Patent Grant
10655440
This U.S. national phase application is based on International Application No. PCT/GB2017/051067, filed on Apr. 18, 2017, which claimed priority to British Patent Application No. 1607168.0, filed on Apr. 25, 2016. Priority benefit of these earlier filed applications is hereby claimed.
The present invention relates to an earphone test system and method of testing earphone devices particularly but not exclusively intended for testing earphone devices with Active Noise Reduction (ANR) functionality.
Earphones (e.g. circumaural or supra-aural earphones of the type connected together by a headband to form headphones or in-ear/in-the-canal earphones configured to be placed at the entrance to or in the auditory canal of a user's ear) are well known in the art. Active earphone systems incorporating an active earphone driver for providing advanced active features such as Active Noise Reduction (ANR) or binaural monitoring are also well known in the art. ANR techniques offer the capability to cancel (at least some useful portion of) unwanted external sound via feedforward control and/or unwanted sound sensed by an internal sensing microphone via feedback control. The development and manufacture of active headphones and earphones and, particularly, those systems that incorporate active noise reduction, require accurate measurement of the electro-acoustic response of the component parts of the system in representative operating conditions.
Conventional testing of active earphone systems is performed using equipment as illustrated in
The conventional test strategy of
The system of
The present applicant has identified the opportunity for an improved form of testing system that permits rapid testing of earphone apparatus in a factory environment as part of the manufacturing process. In particular, the present applicant has devised a testing system with a new architecture, which is not a simple duplication of a multiplicity of instances of the system of
In accordance with a first aspect of the present invention, there is provided an earphone test system comprising: a plurality of test stations each operative to perform a function during testing of an earphone device coupled thereto; wherein during testing of earphone devices coupled to the plurality of test stations the earphone test system is operative to expose each of the plurality of test stations to a noise field generated by a common noise field source.
In this way, an earphone test system suitable for use in a production line environment is provided in which noise field generation resources are shared between multiple test stations. Advantageously, such an arrangement allows the plurality of test stations to be provided in a common space (e.g. room or zone of a factory) allowing simplified access to the test stations when coupling/de-coupling earphone devices to and from the test stations to assist in high volume testing.
In one embodiment, the earphone test system is operative to allow earphone devices coupled to the plurality of test stations to be tested independently of one another. For example, each of the plurality of test stations may be independently instructed to commence a test procedure.
The earphone devices to be tested will typically comprise at least one electroacoustic driver and a processor module.
The earphone devices may take the form of headphones (e.g. a pair of earphone units (typically circumaural or supra-aural earphone units) connected together by a headband) or headbandless in-ear/in-the-canal earphone units configured to be placed at the entrance to or in the auditory canal of a user's ear and held in place by engagement with the user's ears. Typically, the earphone device is a multi-channel (e.g. stereo) device.
In one embodiment, each earphone device comprises at least one microphone and the processor module comprises an audio processing component operative to process signals received from the at least one microphone.
In one embodiment, each earphone device comprises at least one feedback microphone (e.g. for sensing pressure changes in a volume (e.g. sealed volume) between the driver of the earphone device and the auditory canal of a user's ear) and the audio processing component comprises a feedback Active Noise Reduction (ANR) function for processing signals received from the at least one feedback microphone.
In one embodiment, each earphone device comprises at least one feed-forward microphone positioned to sense external ambient acoustic noise and the audio processing component comprises a monitoring function (e.g. feedforward ANR function or binaural monitoring/talk through function) configured to provide an audio signal based on sound measurements obtained from the at least one feedforward microphone.
In a first set of embodiments, the noise field source is configured to provide a localised noise field in a localised zone of the earphone test system and the earphone test system further comprises a transport mechanism for moving the plurality of test stations relative to the localised zone such that the plurality of test stations are exposed sequentially to the localised noise field. Typically the noise field source is fixed relative to the test area and the plurality of test stations move through the localised zone (e.g. in a continuous loop). However, in another embodiment the noise field could be configured to move relative to the test area (e.g. with the plurality of test stations being static).
In one embodiment, the earphone test system is configured to detect the position of the plurality of test stations at at least one point (e.g. at least one point in the continuous loop). For example, the earphone test system may detect when each of the plurality of test stations enters the localised zone (e.g. in order to trigger commencement of a test routine or part of a test routine requiring exposure to an external noise field).
In one embodiment, the localised zone comprises a first region in which a first phase of a test routine is performed and a second region provided in series with the first region and in which a second phase of a test routine is performed. The localised noise field generated in the first region may be the same or different to the localised noise field generated in the second region. In one embodiment, localised noise fields may be generated independently in the first and second regions (e.g. to allow activation at different times).
