automation devices  506 ). In any of the present embodiments, the security monitoring service  528  may have control of at least some of the features and components of the security system and/or the home-automation system (e.g., the security monitoring service  528  may be able to arm and/or disarm the security system, lock and/or unlock doors, activate and/or deactivate one or more of the sensors  504  and/or the automation devices  506 , etc.). For example, the security monitoring service  528  may operate and control their own client devices and/or network of servers/backend devices for monitoring and/or controlling security systems. In such an example, the A/V devices  510 , the hub device  502 , the VA device  508 , the sensors  504 , and/or the automation devices  506  may communicate with the client devices and/or one or more components of the network of servers/backend devices of the security monitoring service  528  over the network (Internet/PSTN)  512  (in some embodiments, via one or more of the components of the network of backend servers/backend devices  520 ). 
       FIG.  6    is a functional block diagram for an A/V recording and communication doorbell device  102  according to various aspects of the present disclosure. The description of  FIG.  6    is made with reference to  FIGS.  1 - 4    above. The A/V recording and communication doorbell device  102  may include one or more processor(s)  610 , a communication module  612 , a power manager  644 , a camera  614 , a computer vision module  616 , a light sensor  618 , an audio CODEC (coder-decoder)  620 , volatile memory  622 , and non-volatile memory  624 . The processor(s)  610  (alternatively referred to herein as a “CPU,” a “controller,” and/or a “microcontroller) may comprise an integrated circuit including a processor core, memory, and programmable input/output peripherals. The processor(s)  610  may receive input signals, such as data and/or power, from the camera  614 , motion sensor(s)  626 , light sensor  618 , microphone(s)  628 , speaker(s)  630 , and/or the communication module  612 , and may perform various functions as described in the present disclosure. In various embodiments, when the processor(s)  610  is triggered by the motion sensor(s)  626 , the camera  614 , the speaker(s)  630 , the microphone(s)  628 , the communication module  612 , and/or another component, the processor(s)  610  performs one or more processes and/or functions. For example, when the light sensor  618  detects a low level of ambient light, the light sensor  618  may trigger the processor(s)  610  to enable a night vision camera mode. The processor(s)  610  may also provide data communication between various components such as between the communication module  612  and the camera  614 . 
     With further reference to  FIG.  6   , the communication module  612  may comprise an integrated circuit including a processor core, memory, and programmable input/output peripherals. The communication module  612  may be operatively connected to the processor(s)  610 . In some embodiments, the communication module  612  is configured to handle communication links between the A/V device  102  and other, external devices, external receivers, external transmitters, and/or external transceivers, including the client devices  514 ,  516 , and to route incoming/outgoing data appropriately. For example, inbound data from an antenna  632  of the communication module  612  may be routed through the communication module  612  before being directed to the processor(s)  610 , and outbound data from the processor(s)  610  may be routed through the communication module  612  before being directed to the antenna  632  of the communication module  612 . As another example, the communication module  612  may be configured to transmit data to and/or receive data from a remote network device (e.g., one or more components of the network(s) of servers/backend devices  520  described in  FIG.  5   ). The communication module  612  may include wireless  634 ( a ) and wired  634 ( b ) adapters. For example, the communication module  612  may include one or more wireless antennas, radios, receivers, transmitters, and/or transceivers (not shown in  FIG.  6    for simplicity) configured to enable communication across one or more wireless networks, such as, without limitation, Wi-Fi, cellular, Bluetooth, Z-Wave, Zigbee, LPWAN(s), and/or satellite networks. The communication module  612  may receive inputs, such as power and/or data, from the camera  614 , the processor(s)  610 , the button  606 , the motion sensors  626 , a reset button (not shown in  FIG.  6    for simplicity), and/or the non-volatile memory  624 . The communication module  612  may also include the capability of communicating over wired connections, such as with a signaling device  608 . For example, when the button  606  is pressed, the communication module  612  may be triggered to perform one or more functions, such as to transmit a signal over the wired  634 ( b ) connection to the signaling device  608  (although, in some embodiments, the signal be transmitted over a wireless  634 ( a ) connection to the signaling device) to cause the signaling device  608  to emit a sound (e.g., a doorbell tone, a user customized sound, a ringtone, a seasonal ringtone, etc.). The communication module  612  may also act as a conduit for data communicated between various components and the processor(s)  610 . 
