Apparatus and method for unobtrusive inspection of an audio device

Abstract

Apparatus and methods unobtrusively inspect an audio device (100). A signal generator (270) receives a pulse signal (272) from a controller (250). A low pass filter circuit (308, 310) creates a first signal (312) in response to the pulse signal (272). The first signal (312) has a fade-in and fade-out discharging phase (436, 446) corresponding to upper and lower voltages of the pulse signal (272), respectively. A transistor (316) creates a second signal (318) in response to the first signal (312). The second signal (318) is a modified version of the first signal (312) that includes a leveled-off portion in the fade-in charging phase (432, 442, 434, 444). The audio device (100) creates a third signal (320) in response to the second signal (318). The third signal (320) is a resulting version of the second signal (318) subjected to an audio element (210) of the audio device (100). The controller (250) determines whether the third signal (320) indicates a fault condition of the audio device (100) in response to subjecting the second signal (318) to the audio element (210) of the audio device (100).

Description

FIELD OF THE INVENTION

[0001] This application relates to the field of public message broadcasting systems and, more particularly, to a broadcasting system capable of inspecting the quality a public addressing speaker.BACKGROUND

[0002] Audio broadcasting systems are capable of communicating to occupants of a public area, such as a building, for public message broadcasting, such as emergencies or safety risks. A typical system includes long wiring between step-up and step-down transformers to connect a system amplifier to public addressing speakers. It is important to check the quality of each speaker on a periodic basis to ensure the entire system operates as intended, particularly when broadcasting alerts. An intrinsic property of each speaker is to produce sound, so each speaker's quality needs to be inspected for defects, such as any unintended audible noises.SUMMARY

[0003] In accordance with one embodiment of the disclosure, there is provided an unobtrusive inspection approach of one or more audio device of a public message broadcasting system. The approach checks for a short fault and an open fault of each audio device, such as a speaker, without producing any unintended audio sound by the device. For an addressable system, the quality of an audio element, such as speaker element or coil, determines whether sufficient information may be emitted by the audio device. The quality of the audio element is inspected periodically to ensure that the public message broadcasting system operates as intended, particularly when activation of the audio device is needed. In addition, unintended or undesirable audible noise should be minimized when inspecting the device's quality. To minimize noise, the device quality may be inspected outside of an audio frequency range, such as 20Hz to 20000 Hz.

[0004] One aspect is an apparatus for unobtrusive inspection of an audio device comprising a controller, a signal generator, and the audio device, in which the signal generator includes a low pass filter circuit and a transistor. The signal generator is coupled to the controller and receives a pulse signal from the controller. The low pass filter circuit is coupled to the controller and creates a first signal in response to the pulse signal. The first signal has a fade-in charging phase corresponding to an upper voltage of the pulse signal and a fade-out discharging phase corresponding to a lower voltage of the pulse signal. The transistor is coupled to the low pass filter circuit and creates a second signal in response to the first signal. The second signal is a modified version of the first signal that includes a leveled-off portion in the fade-in charging phase. The audio device is coupled to the transistor and creates a third signal in response to the second signal. The third signal is a resulting version of the second signal subjected to an audio element of the audio device, where the third signal may be one channel or multiple channels. The controller determines whether the third signal indicates a fault condition of the audio device in response to subjecting the second signal to the audio element of the audio device.

[0005] Another aspect is a method for unobtrusive inspection of an audio device. A pulse signal from a controller is receiving at a signal generator. A first signal is created by a low pass filter circuit of the signal generator coupled to the controller in response to the pulse signal. The first signal has a fade-in charging phase corresponding to an upper voltage of the pulse signal and a fade-out discharging phase corresponding to a lower voltage of the pulse signal. A second signal is created by a transistor of the signal generator coupled to the low pass filter circuit in response to the first signal. The second signal is a modified version of the first signal that includes a leveled-off portion in the fade-in charging phase. A third signal is created by the audio device coupled to the transistor in response to the second signal. The third signal is a resulting version of the second signal subjected to an audio element of the audio device, where the third signal may be one channel or multiple channels. A determination is made at the controller whether the third signal indicates a fault condition of the audio device in response to subjecting the second signal to the audio element of the audio device.

