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Document Feedback 

AS3460 

 

 

ANC Tuning Guide 

 

 

Demo Kit Manual 

• PUBLIC 

 

UG000480 

• v3-00 • 2021-Nov-08 

126

 

│ 60 

 

 

6.1.4 

Performance Evaluation 

Stability Testing 

The next step after loading the new filter to the chip (“Write to AHE”) is to test whether this filter is 
stable in all use cases. An end-user should never experience howling sounds in his ear or feel that the 
earphone is causing a pressure sensation (this would be due to low-frequency overshoots). Also the 
ANC-system should behave normal when confronted with high SPL sounds. The following list gives a 
hint of what tests can be conducted to evaluate the ANC-

system’s stability: 

Figure 80: 
Test to Evaluate ANC-System Stability 

Stability Issue 

Test 

Too much low frequency gain 

● 

Listen for pressure/pumping sensation 

● 

Listen with low frequency test sounds 

● 

Inside of driving car 

Filter close to being unstable 

(might become unstable on a different sample) 

● 

Cup speaker or microphone with hand 

● 

Close speaker opening 

● 

Press on speaker 

● 

Listen for resonant frequencies 

High SPL sensitivity 

● 

Slam a door next to the headphones 

● 

Playback music, press on the ear cup while 
wearing the headphones and listen for 
stuttering 

 

Performance Test 

ANC-Performance can be measured as described in the App-Note on ANC-Performance measuring, 
but it is also important to verify that the measured performance correlates with the simulated 
performance. If this is not the case it could be that the characterization measurements were not 
calibrated correctly, or that the headphone’s fit to the measuring device is not reproducible exact 
enough. 

Also it should be tested if the subjective performance is matching the measured performance. A good 
test environment is to play back pink noise on full range speakers. 

Содержание AS3460

Страница 1: ...User Guide UG000480 AS3460 Digital Augmented Hearing Demo Kit AS3460_EVALUATION_BOARD v3 00 2021 Nov 08...

Страница 2: ...Coefficients 50 6 ANC Tuning Guide 56 6 1 Feedback 56 6 2 Feed Forward 61 6 3 Example 62 7 ALC Tuning Guide 66 7 1 Introduction 66 7 2 Overview 66 7 3 Measuring ALC Headphones 67 7 4 Project Setup 70...

Страница 3: ...digital signal processor AHE supports up to 250 Bi Quad calculations to ideally match the requirements of todays sophisticated acoustics designs and small form factors Unique digital signal processor...

Страница 4: ...0 2021 Nov 08 126 4 FleX Filter Design Tool This tool allows customers to design filters for the AS3460 ANC device Figure 2 FleX Filter Design Tool Software 1 2 Ordering Information Ordering Code Desc...

Страница 5: ...e sure that you have connected the AS3460 Evaluation Board to your PC before you install Flex Software the first time This is mandatory for proper device driver installation 2 1 Hardware Setup To use...

Страница 6: ...first PDM interface selecting on the rising clock edge DMIC1R is the microphone synced on the falling edge Figure 4 Minimal Routing Configuration 2 3 Measurements Calibration Next is loading the XLS f...

Страница 7: ...g on the dots symbol on each line Figure 5 Measurement Sets Depending on the measurement setup it will be necessary to calibrate the measurements To do so click on the eye symbol next to the affected...

Страница 8: ...speaker or reference microphone since their impact cancels out in the calculations 2 4 Simulation Window The simulation window consists of three plots the first two comprise a Bode plot In the Bode pl...

Страница 9: ...nside plot Reset view Click Hold Drag plot 2 5 Filter Tuning For tuning both a feed forward and a feedback system FleX offers intuitive tuning of predefined filters For successful filter design it is...

Страница 10: ...e 10 Shelf Furthermore there is an Allpass filter and a 1st order x2 and you can also import biquad coefficients into Flex so you can load all types of filters with that Adjustable frequency Gain And...

Страница 11: ...mpleting a filter tuning the filter can be activated on the AS3460 by clicking Write to AHE 2 6 Tooltips Within the Flex Software there is an extensive documentation of the features via Tooltips Just...

Страница 12: ...ault Jumper Setting The Evaluation Board has default jumper settings which are marked in the color Orange below Figure 12 Default Jumper Configuration Figure 13 Table Default Jumper Configuration Desi...