     With further reference to  FIG.  6   , the A/V device  102  may include the non-volatile memory  624  and the volatile memory  622 . The non-volatile memory  624  may comprise flash memory configured to store and/or transmit data. For example, in certain embodiments the non-volatile memory  624  may comprise serial peripheral interface (SPI) flash memory. In some embodiments, the non-volatile memory  624  may comprise, for example, NAND or NOR flash memory. The volatile memory  622  may comprise, for example, DDR3 SDRAM (double data rate type three synchronous dynamic random-access memory). In the embodiment illustrated in  FIG.  6   , the volatile memory  622  and the non-volatile memory  624  are illustrated as being separate from the processor(s)  310 . However, the illustration of  FIG.  6    is not intended to be limiting, and in some embodiments the volatile memory  622  and/or the non-volatile memory  624  may be physically incorporated with the processor(s)  610 , such as on the same chip. The volatile memory  622  and/or the non-volatile memory  624 , regardless of their physical location, may be shared by one or more other components (in addition to the processor(s)  610 ) of the present A/V device  102 . 
     With further reference to  FIG.  6   , the A/V device  102  may include the camera  614 . The camera  614  may include an image sensor  636 . The image sensor  636  may include a video recording sensor and/or a camera chip. In one aspect of the present disclosure, the imager sensor  636  may comprise a complementary metal-oxide semiconductor (CMOS) array and may be capable of recording high definition (e.g., 722p, 1800p, 4K, etc.) video files. The camera  614  may include a separate camera processor (not shown in  FIG.  6    for simplicity), or the processor(s)  610  may perform the camera processing functionality. The processor(s)  610  (and/or camera processor) may include an encoding and compression chip. In some embodiments, the processor(s)  610  (and/or the camera processor) may comprise a bridge processor. The processor(s)  610  (and/or the camera processor) may process video recorded by the image sensor  636  and/or audio recorded by the microphone(s)  628 , and may transform this data into a form suitable for transfer by the communication module  612  to the network (Internet/PSTN)  512 . In various embodiments, the camera  614  also includes memory, such as volatile memory that may be used when data is being buffered or encoded by the processor(s)  610  (and/or the camera processor). For example, in certain embodiments the camera memory may comprise synchronous dynamic random-access memory (SD RAM). 
     The camera  614  may further include an IR cut filter  638  that may comprise a system that, when triggered, configures the image sensor  636  to see primarily infrared light as opposed to visible light. For example, when the light sensor  618  detects a low level of ambient light (which may comprise a level that impedes the performance of the image sensor  636  in the visible spectrum), the light emitting components  640  may shine infrared light through an enclosure of the A/V device  102  out to the environment, and the IR cut filter  638  may enable the image sensor  636  to see this infrared light as it is reflected or refracted off of objects within the field of view of the doorbell. This process may provide the A/V device with the “night vision” function mentioned above. 
     With further reference to  FIG.  6   , the recording and communication A/V device  102  may comprise the light sensor  618  and the one or more light-emitting components  640 , such as LED&#39;s. The light sensor  618  may be one or more sensors capable of detecting the level of ambient light of the surrounding environment in which the A/V device  102  may be located. The light-emitting components  640  may be one or more light-emitting diodes capable of producing visible light when supplied with power (e.g., to enable night vision). In some embodiments, when activated, the light-emitting components  640  illuminate a light pipe. 
