SYSTEM AND RELATED METHODS FOR DETECTING THE REMOVAL OF A WEAPON FROM A HOLSTER AND SENDING A CAMERA ACTIVATION SIGNAL

Abstract

 The invention pertains to an unholstering event detection system (100) that employs a unique inductive detection mechanism for identifying the removal of a weapon from a holster. The system is built around a primary inductance sensor (102) that forms an LC resonant circuit and tracks impedance and resonant frequency variations due to the presence or absence of the weapon. The system is designed to establish a calibration baseline, taking into account the specific characteristics of the weapon and the holster, and has the ability to automatically re-calibrate in the event of miscalibration. Activation of associated devices, such as camera units, can be triggered upon successful detection of an unholstering event. While the core functionality is delivered through the inductive detection mechanism, optional secondary sensors can be incorporated to further validate unholstering events and reduce the possibility of false positives.

Description

Field of Invention.

[0001] The present invention relates to the field of weapon management and detection, and more specifically to a system for detecting the removal of a weapon from a holster and subsequently initiating a video recording.

Background

[0002] In various security-related settings, such as police departments, military forces, and government enforcement agencies, the use of body cameras has become prevalent. These devices serve as a crucial tool in recording incidents, especially those involving the use of weapons. The video footage obtained can then be used as evidence in subsequent proceedings, providing a reliable account of whether weapon protocols were adhered to during a given incident. One specific scenario in which it is desirable to initiate a recording is when a security officer draws a weapon from a holster. Detecting this unholstering event and sending a trigger signal in response would be advantageous, but prior systems have fallen short in this area.

[0003] Traditionally, the operation of such recording systems has been either manual or initiated by a trigger signal via a conventional wireless communication protocol. However, these methods present certain limitations. Manual activation, for instance, relies heavily on the individual's judgement and reaction time, which can vary greatly and may lead to significant delays or even missed recordings in high-stress situations. Furthermore, traditional trigger signals are generally not automatic and require some form of user interaction.

[0004] One iteration of a system designed to address the aforementioned issues is described in the applicant's co-pending Application No. GB2103779.1, which discloses a multi-sensor automated triggering system with a magnetometer as one of its primary sensing elements.

[0005] A magnetometer measures the magnitude of the magnetic field along an axis in a point in space, and can detect the magnetic field caused by the presence of metal, such as a weapon, in front of the detection system. This deflection could then be compared to a baseline value to infer a binary decision about the presence or absence of the weapon.

[0006] However, magnetometer-based systems can be affected by the influence of local magnetic field effects, such as the dominant geomagnetic field and various local sources like electromagnetic emitting devices. Additionally, as the user moves, the magnitude projected by the geomagnetic field onto each axis of the magnetometer changes, causing further complications.

[0007] It is within this context that the present invention is provided.

Summary

[0008] The present invention, in contrast, employs an inductance-based approach to overcome the aforementioned limitations. This system detects the presence, removal, and absence of a weapon in a holster by monitoring a primary inductance sensor. When the holstered weapon is removed, the system wirelessly transmits a trigger signal to initiate a recording on one or more connected camera units. The use of an inductance sensor offers a more robust solution against external interference and provides a stronger correlation with the metallic composition of the weapon, the geometry of the system, and the relative position of the weapon with respect to the resonator.

[0009] The primary object of the invention is to provide a reliable, inductance-based system for detecting the removal of a weapon from a holster and subsequently triggering a video recording.

[0010] Another object of the invention is to provide a system which can be easily calibrated for different weapon-holster setups to account for variations in metallic composition, weapon geometry, and device positioning with respect to a holster, and which includes a method for detecting miscalibration to address situations where incorrect user behaviour during calibration could lead to inaccurate readings.

[0011] Once the system is calibrated, it provides a continuous monitoring function, which detects the state of the weapon in the holster, recognizing the presence, absence, or movement of the weapon. Upon detecting the removal of the weapon from the holster, the system sends a trigger signal to initiate a video recording, providing a seamless, automatic response to potential incidents.

[0012] In accordance with these and other objects, the present invention provides a system for detecting the removal of a weapon from a holster and subsequently initiating a video recording, comprising: a primary inductance sensor configured to detect the presence, removal, or absence of a weapon in a holster; a transmitter configured to send a trigger signal upon detection of the weapon removal; and a receiver configured to receive the trigger signal and initiate a video recording on one or more camera units.