In one embodiment, the relative movement between the plurality of test stations and the localised zone is continuous (e.g. under constant speed).
In another embodiment, the relative movement between the plurality of test stations and the localised zone is non-continuous (e.g. stepwise). In this way, earphone devices under test may be positioned at known relative locations for fixed intervals of time as the test stations move relative to the localised zone.
In a second set of embodiment, the noise field generated by the noise field source is a dispersed uniform noise field and the plurality of test stations are arranged in a test array to allow exposure of the plurality of test stations to the noise field in parallel.
In one embodiment, the test array extends in at least two dimensions.
In a first embodiment, the noise field source comprises a distributed array of electro-acoustic drivers operative to generate a dispersed uniform noise field. For example, the distributed array of electro-acoustic drivers and the test array may be substantially planer and disposed substantially parallel to each other. In one embodiment, the distributed array of electro-acoustic drivers has a larger area than the test array (e.g. in order to minimise non-uniformity along edges of the test array).
In a second embodiment, the noise field source comprises a localised noise field source (e.g. substantially point source) and the plurality oftest stations are arranged around the localised noise field source (e.g. concentrically around the localised source). For example, the test array may be disposed on the surface of a notional sphere concentric with the localised noise field source.
In either of the first and second embodiments, an acoustic treatment may be disposed behind the test array to minimise reflections which might reduce uniformity of pressure in the dispersed uniform noise field generated at the test array.
In a third embodiment, the dispersed uniform noise field is generated by housing the noise field source and the plurality of test stations within a reverberant enclosure. Advantageously, this embodiment allows the plurality of test stations to be positioned at various distanced from the noise field source thereby simplifying the test array design and making the positioning of monitoring microphones/movement of users within the noise field less critical.
In one embodiment, the noise field (e.g. dispersed uniform noise field) generated by the noise field source during operation of the earphone test system is continuously generated. This may assist with the independent testing of earphone devices, particularly in the second set of embodiments where the coupling/de-coupling of earphone devices to test stations is typically not synchronised with any drive mechanism.
In another embodiment, the noise field source is activated/deactivated in dependence upon a test status of the plurality of test stations or (in the case of test stations configured to move relative to the noise field) position of the plurality of test stations.
In one embodiment, testing of the earphone devices involves a test routine comprising electrical and/or electro-acoustic testing.
In one embodiment, the test routine further comprises configuring the earphone device based on the results of the test routine.
In one embodiment, the plurality of test stations are configured to signal test results to a system operator (e.g. by means of a visual indicator).
In one embodiment, test system is operative to automatically sort tested earphone devices into pass/reject categories. In one embodiment, the test stations may comprise an automatic mechanism to allow tested earphone devices sorted into pass/reject categories to be released into an appropriate collection region (e.g. pass or fail collection region).
In one embodiment, the plurality of test stations is configured to allow mounting of earphone devices thereto by suspending the earphone devices from an electrical connection.
In one embodiment, wherein the plurality of test stations each comprise an orientating frame for mounting an earphone device to the test station in a predetermined orientation (e.g. predetermined orientation relative to the noise field generated by the noise field source).
In one embodiment, the plurality of test stations is configured to test earphone devices radiating into free-space.
In one embodiment, the plurality of test stations is configured to test earphone devices whilst fitted with a test seal (e.g. sealing cap or sealing grommet) configured to present a high radiation load during a test routine.
In one embodiment wherein the plurality of test stations each comprise a mounting fixture provided both to mount headphones and to provide a mating surface (e.g. sealing surface) configured to provide a high radiation load during a test routine.
In one embodiment, the mounting fixture includes: an ear simulator part defining a passageway leading to an external opening; and an eardrum microphone mounted in the passageway of the ear simulator part. In one embodiment, the mounting fixtures further comprise a head simulator part (e.g. HATS simulator part).
In one embodiment, the earphone test system further comprises at least one monitoring microphone (e.g. at least one array of monitoring microphones) operative to measure the noise field generated by the noise field source.
In one embodiment, the at least one microphone provides observations for a system designated to control or regulate the external noise.
In one embodiment, the uniformity of the noise field generated by the noise field source is monitored by the earphone test system using the at least one monitoring microphone (e.g. by means of at least one array of monitoring microphones distributed along the test array) and adjusted to maintain a predetermined level of uniformity.
In one embodiment, the spectral density of the noise field is monitored by the earphone test system using the at least one monitoring microphone.
In one embodiment, each of the plurality of test stations is operative to communicate with the earphone device to be tested via an interface (e.g. two-way interface) to allow data transmission between the earphone device and the test station during a test/configuration procedure.