[0006] The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. While it would be desirable to provide one or more of these or other advantageous features, the teachings disclosed herein extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned advantages.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects. FIG. 1 is an exploded view of an audio device in an example implementation that is operable to employ techniques described herein. FIG. 2 is a circuit diagram representing a set of electrical components of the audio device of FIG. 1 in an example implementation that is operable to employ techniques described herein. FIG. 3 is a circuit diagram representing a signal generator of the electrical components of FIG. 2 in an example implementation. FIG. 4 is a graphical diagram representing a base signal by the signal generator of FIGs. 2 and 3 in an example implementation. FIG. 5 is a block diagram representing the various components of a controller of the electrical components of FIG. 2 in an example implementation. FIG. 6 is a flow diagram representing an operation of the electronic components of FIG. 2 in an example implementation that is operable to employ techniques described herein. DETAILED DESCRIPTION

[0008] Various technologies that pertain to systems and methods that facilitate unobtrusive inspection of one or more audio devices, such as a public addressing speaker of a public message broadcasting system, will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0009] Referring to FIG. 1, there is shown an exploded view of an audio device 100 in an example implementation that is operable to employ techniques described herein. The audio device 100 includes an audio module 110, such as a speaker module, supported by and within a device housing 120. For example, the device housing 120 may include a front housing 122, such as a faceplate with an audio grill and an optical assembly, and a back housing 124, such as a circuit board cover. The audio module 110 may be supported in the housing 120 by, for example, positioning an audio output component 112, such as a speaker, of the audio module adjacent to the audio grill of the front housing 122. The audio device 100 may also include a main circuit board 130, such as a PCBA, to manage power and general operation of the audio module 110 as well as one or more other components of the device, such as the optical assembly of the front housing 122. The audio device 100 may be mounted or placed on a structural surface. For some embodiments, the audio device 100 may include a mounting plate assembly 140 affixed to the structural surface so that the remainder of the audio device, particularly the rear housing 120, may be attached to and removed from the mounting plate assembly140. It is to be understood that at least a portion of the audio module 110 may be exposed through the rear housing 120, the main circuit board 130, and / or the mounting plate assembly 140 for wired connections and / or accessibility by a technician.

[0010] The audio module 110 and the main circuit board 130 manage quality inspection of one or more audio devices 100 of the public message broadcasting system. The audio module 110 includes the audio output component 112 and a transformer board 114. The transformer board 114 includes an audio connection capable of being coupled to the audio output component 112 for audio signaling and a signaling connection 116 capable of being coupled to the addressable system for addressable signaling. The audio module 110 may also include a transformer 118 to transfer electrical energy between transformer board 114 and another circuit or power source external to the audio module 110.

[0011] Referring to FIG. 2, there is shown a circuit diagram representing an apparatus 200 for unobtrusive inspection of the audio device 100 in an example implementation. The apparatus 200 includes electrical components of the audio device 100. Although the apparatus 200 shown in FIG. 2 includes a main circuit board 202 and a transformer board 204, it is to be understood that various embodiments employing the techniques described herein may utilize multiple boards, a single board, or no boards. The apparatus 200 includes an audio load 210, such as an audio output component or speaker, and a wattage tap circuit 220 coupled directly or indirectly to the audio load. For example, for some embodiments, the apparatus 200 may include a transformer 230, and the transformer may include a primary winding 232 and a secondary winding 234. To couple the wattage tap circuit 220 to the audio load 210, the wattage tap circuit is coupled to the primary winding 232 of the transformer 230 and the secondary winding 234 of the transformer is coupled to the audio load 210.

[0012] The wattage tap circuit 220 has multiple wattage settings corresponding to various, selectable audio output levels of the audio load 210. For some embodiments, the wattage tap circuit 220 may include a mechanical switch having multiple positions corresponding to the wattage settings. The mechanical switch may be moved from one position to another to control an electrical connection at each wattage setting based on a currently selected position. The current position is associated with a particular wattage setting corresponding to the audio output level of the audio load.

