cvc Parameter Manager User Guide May 2006 using cvc HFK-sys2.7.6 for Headset Devices

Transcription

1 _äìéi~ä» cvc Parameter Manager User Guide using cvc HFK-sys2.7.6 for Headset Devices May 2006 CSR Cambridge Science Park Milton Road Cambridge CB4 0WH United Kingdom Registered in England Tel: +44 (0) Fax: +44 (0) Cambridge Silicon Radio Limited 2005

2 Contents Contents 1 Introduction Opening ParamMgr Version and Compatibility Information First Steps - Passive and Monitoring Modes Passive Mode Operation Monitoring Mode Operation Menus and Toolbar File Menu Open PSR Save PSR Save Params to File PS-Store Dropdown List Upload Params Download Params Use Default Parameters Compare Parameters Choose Active PSKeys Security Key DSP Dropdown List Connection Status Timing Monitor Kalimba Log Monitoring View Menu Toolbar Status Bar Administrator Access Gains - Adjustable Tuning Parameters MIC GAIN SEND GAIN SPKR GAIN Side-Tone Generation Automatic, DSP Side Tone Levelling [default] Fixed Gain, decreases with DAC Gain VM Controlled Side Tone Receive Processing Adjustable Tuning Parameters Equalization (PEQ) Automatic Level Tuning and Clipper ALT Parameter Clipper Ref Gain and Latency AEC - Adjustable Tuning Parameters Microphone Saturation Detection Saturation Threshold Saturation Ratio Half Duplex Hold Send VAD (Outgoing Voice Activity Detector) SNR Gamma Minimum Threshold Receive VAD (Incoming Voice Activity Detector) SNR Gamma Page 2 of 45

3 Contents Minimum Threshold Residual Filter and Attenuation Maximum Attenuation State Machine Send State Transition Idle State Transition Comfort Noise Noise Suppression and EQ Parameters Aggressiveness Equalization (7 Band) Terms and Definitions Appendix A Document History List of Tables Table 4.1: cvc license request Bluetooth address range List of Figures Figure 2.1: ParamMgr Main Window... 5 Figure 6.1: Receive Side Processing Diagram Figure 6.2: Default Equalization Figure 7.1: Send Path Processing Diagram Page 3 of 45

4 Introduction 1 Introduction This document describes the Parameter Manager application that is used to fine-tune the cvc HFK v2.7.6 Acoustic Echo Canceller software. The utility s executable is located in: C:\BlueLab3.5\tools\bin\ParamMgr_276.exe Where C:\BlueLab3.5 is the BlueLab install directory. The ParamMgr can also be launch from the Start menu example: Start > Programs > BlueLab 3.5 > Tools -> ParamMgr_276 This document assumes that the stereo_headset software is built including cvc software and has been downloaded to a suitable development hardware platform, e.g. the BC3MM-EXT Headset Example Design DEV- PC-1508B. Page 4 of 45

5 Opening ParamMgr 2 Opening ParamMgr To open the ParamMgr application: 1. From the Start menu: Start > Programs > BlueLab 3.5 > Tools and click on ParamMgr or browse to the location of the executable file: e.g. C:\BlueLab3.5\tools\bin and double-click on ParamMgr.exe. The ParamMgr application main window appears: Figure 2.1: ParamMgr Main Window The following chapters describe the ParamMgr interface, the individual parameters and where appropriate, gives brief guidance on settings and details of default values. Note: Further guidance on the tuning process can be found in the cvc Tuning Guide (CSR ref: blab-ug-016p). This document can be downloaded from the CSR support website ( when available. 2.1 Version and Compatibility Information To display version and compatibility information select About Param Mgr from the Help menu or the the Toolbar. icon on Page 5 of 45

6 First Steps - Passive and Monitoring Modes 3 First Steps - Passive and Monitoring Modes When the ParamMgr_276 application main window appears, it is important to understand the behaviour. The starting condition is always the Passive Mode of operation. To dynamically monitor key variables within the algorithm and enable the ability to real-time adjust parameters, switch to the Monitoring Mode. 3.1 Passive Mode Operation In passive mode the Parameter Manager permits the examination and modification of parameter values linked to PS Keys. These values can be loaded from a file or from the BlueCore PS Store, and can be saved to a file or to the PS Store. These values are linked to specified User PS Keys, which can be changed. Passive operation is the normal starting mode when the application is launched. To Upload parameters from PS- Store, the application and the hardware must be powered and connected. Note: When you switch between Passive and Monitoring modes, the parameters displayed can change. You must save or download parameters while in each mode or the changes may be lost. High-Level Features of the Passive Mode: 1. File I/O to the Parameter Manager memory. These are file operations and do NOT communicate the parameters to the DSP. 2. Communication from Parameter Manager memory to BlueCore PS-Store. 3. Specification of PS Key definition for File I/O and DSP communication. Page 6 of 45

7 First Steps - Passive and Monitoring Modes 3.2 Monitoring Mode Operation In monitoring mode the Parameter Manager permits the examination and real-time modification of parameter values that are actively in use by the Kalimba DSP. These values are retrieved and applied to the DSP while the audio processing code is running. In addition, the Parameter Manager displays information about the processing in real time. Monitoring mode is initiated by clicking the eyeglass icon or by selecting DSP -> Monitor Kalimba from the Menu bar. If in monitoring mode the Title Block indicates [connected monitoring] and the bottom right corner block, indicates MON. As the information is dynamically read from Kalimba memory, the application and the hardware must remain connected via the SPI interface. Note: When you switch between Passive and Monitoring modes, the parameters displayed can change. You must actively save or download parameters while in each mode or the changes may be lost. High Level Features of the Monitoring Mode: 1. Connection to the DSP specifies the communication protocol used to transfer data. 2. Monitoring the DSP generates periodic status updates of the cvc audio processing code. 3. Version number of the DSP code. 4. Kalimba processor resource loading listed in MIPS and Security Status 5. Call State, System Mode and State information 6. Audio Peak statistics used for level feedback to aid in GAIN tuning. Page 7 of 45