Typically, one of each test station/earphone device pairing will include a test module for performing (e.g. rapid) automated testing of the earphone device when mounted on/connected to the test station. Typically, each test module is configured to measure a response of the earphone device to a test pattern reproduced by the noise field source. In one embodiment, each test module is further configured to measure a response of the earphone device to a test pattern reproduced by an electro-acoustic driver of the earphone device.
Each test module may perform one or more of the following the analysing steps: a receiver response check; a receiver polarity check; a plant response check; a plant phase check; a plant fitting check; a gain adjust limit check; a feedback ANR check; an EQ response check; and a balance test.
In one embodiment, each test module is operative to make estimates of electrical and/or electroacoustic transfer functions of the earphone device under test by comparing signals within the earphone device under test.
In one embodiment, each test module is operative to make estimates of electrical and/or electroacoustic transfer functions of the earphone device by comparing a first signal within the earphone device and a second signal external to the earphone device.
In one embodiment, each test module is capable of computing configuration settings for the earphone device under test based on the estimated electrical and/or electroacoustic measurements and/or transfer functions.
In one embodiment, each test module is operative to transmit audio signals to at least one driver of the earphone device/test station pairing and receive measurement signals from at least one microphone of the earphone device/test station pairing (e.g. eardrum microphone of the test station). Typically, each test module is configured to provide a multi-channel output and receive a multi-channel set of responses.
In one embodiment, each test module is configured to store and process received measurements.
In one embodiment, each test module is configured to generate/store one or more pre-generated test pattern operative to produce an input signal to drive the electroacoustic driver of the earphone device.
In one embodiment, each test module is provided as part of the test station and the earphone devices each comprise a test pattern generator configured to generate one or more pre-generated test pattern operative to produce an input signal to drive the electroacoustic driver of the earphone device. In this way, considerable bandwidth/time may be saved since there is no need to transmit the test pattern from the test station to the earphone device during testing.
In one embodiment, the test pattern generator operates according to a deterministic rule known to each test station. For example, the test pattern generator may operate according to a pseudo-random sequence with the method and seed of the pseudo-random sequence being known to each earphone device/test station pairing.
In one embodiment, each test module is connected to a computer network (e.g. local network or extended network).
In one embodiment, each test module is configured to follow a test routine defined by a test routine source component on the computer network.
In one embodiment, the earphone test system is configured to accumulate test results in a central location.
In this way the testing may be observed, controlled and updated centrally (and transparently), ensuring the integrity and security of the testing process.
In one embodiment, the earphone test system further comprises a link to at least one further test module operative to test components or sub-systems from which the earphone devices are assembled. For example, the earphone test system may comprise a link to at least one component-level test module for testing components (e.g. transducers or passive acoustic components) used to assemble the earphone devices or may comprise a link to at least one sub-assembly test module for testing sub-assembly parts (e.g. PCBAs or other completed electronic assemblies) used to assemble the earphone devices. In this way, testing performed at the out-going quality control stage may benefit from information collected during production on the testing of component parts and sub-assemblies which have been used in the assembly of that individual earphone device.
In accordance with a second aspect of the present invention, there is provided a method of testing earphone devices during a production line manufacturing process comprising: providing an earphone test system as defined in the first aspect of the invention (e.g. as defined in any embodiment of the first aspect of the invention); for a first group of earphone devices to be tested: 1) coupling the earphone devices with available ones of the plurality of test stations; 2) exposing the plurality of test stations to the noise field generated by the common noise field source; 3) for each earphone device activating a test routine for testing the earphone device such that at least a phase of the test routine is conducted whilst the test station to which the earphone device is coupled is exposed to the noise field; 4) de-coupling each earphone device from its respective one of the plurality of test stations following completion of at least the phase of the test routine on the earphone device; and repeating steps 1)-4) for a second group of earphone devices to be tested.
In one embodiment the step of coupling the step of coupling the second group of earphone devices to the plurality of test stations is commenced before the step of de-coupling the first group of earphone devices from the plurality of test stations is completed. In this way a continuous process of testing may be achieved.