[0013] The apparatus 200 includes a first relay circuit 240 and a second relay circuit 242. The first relay circuit 240 manages a connection between the wattage tap circuit 220 and an audio amplifier 260 based on first control signals from a controller 250. The second relay circuit 242 manages a connection between a signal generator 270 of the apparatus 200 and the audio load 210 based on second controls signals from the controller 250. Effectively, the second relay circuit 242 switches between an "unobtrusive inspection of speaker" function and a normal audio operating function. For the "unobtrusive inspection of speaker" function, the second relay circuit 242 disconnects the second connection between the audio load 210 and the transformer 230, and connects the audio load 210 to inspection topology as described herein. For the normal audio operating function, the audio load produces an audio alarm output (such as voice, tone, live voice, and the like) in which the second relay circuit 242 disconnects the second connection between the audio load 210 and inspection topology, and connects the audio load 210 to the transformer 230 for normal audio output.

[0014] The system detects valid open / short fault signals by a so called "fade-in and fade-out" topology. The frequency of one entire inspection cycle may be less than, for example, 20Hz by adjusting hardware and / or software parameters. The apparatus 200 includes the controller 250 and the signal generator 270, which operate with other components and devices of the system, the audio device 100, and the apparatus 200 to provide the "unobtrusive inspection of speaker" function.

[0015] The signal generator 270 is coupled to the controller 250 of the audio device 100 by first, second, and third processor connections. The signal generator 270 receives a pulse signal 272 from the controller 250 via the first processor connection and a power feed 274 from the controller via the second processor connection. The controller 250 receives a resulting signal 276 from the signal generator 270 via the third processor connection.

[0016] The audio load 210 of the audio element of the audio device 100 is coupled to the signal generator 270 by first and second device connections. The signal generator 270 sends a generated signal 278 to the audio load 210 via the first device connection and receives the return signal 280 from the audio load via the second device connection in response to the outgoing signal. As a result, the audio device 100 creates the return signal 280 in response to the generated signal 278, which is a resulting version of the generated signal subjected to the audio load 210 of the audio device 100. For some embodiments, the resulting signal 276 may be the same as the return signal 280, so the return signal may pass through or bypass the signal generator 270 to the controller 250. For some embodiments, the resulting signal 276 may be a version of the return signal 280 modified by the signal generator 270. The controller 250 may determine whether resulting signal 276 and / or the return signal 280 indicates a fault condition of the audio device 100 in response to subjecting the generated signal 278 to the audio load 210 of the audio device 100.

[0017] The audio system includes one or more control panels to control public addressing speakers, such as audio load 210, to alert building occupants in case of public message broadcasting, emergencies, and safety risks. The audio system is distributed with long wires between speakers and amplifiers, such as the audio amplifier 260. For a typical system driving voltages are stepped up and a transformer is provided at the speaker end. In particular, for each audio load, the system includes the audio amplifier 260 and a step-up transformer at one end of the long wires and the step-down transformer 230 and the audio load 210 at the other end. As shown in FIG. 2, signals originating from the audio amplifier 260 may feed to the first relay circuit 240 and, from there, continue to the transformer 230 and the audio load 210. The apparatus 200 of the audio device 100 allows the system to read wattage tap settings of connected field devices. The system reviews wattage tap settings of the connected audio loads to determine whether the entire system is reasonable or not, i.e., whether the system can handle the wattage tap settings of all connected devices, i.e., whether the system load is appropriate as opposed to problematic.

[0018] Referring to FIG. 3, there is shown a circuit diagram 300 representing the signal generator 270. The signal generator 270 receives the pulse signal 272 from the controller 250 via a first connector 302 and the power feed 274 from the controller via a second connector 304. The signal generator 270 provides the resulting signal 276 to the controller 250 via a third connector 306. For some embodiments, the pulse signal 272 from the controller 250 is a pulse width modulated signal of a predetermined period having the upper voltage and the lower voltage. For example, the pulse signal 272 may be an excitation or ultrasonic signal working as a carrier signal, having an upper voltage of 3 volts, a lower voltage of 0 volts, and a frequency of at least 20000Hz. The pulse signal 272 may be a rectangular signal, sinusoidal signal, or other signals which can be expressed by a mathematic formula.