8 Menus and Toolbar 4 Menus and Toolbar The ParamMgr application window Menu bar and toolbar is shown below: Menu Bar! File! PS-Store! DSP! View! Help Toolbar! Open.psr File! Save a.psr File! Save a.txt File! Upload parameters from PS Keys! Download parameters to PS Keys! Connect to board via SPI! Set Monitoring Update Rate! Monitoring Mode toggle! Log Monitoring results to a file! Compare PS Keys to DSP memory! Set Security Key! Help - About cvc ParamMgr The menus and the functionality of the menu items are described in sections 4.1 and 4.4. Page 8 of 45

9 Menus and Toolbar 4.1 File Menu The File menu contains options used to manage the data displayed within the ParamMgr:! Open PSR! Save PSR! Save Params to File! Exit Sections to describe the File menu items Open PSR Selecting Open PSR opens a chooser window allowing a.psr file to be opened. The standard file provided with cvc is labelled parameters.psr Selecting a.psr file and clicking Open sets the parameters displayed in the ParamMgr to those contained within the selected.psr file. Note: The settings as displayed in the ParamMgr are not applied to the cvc software running on the target development platform until Download Params (see section 4.2.2) is selected and the BlueCore chip is reset. A file parameters.psr, which contains the default parameter settings for the cvc software, is included in the BlueLab3.5\apps\stereo_headset\cvc folder. This is the normal starting point from which adjustments to the parameters can be made. Note: Opening the parameter.psr as shipped results in the parameters displayed in the ParamMgr being the default values. That is, this has the same result as selecting the Use Default Parameters option in the PS-Store menu, see section Page 9 of 45

10 Menus and Toolbar Save PSR Selecting Save PSR opens the Save As window. The user can save the current parameter values to a file name and location of choice. The saved file will have a.psr extension e.g. Parameters_stereo_headset.psr. If the file name selected is the same as an existing file, the PSR File name already exists window opens, and requires you to take one the following actions. Append & Replace: If you changed the Active PS Keys locations (see Section for details) Append adds the new key parameters to the.psr. If the PS Keys locations were not changed, the current parameters Replace the existing parameter values. Overwrite: Cancel: Independent of the numbers of PS Key set in the existing.psr file, Overwrite will delete all the information and save only the current parameters to the defined.psr file. Cancel closes the PSR File name already exists window without saving a.psr file Save Params to File Selecting Save Params to File opens a Save As window. This allows the parameters to be saved to a user-defined name and location with a.txt extension. The resulting file provides a convenient listing of the parameter keys, providing a useful reference document. However, the.txt file serves no other specific purpose for the operation of the cvc software. Page 10 of 45

11 Menus and Toolbar 4.2 PS-Store Dropdown List The PS-Store menu contains options used to manage the interaction between the BlueCore Persistent Store (PS Key) memory and the ParamMgr_276.exe.! Upload Params! Download Params! Use Default Parameters! Compare Parameters! Choose Active PSKeys! Security Key Sections to describe the PS-Store dropdown list menu items. Note: Before interacting with the PS-Store Parameters, you must have established and be operating with an active SPI connection Upload Params Selecting Upload Params reads the cvc parameters from the BlueCore Persistent Store (PS Key) memory and populates the ParamMgr with these upload values. While parameters are being uploaded (which may take some time, ~ 8 seconds, depending on the connection established) the cursor changes to an hourglass. When upload is completed, the cursor returns to its normal state and the tool reflects the uploaded information Download Params Selecting Download Params writes the parameter displayed in the ParamMgr to the BlueCore Persistent Store (PS Key) memory locations as specified by the tool. While parameters are being downloaded (which may take some time, ~ 3 seconds, depending on the connection being used) the cursor changes to an hourglass. When download is completed, the cursor returns to its normal state. For the downloaded parameters to take effect, the cvc DSP code needs to be reset. Reset by pressing the hardware Reset button on the development board., then re-connect the phone. Once a call is initiated, cvc reloads and resets, updating parameter values Use Default Parameters Selecting Use Default Parameters populates the ParamMgr with the default parameters built within the executable. This is a good starting point when attempting to tune a new device Compare Parameters Selecting Compare Parameters opens the Parameter Comparison window. This data is used to quickly examine the parameters at various stages within the software. The window compares the tools Defaults, the Current state of the parameters, the Persistent Store memory (PS Keys) and the DSP Memory. If any of these are different than the Defaults, the data is highlighted in red. Page 11 of 45

12 Menus and Toolbar If wanting to compare the parameters from a stored.psr file, select Browse then choose an existing.psr file. This new file appears as an additional column for review. Note: Appendix A shows the ParamMgr control that sets each parameter Choose Active PSKeys cvc HFK v requires three user-defined keys within BlueCore Persistent Store memory. The default PS keys are USR10 (Parameters), ( EQ) and USR28 (Security). The security key at USR28 is a fixed location and cannot be changed. However USR10 (Parameters) and ( EQ) can be reassigned with the corresponding VM application changes. Selecting Choose Active PSKeys opens the Set Active PS Keys window. This allows the operator to reassign the default location of the cvc USR keys. If keys are reassigned, the associated VM changes are required and saving the parameters to the.psr is essential for future builds and downloading. Page 12 of 45