     The A/V device  102  may further include one or more speaker(s)  630  and/or one or more microphone(s)  628 . The speaker(s)  630  may be any electromechanical device capable of producing sound in response to an electrical signal input. The microphone(s)  628  may be an acoustic-to-electric transducer or sensor capable of converting sound waves into an electrical signal. In some embodiments, the A/V device  102  may include two or more microphone(s)  628  that are spaced from one another (e.g., located on different sides of the A/V device  102 ) to provide noise cancelling and/or echo cancelling for clearer audio. The speaker(s)  630  and/or microphone(s)  628  may be coupled to an audio CODEC  620  to enable digital audio received by client devices to be decompressed and output by the speaker(s)  630  and/or to enable audio data captured by the microphone(s)  628  to be compressed into digital audio data. The digital audio data may be received from and transmitted to client devices using the communication module  612  (in some embodiments, through one or more intermediary devices such as the hub device  502 , the VA device  508 , and/or one or more components of the network of servers/backend devices  520  as described in  FIG.  5   ). For example, when a visitor (or intruder) who is present in the area about the A/V device  102  speaks, sound from the visitor (or intruder) is received by the microphone(s)  628  and compressed by the audio CODEC  620 . Digital audio data is then sent through the communication module  612  to the network  512  via the user&#39;s network  518 , routed by the backend server  524  and/or the backend API  526  and delivered to the client device(s)  514 ,  516  as described above in connection with  FIG.  5   . When the user speaks, after being transferred through the network  512 , the user&#39;s network  518 , and the communication module  612 , the digital audio data from the user is decompressed by the audio CODEC  620  and emitted to the visitor through the speaker(s)  630 . 
     With further reference to  FIG.  6   , the A/V device  102  may further include a power manager  644 , which may comprise an integrated circuit including a processor core, memory, and/or programmable input/output peripherals. In some embodiments, the power manager  644  is configured to control, among other things, an amount of power drawn from an external power source (e.g., the AC power source  104 , of  FIG.  1   ), as well as an amount of supplemental power drawn from the battery  642  (e.g., an amount of power in addition to the power drawn from the external power source), to power the A/V recording and communication doorbell device  102 . The power manager  644  may, for example, limit the amount of power drawn from the external power source so that a threshold power draw is not exceeded, in order to avoid causing the signaling device  608  to activate, as previously described. The power manager  644  may also be configured to control an amount of power drawn from the external power source and directed to the battery  642  for recharging of the battery  642 . 
     In some embodiments, the A/V device  102  may be battery powered using the battery  642  and/or may be powered using a source of external AC power. In some embodiments, the AC power may have a voltage in the range of 110-220 VAC, for example. The incoming AC power may be received by an AC/DC adapter (not shown), which may convert the incoming AC power to DC (direct-current) and may step down the voltage from 110-220 VAC to a lower output voltage of about 12 VDC and an output current of about 2 A, for example. In various embodiments, the output of the AC/DC adapter is in a range from about 9 V to about 15 V and in a range from about 0.5 A to about 5 A. These voltages and currents are examples provided for illustration and are not intended to be limiting. 
     In some embodiments, power manager  644  is configured to cause the A/V recording and communication doorbell device  102  to draw power from the battery  642 , when the transistor assembly  110  (not shown in  FIG.  6   ) short-circuits the input power bus  120  (not shown in  FIG.  6   ). As previously described, when the transistor assembly  110  is not short-circuiting the input power bus  120 , the power manager  644  controls an amount of power drawn from the AC power source  104 . When the transistor assembly  110  short-circuits the input power bus  120 , however, the voltage across the first node  124  and the second node  126  is approximately zero, resulting in a short circuit in which power is not drawn (or a very minimal amount of power is drawn). Thus, when the transistor assembly  110  short-circuits the input power bus  120 , the power manager  644  may draw at least a portion of power from the battery  642 , in order for the A/V recording and communication doorbell device  102  to perform operations while the transistor assembly  110  short-circuits the input power bus  120 . 
     However, in other embodiments, a battery  642  may not be included. In embodiments that include the battery  642 , the A/V device  102  may include an integrated circuit (not shown) capable of arbitrating between multiple voltage rails, thereby selecting the source of power for the A/V device  102 . The A/V device  102  may have separate power rails dedicated to the battery  642  and the AC power source. In one aspect of the present disclosure, the A/V device  102  may continuously draw power from the battery  642  to power the A/V device  102 , while at the same time routing the AC power to the battery, thereby allowing the battery  642  to maintain a substantially constant level of charge. Alternatively, the A/V device  102  may continuously draw power from the AC power source to power the doorbell, while only drawing from the battery  642  when the AC power source is low or insufficient. Still, in some embodiments, the battery  642  comprises the sole source of power for the A/V device  102 . In such embodiments, the components of the A/V device  102  (e.g., spring contacts, connectors, etc.) are not be connected to a source of AC power. When the battery  642  is depleted of its charge, it may be recharged, such as by connecting a power source to the battery  642  (e.g., using a USB connector). 