Страница 13: ...ov 08 126 13 3 2 Power Supply There are three different options to supply the hardware Figure 14 Different Supply Options The schematic drawing describes the different supply options which can be chos...

Страница 14: ...er 5 V USB Connector on the Raspberry Pi Board Ensure that the USB port of the PC is USB 3 0 This setting will be the standard configuration setting on the board Figure 16 Select Supply Power Pin 5 V...

Страница 15: ...wer supply 3 3 V 5 V or with a Li Ion Battery which can be connected to the External Supply headers or connectors Figure 18 External Supply headers and connectors The schematic below shows the externa...

Страница 16: ...Option 3 Li Ion Battery The Evaluation Board can be powered via a Li Ion Battery which can be soldered on the bottom side of the PCB There are two solder pins called LI ION Battery Connection Bat 1 B...

Страница 17: ...in LI ION Bat Pin Please see jumper setting in Figure 23 below Figure 23 Select Supply Power Pin to LI ION Bat At the PMU Power Management Unit section there is a charger assembled which provides the...

Страница 18: ...anual PUBLIC UG000480 v3 00 2021 Nov 08 126 18 Figure 25 Measurement Pins Power Pin and DCDCs There are also measurement pins of the DCDC below the Raspberry Pi PCB Power Pin 3 3 V DCDC to 3 3V and Po...

Страница 19: ...d pop noise when shutting down the device completely Connect the power supply to the board choose one of the three options mentioned above To enable the AS3460 on the evaluation board the Enable AS346...

Страница 20: ...the board These LEMO connectors are used for all ams reference designs reference earbud demonstrators Figure 28 Headphone Connectors The LEMO connectors can be soldered on the evaluation board For so...

Страница 21: ...I2S input and two stereo output channels In addition the AS3460 Evaluation Board has a Line Input ADC Connector 3 5 mm audio jack connectors and headers for music playback Figure 30 Line Input Connect...

Страница 22: ...ration modes of the device the microphone is not needed Furthermore it is possible to invert the clock output to improve the EMI interference in an application The integrated oscillator and PLL do pro...

Страница 23: ...a input Furthermore additional multiplexers are available to feed back any microphone signal from any input channel to the I2S 0 and I2S 1 interface Figure 34 Digital Microphone Headers The schematic...

Страница 24: ...3460 Evaluation Board Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 24 Figure 36 Clock Buffers The schematic below shows the used buffers and the pin configuration of these parts Figure 37 Sch...

Страница 25: ...ich are application dependent and not part of the device firmware The interface requires two pull up resistors for proper operation The two interface pins SCL and SDA do support a wide supply voltage...

Страница 26: ...s function allows sharing for example the ANC microphones to be used as voice call microphones In order to be synchronous to the host the audio data is synchronized via a second four channel ASRC2 to...

Страница 27: ...ards Left Justified I2S The I2S connection highlighted I2S Selection gives the option to connect the I2S pins of the AS3460 to the ADC for music playback or to the Raspberry Pi Board Figure 41 I2 S Se...

Страница 28: ...ion Schematic Besides the button input function an I2S stereo output can also be mapped to any of the GPIO pins of AS3460 Please also mind that due to the integrated GPIO multiplexer any button or I2S...

Страница 29: ...Feedback AS3460 Evaluation Board Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 29 Figure 45 Measurement Header Pinout of the measurement header J300 is shown below Figure 46 Measurement Heade...

Страница 30: ...Figure 47 AS3460 IC with External Components on Evaluation Board The zoom in picture displays the AS3460 IC with the passive components capacitors and resistors around in detail Figure 48 Zoom in AS3...

Страница 31: ...ne via soldering the 0R resistors to the corresponding footprint The standard configuration of this Evaluation Board is the following VDDPA 1 8 V R1 VDDC 1 8 V R16 VANA 1 8 V R2 VDDIO 1 8 V R6 Figure...

Страница 32: ...e of a single sided PCB Figure 51 Table PCB Area Calculation Single Sided PCB Component Description Component Count Footprint INCH PCB Area Total mm2 AS3460 ANC companion device 1 AS3460_BGA36 10 240...

Страница 33: ...Board PCB layout recommendation for the AS3460 shown in Figure 50 and Figure 52 is given below Figure 52 PCB Area Calculation Single Sided PCB It is recommended to use a four Layer PCB to route all p...