[0013] The system further includes a calibration procedure, allowing the user to establish a baseline inductance for the particular weapon-holster setup. An algorithm can then compare the current inductance measured by the sensor to this baseline inductance to determine the state of the weapon. Furthermore, the system includes a miscalibration detection feature, allowing it to recognize and correct instances where the user's behavior during calibration may lead to inaccurate readings.

[0014] Other objects, features, and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings

[0015] Various embodiments of the invention are disclosed in the following detailed description and accompanying drawings.

FIG.1 illustrates a block diagram of an example configuration of an unholstering detection unit suitable for use in a system according to the present disclosure, the unit having a primary inductance sensor and multiple secondary sensors.

FIG.2 illustrates a perspective view of an example physical configuration of an unholstering detection unit according to the present disclosure, installed on a holster and with a metallic weapon holstered.

FIG.3 illustrates a flow diagram of a set of steps carried out by a controller of an unholstering event detection unit during initial calibration, a detection of a miscalibration, a second successful calibration, and entering into armed mode.

FIG.4 illustrates a flow diagram of a set of steps carried out by a controller of an unholstering event detection unit during detection of a valid trigger event due to an unholstering event, resulting in a beacon signal being sent to activate a camera unit.

[0016] Common reference numerals are used throughout the figures and the detailed description to indicate like elements. One skilled in the art will readily recognize that the above figures are examples and that other architectures, modes of operation, orders of operation, and elements/functions can be provided and implemented without departing from the characteristics and features of the invention, as set forth in the claims.

Detailed Description and Preferred Embodiment

[0017] The following is a detailed description of exemplary embodiments to illustrate the principles of the invention. The embodiments are provided to illustrate aspects of the invention, but the invention is not limited to any embodiment. The scope of the invention encompasses numerous alternatives, modifications and equivalent; it is limited only by the claims.

[0018] Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. However, the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.

DEFINITIONS:

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0020] As used herein, the term "and/or" includes any combinations of one or more of the associated listed items.

[0021] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise.

[0022] It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0024] The terms "first," "second," and the like are used herein to describe various features or elements, but these features or elements should not be limited by these terms. These terms are only used to distinguish one feature or element from another feature or element. Thus, a first feature or element discussed below could be termed a second feature or element, and similarly, a second feature or element discussed below could be termed a first feature or element without departing from the teachings of the present disclosure.

[0025] Referring now in detail to the drawings, wherein like numerals indicate like elements throughout the several views, the invention as disclosed in this patent document is an inductance-based system and method for detecting the removal of a weapon from a holster and subsequently triggering a video recording.

[0026] As shown in FIG.1, an unholstering detection unit 100 is disclosed. This unit is equipped with a primary inductance sensor 102 for detecting the presence, removal, or absence of a weapon in a holster. The primary inductance sensor 102 is designed to detect the change in inductance caused by the removal of a metallic weapon from the proximity of the sensor. The use of an inductance sensor provides several advantages such as a stronger correlation with the metallic composition of the weapon and the relative position of the weapon with respect to the resonator. This results in a more reliable detection of the unholstering event, thus reducing false triggers and enhancing the system's operational efficiency.

[0027] The primary inductance sensor 102 operates on the principle of electromagnetic induction, specifically, by measuring the impedance and resonant frequency of an LC (inductor-capacitor) resonant circuit. In the present example, this LC circuit is composed of a spiral copper trace etched onto a printed circuit board (PCB) and a capacitor, both strategically positioned on the triggering device, which in turn is affixed onto or integrated with the holster for the weapon to be monitored.

[0028] The LC circuit serves as a resonator, entering a state of resonance when its inductive and capacitive reactances balance each other out. This resonance occurs at a specific frequency, which is the resonant frequency of the circuit. When a conductive object such as a metallic weapon comes into proximity, the spiral copper trace in the LC circuit inductively couples with it, and this inductive coupling alters the impedance of the LC circuit and shifts its resonant frequency.

[0029] Impedance is the measure of the opposition that a circuit presents to the passage of current when a voltage is applied. It is a complex quantity encompassing both resistance and reactance (inductive and capacitive), and its change is reflective of the coupling between the LC circuit and the conductive object. The system is configured to maintain the oscillation amplitude of the resonator at a constant level in a closed-loop configuration while measuring the energy dissipated by the resonator. The amount of power required to keep the amplitude constant provides an estimate of the equivalent parallel resistance (RP) of the LC resonant circuit. This resistance reflects the energy losses in the circuit, including those due to the inductive coupling. By comparing the oscillation frequency of the LC circuit to a reference frequency, the system can thus determine the inductance of the LC circuit.