     In some embodiments, the processor(s)  610  serves as the control circuitry  112  to generate the first control signal ϕ 1 , the second control signal ϕ 2 , the third control signal ϕ 3 , and the fourth control signal ϕ 4 , to control the first transistor  132 , the second transistor  134 , the third transistor  136 , and the fourth transistor  138 , respectively. 
     Although not illustrated in  FIG.  6    in some embodiments, the A/V device  102  may include one or more of an accelerometer, a barometer, a humidity sensor, and a temperature sensor. The accelerometer may be one or more sensors capable of sensing motion and/or acceleration. The one or more of the accelerometer, the barometer, the humidity sensor, and the temperature sensor may be located outside of a housing of the A/V device  102  so as to reduce interference from heat, pressure, moisture, and/or other stimuli generated by the internal components of the A/V device  102 . 
     With further reference to  FIG.  6   , the A/V device  102  may include one or more motion sensor(s)  626 . However, in some embodiments, the motion sensor(s)  626  may not be included, such as where motion detection is performed by the camera  614  or another device. The motion sensor(s)  626  may be any type of sensor capable of detecting and communicating the presence of an entity within their field of view. As such, the motion sensor(s)  626  may include one or more (alone or in combination) different types of motion sensors. For example, in some embodiments, the motion sensor(s)  626  may comprise passive infrared (PIR) sensors, which may be secured on or within a PIR sensor holder that may reside behind a lens (e.g., a Fresnel lens). In such an example, the PIR sensors may detect IR radiation in a field of view, and produce an output signal (typically a voltage) that changes as the amount of IR radiation in the field of view changes. The amount of voltage in the output signal may be compared, by the processor(s)  610 , for example, to one or more threshold voltage values to determine if the amount of voltage in the output signal is indicative of motion, and/or if the amount of voltage in the output signal is indicative of motion of an entity that is to be captured by the camera  614  (e.g., motion of a person and/or animal may prompt activation of the camera  614 , while motion of a vehicle may not). Although the above discussion of the motion sensor(s)  626  primarily relates to PIR sensors, depending on the embodiment, the motion sensor(s)  626  may include additional and/or alternate sensor types that produce output signals including alternative data types. For example, and without limitation, the output signal may include an amount of voltage change based on the presence of infrared radiation in a field of view of an active infrared (AIR) sensor, the output signal may include phase shift data from a microwave-type motion sensor, the output signal may include doppler shift data from an ultrasonic-type motion sensor, the output signal may include radio wave disturbance from a tomographic-type motion sensor, and/or the output signal may include other data types for other sensor types that may be used as the motion sensor(s)  626  of the A/V device  102 . 
     In some embodiments, computer vision module(s) (CVM)  616  may be included in the A/V device  102  as the motion sensor(s)  626 , in addition to, or alternatively from, other motion sensor(s)  626 . For example, the CVM  616  may be a low-power CVM (e.g., Qualcomm Glance) that, by operating at low power (e.g., less than 2 mW of end-to-end power), is capable of providing computer vision capabilities and functionality for battery powered devices (e.g., the A/V device  102  when powered by the battery  642 ). The low-power CVM may include a lens, a CMOS image sensor, and a digital processor that may perform embedded processing within the low-power CVM itself, such that the low-power CVM may output post-processed computer vision metadata to the processor(s)  610  (e.g., via a serial peripheral bus interface (SPI)). As such, the low-power CVM may be considered to be one or more of the motion sensor(s)  626 , and the data type output in the output signal may be the post-processed computer vision metadata. The metadata may include information such as the presence of a particular type of entity (e.g., person, animal, vehicle, parcel, etc.), a direction of movement of the entity, a distance of the entity from the A/V device  102 , etc. In various embodiments, the motion sensor(s)  626  include a plurality of different sensor types capable of detecting motion such as PIR, AIR, low-power CVM, and/or cameras. 