Страница 34: ...ch provides the necessary supply voltage for the DAC and headphone amplifier The integrated regulator allows AS3460 to be supplied directly with a DCDC converter maintaining highest audio quality leve...

Страница 35: ...ignal lines for headphone wires and for the supply A weak signal line on any of these connections can influence channel separation of the device The ground pins of the AS3460 IC and the external compo...

Страница 36: ...As already mentioned above it is important to put the coupling capacitors as close as possible to the supply pins Figure 57 PCB Layout Top Layer All Pins Routed Ensure that the digital signal paths d...

Страница 37: ...Document Feedback AS3460 PCB Design Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 37 Figure 58 PCB Layout Signal Layer 1 All Pins Routed Figure 59 PCB Layout Signal Layer 2 All Pins Routed...

Страница 38: ...Document Feedback AS3460 PCB Design Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 38 Figure 60 PCB Layout GND Layer All Pins Routed...

Страница 39: ...NG PLANE 0 10 C B A 0 10 C A B 0 10 C 0 9 0 1 0 08 C C 0 45 0 260 0 04 0 18 0 05 0 15 C B A C 0 05 0 40 0 500 0 500 0 40 2 00 2 00 3 00 3 00 NOTES 1 THE DIMENSIONS IN PARENTHESIS ARE REFERENCE 2 ALL D...

Страница 40: ...here are several filter types Some filter stages are fixed in the system while others stages can have different filter types and can be bypassed Filter Controls The filters can be controlled by either...

Страница 41: ...AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 41 High Pass Figure 63 High Pass 3dB at cutoff frequency 6dB per Octave below cutoff frequency From 90 to 45 at cut...

Страница 42: ...dback AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 42 Automatic Gain Control AGC Figure 64 Automatic Gain Control Limiter with adjustable threshold attack and r...

Страница 43: ...al PUBLIC UG000480 v3 00 2021 Nov 08 126 43 Downsampler Lowpass Figure 65 Downsampler Lowpass Four filter types LowpassX1 LowpassX2 Chebyshey Butterworth Available settings and frequency response depe...

Страница 44: ...Feedback AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 44 Gain Figure 66 Gain Gain of up to 24 dB Inverting provides a phase shift of 180 without affecting the a...

Страница 45: ...Document Feedback AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 45 Shelf Figure 67 Shelf 6 dB per Octave until specified gain was reached...

Страница 46: ...0 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 46 Peak or Notch Figure 68 Peak or Notch Specified gain at center frequency Adjustable Q Factor or bandwidth 0 phase shi...

Страница 47: ...dback AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 47 Low Pass Figure 69 Low Pass 6 db per octave above cutoff frequency 0 to 45 phase shift at cutoff frequency...

Страница 48: ...Document Feedback AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 48 Allpass Figure 70 Allpass Used for phase optimizing...

Страница 49: ...Document Feedback AS3460 FleX Filter Description Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 49 1st Order x2 Figure 71 1st Order x2 Combines 2 first order filter...

Страница 50: ...imported into FleX as biquad The term biquad is equivalent to the term second order section Each biquad has 6 floating point coefficients one of which a0 is normalized to 1 0 Option to import biquad c...

Страница 51: ...icient a0 1 0 A constant value always equal to 1 0 a1 2 0 2 0 The first feedback coefficient a2 2 0 2 0 The second feedback coefficient 1 The coefficients for a single biquad second order section 2 Th...

Страница 52: ...ab Examples for importing multiple biquad filters are given in Section 3 5 2 2 Data Format Requirements for the data in the file containing biquad coefficients are as follows The coefficients will be...

Страница 53: ...t formats are shown below 2 61652695e 04 5 23305390e 04 2 61652695e 04 1 0 1 95372795e 00 9 54774560e 01 0 02162072 0 04324144 0 02162072 1 1 54312113 0 629604 Low pass at 10kHz 0 99768867 1 99537735...

Страница 54: ...C UG000480 v3 00 2021 Nov 08 126 54 5 2 3 Examples Multiple Biquad Import Example 1 Figure 76 Import Example 1 Import example where there are 4 Biquad Coefficients controls and 4 sets of coefficients...

Страница 55: ...PUBLIC UG000480 v3 00 2021 Nov 08 126 55 Multiple Biquad Import Example 2 Figure 77 Import Example 2 Import example where there are multiple Biquad Coefficients controls in a row but there are more s...