[0019] The signal generator 270 includes a low pass filter circuit 308, 310 coupled to the controller 250. For some embodiments, the low pass filter circuit is a low pass filter circuit at first order circuit having a single filter circuit producing a gradual roll-off of frequencies within the cutoff frequency. For some embodiments, the low pass circuit is a low pass filter circuit at a non-first order circuit having multiple filter circuits producing a steeper roll-off within the cutoff frequency. Also, for these embodiments, the low pass filter includes a first filter component 308 and a second filter component 310. For example, the low pass filter circuit may include a resistor R1 308 and a capacitor D1 310 but is not limited to these specific components. The low pass filter circuit 308, 310 creates a first signal 312 in response to the pulse signal based on the pulse signal 272 and a ground 314. The first signal 312 has a fade-in charging phase corresponding to an upper voltage of the pulse signal and a fade-out discharging phase corresponding to a lower voltage of the pulse signal.

[0020] The signal generator 270 includes a transistor (Q1) 316 coupled to the low pass filter circuit 308, 310, such as a bi-polar transistor. The transistor 316 creates a second signal 318 at an emitter in response to the first signal 312 coupled to a base and the power feed 274 coupled to a collector. The second signal 318 is a modified version of the first signal 312 that includes a leveled-off portion in the fade-in charging phase. For example, the second signal 318 may be an exiting infrasonic signal working as a modulated signal.

[0021] The low pass filter circuit 308, 310 may include any type of low pass filter. The low pass filter may also include more than one filter in a cascaded configuration, such as a filter acting as a bypass to another filter. Examples of low pass filter circuits 308, 310 includes, but are not limited to, a resistor-capacitor circuit, an inductor-resistor circuit, an inductor-capacitor circuit, and an inductor-capacitor-resistor circuit. Some embodiments are represented by FIG. 3 as including a resistor-capacitor circuit but it is to be understood that other embodiments may include a different type of low pass filter or multiple low pass filters.

[0022] The audio load 210 of the audio device 100, which is external to the signal generator 270, is coupled to the emitter of the transistor 316 of the signal generator. The second signal 318, which is also the generated signal 278, is provided to the audio load 210. The audio load 210 of the audio device 100 creates the return signal 280, which is also resulting signal 276 (i.e., a third signal 320), in response to the second signal 318. The third signal 320 is a resulting version of the second signal 318 subjected to the audio element (such as the audio load 210) of the audio device 100. The audio device 100 includes a first audio end 322 coupled to the emitter of the transistor 316 and the audio load 210, as well as a second audio end 324 coupled to the controller 250 and the audio load. For some embodiments, the audio device 100 includes the second relay 242 manages the connection between the signal generator 270 of the apparatus 200 and the audio load 210 of the audio device 100 based on second controls signals from the controller 250.

[0023] The third signal 320, i.e., the resulting signal 276 and / or the return signal 280, are provided to the controller 250. The controller 250 determines whether the third signal 320 indicates a fault condition of the audio device 100 in response to subjecting the second signal 318 to the audio element or load 210 of the audio device. For some embodiments, the controller determines whether the third signal indicates the fault condition of the audio device based solely on the third signal 320. For some embodiments, the controller determines whether the third signal indicates the fault condition of the audio device based on a differential between the second signal 318 and the third signal 320.

[0024] The output signal of the audio load 210, i.e., the third signal 320, is a modulated signal of the carrier signal allowing the controller 250 to inspect the quality of the audio device 100. Also, the spectrum of the envelope may be less than 20Hz so, as a result, the out-of-audio-band signal will be subjected to the audio element or load 210 to implement the open / short check while causing minimal audible noise to be heard by proximal human beings. If the audio load 210 becomes shorted, then the resistance of the audio load will drop substantially. As a result, the analog voltage of the audio load 210 will be greater than typical values. If the audio load 210 becomes open, then the resistance of the audio load 210 will increase substantially. As a results, the analog voltage of the audio load 210 will be minimized, such as close to zero volts. The controller 250 determines whether the third signal 320 indicates a fault condition of the audio device 100 by comparing or correlating the third signal 320 to predetermined threshold range representing an acceptable operating range. For example, the acceptable operating range may be between, and not at or proximal to, the voltage of the power feed 274 and zero voltages. Outside of this acceptable operating range, the controller 250 determines that the fault condition of the audio device 100 exists.