In one embodiment, the step of activating a test routine is carried out independently for each earphone device.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:
It should be noted that test stations 22 are not simply repeated instances of the system of
Earphone test system 10 benefits from the ability to link to a group of further test modules 100 which are used to test elements from which the earphone devices under test 12 are assembled. The group of further modules 100 may include component-level test systems for the transducers in the earphones under test 12, including multiple instances of speaker test modules 110 and microphone test modules 120 and for critical passive acoustic components, such as multiple instances of earpad test modules 130. Earphone test system 10 may further benefits from the ability to link to modules which are used to test sub-systems from which the earphones under test are assembled, including multiple instances of assembly test modules 140 for testing PCBAs or other completed electronic assemblies. By these means, the testing performed at out-going quality control on a completed earphone device under test 15 may benefit from information aggregated during production on the testing of the component parts and sub-assemblies which have been used in the assembly of that individual sample (as all components and sub-assemblies are traceable). This level of traceability delivers additional benefit in the provision of diagnostic information, particularly in the event of a No-go result, where a unit has to be re-worked.
The distribution of the test functionality, ‘test store’ (150), ‘results store’ (160) and ‘results presentation’ (170) resources from the test computer 3 of the ‘single’ test system of
The structure and functionality of earphone test assembly 20 will now be discussed with reference to
With reference to
In use, the earphone device under test 12 is mounted on the next vacant test station 22, through a handling process 36, after which this unit moves away to begin testing and presents the operative with another vacant station to load the next earphone device.
As illustrated in
In the configuration illustrated in
As the earphone devices 12 move along the test process, they move sequentially into a localised zone 38 in which there is a carefully controlled external localised noise field 39. The noise field is generated by an array of loudspeakers, 29 and is monitored by an array of microphones 40 such that the level and spectral content (and potentially the actual pressure signal itself) associated with the external noise field 39 can be used in the measurements undertaken by the test station since this external field data is known to the test station 22 adjacent to the insonified localised zone 38. The localised noise field 39 in the insonified zone 38 may optionally be turned on and off by the test station adjacent to the speaker array 29.
When the earphone device 12 under test has reached the end of the measurement process (and the end of the ‘conveyor’ system) it is dismounted (e.g. by a manual or automated handling process 41), noting whether it has passed or failed the test.
Earphone device under test 12 is shown in sectional form in
Each of the two sides of the generally binaural device under test has at least one miniature loudspeaker or receiver, 13, which radiates into an acoustic space 14. In the case described above, this space may be partially bounded by the sealing cap 17 during testing. Earphone device 12 includes on each side at least one microphone 15, positioned so as to be sensitive to the pressure in space 14. Earphone device 12 includes on each side a further at least one microphone 16, positioned so as to be sensitive to the sound outside the device and substantially insensitive to the sound in the space 14.
In use, the receiver 13 is responsible for reproducing music and other program material for the end user of the device and for generating active noise cancelling signals. Microphone(s) 15 are responsible for providing the signals to implement ‘feedback’ active noise control, according to methods which are widely understood. Microphone(s) 16 are responsible for providing the signals to implement ‘feed-forward’ active noise control and ‘talk-through’ or ‘monitoring’ features, which are well-known in the art. Microphone(s) 15 may optionally further observe the progress of schemes to optimise the performance of an adaptive implementation of either feed-forward, feedback control, and to the automatic optimisation of other aspects of the electro-acoustic performance of the earphone device.
Each of the test stations 22 in the measurement system disclosed herein has access to the electrical signals associated with the receiver 13, the microphone(s) 15, and the microphone(s) 16 of the earphone device under test which is connected to it. This access is secured by the connection through interface 34.
The present invention does not prescribe any ordering for the test procedure which is imposed upon the earphone device under test. However, in one embodiment, the test system first performs measurements associated with estimation of transfer functions between the receiver drive voltage and the resulting voltage induced at the output of microphone(s) 15. These transfer functions are required to confirm the correct operation of the ordinary receiving response of the earphone device under test and of feedback active control. Such initial measurements take place notionally at the left hand end of
It should be noted that the investigation of transfer functions between internal receiver 13 and the internally sensitive microphone(s) 15 require no external resources. By contrast, investigation of the relationship between the signals associated with internal transducers 13, 15 and external transducer(s) 16 requires that the earphone device under test be exposed in an orderly fashion to a precisely engineered and observed external stimulus. It is the provision of this test regime, in a fashion which is scalable to very high throughput, which is a particular feature of the present invention.
Although the earphone test assembly 20 has been presented thus far with reference to ‘in-ear’ earphone-type devices, it is understood to be suitable for adaptation to the testing of headphones. This is illustrated in
As illustrated in
Similarly, as illustrated in
As illustrated in
Alternatively, the system may be adapted automatically to sort the units into pass/fail groups. This is illustrated in
In view of the spatially extended nature of the earphone test assembly 20, earphone devices under test can be deposited into both pass and fail bins 62, 64 at the same instant, as shown in
The use of mechanically releasing electrical connections and gravity feed into sorting bins, as described above, is appropriate to the overhead ‘conveyor’ embodiment of the present invention. Alternative means of sorting pass and fail devices are immediately apparent to the ordinarily skilled process engineer in the case of embodiments of this new, specialist test system using other transport systems (such as rail- or gantry-based systems, in which switch technologies may be required).