     As indicated above, the A/V device  102  may include the CVM  616  (which may be the same as the above described low-power CVM  616  implemented as one or more motion sensor(s)  626 , or may be additional to, or alternative from, the above described low-power CVM  616 ). For example, the A/V device  102 , the hub device  502 , the VA device  508 , and/or one or more component of the network(s) of servers/backend devices  520  may perform any or all of the computer vision processes and functionalities described herein. In addition, although the CVM  616  is only illustrated as a component of the A/V device  102 , the computer vision module  616  may additionally, or alternatively, be included as a component of the hub device  502 , the VA device  508 , and/or one or more components of the network of servers/backend devices  520 . With respect to the A/V device  102 , the CVM  616  may include any of the components (e.g., hardware) and/or functionality described herein with respect to computer vision, including, without limitation, one or more cameras, sensors, and/or processors. In some of the present embodiments, with reference to  FIG.  6   , the microphone(s)  628 , the camera  614 , the processor(s)  610 , and/or the image sensor  636  may be components of the CVM  616 . In some embodiments, the CVM  616  may include an internal camera, image sensor, and/or processor, and the CVM  616  may output data to the processor(s)  610  in an output signal, for example. 
     As a result of including the CVM  616 , some of the present embodiments may leverage the CVM  616  to implement computer vision for one or more aspects, such as motion detection, object recognition, and/or facial recognition. Computer vision includes methods for acquiring, processing, analyzing, and understanding images and, in general, high-dimensional data from the real world in order to produce numerical or symbolic information, e.g., in the form of decisions. Computer vision seeks to duplicate the abilities of human vision by electronically perceiving and understanding an image. Understanding in this context means the transformation of visual images (the input of the retina) into descriptions of the world that can interface with other thought processes and elicit appropriate action. This image understanding can be seen as the disentangling of symbolic information from image data using models constructed with the aid of geometry, physics, statistics, and learning theory. Computer vision has also been described as the enterprise of automating and integrating a wide range of processes and representations for vision perception. As a scientific discipline, computer vision is concerned with the theory behind artificial systems that extract information from images. The image data can take many forms, such as video sequences, views from multiple cameras, or multi-dimensional data from a scanner. 
     One aspect of computer vision comprises determining whether or not the image data contains some specific object, feature, or activity. Different varieties of computer vision recognition include: Object Recognition (also called object classification)—One or several pre-specified or learned objects or object classes can be recognized, usually together with their 2D positions in the image or 3D poses in the scene. Identification—An individual instance of an object is recognized. Examples include identification of a specific person&#39;s face or fingerprint, identification of handwritten digits, or identification of a specific vehicle. Detection—The image data are scanned for a specific condition. Examples include detection of possible abnormal cells or tissues in medical images or detection of a vehicle in an automatic road toll system. Detection based on relatively simple and fast computations is sometimes used for finding smaller regions of interesting image data that can be further analyzed by more computationally demanding techniques to produce a correct interpretation. 
     Several specialized tasks based on computer vision recognition exist, such as: Optical Character Recognition (OCR)—Identifying characters in images of printed or handwritten text, usually with a view to encoding the text in a format more amenable to editing or indexing (e.g., ASCII). 2D Code Reading—Reading of 2D codes such as data matrix and QR codes. Facial Recognition. Shape Recognition Technology (SRT)—Differentiating human beings (e.g., head and shoulder patterns) from objects. 
     Image acquisition—A digital image is produced by one or several image sensors, which, besides various types of light-sensitive cameras, may include range sensors, tomography devices, radar, ultra-sonic cameras, etc. Depending on the type of sensor, the resulting image data may be a 2D image, a 3D volume, or an image sequence. The pixel values may correspond to light intensity in one or several spectral bands (gray images or color images), but can also be related to various physical measures, such as depth, absorption or reflectance of sonic or electromagnetic waves, or nuclear magnetic resonance. 
