FCC ID: 2AM72-BAPX-BT2 APx 525D2, APx 526D2, APx 582D2, APx585D2, APx 586D2, APx 555D2

17 Bluetooth I/O Bluetooth Discovery, Pairing and Con-

nection Bluetooth connections require successful radio fre-

quency (RF) communication between the APx ana-

lyzer and the DUT, and successful device handshaking through device discoverability, pairing and connection protocols. Data transfer is encrypted and must be authorized by the exchange of link keys, and personal identification number (PIN) codes may be required. Bluetooth Settings are Global Bluetooth settings are unique in APx500, in that they are global. This means the settings made in the Blue-

tooth Settings dialog affect the entire project: all mea-

surements, all signal paths. Source, Sink, Output and Input When the APx Output Configuration is set to Blue-

tooth, the instrument can transmit audio using the A2DP Source profile, the HFP Audio Gateway profile, or the HSP Audio Gateway profile. When the APx Input Configuration is set to Bluetooth input, the instrument can receive audio using the A2DP Sink profile, the HFP Hands Free profile, or the HSP Headset profile. There is one case where you are allowed to output audio and input audio simultaneously: Set the APx Profile to A2DP Sink, HFP Hand Free AVRCP Control-

ler. Connect to the DUT using the HFP Profile. Since HFP is a bi-directional link, you can both send and receive audio. Introduction The APx Bluetooth Duo option (page 9) is a hardware module available for the APx modular analyzers (the APx555, and the APx525 and 585 families of analyz-

ers, including the APx582). It provides Bluetooth wire-

less technology source and sink interfaces. The APx Bluetooth profiles support audio in a lower-

quality (voice) mode (the HFP and HSP profiles) and in a higher-quality (music) mode (the A2DP profile). See more About Bluetooth on page 140 and Using Bluetooth in a Sequence on page 555. See More About Supported Bluetooth Profiles on page 141. This chapter discusses operation of the Bluetooth Duo option.APx500 version 4.5 supports the Bluetooth Duo option, and also provides support for the legacy Bluetooth modules. Operation of the legacy Bluetooth modules is discussed in Chapter 18. Identification The most obvious difference between the legacy Blue-

tooth modules and the Bluetooth Duo module is the number of external antennas: the legacy modules have one; Bluetooth Duo has two. The Bluetooth Duo module carries the model number 229, and is identified in the Help > About product components list as Bluetooth Duo Module. See more About Bluetooth on page 140, and Using Bluetooth in a Sequence on page 555. See More About Supported Bluetooth Profiles on page 141. The Bluetooth Monitor The status of a number of current Bluetooth settings is shown in the Bluetooth Monitor. Additionally, Blue-

tooth actions, settings and utility functions are avail-

able through a context menu (right-click in the Bluetooth Monitor display.) See Bluetooth Monitor on page 36. APx500 Users Manual 129 Chapter 17: Bluetooth I/O Output Configuration: Bluetooth This Signal Path Setup I/O selection enables output of audio from the APx generator to a Bluetooth device under test, using Bluetooth radio frequency (RF) trans-

mission. Note: The Bluetooth choice is only available for analyzers fitted with the APx Bluetooth Option module. Connector Choose Bluetooth here. Since the Bluetooth connec-

tion isnt valid until you choose, pair and connect with a device, the Bluetooth Settings dialog opens immedi-

ately. See page 132. Settings Click the Settings... button to discover, select, pair, connect and otherwise configure a Bluetooth link. See page 132. Friendly Name The friendly name of the APx Bluetooth modules source chip will appear here. Address The address of the APx Bluetooth modules source chip will appear here. A2DP The codec settings for the A2DP profile can be viewed and edited here. Audio Profile This displays the active profile, if any. See More About Supported Bluetooth Profiles on page 141. Connect If the APx is already paired with one or more Blue-

tooth devices, you can open the Connect flyout menu to select a device and one or more profiles for connec-