13 Menus and Toolbar The ParamMgr_276.exe is designed to control one set of parameters at a time. You can support two or more sets of tuned parameters by setting active PS keys unique to each other. parameters.psr manages the multiple sets of parameters, however USR28 needs to be defined only once. An example, a project with multiple parameter sets, could define USR keys such as: USR10 = Parameter Key set 1 = EQ Key set 1 USR34 = Parameter Key set 2 USR37 = EQ Key set 2 USR28 = Security keys (location fixed) If your application has a.psr with multiple parameter sets, the ParamMgr when started will prompt the user to Set Active PS Keys to view Security Key cvc software is a fee-based licensed product. The cvc software has time-limited security that mutes the audio after 5 minutes unless a validated security key is found. To enable the software for commercial applications, a security key must be obtained and applied. Each security key covers a range of consecutive Bluetooth addresses. To request a security key, contact CSR Sales, supplying the range of Bluetooth addresses to be licensed, similar to the example below. Note: The NAP and UAP portion of the range of Bluetooth addresses must be the same for a single key i.e. only the LAP can vary. See Table 4.1. cvc license request - Bluetooth address range address range Starting Bluetooth Address Ending Bluetooth Address Total number of addresses 5000 NAP UAP LAP xxxx xx xxxxxx B 00A B 00B388 Table 4.1: cvc License Request Bluetooth Address Range CSR will supply a security key for each range of consecutive addresses supplied. With a valid security key, the software can be activated by following the procedure described below. Page 13 of 45

14 Menus and Toolbar To enter a security key: 1. Select Security Key to open the Security Encryption Key window. 2. Enter the Security Key supplied by CSR in the designated area. Note: If a missing or invalid security key is entered the audio mutes after 5 minutes. 3. Click Apply. The key entered is written to USR28 within BlueCore Persistent Store memory. The USR28 filed will reflect the Security Key information. Click OK to close windows. If the device s Bluetooth address is within the specified range of the security key, the cvc software will be fully functional. Note: This key must also be included in the.psr file used to configure the application PS keys during product manufacture. Exclude USR28 from save and download The ParamMgr default normally excludes writing the security key information to the parameters.psr file. This avoids accidentally changing the key when using the executable. Should the user wish to write the USR28 security information to the.psr file, untick the checkbox, press OK and save the file. 4.3 DSP Dropdown List The DSP dropdown menu contains options used to manage the Kalimba DSP data exchange within the ParamMgr. Options include:! Connection! Status Timing! Monitor Kalimba! Log Monitoring Sections to describe the DSP dropdown list menu items. Page 14 of 45

15 Menus and Toolbar Connection Selecting Connection opens the Connection Selection window for selecting the SPI communication transport layer between PC and development platform. Depending on the connections that are established between the PC and the development board, the list of communication transports may vary. To establish a connection, a fully defined transport must be chosen (as indicated when the OK button becomes enabled). Fully defined transports are the lowest level on the hierarchy, and have no sub categories. When a transport layer has been chosen, the Connection Selection windows is closed and the main window displays this state by changing the title bar to read [connected] rather than [not connected] Status Timing Selecting Status Timing opens the Status Update Control window for selecting the update rate during monitoring. The Status Update Control determines the refresh rate at which data is requested from the Kalimba processor. CSR recommend this period is set in the range 0.5 to 5 seconds. The service loop of the software is ~ 350 ms. If the update rate is set below this time, overhead is added and could effectively slow the actual update rate. The default is 1 second. Note: When using xide BlueLab 3.x and the stereo_headset application has Enable debug set to yes, the SPI messaging traffic increases which could significantly slow the ParamMgr_276 status update responds rate. The BlueCores audio performance is maintained; only the update rate will slow. Page 15 of 45

16 Menus and Toolbar Monitor Kalimba Monitoring mode is initiated by pressing the eyeglass icon on the toolbar or select the Monitor Kalimba menu item from the DSP dropdown list. When cvc is active (e.g. during a call) and monitoring is operational, the main window is active displaying a wealth of information. A brief list of the displayed information is as follows: HFK v b 2 Indicated the cvc version label and build #. If a non-cvc DSP application is running the display reads Unknown DSP Software. MIPS Indicates the peak Kalimba processor load between updates. Demo Send In Peak If a valid security key is entered, the display reads Sec OK. If the security has failed, the display indicates Demo xxx s where xxx is a countdown timer in seconds. After the timer expires (Demo 0 s), the audio at the CODEC is muted. Is a running peak statistic of the Send In level (microphone input) as measured after the ADC. The maximum level is 0dB or decimal. Adjusting the MIC GAIN directly controls this level. Send Out Peak Is a running peak statistic of the Send Out level after the cvc processing. The maximum level is 0dB or decimal. Adjusting the SEND GAIN is the last level control. Rcv In Peak Is a running peak statistic of the Receive In level from the SCO link after the Equalization. The maximum level is 0dB or decimal. This level is heavily influenced by the cellular network, and phone model. Adjusting the Equalization Gains, control this level. Ref Gain Peak Is a running peak statistic of the Ref Gain level after the cvc processing. This level is the reference signal used by the CVC Echo Canceller. The maximum level is 0dB or decimal. Adjusting the REF GAIN is the last level control. Vol: xx Gain:yy Is a display that reflects the CODEC Gain per the volume table configured within the VM application code. Vol: xx where xx equals the Bluetooth volume position from 0 to 15 (max). Gain yydb (0xz) where yy is the corresponding CODEC gain, reference in db (from -45 to 0dB). 0xz where z is the hexadecimal gain value entered into the volume table. Page 16 of 45