Although the description to this point has disclosed only a single area of insonification by an externally controlled noise field, it is understood that the entire path followed by the earphone devices under test 12 may be made long enough to facilitate the test as conceived by the test designer. Accordingly, as taught in
The present invention allows for any number of zones of external insonification, as required to facilitate testing to the degree of rigor required.
The transport system 30 may advance the earphone devices under test 12 at constant speed or may move in a step-wise fashion, allowing the earphone devices under test 12 to be positioned at known relative location to external fixtures (such as noise sources and drop bins) for fixed intervals.
Having described the novel features of the earphone test assembly 20 in an embodiment in which a transport system 30 is used to secure serial measurement of earphone devices moved individually past a localised zone 38 or zones 38A, 38B of external noise, an alternative approach is now illustrated in
Although this embodiment of the invention has been differentiated from the earlier systems by reference to ‘parallel’ exposure to the external noise field, it is important to emphasise that there is no requirement for the individual test stations 22′ to act synchronously. The start of the individual tests may be entirely asynchronous. The external noise field in this ‘parallel’ mode may also operate continuously. The earphone device under test's own passive attenuation and the averaging used in the signal processing may be used to overcome any noise contamination detrimental to measurement of internal properties of the earphone device.
It is important that each earphone device to be tested experiences the same test, independently of where it happens to be placed on the array. This casts demands on the uniformity of the external noise field, which is monitored by a number of microphones 40′ distributed in the test array, as seen in
Practical provision of the uniform external noise field is possible by a number of alternative approaches.
The first uses a distributed array of loudspeakers 29′ to generate sound, which is fired at the test array, as shown in
The second approach uses a compact source 29″, as illustrated in
A third approach uses a similarly compact source 29′″, but constrains source and test array 80′″ within a reverberant enclosure 90, as illustrated in
In both groups of embodiments of the invention, the external noise field should be substantially uniform across the test zone(s) 38, 38A, 38B, or the test array 80, 80′, 80″, 80′″. This uniformity may tested in use by driving the noise field generator system by a broadband noise source and measuring sound pressure level at any two positions in the zone(s) or at any two feed-forward microphone positions in a populated test array. The accuracy of the measurement system is limited by the differences revealed between the pressures at such test positions. The sound pressure levels at these two test points should ideally not differ by more than 1.5 dB in any ⅓ octave band, between 75 Hz and 3 kHz.
Test patterns may be generated and played on the earphone device under test and input and response communicated back to the test system. The conventional observation of test pattern, and those signals at the input and output of the system-under-test, which the test pattern provokes, places a stringent instrumentation task at the heart of any successful measurement system. The present disclosure manages the impact of this instrumentation task, offering a range of implementations, from simple low-bandwidth solutions up to full, bespoke implementation.
In all cases, the time alignment between input and output data required to permit phase-synchronous transfer function estimation is preserved.
In the case of a transfer function estimation of an individual aspect of the earphone device under test, the input and response signals may be communicated back to the test system as left and right channels of a ‘stereo’ audio link, thereby assuring compatibility with a wide range of audio communication protocols, whilst preserving perfect time synchronisation between input and output signals. This may be performed at standard bandwidth over the audio link between the earphone device under test and test system.
If two transfer functions are to be estimated at once (i.e. left and right sides of a binaural device) then the two tests may be conducted sequentially or the bandwidth requirement over the communication link may be doubled.
Test patterns may be generated on the earphone device under test, which are made according to some deterministic rule, such that it is not necessary to communicate the test pattern back to the test system (as the ‘input’ signal in a transfer function estimation)—merely the response it provokes. Instead, the test system knows the deterministic rule by which the test pattern was generated on the earphone device under test and is able to recreate the same pattern, saving the time and bandwidth required to communicate it. Such rules include those governing the generation of maximum length sequences, etc. (Many other long limit-cycle automata would form suitable candidates).
Suitable test signals may be generated inside the earphone device under test using a linear-feedback shift register to generate a pseudo-random sequence (or other equivalent methods). These numerical sequences may be further conditioned before use by the application of (e.g.) filtering means to ensure an appropriate disposition of energy over frequency. Such filtering means may be applied by conventional filtering strategies, particularly those which are easily supported on the processing means available within the computational resources available on the earphone device under test. Further conditioning of the numerical sequence may be used subsequent to generation and before its use as a test pattern. Such conditioning might include processing to modify the amplitude distribution of the signal (compression or limiting etc.).