[0030] The inductance is directly related to the physical characteristics of the copper trace and its inductive coupling with the nearby conductive object. The equivalent parallel resistance RP is dependent on the distance between the LC oscillator and the coupled conductive object, i.e. by how close the metallic weapon is to the coil and the holster. Therefore, by monitoring RP and the oscillation frequency, the sensor can evaluate the proximity of the weapon. This information allows the controller 112 to determine whether the weapon has been unholstered, as changes in these parameters indicate a change in the position of the weapon relative to the holster. This detailed monitoring and the subsequent analysis form the basis for the reliable detection of unholstering events.

[0031] The unholstering detection unit 100 of the present example also comprises multiple secondary sensors, including a microphone 104, an RFID sensor 106, and an Inertial Measurement Unit (IMU) sensor 108. Each of these sensors provides additional context and data about the state of the weapon in the holster, further improving the reliability of the system - although these secondary sensors are not essential to the operation of the system, which can in fact function solely using the measurements obtained from the inductance sensor 102.

[0032] The IMU sensor 108, which can include accelerometers, gyroscopes, and magnetometers, can detect changes in motion or orientation of the holster.

[0033] A microphone 104 can detect the unique acoustic signature associated with the unholstering of the weapon, providing yet another data point for the controller 112 to use in determining whether an unholstering event has occurred.

[0034] The detection unit 100 further includes a power source 110, a controller 112, a wireless communications module 114, and at least one indicator LED 116. The power source 110 supplies power to the various components of the unit. The controller 112 manages the operations of the sensors and communication module, executing the calibration and detection algorithms. The wireless communication module 114 allows the unit to communicate with an external camera unit, sending a beacon signal to activate the camera unit when an unholstering event is detected. The indicator LED 116 provides a visual indication of the system status.

[0035] The power source 110 could be a battery, a power management circuit connected to a vehicle's electrical system, or any other suitable source of power.

[0036] The controller 112 is a programmable device that manages the operations of the unholstering detection unit 100. The controller 112 is responsible for initiating and overseeing the calibration process, monitoring the inputs from the primary and secondary sensors, determining whether an unholstering event has occurred, and controlling the wireless communications module 114 and indicator LED 116 in response to these determinations.

[0037] The wireless communications module 114 provides a means for the unholstering detection unit 100 to communicate with other devices. For example, when an unholstering event is detected, the controller 112 can instruct the wireless communications module 114 to send a beacon signal to a nearby camera unit, causing the camera to begin recording.

[0038] The indicator LED 116 provides a visual indication of the status of the unholstering detection unit 100. This LED could indicate, for example, whether the system is in an armed or disarmed state, whether the system is properly calibrated, or whether a malfunction has been detected.

[0039] FIG.2 illustrates a perspective view of the unholstering detection unit 100 integrated with a holster 118 with a metallic weapon 120 holstered.

[0040] As can be seen, the primary inductance sensor 102 is integrated into the triggering device 100 and holster 118. The triggering device 100 is designed in such a manner that it is non-obtrusive and does not impede the weapon's holstering or unholstering process. If not integrated with the holster 118 itself, the placement of this device 100 is typically on the interior surface of the holster, in close proximity to the weapon when holstered, to optimize the inductive coupling between the weapon 120 and the sensor 102.

[0041] The LC resonant circuit, formed by a PCB spiral copper trace, is a key component of the primary inductance sensor 102. The spiral copper trace is designed to be thin and flexible, allowing it to conform to the shape of the holster without adding significant bulk or changing the holster's form factor. The capacitor that completes the LC circuit can be either integrated on the same PCB or positioned separately within the triggering device, depending on design requirements.

[0042] The controller, power source, and wireless communication module are housed within a compact enclosure that can be integrated with or mounted on the exterior surface of the holster 118, ensuring minimal impact on the holster's form and function. An indicator LED 116 is positioned on the exterior of the holster, providing a visible indication of the system's status. This LED 116 may signal various states such as power-on, calibration in progress, successful calibration, and unholstering event detected.