17 Menus and Toolbar Gain Connected Mode Is the computed Side-tone applied Gain. This test point reflects the gain knowing the volume index, side-tone method, and user defined gain. Reflects the CallState condition. Variations include Connecting, Connected and Mute. Reflects the SysMode condition. Variations include HFK, ASR and PSTHRGH. Call State Receive Reflects the state machines decision for the last frame before an update. R (Receive VAD =1), S (Send VAD = 1), C (Comfort Noise = 1). Duplex Based on the echo severity, this will report either Full or Half Duplex. Additional SysMode displays: The cvc SysMode is under VM control. If the SysMode changes while monitoring, the graphical layout changes by greying the inactive parts of the software. See the ASR and PSTHRGH examples below. SysMode_ASR SysMode_PSTHRGH Page 17 of 45

18 Menus and Toolbar Log Monitoring Monitoring mode is initiated by pressing the write log icon on the toolbar or by selecting the Log Monitoring menu item from the DSP drop list. Once selected a new log window is opened. This log window fills with data whenever the ParamMgr is placed in Monitoring mode and cvc is active. To stop the logging of data, you can exit the Monitoring Mode by clicking the eyeglass icon or click the Write Log icon. If the Write Icon is pressed, you will be prompted by a Save As windows to save or discard your log. An automatically generated file name is presented. If you choose Save, the file is saved to the specified location. If you choose Cancel the file is closed and the data is lost. If you stopped Monitoring and the Log Window is still open, from the File menu you can Open, Save, Print and Close (standard windows functions) and from the Edit menu you can Clear. Clear empties the file contents and you can resume monitoring with new data. Page 18 of 45

19 Menus and Toolbar 4.4 View Menu The View menu contains options used to manage the appearance of the ParamMgr by enabling or disabling the tool and status bars. The View menu contains:! Toolbar! Status Bar! Administrator Access Sections to describe these facilities Toolbar Selecting Toolbar enables and disables the row of icons. When the check appears, the icons are displayed. The default setting is to display the toolbar Status Bar Selecting the Status Bar enables and disables the status row located at the bottom of the window. When the check appears, the status is displayed. The default setting is to display the Status Bar Administrator Access Selecting Administrator Access from the View menu is reserved for use by CSR Administrators. When an Administrator Access password is entered, additional utilities are made available within the ParamMgr tool. Details enabled by the Administrator Access are restricted and are not documented in this User Guide. Page 19 of 45

20 Gains - Adjustable Tuning Parameters 5 Gains - Adjustable Tuning Parameters ParamMgr provides the following access to gain control parameters:! MIC Gain! SEND Gain! SPKR Gain! Side-Tone Gain Sections 5.1 to 5.4 describe these options. 5.1 MIC GAIN This option determines the gain applied to the incoming microphone signal. To adjust this setting: 1. Click the MIC GAIN block in the ParamMgr main window. The Microphone Gain Setting window appears with the current Gain [dbr] value and Pre-amp selection. The combination of these values results in the Applied Gain: xx.x db which is calculated and used by the software. 2. To change use the drop down list to select the required Microphone gain settings, and check or uncheck the Enable 20 db Pre-Amp box. 3. When satisfied with the selected settings, click OK. The Microphone Gain Setting reflects the combination of the analog pre-amplifiers and digital multipliers, resulting in an overall Applied Gain ranging from -45dB to +42dB. The default Applied Gain value is +17.5dB (Gain [dbr] = -3 and Enable 20dB Pre-Amp selected). Note: It is best to avoid Digital Gain where possible. Digital Gain increases the noise floor and could affect the overall voice quality of the product. CSR recommends operating the Gain [dbr] from -21dB to 0dB to avoid using digital gain. This is highlighted by the black text; the red values should be avoided if possible. The MIC Gain level tuning is critical to achieve optimised performance:! If the Gain parameter is set too high, there will be more acoustic coupling and possible saturation.! If the Gain parameter is set too low, the near end user will sound distant and the resolution for the AEC / NS (Acoustic Echo Cancellation / Noise Suppression) algorithms may be too low, causing distortions such as choppy send speech. Refer to the Tuning Guide for further guidance on setting the MIC Gain parameter. Page 20 of 45

21 Gains - Adjustable Tuning Parameters 5.2 SEND GAIN The Send Gain parameter determines the amount of digital gain applied to the Send-Out signal. Clicking the SEND GAIN block displays the Digital Gain for SCO Out Signal window: The gain variable range is -90dB to 24dB. The default value is 3.0. Tip: One trick used to reduce acoustic echo is to reduce the Input Gain and increase the Send Out gain. This can be done but there may be some slight distortions introduced due to the input signal having low resolution. 5.3 SPKR GAIN For debug assistance, this option allows the Speaker Gain setting to be TEMPORARILY adjusted. Speaker Gain determines the gain applied at the DAC (Digital to Analogue Converter) which drives the loud-speaker. As the note in the dialog box indicates, for the final configuration you must edit the volume table in the VM application. To temporarily adjust the Speaker Gain parameter settings: 1. In Monitoring Mode, click on the SPKR GAIN block in the ParamMgr main window. The Speaker Gain Setting window appears. The Gain Select value shown is based on the phone volume index. As the phone volume changes, close and reopen the SPKR GAIN block for updated values. 2. Select the desired Gain Settings from the drop down menu. Page 21 of 45