Classes of measurement in which internally-generated test patterns are important include the characterisation of receiving response of an active earphone device (i.e., the relationship between the applied audio signal and the resulting pressure developed inside the earphone device) which has onward implications for the implementation of feedback active control measures on the earphone device under test.
Transfer functions may also be estimated between signals on the earphone device under test, which are provoked by external excitation. In such cases, the input and response may be communicated back to the test system as left and right channel of a ‘stereo’ audio link, thereby assuring compatibility with a wide range of audio communication protocols, whilst preserving perfect time synchronisation.
An important class of such externally excited measurements are associated with characterisations of sound transmission over the earphone device under test for the purposes of understanding passive attenuation, feed-forward active noise control and ‘monitoring’ or ‘talk-through’, in which the external excitation is provided by an external sound field.
The system of the present invention comprises the following sets of functionality:
Additionally there are further characteristics of the present system which make it attractive in a manufacturing context:
The system of the present invention scales to bring throughput to high volume levels by testing a plurality of earphone devices in parallel. Here are the steps that an operator would take in testing a quantity of earphones devices in parallel:
2. Unlike currently deployed SSPs no error label is generated. A red indicator light at the end of the test indicates a failure. Failed HUTS are simply placed by the operator in a red bin and transferred to the repair station as they would be in instances of failure at other places on the production line. At the repair station, the engineer connects the earphone to an installation of Mission control and receives the test and repair history, the measurement data, and a root cause estimation of the headphone under repair by referencing the UUID stored in the headphone.
The diagram is segmented along the horizontal into three physical areas:
This is a standard network component with the following ports opened: SSH (TCP 22). HTTP (TCP 80), HTTPS (TCP 443), NTP (UDP 123—bidirectional). The NTP port can be removed in the case of Topology Variant Three where it is replaced with a private NTP server synchronized with GPS within the trusted zone of the Network.
An example of a suitable Firewall is the Cisco ASA5512-KS ASA 5512-X (which integrates a Firewall and 6-port Router).
Router
This is a standard network component connecting each 8 bit subnet to the WAN via the Firewall.
An example of a suitable Router is the Cisco ASA5512-KS ASA 5512-X (which integrates a 6-port Router and Firewall).
Switch
This is a standard network component that creates each of the subnets present at each Manufacturing Production Line. Each subnet contains the following networked components:
up to 250 Headstands;
an Ambient Noise Field Generator;
a Monitor.
Each subnet tests one Headphone product type
Note that the Switch element shown in the diagram, may in reality be a hierarchical structure of switches and aggregate switches depending on the number of Headstands within the subnet.
An example of a suitable switch is the Cisco SF300-48PP 48-port 10/100 PoE+ Managed Switch.
Monitor
This is an optional, non-interactive component within a subnet. It provides a view into the performance of the subnet that is useful for production line managers and quality assurance staff:
a real-time status display of all test stations in the subnet including:
No configuration of the Monitor is required as the software running on the Monitor is able to scan the subnet for other components within the Network and to calibrate the display according to the number and type of components discovered.
Implementation of Monitor consists of a standard embedded computation hardware connected to the subnet and an HELLO monitor. Software running on the unit scans the subnet for expected devices by attempting to receive a response to the HELLO API command from each possible device at 192.168.m.0-192.168.m.255 (where m is known by the Monitor since the Monitor knows its own IP address). Once each subnet device has been identified, the monitor subscribes to each device's status log (an asynchronous stream of status updates emitted by each device) by opening a standard Websocket connection to each device. (See Status Log below).
Like other networked devices within the subnet, the Monitor also implements the following software components to enable identification, configuration, monitoring, and control: a) API Server; b) Status Server; c) Log Server.
Ambient Noise Field Generator
An ambient noise field used in testing is generated by this component. Similar to a test station, the Ambient Noise Generator runs the following software components—a) API Server; b) Status Server; c) Log Server.
The properties of the noise field are stored within non-volatile memory within the device and are configured by loading a test into the device at time of deployment via the API Server. The API Server (see below for more information) also responds to HELLO API commands to enable the Monitor to identify the presence of an Ambient Noise Field Generator on the subnet.
VARIANT FIVE: Ambient Noise Field Generators scan the subnet for test stations, then subscribe to each test station status log. When there is at least one test station requesting a noise field the generator automatically starts emitting noise. The noise field is automatically deactivated when the status logs of each test station advise that no test station requires a noise field.
VARIANT SIX: As an alternative where test stations are mounted in such a way as to pass by the external noise field, the test station detects the proximity to the noise field and issues the noise field request via the status log.