     Pre-processing—Before a computer vision method can be applied to image data in order to extract some specific piece of information, it is usually beneficial to process the data in order to assure that it satisfies certain assumptions implied by the method. Examples of pre-processing include, but are not limited to re-sampling in order to assure that the image coordinate system is correct, noise reduction in order to assure that sensor noise does not introduce false information, contrast enhancement to assure that relevant information can be detected, and scale space representation to enhance image structures at locally appropriate scales. 
     Feature extraction—Image features at various levels of complexity are extracted from the image data. Typical examples of such features are: Lines, edges, and ridges; Localized interest points such as corners, blobs, or points; More complex features may be related to texture, shape, or motion. 
     Detection/segmentation—At some point in the processing a decision may be made about which image points or regions of the image are relevant for further processing. Examples are: Selection of a specific set of interest points; Segmentation of one or multiple image regions that contain a specific object of interest; Segmentation of the image into nested scene architecture comprising foreground, object groups, single objects, or salient object parts (also referred to as spatial-taxon scene hierarchy). 
     High-level processing—At this step, the input may be a small set of data, for example a set of points or an image region that is assumed to contain a specific object. The remaining processing may comprise, for example: Verification that the data satisfy model-based and application-specific assumptions; Estimation of application-specific parameters, such as object pose or object size; Image recognition—classifying a detected object into different categories; Image registration—comparing and combining two different views of the same object. 
     Decision making—Making the final decision required for the application, for example match/no-match in recognition applications. 
     One or more of the present embodiments may include a vision processing unit (not shown separately, but may be a component of the CVM  616 ). A vision processing unit is an emerging class of microprocessor; it is a specific type of AI (artificial intelligence) accelerator designed to accelerate machine vision tasks. Vision processing units are distinct from video processing units (which are specialized for video encoding and decoding) in their suitability for running machine vision algorithms such as convolutional neural networks, SIFT, etc. Vision processing units may include direct interfaces to take data from cameras (bypassing any off-chip buffers), and may have a greater emphasis on on-chip dataflow between many parallel execution units with scratchpad memory, like a manycore DSP (digital signal processor). But, like video processing units, vision processing units may have a focus on low precision fixed-point arithmetic for image processing. 
     Some of the present embodiments may use facial recognition hardware and/or software, as a part of the computer vision system. Various types of facial recognition exist, some or all of which may be used in the present embodiments. 
     Some face recognition algorithms identify facial features by extracting landmarks, or features, from an image of the subject&#39;s face. For example, an algorithm may analyze the relative position, size, and/or shape of the eyes, nose, cheekbones, and jaw. These features are then used to search for other images with matching features. Other algorithms normalize a gallery of face images and then compress the face data, only saving the data in the image that is useful for face recognition. A probe image is then compared with the face data. One of the earliest successful systems is based on template matching techniques applied to a set of salient facial features, providing a sort of compressed face representation. 
     Recognition algorithms can be divided into two main approaches, geometric, which looks at distinguishing features, or photometric, which is a statistical approach that distills an image into values and compares the values with templates to eliminate variances. 
     Popular recognition algorithms include principal component analysis using eigenfaces, linear discriminant analysis, elastic bunch graph matching using the Fisherface algorithm, the hidden Markov model, the multilinear subspace learning using tensor representation, and the neuronal motivated dynamic link matching. 
     Further, a newly emerging trend, claimed to achieve improved accuracy, is three-dimensional face recognition. This technique uses 3D sensors to capture information about the shape of a face. This information is then used to identify distinctive features on the surface of a face, such as the contour of the eye sockets, nose, and chin. 
     One advantage of 3D face recognition is that it is not affected by changes in lighting like other techniques. It can also identify a face from a range of viewing angles, including a profile view. Three-dimensional data points from a face vastly improve the precision of face recognition. 3D research is enhanced by the development of sophisticated sensors that do a better job of capturing 3D face imagery. The sensors work by projecting structured light onto the face. Up to a dozen or more of these image sensors can be placed on the same CMOS chip—each sensor captures a different part of the spectrum. 
     Another variation is to capture a 3D picture by using three tracking cameras that point at different angles; one camera pointing at the front of the subject, a second one to the side, and a third one at an angle. All these cameras work together to track a subject&#39;s face in real time and be able to face detect and recognize. 