[0043] An RFID / NFC tag 107 is shown placed on the weapon to pair with RFID / NFC sensor 106.

[0044] FIG.3 and FIG.4 illustrate flow diagrams detailing the operational steps carried out by the controller 112 of the unholstering detection unit 100 during various stages.

[0045] FIG.3 shows the initial calibration procedure, a detection of a miscalibration, a second successful calibration, and the system entering into an armed mode.

[0046] The calibration procedure establishes a baseline inductance for the particular weapon-holster setup, allowing the controller 112 to compare the current inductance measured by the primary sensor 102 to this baseline inductance to determine the state of the weapon.

[0047] The calibration process for the unholstering detection unit begins with power-on and is important for establishing a baseline of operation that accounts for the unique characteristics of each individual system, such as the composition and distribution of metal in the weapon, the overall geometry of the weapon and holster, and the placement of the triggering mechanism on the holster.

[0048] Power-On and Initiation of Calibration (Step 200): The calibration procedure commences automatically when the triggering device is powered on. During this phase, the controller 112 initializes the primary inductance sensor 102 and prepares it for data collection.

[0049] Holstering the Weapon (Step 202): The user is required to holster the weapon at least once during the calibration period. By holstering the weapon, the system is able to gather data about the inductive coupling between the primary inductance sensor 102 and the weapon at minimum distance and maximum inductive coupling.

[0050] Sampling the Impedance (Step 204): Once the weapon is holstered, the controller 112 begins sampling the equivalent parallel resistance (RP) of the LC circuit continuously. This RP value, which varies with the proximity of the weapon to the primary inductance sensor 102, is indicative of the level of coupling between the weapon and the sensor.

[0051] Unholstering the Weapon (Step 206): To gather a complete range of data, the user is required to unholster the weapon at least once during the calibration period. This action allows the system to observe the changes in RP as the weapon moves away from the primary inductance sensor 102.

[0052] Recording the Maximum and Minimum Impedance (Step 208): As the weapon is holstered and unholstered, the controller 112 records the maximum impedance RPmax, which corresponds to the minimum coupling (weapon absence), and the minimum impedance RPmin, which corresponds to maximum coupling (weapon presence). These values provide the system with clear reference points for the states of the weapon being holstered and unholstered.

[0053] Calculating the Threshold Impedance (Step 210): The controller 112 then calculates a threshold impedance RPthr, which serves as the trigger point for detecting an unholstering event. This threshold may be set as a predetermined percentage of the difference between RPmin and RPmax. Alternative methods are also possible as described below.

[0054] Validating Maximum and Minimum Impedance (Step 212): The controller 112 is configured to detect miscalibration by checking the difference between the maximum and minimum impedance values (RPmax - RPmin). If this difference is found to be less than a predetermined value Deltamin, the system identifies this as a miscalibration event and goes to step 218. If the difference is greater than Deltamin then the controller validates the result and proceeds to step 214. Deltamin is experimentally determined as the minimum signal separation required to positively detect a trigger event.

[0055] Final Holstering and Completion of Calibration (Step 214): The calibration process ends with the user holstering the weapon again. The controller 112 verifies the values of RPmax, RPmin, and RPthr before concluding the calibration process.

[0056] Activation of the Unholstering Detection (Step 216): Once the calibration procedure is successfully completed, the system becomes operational. The controller 112 monitors the RP and compares it against the established thresholds, ready to detect an unholstering event and trigger a beacon signal to activate the camera units. It may do so in a low power mode with most of the circuitry disabled until the next sample reading is made available for processing.

[0057] Miscalibration can occur if the user does not correctly follow the calibration procedure. The system may be designed to detect such cases and ensure that a valid calibration is achieved.

[0058] Provided below is a step-by-step process of how the system responds to a miscalibration event detected during Step 208:
Invalidating the Calibration (Step 218): Upon detection of a miscalibration event, the controller 112 invalidates the current calibration. This involves resetting the stored RPmax, RPmin, and RPthr values and preparing the system for a new calibration procedure.

[0059] User Notification (Step 220): The controller 112 then triggers the indicator LED 114 to alert the user about the miscalibration. This could be, for example, a specific blinking pattern or color change, which communicates to the user that the previous calibration attempt was unsuccessful and needs to be repeated.

[0060] Restarting the Calibration Procedure (Step 222): Following the invalidation of the calibration and user notification, the system automatically restarts the calibration procedure. The user is again required to correctly holster and unholster the weapon during the calibration period.