22 Gains - Adjustable Tuning Parameters 3. When satisfied with the selected settings, click OK. The Gain selected is applied until a volume change is made at the phone or by pressing a volume button on the hardware. The Speaker Gain Settings reflect the combination of the digital and analogue stages, resulting in an overall Gain range from -45dB to 0dB. The default is 0dBr. Note: It is best to avoid Digital Gain where possible. Digital Gain increases the noise floor and is likely to distort or clip the audio out of the CODEC, which would affect the overall voice quality of the product. CSR recommends operating in the Gain Table [dbr] range from -45dB to 0dB and therefore avoiding the use of Digital Gain. Note: The Gain Selected from this drop list is temporary. It is overwritten by a volume change. Once the gain per volume step is determined, for final configuration you need to add these values to the table within the VM application code. 5.4 Side Tone Generation Side-tone is a direct path from the Microphone input to the Loudspeaker output (ADC to DAC). For typical headset applications, audio feedback via the side-tone reassures the user the device is operational. This feedback path must be set to a low level (typically -25dB) to avoid positive feedback that could cause howling and to ensure the receive path does not saturate. Side Tone Generation supports one of three different methodologies, based on the user definitions. Clicking the SIDE TONE block displays the Side Tone Generation window. By selecting one of the radio buttons, the user can specify the method, then set the parameters accordingly. SIDE-TONE LIMIT: With the current cvc 276 implementation the DSP limits the side-tone mix to -11dB maximum. If the user enters a larger value, the calculated applied Gain at the test point reflects the -11dB maximum. This is to ensure the Receive Path speech and tones do not saturate the DAC when side-tone is mixed Automatic, DSP Side Tone Levelling (default) Method 1 The Side Tone level is automatically adjusted by the DSP. As the Bluetooth phone volume decreases (lowering of the DAC gain) the Side Tone Gain ratio increases, in an effort to maintain a constant level heard by the user. This levelling effect is active while there is available gain overhead in the receive path. Once the overhead is consumed the side-tone level plateaus (-11dB). From this plateau point, the side-tone ratio is fixed and the level decreases proportionally for the remaining volume reductions. Page 22 of 45

23 Gains - Adjustable Tuning Parameters Side-Tone Gain Setting Method 1 1. In Monitoring Mode, click on the SIDE TONE block in the ParamMgr main window. The Side Tone Generation window appears. Select the Automatic, DSP Side Tone Levelling (default) radio button. 2. It is suggested that the phone s volume is adjusted to its maximum setting. 3. Enter the desired Gain (amount to mix with the Receive audio) within the range from -90 to 0dB. CSR recommends less than -20dB (-25dB default, -11dB maximum). 4. When satisfied with the selected settings, click OK. The Gain selected is applied. To save settings, download or save the.psr file. Based on the volume index and entered Gain value, the DSP computes the available headroom and automatically adjusts the side-tone ratio with each volume change. This computed applied Gain is displayed at the test point during monitoring Fixed Gain, decreases with DAC Gain Method 2 The Side Tone level is applied by the DSP. As the Bluetooth phone volume is decreased (lowering of the DAC gain) the Side Tone Gain level will proportionally decrease. Side-Tone Gain Setting Method 2 1. In Monitoring Mode, click on the SIDE TONE block in the ParamMgr main window. The Side Tone Generation window appears. Select the Fixed Gain, decreases with DAC Gain radio button. 2. It is suggested that the phone s volume is adjusted to its maximum setting.. 3. Enter the desired Gain within the range from -90 to 0dB. CSR recommended less than -20dB (-25dB default, -11dB maximum). 4. When satisfied with the selected settings, click OK. The Gain selected is applied. To save settings, download or save the.psr file VM Controlled Side Tone Method 3 The Side Tone level is controlled by the VM application with a Side-tone gain message sent to the DSP. Within the VM code a table should be created relating the Bluetooth phone volume to a corresponding Side-Tone Gain. This provides the product designers, full manual configuration of side tone. For this mode, the ParamMgr applies no GAIN control. Only the Gain test point shown during Monitoring reflects the applied Side-Tone Gain. Side-Tone Gain Setting Method 3 To set the VM Controlled Side Tone Gain parameter settings: 1. In Monitoring or Passive Mode, click on the SIDE TONE block in the ParamMgr main window. The Side Tone Generation window appears. Select the VM Controlled Side Tone radio button. 2. Click OK. 3. To save this setting, download or save the.psr file. During Monitoring Mode the applied Gain test point value shown, is based on phone volume index table settings. As the phone volume changes, the value updates. Note: As noted in the dialog box, for the final side-tone volume configuration the table in the VM application must be updated. Page 23 of 45

24 Receive Processing Adjustable Tuning Parameters 6 Receive Processing Adjustable Tuning Parameters The receive processing facilities provided within the ParamMgr are split into several areas of functionality accessed by clicking on the blocks:! PEQ - Equalization for loud-speaker frequency correction! ALT and Clipper - Automatic Level Tuning and Clipper includes Boost! REF GAIN Controls the receive level feed to the primary AEC Figure 6.1 is a simplified view of the adjustable components in the receive side processing. The signal flows from right to left, starting with the Bluetooth RCV-In SCO data to the Rcv-Out signal which drives the loud-speaker. The Clipper, Boost and ALT are contained within a single block. Also shown are the red Test Point blocks. These represent the Peak Statistics as shown within the ParamMgr during monitoring mode. CODEC Primary AEC RX REF Gain out SPKR Gain Rcv-AEC Rcv-Out Volume Control Test Point Rcv. Level Statistics Clipper BOOST ALT Automatic Pre- Digital Level Clipper Boost Tuning Figure 6.1: Receive Side Processing Diagram Sections 6.1 to 6.3 describe these functions in more detail. Test Point Rcv. SCO Level PEQ Equalization Bluetooth PCM Data Rcv-In SCO Page 24 of 45