     Another emerging trend uses the visual details of the skin, as captured in standard digital or scanned images. This technique, called skin texture analysis, turns the unique lines, patterns, and spots apparent in a person&#39;s skin into a mathematical space. 
     Another form of taking input data for face recognition is by using thermal cameras, which may only detect the shape of the head and ignore the subject accessories such as glasses, hats, or make up. 
     Further examples of automatic identification and data capture (AIDC) and/or computer vision that can be used in the present embodiments to verify the identity and/or authorization of a person include, without limitation, biometrics. Biometrics refers to metrics related to human characteristics. Biometrics authentication (or realistic authentication) is used in various forms of identification and access control. Biometric identifiers are the distinctive, measurable characteristics used to label and describe individuals. Biometric identifiers can be physiological characteristics and/or behavioral characteristics. Physiological characteristics may be related to the shape of the body. Examples include, but are not limited to, fingerprints, palm veins, facial recognition, three-dimensional facial recognition, skin texture analysis, DNA, palm prints, hand geometry, iris recognition, retina recognition, and odor/scent recognition. Behavioral characteristics may be related to the pattern of behavior of a person, including, but not limited to, typing rhythm, gait, and voice recognition. 
     The present embodiments may use any one, or any combination of more than one, of the foregoing biometrics to identify and/or authenticate a person who is either suspicious or who is authorized to take certain actions with respect to a property or expensive item of collateral. For example, with reference to  FIG.  6   , the CVM  616 , and/or the camera  614  and/or the processor(s)  610  may receive information about the person using any one, or any combination of more than one, of the foregoing biometrics. 
     With further reference to  FIG.  6   , in embodiments where the button  606  is a mechanical button (e.g., has a range of movement), the button  606  may make contact with a button actuator located within the video doorbell  102  when the button  606  is pressed. In embodiments where the button  606  is not mechanical (e.g., has no range of motion), the button  606  may include a capacitive touch button, a resistive touch button, a surface acoustic wave (SAW) button, an infrared (IR) button, an optical imaging button, an acoustic pulse recognition button, and/or a button that implements a low-power CVM for the detection of a person (e.g., a finger, hand, etc., of a person). When the button  606  is pressed, touched, and/or otherwise triggered, the processor(s)  610  may receive an output signal from the button  606  that may activate one or more functions of the video doorbell  102 ( c ), such as causing the transistor assembly  110  to short-circuit the input power bus  102 , and/or transmitting an output signal, using the communication module  612 , to the signaling device  608  to cause the signaling device  608  to output a sound (e.g., via the wired  634 ( b ) connection to the signaling device  608  and/or a wireless  634 ( a ) connection to the signaling device  608 ). In addition, the processor(s)  610  may transmit an output signal (e.g., a user alert), using the communication module  612 , to the client device(s)  514 ,  516  to indicate to the user(s) of the client device(s)  514 ,  516  that a person is present at the A/V device  510  (in some embodiments, via at least one of the hub device  502 , the VA device  508 , and/or one or more component of the network of servers/backend devices  520 ). 
     Although the A/V recording and communication device  102  (or A/V device  102 ) is referred to herein as an “audio/video” device, the A/V device  102  need not have both audio and video functionality. For example, in some embodiments, the A/V device  102  may not include the speakers  630 , microphones  628 , and/or audio CODEC. In such examples, the A/V device  102  may only have video recording and communication functionalities. In other examples, the A/V device  102  may only have the speaker(s)  630  and not the microphone(s)  628 , or may only have the microphone(s)  628  and not the speaker(s)  630 . 
     Processes  700  and  800 , described below, are illustrated as a collection of blocks in a logical flow graph, which represent a sequence of operations that may be implemented in hardware, software, or a combination thereof. In the context of software, the blocks represent computer-executable instructions stored on one or more computer-readable storage media that, when executed by one or more processors, perform the recited operations. Generally, computer-executable instructions include routines, programs, objects, components, data structures, and the like that perform particular functions or implement particular abstract data types. The order in which the operations are described is not intended to be construed as a limitation, and any number of the described blocks may be combined in any order and/or in parallel to implement the processes. Additionally, any number of the described blocks may be optional and eliminated to implement the processes. 