[0025] The steady state of the signal generator follows the following expression: i b = DV s − V be βR + R 1 V b = DV s − DV s − V be βR + R 1 R 1

[0026] For the above expressions, i b represents the current at the base of the transistor, and V b represents the voltage at the base of the transistor. D represents the duty cycle of PWM signal, V s represents the source voltage, and V be represents the forward voltage of base-to-emitter of the employed transistor 316. A represents the summation of the audio load 210 and the detection resistor 326, β represents multiplying factor of the voltage or resistor divider, and R 1 represents the resistance R1 308 of the low pass filter circuit.

[0027] Unintended noises from the audio device 100, such as a pop or click, may be caused by current passing through the speaker element or load 210. The system suppresses these noises in a cost effective way with minimal sound emanating from the audio device 100. Resistor R1 308 and capacitor C1 310 determine the rising time of an exponential curve so that a noise is minimized. For example, for some embodiments, the frequency range of the audio device 100 may be between 300 hz to 8000 hz, so resistor R1 308 may be between about 1 kohms to about 100 kohms (such as 10 kohms). For this example, the capacitor C1 310 should be between about 100 nano farads to about 47 farads (such as 10 farads). The speaker quality may be difficult to determine if the current is not constant, so the transistor 316 ensures that the current flowing through the audio element or load 210 is constant. The third signal 320 may be created based on a voltage divider or resistor divider using other components in conjunction with the audio load 210, such as a detection resistor 326 of the signal generator 270 of the apparatus 200 connected in series with the audio load.

[0028] Referring to FIG. 4, there is shown a graphical diagram 400 representing waveforms, of the incoming signal to the audio element, i.e., audio load 210, in an example implementation. For this diagram 400, the x-axis 410 represents the time in milliseconds (msec) of the generated signal 278 based on the corresponding of the pulse signal provided by the controller 250. The y-axis 420 represents the voltage of the generated signal 278 at one point or differential of two points of the signal generator 270. For some embodiments where only one point is considered, the controller 250 determines whether the third signal indicates the fault condition of the audio device. Only one signal shown in FIG. 4 represents the third signal 320. For some embodiments where two points are considered, the controller 250 determines whether the third signal indicates the fault condition of the audio device based on a comparison or differential between the second signal 318 and the third signal 320. One signal shown in FIG. 4 represents the second signal 318 and the other signal represents the third signal 320. FIG. 4 represents embodiments in which two waveforms taken at two different points are considered but it is to be understood that, for some embodiments, only one waveform taken at one point may be used.

[0029] FIG. 4 represents waveforms 430, 440 for a second signal 318 and a third signal 320 of the signal generator 270, particularly for a properly functioning audio load 210. Both waveforms 430, 440 include a fade-in charging phase 432, 442, 434, 444 and a fade-out charging phase 436, 446. The low pass filter circuit 308, 310 increases the first signal 312 gradually, from the upper voltage of the pulse signal 272, during a first part of the fade-in charging phase 432, 442 to minimize unintended audio noise by the audio device. For some embodiments, the low pass filter circuit 308, 310 decreases the first signal gradually, from the lower voltage of the pulse signal 272, during the fade-out discharging phase 436, 446 to minimize unintended audio noise by the audio device. The transistor 316 levels-off the signal at a second part of the fade-in charging phase 434, 444 of the second signal to facilitate the determination by the controller of whether the third signal indicates the fault condition of the audio device. For example, the rising process may be about 50 msec, the duration of the leveling-off portion may be about 100 msec, and the falling process may be 50 msec or longer.

[0030] The signal generator 270 detects the resistance of the audio element or load 210 (such as a speaker coil), and the controller 250 analyzes this detected resistance. When the resistance is within a predetermined range, then the probability of functioning properly is very high. However, if the resistance of the audio load 210 is shorted (for example, greater than 1 V) or open (for example, less than 200 mV), then the audio device 100 does not operate properly and is considered to be at fault.