Control Station
The Control Station is a native software running on Windows that provides users with:
Note that the Control Station has no direct contact with the production equipment deployed on the production line. All communication that configures, controls, and monitors production is between the Control Station and the Data Warehouse and Analytics Infrastructure via the Administrator API (see below); this simplifies and therefore strengthens security.
NTP Server
Encryption used to communicated across the untrusted zone, as well the application of a correct timestamp to test results, requires that all test stations in use maintain an accurate time. An NTP server is a standard piece of Internet infrastructure that provides this capability. A publicly available NTP Server can be replaced by a private NTP Server within the trusted zone at each Manufacturing Production Line site. One such equipment is the Meinberg LANTIME M300 https://www.meinbergglobal.com/english/products/rack-mount-1u-ntp-server.htm
Result Inbox
The Result Inbox is a repository of test results. Each test station's Result Uploader component (see below) moves its locally cached test result data into this repository. The repository is write only to protect against nefarious users attempting to steal information regarding the products and tests of other products.
When each test result arrives in the Result Inbox, a new On Demand Compute Service starts to process the test result (see below). Processing each test result includes:
Control and configuration capability is exposed by the Administrator REST API. The principle client utilizing the API is Control Station although command line clients are also used primarily where batch processing or automation is required such as for administration tasks.
Each request from a client includes.
A request received by the API gateway spawns an On Demand Compute Services (see below) to action the request and to provide a response to the client. The spawned compute service first authenticates the client making the request and second determines whether the client is allowed to perform the action with the parameters required. Valid requests are then actioned by the compute service. All requests return a synchronous response to the client. All actions are logged:
Clients Users will sometimes need to receive information asynchronously. One example of this is the case where a Control Station makes a configuration update to a test station. This configuration change should appear to happen on the test station immediately. Another example is a client monitoring the status of a piece of equipment, status messages can update rapidly and this should be reflected on the monitoring client in real time.
Each client has its own message queue in the Message Outbox. System components wanting to update clients, post messages in client message queues Running clients connect to their message queues when they start and receive messages posted there in their order of posting. Messages may be posted with different timeouts depending on the message. A message that times out is removed from the queue even if the client has not received the message. Informational messages such as status information are only useful when they are consumed within a short time of posting; these messages are posted with short timeouts. Configuration information is always valid and these messages are posted without timeout.
Authentication and Authorization
Each client is assigned a universal identifier that doubles as both a means of identifying the client, as well as a cryptographic key to sign all interactions with the Data Warehouse and Analytics Infrastructure. This ensures that requests arriving from clients are genuine and untampered with.
Clients are only authorized to operate under the following conditions:
Results arriving from test stations in the Results Inbox spawn On Demand Compute Services to process the result data. One of the actions performed by this processing is to update the Dashboard Store. The Dashboard Store contains pre-processed summary information ready to display in a dashboard format. Clients requesting dashboard data request data directly from the Dashboard Store: no processing of result data is required as this would be prohibitively arduous in cases where millions of data sets needed to be processed in order to return the summary data.
Data are stored in a simple key-value database optimized for scalability One of the problems associated with collecting summary data in this form, when using a database of this type, is that there are no guarantees that the results arrive and/or are processed in chronological order Network and/or test station outages, as well as the highly parallel structure of the system, mean that no guarantee to the ordering of result data can be assumed. Additionally, since it is likely that multiple writes to the store are taking place at any given time there may be no dependencies between data sets and all updates to the database must be atomic. These real-time and parallel processing requirements place a restriction of the type of data that can be collected, how they are processed, and how they are stored.
The data maintained includes:
Results arriving from test stations in the Results Inbox spawn On Demand Compute Services to process the result data. One of the actions performed by this processing is to move the result data out of the Result Inbox into a permanent storage location.
The result data is moved to the Result Store unchanged as it arrives from the originating Headstand. The result data is indexed by the Result Index (see below).
Result Index
Result data in the Result Store is indexed by this component as part of the processing initiated by new result data arriving in the Result Inbox. Indexing allows raw result data to be quickly located among multiple-millions of results. The component compiles the following indices where the first in the pair is the primary key, and the second in the pair is the secondary key and each entry points to a result in the Result Store (hyphen separation of keys denotes concatenation):
Tests are defined by a set of data. Tests are stored in this component and made available to test stations for configuration.