25 Receive Processing Adjustable Tuning Parameters 6.1 Equalization (PEQ) The first processing block in the receive path is the PEQ. The PEQ allows the user to alter the frequency response effectively correcting the loudspeaker. The PEQ is a graphical user interface allowing the user to configure up to 5 biquad filter stages to achieve the required correction response. The default configuration shown in Figure 6.2 has the PEQ bypassed, no stages selected. The Red line shown in the plot area represents the equalization curve. Figure 6.2: Default Equalization The PEQ interface supports multiple views of the equalizer without needing to close the window. Several of the view options and user controls include: Master Gain: Linear / Log: Presets: You can shift the curve up or down without changing the shape. The gain range is -90 to +12dB of combined gain between the stage and master gains. The default value is 0dB. This switches the curve plot view from Linear (0 to 4000 Hz) to Logarithmic (200 to 4000 Hz). This is used for display purposes only and does not alter the equalization curve. Are a collection of sample curves. A drop list containing several examples including Default, Low Boost, Mid Softener, Gentle High Boost, V Curve and 5 Stage Graphic EQ. If the user alters a curve profile, the preset field will blank. Graphic EQ / EQ: This button controls the freedom of data entry into the biquad stage fields. In Graphic EQ mode only the Gain and number of stages are variable while the Freq, Q=f/BW and BW are locked at optimum pre-determined values based on the 4000 hertz bandwidth. The user ticks the desired stages and enter the gain value or drag the corresponding number in the curve to the desired gain. When in EQ mode the Stage, Gain, Freg and either the Q=f/BW or BW is alterable. The user can enter the values directly into the required fields or can drag the corresponding number in the curve to the required location. Reset: Cancel: When creating a filter curve, pressing the Reset button reverts the curve back to the last OK state. Closes the Equalization window without saving. Page 25 of 45

26 Receive Processing Adjustable Tuning Parameters Apply: OK: When in monitoring mode, clicking Apply writes the equalization parameters immediately to DSP memory and the changes take effect. To save permanently you must click OK and Download to PS-Store or save parameters to a.psr file. You can Apply unlimited parameters curves and the window does not close until Cancel or OK is pressed. Similar to Apply, when you select OK the equalization parameters are written to DSP memory and the PEQ window is closed. To save permanently you must Download PS Keys or save parameters to a.psr file. Vertical and Horizontal Scale Bars Scale Bar User Controls: Zoom In: Zoom Out: Scale Drag: Using the mouse, point to a starting point on the grey scale bar. Left click and hold, drag to the desired end point and release mouse button. The plot area will zoom to the required scale selected. To return to the default scale, double click the left mouse button within the grey scale bar. You can drag the curve within the plot area by a right mouse button hold within the Scale Bar, then drag to required location and release the mouse button. The horizontal scale will only drag if the scale is zoomed. Page 26 of 45

27 Receive Processing Adjustable Tuning Parameters 6.2 Automatic Level Tuning and Clipper Select the ALT & Clipper block to access the Automatic Level Tuning and Clipper volume control facilities: Clipper Parameters The parameters that are set within this window are described in sections and ALT Parameter The cvc algorithm applies the ALT (automatic gain control) to the RCV-In signal after the PEQ. The ALT slowly adjusts the gain from the far end speech to compensate for the level variance amongst different phone manufacturers and carrier sensitivities. ALT Volume Table Parameters ALT Parameter The volume used by the cvc application for loudspeaker control is partially determined by the ALT slider position. This slider control sets the Maximum volume loudness and remains fixed across all Bluetooth phone volume levels. This maximum volume determines the largest possible signal delivered to the CODEC input. Note: The VM volume table controls the CODEC (DAC), mapping an output level to each Bluetooth volume step. The maximum volume supports the range -20dB to +0dB with the default set to -0.5dBFS. Page 27 of 45

28 Receive Processing Adjustable Tuning Parameters Clipper If your loudspeaker distorts before the CODEC reaches full scale. The Clipper may be used as a hard clipping limiting mechanism for the CODEC output and provides a pre-clipped reference signal to the primary AEC so the optimal echo cancellation can be performed. The user adjustable Clipper variables are:! Saturation Point! Loudness Boost! Disable Soft Clip Saturation Point The Saturation Point sets the saturation amplitude or clipping point of the receive signal. This provides the saturation threshold value for RCV-OUT. Any RCV-OUT signal above the Saturation Point will be pre-clipped to the Saturation Point. To set the Saturation Point use the Clipper slider control or directly enter the [db Full Scale] threshold into the field at the bottom of the slider. The supported range for this variable is -20dBFS to 0dBFS. The default value is disabled (0dBFS).! If the saturation point is not set low enough, so that the actual saturation point is below the clipper saturation point, the primary filter cannot cancel as much acoustic echo.! If the saturation point is set too low, so that the actual saturation point is above the clipper saturation point, the primary filter can cancel the maximum amount of acoustic echo. However, the loudspeaker sounds more distorted. Loudness Boost The Loudness Boost is a pure digital gain to the receive signal just prior to the Clipper. The Boost gains the signal then the Clipper cuts the top at the Saturation Point. This effectively raises the apparent loudness at the loudspeaker without overdriving the loudspeakers saturation point. The variable range is 0.0 (no boost) to +20dB (extreme boost). The default value is 0dB.! Loudness Boost can only be applied when the Clipper is enabled.! Any Boost compression (gain) degrades the audio quality. Add more boost, the audio further degrades. Disable Clipper Ticking this check box disables the Clipper and the code is bypassed. If checked, the parameters are applied. The default value is disabled. Important Note: The Clipper should be disabled if the system is used with high-quality (low distortion) loudspeakers. Page 28 of 45