[0031] Referring to FIG. 5, there are shown system components 500 of the controller 250 in an example implementation. The system components 500 comprise one or more communication lines 502 for interconnecting other system components directly or indirectly. The other system components include one or more processors 506 and one or more memory components 508. The processor or processors 506 may send data to, and process commands received from, other components of the system components, such as information of the memory component 508. Each application includes executable code to provide specific functionality for the processor 506 and / or remaining components of the controller 250.

[0032] Examples of applications executable by the processor 506 include, but are not limited to, an operation module 510 and an inspection module 512. The operations module 510 may perform general operations to manage the controller 250, such as communications with other devices and audio output at the audio output component 112 or audio load 210. The inspection module 512 may determines whether an incoming signal or incoming signals indicates a fault condition of the audio device.

[0033] Data stored at the memory component 508 is information that may be referenced and / or manipulated by a module of the processor 506 for performing functions of the controller 250. Examples of data associated with the controller 250 and stored by the memory component 508 may include, but are not limited to, incoming signal(s) 514 and fault conditions 516. The incoming signals 514 includes the third signal 320, such as the return signal 280 or the resulting signal 276, and may also include the second signal 318. The fault condition 516 is determined and may be stored in response to analysis of the incoming signal(s) 514.

[0034] The system components 500 may include input components 518 and output components 520 that manages one or more input components and / or an output component. The input components and the output components 518, 520 of the system components may also include one or more communication, signaling, visual, audio, mechanical, or other components that receive and / or provide information with an entity external to the controller 250. For example, an input component 518 may receive the resulting signal 276, the return signal 280 or the third signal 320, and an output component 250 may send the pulse signal 272 and the power feed 274 to the signal generator 270. The output component 250 may send control signal to other components, such as the first relay circuit 240 and the second relay circuit 242, to switch between normal operations and special operations. Special operations include inspection of the audio load 210 of one or more audio devices 100.

[0035] It is to be understood that FIG. 5 is provided for illustrative purposes only to represent an example implementation of the controller 250 and is not intended to be a complete diagram of the various components that may be utilized by the device. The controller 250, may include various other components not shown in FIG. 5, may include a combination of two or more components, or a division of a particular component into two or more separate components, and still be within the scope of the present invention. Also, the system components 500 may be coupled directly or indirectly to each other to perform the operations of the controller 250. For example, the processor 506 may be coupled, directly or indirectly, to the input / output components 518, 520.

[0036] Referring to FIG. 6, there is shown a flow diagram representing an example operation 600 of the audio device in an example implementation. The example operation 600 depicts a method for unobtrusive inspection of the audio device 100. For the operation 600, the controller 250 and the signal generator 270 are established (602), i.e., activated, in the apparatus 200 of the audio device 100. Subsequent to establishing (602) the apparatus 200, the signal generator 270 receives (604) a pulse signal from the controller 250. For example, the signal generator 270 may receive (604) a pulse signal from the controller 250 on a periodic basis. For some embodiments, the pulse signal is a pulse width modulated signal of a predetermined period having the upper voltage and the lower voltage.

[0037] In response to receiving (604) the pulse signal, the low pass filter circuit 308, 310 of the signal generator 270 creates (606) a first signal 312 . The first signal 312 includes a fade-in charging phase corresponding to an upper voltage of the pulse signal and a fade-out discharging phase corresponding to a lower voltage of the pulse signal. For some embodiments, the first signal 312 is created (606) by increasing gradually the first signal during the fade-in charging phase. For some embodiments, the first signal 312 is created (606) by decreasing gradually the first signal during the fade-out discharging phase. For some embodiments, the first signal 312 is created (606) by increasing gradually during one phase and decreasing gradually during another phase.

[0038] In response to creating (606) the first signal 312, the transistor 316 creates (608) the second signal 318. The second signal 318 is a modified version of the first signal 312 that includes a leveled-off portion in the fade-in charging phase. For some embodiments, the second signal 318 is created (608) by leveling-off the fade-in charging phase of the second signal. In response to creating (608) the second signal 318, the audio load 210 of the audio device 100 creates (610) the third signal 320 (also 276 and 280). The third signal 320 is a resulting version of the second signal 318 subjected to the audio element or load 210 of the audio device 100.