Страница 56: ...rophone is positioned inside the ear cup next to the speaker The microphone is sensing the noise coming from outside already damped by the passive attenuation of the headphone cup Also the microphone...

Страница 57: ...as much as possible to ensure stability Since the phase and gain of a filter can generally not be controlled separately it is not a trivial task to find the optimal filter Additionally the DFBM trans...

Страница 58: ...erformance where the maximum achievable performance is a property of the headphone s acoustics A large speaker will have a better low frequency response allowing to bring down the phase at a lower fre...

Страница 59: ...v 08 126 59 2 3 4 5 1 2 3 4 5 High Pass Prevent instabilities in the infrasound region Low Shelf Boost low frequencies to match phase Peak Make gain where filter phase is 120 from ideal phase Notches...

Страница 60: ...ten with low frequency test sounds Inside of driving car Filter close to being unstable might become unstable on a different sample Cup speaker or microphone with hand Close speaker opening Press on s...

Страница 61: ...hones it would give perfect noise cancellation In the real world it is not possible to obtain a perfect replication but it is possible to create an electrical or digital filter that can match magnitud...

Страница 62: ...mportant to evaluate the target curve for several samples and fits to know what parts of the transfer function a reproducible and should be taken into account for the filter design and what parts chan...

Страница 63: ...Document Feedback AS3460 ANC Tuning Guide Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 63 Figure 82 Example part 1...

Страница 64: ...Document Feedback AS3460 ANC Tuning Guide Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 64 Figure 83 Example part 2...

Страница 65: ...Document Feedback AS3460 ANC Tuning Guide Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 65 Figure 84 Example part 3...

Страница 66: ...d the Flex manual and the evaluation kit handbook 7 2 Overview The whole complex ALC algorithm can be split in several sections and sub algorithms there is the basic feed forward ANC adaption a feedba...

Страница 67: ...leakage for loose fit or 8mm for sealed fit headphones Examine these measurements regarding the isolation between speaker and feedback microphone The gain difference of the driver response at the drum...

Страница 68: ...asstube resonance The basstube helps to maintain a good low frequency response at high leakages In addition you can check the isolation of the feed forward microphone from the speaker Figure 87 Driver...

Страница 69: ...leak i e it should sit in the ear quite loosely but still secure enough to not fall out and thereby representing the highest realistic leakage at which a user might wear the earphone The algorithm wor...

Страница 70: ...and the lowest leakage with equal spacing Although the filter tuning in Flex is based on tuning only two filter sets one for the lowest and one for the highest leakage case it is necessary to have mea...

Страница 71: ...both because a specific version of Flex will only be compatible with the correct backend and firmware All versions of Flex are capable of up or downgrading the firmware and backend as required Once u...

Страница 72: ...e attenuation and music equalization However all required calculations and simulations are based on the feed forward and feedback microphone responses A2FF A2FB and D2FF D2FB This works because when f...

Страница 73: ...Document Feedback AS3460 ALC Tuning Guide Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 73 Figure 91 Recommended Folder and File Structure Figure 92 Measurement Data Import...

Страница 74: ...lab setup we use an AudioPrecision device set to 20dBV output level and an 0dB gain headphone amplifier therefore the gain offset amounts to 20 dB Since you will probably perform all measurements wit...

Страница 75: ...bottom port as the feedback microphone it will be necessary to invert the microphone signal before it enters the algorithm You can do this in the routing tab Because of this you will need to also inve...

Страница 76: ...ode To do so turn off the Support Algorithm in the startup settings and select only preset 1 on startup Figure 94 Example Routing Settings for Starting an ALC Project Note For testing on the EVK it is...

Страница 77: ...l filters in all presets except for the low leakage feed forward filter and tune this filter to match the target The tuning of course heavily depends on the headphone s acoustic properties A typical c...

Страница 78: ...n write the program to AHE and evaluate the ANC performance Before putting the earphone into your ear please check that it is stable and that e g when placing the earphone in a cupped hand it does not...

Страница 79: ...y and high frequency overshoot is within acceptable levels and if different people experience the same ANC performance With regular listening setups it can be hard to spot a low frequency overshoot We...

Страница 80: ...gains for maximum noise cancellation adapts the gains to zero or the maximum check if the settings in the routing tab are correct In this case it is likely that an inverted driver or inverted micropho...

Страница 81: ...ithm adaption speed control if improving the filter design did not improve the adaptions speed Turning up the algorithm adaption speed control too much will lead to a nervousness of the noise cancella...