29 Receive Processing Adjustable Tuning Parameters 6.3 Ref Gain and Latency Clicking the Ref Gain and Latency block displays the Digital Gain for AEC Reference Signal window: Ref Gain The Gain parameter determines the amount of digital gain applied to the RCV-IN signal before the AEC block. It does not get applied to the RCV-OUT signal at the CODEC. The parameter is used to help ensure that there is a lossy echo path. The AEC algorithm implemented recommends that the RCV-IN-AEC signal is greater in amplitude than the SEND-IN-AEC signal for the primary filter to operate correctly. The default entry is 0. Latency Latency is the delay buffer used to compensate for the time the data travels from the DAC to the loudspeaker, over the air transfer, ADC and presented to the AEC. This overall latency in entered in milliseconds. The range is 0 to 24 milliseconds. The default setting is 10ms. Note: If the delay is excessive the microphone signal with echo arrives at the AEC before the reference signal, resulting in directly passing the echo. If the delay is too short, the algorithm s effective echo tail length of 16ms is being reduced. Page 29 of 45

30 AEC - Adjustable Tuning Parameters 7 AEC - Adjustable Tuning Parameters The AEC (Acoustic Echo Cancellation) section of the ParamMgr is accessed through the dark blue blocks shown the Figure 7.1: Send-IN Test Point Mic Level Statistics Test Point Send Level Statistics TX in Microphone CODEC MIC GAIN Microphone Saturation Detection Primary AEC Residual Filter & Attenuation CNG Noise Reduction and EQ Send VAD AEC - Adjustable State Tuning Parameters Rcv VAD From REF GAIN Figure 7.1: Send Path Processing Diagram! Microphone Saturation Detection: Microphone Saturation settings! Send VAD: Outgoing Voice Activity Detector settings! Receive VAD: Incoming Voice Activity Detector settings! Residual Filter & Attenuation: Receive State Attenuation settings! State Machine: State Control settings! Comfort Noise Generation: Comfort Noise settings The parameter settings for these areas is described in sections 7.1 to 7.6. SEND GAIN Bluetooth PCM Data SCO Send-Out Page 30 of 45

31 AEC - Adjustable Tuning Parameters 7.1 Microphone Saturation Detection Microphone Saturation Detection is a variable used to force the echo canceller software into a half-duplex mode when the microphone signal reaches certain criteria. It is particularly relevant when the microphone and loudspeaker have high acoustic coupling (i.e. there is a short distance between them) or the loudspeaker volume is excessive. Clicking the Microphone Saturation Detection block displays the Configure Microphone Saturation Detection window: Microphone saturation protection scans the 64 samples in each input buffer. It counts the number of samples that exceed the Saturation Threshold and if the percentage of samples exceed the Saturation Ratio, the AEC enters half-duplex mode for the period specified by Half Duplex Hold. Three parameters make up the Microphone Saturation Detection:! Saturation Threshold! Saturation Ratio! Half Duplex Hold Note: Typical settings to enable the Microphone Saturation are Saturation Threshold = dB, Saturation Ratio = % and Half Duplex Hold = 500 msec. These parameters are described in sections to Saturation Threshold This parameter specifies the threshold value (in the range 0dB to -90bB) that a sample must exceed to be included in the ratio calculation. This threshold trigger point is specified in db, where 0dB is full scale. The default setting is 0dB, typical is dB. Note: The value displayed may not be exactly as measured due to the parameter resolution and rounding errors. Page 31 of 45

32 AEC - Adjustable Tuning Parameters Saturation Ratio This parameter specifies as a percentage how many samples (over the threshold trigger point) are allowed in a frame before Half Duplex is invoked. Note: The following formula can be used to determine the actual number of samples (over the saturation threshold in a frame), permitted by a given percentage: number of samples allowed = Saturation Ratio * 64 When the Saturation Ratio is set very low, Microphone Saturation Detection is effectively set to the Threshold value. For example, if the ratio is set at 1.56% (i.e. 1 sample per frame) the saturation threshold needs only to be met once for the Microphone saturation condition to be met and half-duplex invoked. The default setting is 100%, a typical setting is % (3 samples) Half Duplex Hold This parameter (specified in milliseconds) sets the period the AEC is forced into half-duplex when the Saturation conditions have been met. The supported range is from 0 to 1,000ms. The default parameter value is 0ms, a typical value is 500ms. 7.2 Send VAD (Outgoing Voice Activity Detector) Clicking the Send VAD block displays the AEC Mic Voice Activity Detector (VAD) window: The Voice Activity Detector uses a short time estimate and a long time estimate to determine if speech is present. The parameters that are configurable within this function for outgoing VAD are:! SNR: Signal to Noise Ratio! Gamma! Minimum Threshold These parameters are described in sections to SNR SNR (Signal to Noise Ratio) is a method of identifying speech from noise, i.e. a speech detector. Speech is classified when the short time estimate is greater than the long time estimate. This parameter determines the acceptable ratio at which the signal is classified as detected speech. The larger the value set for this parameter the more difficult it is for a speech event to be detected which means the device has more difficulty entering the Send State, i.e. the device behaves more like a half-duplex device. The parameter range for this variable is 0dB to 90dB. The default value is Page 32 of 45