[0039] In response to creating (610) the third signal 320 by subjecting the second signal 318 to the audio element or load 210 of the audio device 100, the controller 250 determines (612) whether the third signal indicates a fault condition of the audio device 100. For some embodiments, the audio device 100 includes a first audio end 322 coupled to the transistor 316 and a second audio end 324 coupled to the controller 250. For some embodiments, the controller 250 determines (612) whether the third signal 320 indicates the fault condition of the audio device 100. For some embodiments, the controller 250 determines (612) whether the second and third signals 318, 320 indicate the fault condition of the audio device 100. For example, the fault condition may be determined (612) based on a differential between the second signal 318 and the third signal 320.

[0040] If the controller 250 does not determine (612) that a fault condition exists, then the apparatus 200 may continue its inspection operation (614) with another audio device or continue with its general operations until the next determined time to perform the inspection operation (614) of the audio devices of the system. If the controller 250 determines (612) that a fault condition exists, then the apparatus 200 may perform (616) an alert function in response to this determination. For some embodiments, the apparatus 200 may cause a work order to be created so that the faulty audio device may be, or may be scheduled to be, repaired or replaced. For some embodiments, the apparatus 200 cause an alert to be sent to a remote device, such as a safety monitoring workstation, a mobile device, or a report logging system.

[0041] Those skilled in the art will recognize that, for simplicity and clarity, the full structure and operation of all data processing systems suitable for use with the present disclosure are not being depicted or described herein. Also, none of the various features or processes described herein should be considered essential to any or all embodiments, except as described herein. Various features may be omitted or duplicated in various embodiments. Various processes described may be omitted, repeated, performed sequentially, concurrently, or in a different order. Various features and processes described herein can be combined in still other embodiments as may be described in the claims.

[0042] It is important to note that while the disclosure includes a description in the context of a fully functional system, those skilled in the art will appreciate that at least portions of the mechanism of the present disclosure are capable of being distributed in the form of instructions contained within a machine-usable, computer-usable, or computer-readable medium in any of a variety of forms, and that the present disclosure applies equally regardless of the particular type of instruction or signal bearing medium or storage medium utilized to actually carry out the distribution. Examples of machine usable / readable or computer usable / readable mediums include nonvolatile, hard-coded type mediums such as read only memories (ROMs) or erasable, electrically programmable read only memories (EEPROMs), and user-recordable type mediums such as floppy disks, hard disk drives and compact disk read only memories (CD-ROMs) or digital versatile disks (DVDs).

[0043] Although an example embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

Claims

1. An apparatus for unobtrusive inspection of an audio device (100), the apparatus comprising: a controller (250) of the audio device (100); a signal generator (270) coupled to the controller (250), the signal generator (270) receiving a pulse signal (272) from the controller (250); an low pass filter circuit (308, 310) of the signal generator (270) coupled to the controller (250), the low pass filter circuit (308, 310) creating a first signal (312) in response to the pulse signal (272), the first signal (312) having a fade-in charging phase (432, 442, 434, 444) corresponding to an upper voltage of the pulse signal (272) and a fade-out discharging phase (436, 446) corresponding to a lower voltage of the pulse signal (272); and a transistor (316) of the signal generator (270) coupled to the low pass filter circuit (308, 310), the transistor (316) creating a second signal (318) in response to the first signal (312), the second signal (318) being a modified version of the first signal (312) that includes a leveled-off portion in the fade-in charging phase (432, 442, 434, 444), wherein the audio device (100) is coupled to the transistor (316), the audio device (100) creating a third signal (320) in response to the second signal (318), the third signal (320) being a resulting version of the second signal (318) subjected to an audio element (210) of the audio device (100), and wherein the controller (250) determines whether the third signal (320) indicates a fault condition of the audio device (100) in response to subjecting the second signal (318) to the audio element (210) of the audio device (100).

2. The apparatus as described in claim 1, wherein the low pass filter circuit (308, 310) increases the first signal (312) gradually during the fade-in charging phase (432, 442, 434, 444) to minimize unintended audio noise by the audio device (100).

3. The apparatus as described in claim 1, wherein the low pass filter circuit (308, 310) decreases the first signal (312) gradually during the fade-out discharging phase (436, 446) to minimize unintended audio noise by the audio device (100).