Страница 82: ...ities still occur you can tune its sensitivity in the FF stabilizer section of the ALC configuration Use the pre defined watchers eye symbol at FF stabilizer then click on the eye symbol of Flex s top...

Страница 83: ...sub algorithm which manages the influence of the feedback noise cancellation on the feed forward noise cancellation This will only work properly once the music compensation has been tuned therefore it...

Страница 84: ...corresponding watchers FB Stabilizer Watcher Preset fb_hl_gain fb_ll_gain There you can observe the instability metric during a push in and then set the attenuation threshold so that the stabilizer re...

Страница 85: ...resonance will likely be at 1 to 2 kHz and it will be more obvious less damped Your setting of this adaptive peak filter serves only for the simulation and will be overwritten by the auto adaption On...

Страница 86: ...speaker and if you intend to perform the measurement in your ear instead of the ams leakage adapter to avoid hearing damage The music response checker will require a WAVE file containing white noise n...

Страница 87: ...ots show the two driver responses and the bottom plot shows the difference between them Typically the driver response difference between ANC on off will not be noticeable if it is less than 2 dB Repea...

Страница 88: ...e feedback ANC and at different leakages monitor the noise cancellation attenuation and note at which value it stabilizes Set the noise cancellation effectiveness threshold 1 75 of this value Threshol...

Страница 89: ...grates with the adaption algorithm therefore settings such as time constants are governed internally Adjust the Near clip threshold to control the level onset of gain adjustments Below this threshold...

Страница 90: ...w filter stage denoted Special will then appear in the tuning tab at the end of the feed forward filter chain You can then try to run the auto adapt function However if the process times out with the...

Страница 91: ...nual PUBLIC UG000480 v3 00 2021 Nov 08 126 91 8 Dual Chip Operation 8 1 How to Operate in Dual Mode 8 1 1 Basic Setup Connect the 2 boards as shown in Figure 103 The board with the GPIO A0 pulled high...

Страница 92: ...Dual Board Configuration The drop down menu in the connection tab can be used to manually switch between the 2 chips When using Flex in dual mode one of the Dual Chip items must be selected Remove I2...

Страница 93: ...e 104 Dual Chip Address Both chips must be set to AHE Mono mode When Dual mode is selected it is also shown in the AHE Mode selector Figure 105 Dual Mono Mode in Flex Depending on the selected channel...

Страница 94: ...re 106 Left Right Selection Note Only the filter parameters are synchronized with the L R selector when writing to AHE The routing and all other chip settings are written to the currently selected chi...

Страница 95: ...flip the left and right I2S music input channel This feature will be needed if 2 AS3460 in mono mode are connected to e g 1 stereo Bluetooth device Because the AS3460 in mono mode is always using the...

Страница 96: ...nt Feedback AS3460 I2S Swap Function Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 96 If 2 chips are connected the swap function will be stored to each chip separately TDM will swap channels 0...

Страница 97: ...ection APS Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 97 10 Automatic Preset Selection APS 10 1 How Does Automatic Preset Selection APS Work 10 1 1 Basic Functionality of the APS Algorithm...

Страница 98: ...Document Feedback AS3460 Automatic Preset Selection APS Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 98 Figure 110 APS Algorithm...

Страница 99: ...band where the most energy of the noise signal is located Base for the calculation of in which band the most noise cancellation is done is the simulation The algorithm looks for the dominant signal i...

Страница 100: ...Example 10 1 2 Selectable Presets You can select if the algorithm switches between 2 3 or 4 presets The Algorithm automatically detects which frequency band is corresponding best to the filter that wa...

Страница 101: ...the ALC Hybrid Topology 10 2 Using APS in Flex APS can be activated and controlled via the APS Tab in the Configuration Tab Note The Enable support Algorithm Bit must be activated to run APS Figure 1...

Страница 102: ...xceeded before switching presets HoldTime 0 5 1 0 10 0 seconds The time after entering a new preset when the algorithm can consider changing preset Band weighting 1 60 0 0 0 0 dB Manual weighting for...

Страница 103: ...gy Figure 116 Opening APS Example Project 10 3 2 Load Frequency Response with All Zeros For this step you need the Excel File with zeros at all frequency steps and at all phase steps ALL_zero xls you...