[0061] Second Successful Calibration and Activation (Steps 202-214): The system then proceeds through the standard calibration steps as detailed earlier, storing new values for RPmax, RPmin, and RPthr. Assuming correct user behavior, the second calibration attempt should be successful, and the system will become operational, actively monitoring for unholstering events.

[0062] The calibration process could also be accomplished using hysteresis loop limits to establish the threshold impedance (RP thr). This alternate method is beneficial for detecting both unholstering and re-holstering events, enabling the system to not only initiate but also halt the beacon signal that activates the camera units.

[0063] The controller 106 would start similarly by sampling the impedance (RP) of the LC resonant circuit throughout the calibration period as the weapon is holstered and unholstered. These readings continue to yield a maximum impedance (RP max) when the weapon is unholstered and a minimum impedance (RP min) when the weapon is holstered.

[0064] Following this, instead of setting the threshold impedance (RP thr) as a predetermined percentage of the difference between RP max and RP min, the controller 106 determines the midpoint of a hysteresis band as the RP thr. This hysteresis band effectively provides a margin around the threshold impedance to account for minor fluctuations in the impedance reading, thereby reducing the likelihood of erroneous trigger events due to marginal sensor data. The width of the hysteresis band can be determined experimentally. In an ideal setup, a frequency response analysis could be performed by having the user carry out multiple unholstering/reholstering cycles. However, to keep the calibration process user-friendly, a single unholstering/reholstering cycle should suffice. Therefore, the hysteresis band width would be determined experimentally based on this single cycle, and then a safety margin would be added to this width to account for minor variances in user behaviour and environmental factors.

[0065] With this modification, step 210 of the usual calibration process becomes the continuous monitoring of the impedance and comparing it to the threshold impedance (RP thr) as well as the hysteresis band limits. This allows the system to accurately detect unholstering events, trigger the beacon to activate the camera units, as well as detect re-holstering events and stop the beacon accordingly. This ensures that the camera units are only active when they are needed, thereby saving energy and reducing unnecessary data storage.

[0066] FIG.4 shows a flow diagram of a set of steps carried out by a controller of an unholstering event detection unit during detection of a valid trigger event due to an unholstering event, resulting in a beacon signal being sent to activate a camera unit. The method involves the following steps:

[0067] Entering Armed Mode (Step 300): Upon successful calibration, the controller 112 enters the armed mode, monitoring for potential unholstering events.

[0068] Continuous Monitoring (Step 302): The controller monitors the impedance RP of the LC resonant circuit formed by the primary inductance sensor 102. The controller compares the sampled RP values with the stored threshold impedance RPthr determined during calibration.

[0069] Detection of Potential Unholstering Event (Step 304): When the controller 112 detects an increase in impedance RP beyond the stored threshold impedance RPthr, it identifies this as a potential unholstering event.

[0070] Sending the Beacon Signal (Step 306): If the potential unholstering event is not invalidated, the controller 112 sends a beacon signal via the wireless communication module 116 to activate the camera units.

[0071] This process can be added to by integrating a weighted validation mechanism that incorporates inputs from the secondary sensors 104, 106, 108. Upon detection of a potential unholstering event, the controller 112 also gathers data from the secondary sensors, including at least one of the microphone 104, RFID sensor 106, and IMU sensor 108. Each secondary sensor's input is assigned a weight based on its reliability and relevance to unholstering event detection. The controller 112 consolidates the inputs from the secondary sensors according to their assigned weights. This weighted sum provides a validation score for the potential unholstering event. The controller 112 compares the validation score with a predetermined validation threshold. If the score exceeds the threshold, the unholstering event is validated; otherwise, it is discarded. This weighted validation mechanism improves the system's reliability and reduces the likelihood of false positives by considering multiple sensor inputs before confirming an unholstering event.

TECHNICAL TERMS:

[0072] A sensor or detector may store information in a memory (e.g., a log). Information stored by a detector may include information related to the operation and/or status of the detector. Information stored by a detector may be stored as an entry in the log. Each entry in a log may include the date and time of recording the entry. Information stored in a log may include detecting withdraw of a weapon from a holster, detecting insertion of a weapon into a holster, activation (e.g., starting, operation of) a mute operation of the recorder, resetting of the detector, setting of the time of the circuit used to generate timestamps or to record actions in the log, executing a software (e.g., firmware) upgrade, updates to user settings, reverting to an earlier version of software, and/or detecting a system fault. The mute operation, discussed in more detail below, alters the information transmitted in one or more notices for a period of time.