4. The apparatus as described in claim 1, wherein the transistor (316) levels-off the fade-in charging phase (432, 442, 434, 444) of the second signal (318) to facilitate the determination by the controller (250) of whether the third signal (320) indicates the fault condition of the audio device (100).

5. The apparatus as described in claim 1, wherein the pulse signal (272) from the controller (250) is a pulse width modulated signal of a predetermined period having the upper voltage and the lower voltage.

6. The apparatus as described in claim 1, wherein the audio device (100) includes a first audio end coupled to the transistor (316) and a second audio end coupled to the controller (250).

7. The apparatus as described in claim 1, wherein the controller (250) determines whether the third signal (320) indicates the fault condition of the audio device (100) based on a differential between the second signal (318) and the third signal (320).

8. A method for unobtrusive inspection of an audio device (100), the method comprising: receiving (604), at a signal generator (270), a pulse signal (272) from a controller (250); creating (606) a first signal (312) by an low pass filter circuit (308, 310) of the signal generator (270) in response to the pulse signal (272), the first signal (312) having a fade-in charging phase (432, 442, 434, 444) corresponding to an upper voltage of the pulse signal (272) and a fade-out discharging phase (436, 446) corresponding to a lower voltage of the pulse signal (272); creating (608) a second signal (318) by a transistor (316) of the signal generator (270) in response to the first signal (312), the second signal (318) being a modified version of the first signal (312) that includes a leveled-off portion in the fade-in charging phase (432, 442, 434, 444); creating (610) a third signal (320) by the audio device (100) in response to the second signal (318), the third signal (320) being a resulting version of the second signal (318) subjected to an audio element (210) of the audio device (100); and determining (612), at the controller (250), whether the third signal (320) indicates a fault condition of the audio device (100) in response to subjecting the second signal (318) to the audio element (210) of the audio device (100).

9. The method as described in claim 8, wherein creating (606) the first signal (312) includes increasing gradually the first signal (312) during the fade-in charging phase (432, 442, 434, 444) to minimize unintended audio noise by the audio device (100).

10. The method as described in claim 8, wherein creating (606) the first signal (312) includes decreasing gradually the first signal (312) during the fade-out discharging phase (436, 446) to minimize unintended audio noise by the audio device (100).

11. The method as described in claim 8, wherein creating (608) the second signal (318) includes leveling-off the fade-in charging phase (432, 442, 434, 444) of the second signal (318) to facilitate the determination of whether the third signal (320) indicates the fault condition of the audio device (100).

12. The method as described in claim 8, wherein the pulse signal (272) is a pulse width modulated signal of a predetermined period having the upper voltage and the lower voltage.

13. The method as described in claim 8, wherein the audio device (100) includes a first audio end coupled to the transistor (316) and a second audio end coupled to the controller (250).

14. The method as described in claim 8, wherein determining (612) whether the third signal (320) indicates a fault condition of the audio device (100) includes determining whether the third signal (320) indicates the fault condition of the audio device (100) based on a differential between the second signal (318) and the third signal (320).

15. A non-transitory computer readable medium including executable instructions which, when executed, causes at least one processor to unobtrusively inspect an audio device (100) by: receiving (604), at a signal generator (270), a pulse signal (272) from a controller (250); creating (606) a first signal (312) by an low pass filter circuit (308, 310) of the signal generator (270) in response to the pulse signal (272), the first signal (312) having a fade-in charging phase (432, 442, 434, 444) corresponding to an upper voltage of the pulse signal (272) and a fade-out discharging phase (436, 446) corresponding to a lower voltage of the pulse signal (272); creating (608) a second signal (318) by a transistor (316) of the signal generator (270) in response to the first signal (312), the second signal (318) being a modified version of the first signal (312) that includes a leveled-off portion in the fade-in charging phase (432, 442, 434, 444); creating (610) a third signal (320) by the audio device (100) in response to the second signal (318), the third signal (320) being a resulting version of the second signal (318) subjected to an audio element (210) of the audio device (100); and determining (612), at the controller (250), whether the third signal (320) indicates a fault condition of the audio device (100) in response to subjecting the second signal (318) to the audio element (210) of the audio device (100).

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