       FIG.  7    is a flowchart illustrating an example process  700  performed by an A/V recording and communication doorbell device to transfer electrical power from an input power bus to an output power bus, according to various aspects of the present disclosure. The process, at block  702 , detects a first DC voltage at a first node of an input power bus. For example, the processor(s)  610  may detect a first DC voltage at the first node  124  of the input power bus  120 . At block  704 , the process detects a second DC voltage at a second node of the input power bus. For example, the processor(s)  610  may detect a second DC voltage at the second node  126  of the input power bus  120 . At block  706 , the process determines whether the first DC voltage is greater than the second DC voltage. For example, the processor(s)  610  may determine whether the first DC voltage detected at the first node  124  is greater than the second DC voltage detected at the second node  126 . 
     At block  708 , the processor provides a first DC path between the input power bus and the output power bus to transfer electrical power between the input power bus and the output power bus, when the first DC voltage is greater than the second DC voltage. For example, the processor(s)  610  may generate the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the fourth transistor  138  operate in their respective on-states, and the second transistor  134  and third transistor  136  operate in their respective off-states, when the first DC voltage is greater than the second DC voltage, to provide the first DC path. At block  710 , the processor provides a second DC path between the input power bus and the output power bus to transfer electrical power between the input power bus and the output power bus, when the first DC voltage is not greater than the second DC voltage. For example, the processor(s)  610  may generate the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  such that the first transistor  132  and the fourth transistor  138  operate in their respective off-states, and the second transistor  134  and third transistor  136  operate in their respective on-states, when the first DC voltage is not greater than the second DC voltage, to provide the second DC path. 
       FIG.  8    is a flowchart illustrating an example process  800  performed by an A/V recording and communication doorbell device to transfer electrical power from an input power bus to an output power bus, according to various aspects of the present disclosure. The process, at block  802 , detects an AC voltage at a node of the input power bus. For example, the processor(s)  610  may detect an AC voltage at the first node  124  of the input power bus  120 . At block  804 , the process detects a DC voltage at a node of an output power bus. For example, the processor(s)  610  may detect a DC voltage at the third node  128  of the output power bus  122 . 
     At block  806 , the process determines whether the AC voltage is greater than the DC voltage. For example, the processor(s)  610  may determine whether the AC voltage detected at the first node  124  is greater than the DC voltage detected at the third node  128 . At block  808 , the process controls a transistor assembly to transfer electrical power between the input power bus and the output power bus, upon determining that the AC voltage is greater than the DC voltage. For example, the processor(s)  610  may generate the control signals ϕ 1 , ϕ 2 , ϕ 3 , and ϕ 4  to control the transistor assembly  110  such that the first transistor  132  and the fourth transistor  138  operate in their respective on-states, and the second transistor  134  and third transistor  136  operate in their respective off-states, upon determining that the AC voltage is greater than the DC voltage. 
     As used herein, the phrases “at least one of A, B and C,” “at least one of A, B, or C,” and “A, B, and/or C” are synonymous and mean logical “OR” in the computer science sense. Thus, each of the foregoing phrases should be understood to read on (A), (B), (C), (A and B), (A and C), (B and C), and (A and B and C), where A, B, and C are variables representing elements or features of the claim. Also, while these examples are described with three variables (A, B, C) for ease of understanding, the same interpretation applies to similar phrases in these formats with any number of two or more variables. 
     The above description presents the best mode contemplated for carrying out the present embodiments, and of the manner and process of practicing them, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which they pertain to practice these embodiments. The present embodiments are, however, susceptible to modifications and alternate constructions from those discussed above that are fully equivalent. Consequently, the present invention is not limited to the particular embodiments disclosed. On the contrary, the present invention covers all modifications and alternate constructions coming within the spirit and scope of the present disclosure. For example, the steps in the processes described herein need not be performed in the same order as they have been presented, and may be performed in any order(s). Further, steps that have been presented as being performed separately may in alternative embodiments be performed concurrently. Likewise, steps that have been presented as being performed concurrently may in alternative embodiments be performed separately.