[0073] A processing circuit of a controller or microprocessor may further include conventional passive electronic components (e.g., resistors, capacitors, inductors) and/or active electronic component (op amps, comparators, analog-to-digital converters, digital-to-analog converters, programmable logic). A processing circuit may include conventional data buses, output ports, input ports, timers, memory, and arithmetic units.

[0074] A processing circuit includes any circuitry, component, and/or electrical/electronic subsystem for performing a function. A processing circuit may include circuitry that performs (e.g., executes) a stored program. A processing circuit may include a digital signal processor, a microcontroller, a microprocessor, an application specific integrated circuit, a programmable logic device, logic circuitry, state machines, MEMS devices, signal conditioning circuitry, communication circuitry, a conventional computer, a conventional radio, a network appliance, data busses, address busses, and/or a combination thereof in any quantity suitable for performing a function and/or executing one or more stored programs.

[0075] A processing circuit may provide and/or receive electrical signals whether digital and/or analog in form. A processing circuit may provide and/or receive digital information via a conventional bus using any conventional protocol. A processing circuit may receive information, manipulate the received information, and provide the manipulated information. A processing circuit may store information and retrieve stored information. Information received, stored, and/or manipulated by the processing circuit may be used to perform a function and/or to perform a stored program.

[0076] A processing circuit may have a low power state in which only a portion of its circuits operate or it performs only certain function. A processing circuit may be switched (e.g., awoken) from a low power state to a higher power state in which more or all of its circuits operate or it performs additional certain functions or all of its functions.

[0077] A processing circuit may control the operation and/or function of other circuits and/or components of a system. A processing circuit may receive status information regarding the operation of other components, perform calculations with respect to the status information, and provide commands (e.g., instructions) to one or more other components for the component to start operation, continue operation, alter operation, suspend operation, or cease operation. Commands and/or status may be communicated between a processing circuit and other circuits and/or components via any type of bus including any type of conventional data/address bus. A processing circuit may instruct a circuit or component to enter a low power state. A processing circuit may instruct a circuit or component to exit a low power state.

[0078] A memory stores information. A memory provides previously stored information. A memory may provide previously stored information responsive to a request for information. A memory may store information in any conventional format. A memory may store electronic digital information. A memory may provide stored data as digital information.

[0079] A memory includes any semiconductor, magnetic, or optical technology (e.g., device, chip, system), or a combination thereof for storing information. A memory may receive information from a processing circuit for storage. A processing circuit may provide a memory a request for previously stored information. Responsive to the request the memory may provide stored information to the processing circuit.

[0080] A memory may include any circuitry for storing program instructions and/or data. Storage may be organized in any conventional manner (e.g., program code, buffer, circular buffer, database). Memory may be incorporated in and/or accessible by a transmitter, a receiver, a transceiver, a sensor, a controller, and/or a processing circuit.

[0081] A communication circuit transmits and/or receives information (e.g., data). A communication circuit may transmit and/or receive (e.g., communicate) information via a wired and/or wireless communication link. A communication circuit may communicate using wireless (e.g., radio, light, sound, vibrations) and/or wired (e.g., electrical, optical) mediums. A communication circuit may communicate using any wireless (e.g., Bluetooth, Zigbee, WAP, WiFi, NFC, IrDA, LTE, BLE, EDGE, EV-DO) and/or wired (e.g., USB, RS-232, Firewire, Ethernet) communication protocols.

[0082] A sensor circuit detects (e.g., measures, witnesses, discovers, determines) a physical property (e.g., intensive, extensive, isotropic, anisotropic). A physical property may include momentum, capacitance, electric charge, electric impedance, electric reactance, inductance, electric potential (e.g., electromotive force), frequency, luminance, luminescence, magnetic field, magnetic flux, mass, electromagnetic field, pressure, spin, stiffness, temperature, tension, velocity, sound, heat, and time. A sensor circuit may detect a quantity, a magnitude, and/or a change in a physical property. A sensor circuit may detect a physical property and/or a change in a physical property directly and/or indirectly. A sensor circuit may detect a physical property and/or a change in a physical property of an object.