Log Store
The system is modified by requests to the Administrator REST API. Changes to the system are logged to this component. Specifically, the following system changes are logged:
An On Demand Compute Service is spawned asynchronously to execute a function in response to some defined event. The system employs On Demand Compute Services from three different event types:
Existing solutions to connect test systems to earphone devices under test incorporate special purpose, multi-pin connectors. These connections normally entail a separate connector be employed on the PCB for the sole purpose of testing. This adds cost to the product and because product designers are looking to avoid exposing the test interface to consumers, the means to connect the earphone device under test are often clumsy and slow in a manufacturing context with operators often needing to feed ribbon cables into the earphone device.
The solution to this problem is to employ the same physical interface as used by the consumer. This reduces the material cost of the earphone device and ensures a mechanically robust solution that is fully exposed to the operator during manufacturing.
The problem however with taking this approach is that an interface for consumer electronics is not always suitable to an interface for testing. In the below we present a solution to this problem that enjoys the benefits of using the consumer interface, while maintaining a set of requirements that are unique to the testing of noise cancellation earphones.
The two connectors used by consumers in earphone applications are: a) 3.5 mm audio connector; and b) USB-C connector.
Physical Interface
VARIANT SEVEN. The earphone device under test has a USB-C connector and receives analogue audio.
The test station is connected to the earphone under test by a USB-C cable.
The test station detects that the earphone device only receives analogue audio by using the standard USB-C means as per the USB-C Specification Appendix A The test station responds by switching the SCK and SDA signals mentioned below onto the Dn1 and Dp1 lines respectively of the USB-C cable.
VARIANT EIGHT: The earphone device under test has a 3.5 mm audio connector.
The test station is connected to the earphone device by a USB-C to 3.5 mm patch cable. (test station has USB-C receptacle, earphone has 3.5 mm receptacle). The wiring of the patch cable is described in the USB-C Specification Appendix A. The test station switches SCK and SDA signals on the Dn1 and DP1 lines of the USB-C cable.
VARIANT NINE. The earphone device under test has a USB-C connector and implements a digital USB interface.
The test station is connected to the earphone under test by a USB-C cable. The test station detects by using the normal USB-C means that the earphone under test is capable of receiving an Alternative Mode specific to the purposes of testing noise cancellation earphones. The earphone device performs the standard USB-C handshake to setup the Alternative Mode and then places the SCK and SDA signals on any two of the re-assignable pins available to devices implementing an Alternative Mode.
In all three cases the protocol of communicating between the test station at the earphone device is the same. The above three variants exist only as alternative means of establishing a signalling path between the test station and various earphone devices.
Noise Cancellation Device
As described above only two signals are allocated to digitally communicate between the test station and the earphone device under test. The reason for this is simplicity in the implementation of a test solution across the variety of earphone device classes listed in the above section.
The earphone device incorporates a noise cancellation device that utilizes a standard SPI (Serial Port Interface). The SPI is a four-connector interface. In order to be able to use this interface over the two connector cable the following circuit-level changes are made:
In the case of Variant Seven or Variant Eight where the input signal to the earphone device is an analogue signal, the earphone device design has two possibilities:
In both cases the Dn1 and Dp1 signals are also connected to the SCK and SDA inputs on the noise cancellation device. The noise cancellation device detects the presence of the digital test interface signals on these pins identifying them as digital signals and not analogue audio and the noise cancellation device internally disconnects its digital audio input pins. This identification takes place as either a simple initial line-level detection, the recognition of a burst of known digital signalling on these lines, or a combination of both.
Additionally, the noise cancellation device incorporates the means to generate digital FIR filtered pseudo random stimulus signal that can be configured via the same means that other aspects of the device are configured such as the reading and writing to registers within the device. Configuration parameters for each stimulus signal allow:
The above physical interface is sufficient for the two-way communication between the test station and the earphone device under test because
Note that during a test the earphone device must in this example be capable of writing a minimum of 3fs 16-bit samples per second (minimum), 6fs 16-bit samples per second (reduced test time) assuming a worst case receiving response measurement requiring three signals per channel plus overhead. “Overhead” is a one byte identifier placed ahead of each sample to indicate the source of the sample.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1607168.0 | Apr 2016 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2017/051067 | 4/18/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/187136 | 11/2/2017 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5400406 | Heline, Jr. | Mar 1995 | A |
| 6232785 | Kelsey | May 2001 | B1 |
| 10045128 | Shennib | Aug 2018 | B2 |
| 20140146973 | Liu | May 2014 | A1 |
| 20190037324 | Darlington | Jan 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 103248766 | Aug 2013 | CN |
| 1865746 | Dec 2007 | EP |
| 2728906 | May 2014 | EP |
| Entry |
|---|
| International Search Report and Written Opinion in corresponding International Application No. PCT/US2017/051067, dated Jul. 21, 2017, 12 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20190153830 A1 | May 2019 | US |