33 AEC - Adjustable Tuning Parameters Gamma The Gamma parameter determines the amount of noise suppression to apply to the short time estimate. The smaller this value, the more noise suppression applied. The parameter range for this variable is 0.0 (maximum gamma) to 1.0 (minimum gamma). The default value is Minimum Threshold The Minimum Threshold parameter is the minimum amplitude value of the short time estimate that can be recognized as speech, even if the other constraints are met. If the amplitude value of the short time estimate is less than this Minimum Threshold parameter, no speech is detected, even if the short time estimate is some factor greater than the long time estimate. This value is used to reduce the amount of false speech detected due to noise. This value is usually set to the noise floor of the send path. This parameter ranges from -138dB to 0dB. If this value is set to 0dB, the SEND VAD never detects send speech. The default value is Page 33 of 45

34 AEC - Adjustable Tuning Parameters 7.3 Receive VAD (Incoming Voice Activity Detector) Clicking the Receive VAD block displays the AEC Reference Voice Activity Detector (VAD) window: The Voice Activity Detector uses a short time estimate and a long time estimate to determine if speech is present. The parameters that are configurable within this function for incoming VAD are:! SNR: Signal to Noise Ratio! Gamma! Minimum Threshold These parameters are described in sections to SNR SNR (Signal to Noise Ratio) for receive detection is a method of identifying speech from noise, i.e. a speech detector. Speech is classified when the short time estimate is greater than the long time estimate. This parameter determines the acceptable ratio at which the signal is classified as detected speech. The larger the value set for this parameter the more difficult it is for a received speech event to be detected. The parameter range for this variable is 0dB to 90dB. The default value is 0dB Gamma The Gamma parameter determines the amount of noise suppression to apply to the short time estimate. The smaller this value, the more noise suppression is applied. The parameter range for this variable is 0.0 (maximum) to 1.0 (minimum). The default value is Minimum Threshold The Minimum Threshold parameter is the minimum amplitude value of the short time estimate that can be recognized as speech, even if the other constraints are met. If the amplitude value of the short time estimate is less than this Minimum Threshold parameter, no speech is detected, even if the short time estimate is some factor greater than the long time estimate. This value is used to reduce the amount of false speech detects due to noise. This value is usually set to the noise floor of the send path. This parameter ranges from -138dB to -12dB. If this value is set to -12dB, the SEND VAD never detects send speech. The default value is dBFS. Page 34 of 45

35 AEC - Adjustable Tuning Parameters 7.4 Residual Filter and Attenuation Clicking the Residual Filter and Attenuation block displays the Receive State Attenuation Settings window: Receive Attenuation controls the parameters for the Receive Attenuator (RA). The RA attenuates residual send, if in pure receive state Maximum Attenuation The Maximum Attenuation parameter sets the maximum amount of attenuation the residual filter can apply. The parameter range for this variable is from -138dBFS to 0dBFS. The default value is This value should be decreased if there is some slight residual echo heard on the Send-Out signal. Setting this value too low, however, can make the send-out noise floor sound unnatural. 7.5 State Machine This facility controls how the residual filter behaves in the various states:! Send State Transition! Idle State Transition Clicking the State Machine block displays the State Control Settings window: The parameter variables are described in sections and Page 35 of 45

36 AEC - Adjustable Tuning Parameters Send State Transition The Send State Transition defines two variables:! Time Constant! Cut Off Time Constant The Time Constant parameter controls the rate at which the amount of residual attenuation changes during the Send State. There is no residual attenuation applied in the Send State. However, the attenuation value is updated while in the Send State. The updating of the attention value during the send state is proportional to the Time Constant parameter value. The parameter range for this variable is from 0 to 2. The default value is Cut Off Note: Values greater than 1.0 indicate that the attenuation is decreasing while values of Time Constant less than 1.0 indicate that the attenuation is increasing. Setting this parameter to a value less than 1.0 makes the overall system more HALF-DUPLEX. The Cut Off parameter is the maximum value that the residual attenuation value can be while in the Send State. The parameter range for this variable is from 0 to 1. The default value is Decreasing this value makes the overall system more HALF-DUPLEX because the residual attenuation cannot lessen as much during the SEND- STATE Idle State Transition The Idle State Transition defines one parameter: Time Constant The Time Constant parameter controls the rate at which the amount of residual attenuation changes during the Idle State. The parameter range for this variable is from 0 to 1. The default value is The lower this parameter is set, the faster the increase in attenuation during the IDLE STATE and so the more half duplex the system becomes. Page 36 of 45

37 AEC - Adjustable Tuning Parameters 7.6 Comfort Noise Comfort Noise is added to the Send-Out signal after the noise suppression block and is used to mitigate the noise floor modulations introduced by the residual attenuation generated by the AEC. Comfort noise can also be used to mask low-level acoustic echo. Clicking the Comfort Noise block displays the Comfort Noise Generation Settings window: Comfort Noise defines a single Gain parameter: Gain The Gain parameter sets the amplitude level of the added comfort noise signal. The parameter range for this variable is from -90 to 0dB. The default value is Page 37 of 45

38 Noise Suppression and EQ Parameters 8 Noise Suppression and EQ Parameters The noise suppression removes background interference noise from the microphone send path. This improves the SNR of speech resulting in improved speech intelligibility. A seven-band graphic equalization utility allows the user to apply frequency correction to the send path. This is normally required due to microphone frequency response or materials placed in front of microphones. Clicking the Noise Suppression block in the OMS area of the ParamMgr main application window displays the Noise Suppression window: 8.1 Aggressiveness 7 Band Graphic EQ Slider Control Gain Values in db The Aggressiveness parameter determines the aggressiveness of the noise suppression algorithm. This parameter ranges from 0.0 (minimum aggressiveness) to 1.0 (maximum aggressiveness). Typically, this value is set between 0.9 to 1.0. This provides the highest noise suppression while maintaining good speech quality. The default value for this parameter is Page 38 of 45