[0083] A sensor circuit may detect a physical quantity (e.g., extensive, intensive). A physical quantity may be positive, negative, or zero. A sensor circuit may detect a change in a physical quantity directly and/or indirectly. A sensor circuit may detect one or more physical properties and/or physical quantities at the same time (e.g., in parallel), at least partially at the same time, or serially. A sensor circuit may deduce (e.g., infer, determine, calculate) information related to a physical property. A physical quantity may a magnitude of any of the physical properties discussed above. For example, a physical quantity may include an amount of time, an elapse of time, a magnitude of an electric current, an amount of electrical charge, a magnitude of a current density, a magnitude of a voltage, an amount of capacitance, an amount of inductance, a magnitude of impedance, a magnitude of reactance, a magnitude of a magnetic field, and a flux density.

[0084] A sensor circuit may provide force to detect a physical property and/or a physical quantity. A force may include an electromotive force (e.g., voltage, current). A force may be provided before, coincident with, and/or after detecting. A force may be provided once, periodically, repeatedly, and/or as needed. An electromotive force may include a direct current ("DC") or an alternating current ("AC"). For example, a sensor circuit may provide a voltage to detect a capacitance. A sensor circuit may provide a current to generate an electromagnetic field and/or to detect a change in an electromagnetic field. A sensor circuit may provide a current to an LC circuit (e.g., LC tank circuit) to cause the LC circuit to oscillate. Providing a force may include providing a current to a coil to produce an electromagnetic field.

[0085] Unless otherwise defined, all terms (including technical terms) used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0086] The disclosed embodiments are illustrative, not restrictive. While specific configurations of the unholstering event detection system and methods have been described in a specific manner referring to the illustrated embodiments, it is understood that the present invention can be applied to a wide variety of solutions which fit within the scope and spirit of the claims. There are many alternative ways of implementing the invention.

[0087] It is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.

Claims

1. An unholstering detection system comprising one or more unholstering detection units, each unit comprising a primary inductance sensor forming an LC resonant circuit, a wireless communications unit, a power source, and a controller configured to:

in response to an activation of the unit, perform an initial calibration operation by measuring the impedance of the primary inductance sensor over a predetermined period of time and determining a maximum impedance, a minimum impedance, and a threshold impedance, and

after the initial calibration, monitor for an unholstering event by sampling the impedance and comparing the samples impedance to the threshold impedance, and

in response to a detection of a sample impedance less than or equal to the threshold impedance, send a beacon signal to activate one or more camera units and trigger a video recording.

2. The system of claim 1, wherein the threshold impedance is determined as a predetermined percentage of the difference between the maximum impedance and the minimum impedance.

3. The system of claim 1, wherein the controller is further configured to determine the threshold impedance as the midpoint of a hysteresis band during the calibration operation.

4. The system of claim 3, wherein the controller is further configured to stop the beacon signal when the impedance crosses the lower limit of the hysteresis band, indicating a re-holstering event.

5. The system of claim 1, wherein the unholstering detection units comprise one or more secondary sensors, and the controller is further configured to perform a validation step considering the inputs from one or more secondary sensors.

6. The system of claim 5, wherein each the one or more secondary sensors are selected from the group consisting of: a microphone, an RFID sensor, and an IMU sensor.

7. The system of claim 5, wherein the inputs from the one or more secondary sensors each have an associated weight.

8. The system of claim 1, wherein the controller is further configured to invalidate the calibration operation if the difference between the maximum impedance and the minimum impedance is less than a predetermined minimum signal separation.

9. The system of claim 8, wherein the controller is further configured to perform a second calibration operation if the first calibration operation is invalidated.

10. The system of claim 1, wherein each unholstering detection unit includes an indicator LED that is activated when the beacon signal is initiated.

11. The system of claim 1, wherein the primary inductance sensor of each unit is formed by a spiral copper trace and a capacitor positioned on a triggering device located on the holster.

12. The system of claim 11, wherein the primary inductance sensor inductively couples with a metallic object in proximity, altering the impedance and resonant frequency of the sensor.

13. The system of claim 12, wherein the controller is configured to monitor the oscillation frequency of the primary inductance sensor to determine the inductance of the sensor and the equivalent parallel resistance of the resonator.

14. The system of claim 1, wherein the controller of each unit is further configured to automatically start the calibration procedure upon power-on of the unholstering detection unit.

Drawing