Страница 104: ...Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 104 In the end it should look like this Figure 117 APS Example Project Tab 10 3 3 Routing In the routing tab please route DMIC1L to FF Left and DM...

Страница 105: ...8 APS Example Routing Tab 10 3 4 Tuning In the Tuning Tab we now prepare the 4 presets so that we can use it afterwards for the Automatic Preset Selection APS Preset 1 In Preset 1 apply a Peak Filter...

Страница 106: ...Document Feedback AS3460 Automatic Preset Selection APS Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 106 Figure 119 APS Example Preset 1...

Страница 107: ...Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 107 Preset 2 In Preset 2 apply a Peak Filter with a Q of 2 00 to a frequency of 100 Hz with the gain of 1 dB This creates a noise cancellation at...

Страница 108: ...Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 108 Preset 3 In Preset 3 apply a Peak Filter with a Q of 2 00 to a frequency of 300 Hz with the gain of 1 dB This creates a noise cancellation at...

Страница 109: ...emo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 109 Preset 4 In Preset 4 apply a Peak Filter with a Q of 2 00 to a frequency of 1400 Hz with the gain of 3 dB This creates a noise cancellation at...

Страница 110: ...ault values just press the Default button before activating APS Figure 123 APS Example Start Algorithm 10 3 6 Testing the APS Algorithm If you now feed a sine signal with 30 Hz 100 Hz 300 Hz or 1000 H...

Страница 111: ...icial head like the GRAS 45 To ensure a good measurement outcome following points have to be controlled The earbud has to have a good sealing in the coupler Leakage during measurement has to be avoide...

Страница 112: ...l PUBLIC UG000480 v3 00 2021 Nov 08 126 112 The Audio Precision Templates provide the following output files D2E D2FB D2FF A2E A2FB A2FF A2E Open remove headphone earbud from measurement equipment The...

Страница 113: ...for all acoustic leakage conditions It is necessary to characterize 5 different leakage conditions to cover the whole acoustic leakage range that can occur when people wear the headphones 12 1 Charac...

Страница 114: ...the holder with acoustic putty such that acoustic leakage is only introduced by the leakage spacer The AP_ALC_Template_UCU approx AP template provided by ams should be used here The template will gene...

Страница 115: ...ll be compensated is physically limited by the acoustics of the headphone and the speaker that is used As a rule of thumb the difference between lowest and highest leakage should not be more than 25 d...

Страница 116: ...and for the highest leak the fit should be loose but not too loose D2E approx 20 dB below lowest leak see previous section The intermediate leakages should be evenly spaced between lowest and highest...

Страница 117: ...Document Feedback AS3460 ALC Characterization Demo Kit Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 117 Figure 130 Human Head Measurement Setup...

Страница 118: ...it Manual PUBLIC UG000480 v3 00 2021 Nov 08 126 118 13 Codec Mode Codec Mode is a power saving music only mode ANC Off Figure 131 Codec Mode Enabling The music filters for Codec mode must be applied i...

Страница 119: ...port is mandatory to run the codec mode The proper sample rate must be adjusted in the I2S settings on the routing tab Figure 133 I2S0 Settings As long as AS3460 is in Codec operation mode a host MCU...

Страница 120: ...ne amplifier of a Bluetooth SoC System on Chip device while augmented hearing is disabled This implementation might bring power advantages in case the SoC device features a headphone amplifier with hi...

Страница 121: ...o that the wind noise detector can use the difference between the two external microphones to estimate wind noise All other filter design and tuning should have taken place already so that the amount...

Страница 122: ...e probability of wind events The wind metric value can be observed by using a watcher in FleX Two thresholds can be set to determine at which wind metric level the wind suppression will activate and a...

Страница 123: ...e evaluating any changes This will allow the ARM to update the required configuration parameters that the wind noise suppression metric requires Activation Range Low Wind Threshold Setup an environmen...

Страница 124: ...ovides no attenuation Note that this only affects how quickly the gain will respond to rapid increases in the current wind level as observed in runtime register WIND_NOISE_METRIC 15 4 Parameters Low H...

Страница 125: ...Added I2S Swap chapter 99 100 Added Deep Sleep Mode section 124 Added ANC Filter Design chapter 56 65 Added ALC Filter Design chapter 66 94 Added ANC Characterization chapter 115 116 Added ALC Charact...

Страница 126: ...the technical data herein No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services RoHS Compliant ams Green Statement RoHS...

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