tion. See More About Supported Bluetooth Profiles on page 141. Disconnect If the APx is already connected to a Bluetooth device, you can click the Disconnect button to terminate the connection. Actions Click Actions to open the Bluetooth Actions dialog. If the APx is already connected to a Bluetooth device, you can initiate Bluetooth Actions from this dialog. Only the actions appropriate to the current connec-

tion and profile are shown. See Actions on page 139. Input Configuration: Bluetooth This selection enables input of audio from a Blue-

tooth device under test, using Bluetooth radio fre-

quency (RF) transmission. Note: The Bluetooth choice is only available for analyzers fitted with the APx Bluetooth Option module. Loopback Loopback is not available when either the Output or Input Configuration is set to Bluetooth. Connector Choose Bluetooth here. Since the Bluetooth connec-

tion isnt valid until you choose, pair and connect with a device, the Bluetooth Settings dialog opens immedi-

ately. See page 132. Settings Click the connect and otherwise configure a link with a Blue-

tooth device. See page 132. Settings... button to discover, select, pair, 130 APx500 Users Manual Chapter 17: Bluetooth I/O result referencing audio from the unlocked input will display an ---- (invalid) result. See page 632 for more about invalid results. Edit Channel Labels dialog you can rename the In the Channel Labels input channels with names of your choice. See page 56. These settings are project-wide, but can be over-

ridden for any measurement result. To set project col-

ors, click the Project Colors... button in the Labels dialog, or go to the Project/Sequence Properties dia-

log, Colors tab. See Setting Graph Colors and Styles on page 30. Channels This is a reading field that displays the current input channel count, determined by profile settings. Friendly Name The friendly name of the APx Bluetooth modules sink chip will appear here. Address The address of the APx Bluetooth modules sink chip will appear here. A2DP The codec settings for the A2DP profile can be viewed and edited here. Audio Profile This displays the active profile, if any. See More About Supported Bluetooth Profiles on page 141. Connect If the APx is already paired with one or more Blue-

tooth devices, you can open the Connect flyout menu to select a device and one or more profiles for connec-

tion. See More About Supported Bluetooth Profiles on page 141. Disconnect If the APx is already connected to a Bluetooth device, you can click the Disconnect button to terminate the connection. Actions Click Actions to open the Bluetooth Actions dialog. If the APx is already connected to a Bluetooth device, you can initiate Bluetooth Actions from this dialog. Only the actions appropriate to the current connec-

tion and profile are shown. See Actions on page 139. Operation with absent or corrupt inter-

face signal When Input Configuration is set to a digital input and no signal is present, or if the signal is corrupt or out of range, the input receiver cannot lock (synchronize) to the interface signal, and no valid audio can be recov-

ered. The sample rate indicator in the Status Bar will display an unlocked warning, and any measurement APx500 Users Manual 131 Chapter 17: Bluetooth I/O Bluetooth settings dialog for Bluetooth Duo Bluetooth Settings dialog for Bluetooth Duo, shown in the A2DP Source, HFP Audio Gateway, AVRCP Target profile set. This topic explores Bluetooth Duo settings dialog. The legacy Bluetooth settings dialog is discussed begin-

ning on page 148. This dialog provides settings for Bluetooth discovery, pairing, connection and other configuration. Unlike most APx settings, Bluetooth profile selection, pairing and connection settings are global to the APx project. Settings made here affect both Bluetooth source and sink configurations across all signal paths in the proj-

ect. A flow chart depicting discovery, pairing and connec-

tion paths is shown on page 139. APx Profile Set APx has four sets of profiles that the Bluetooth Option module can assume. Each set lists the profiles avail-

able for connection and/or the profiles available for access by a remote device. Choose an APx Bluetooth Profile Set here. A2DP Source, HFP Audio Gateway, AVRCP Target A2DP Source, HSP Audio Gateway, AVRCP Target A2DP Sink, HFP Hands Free, AVRCP Controller A2DP Sink, HSP Headset, AVRCP Controller In A2DP Source, the APx Bluetooth trans-

mitter mutes the audio when the average signal level falls below 54 dBFS for more than 1 second. We recommend maintain-

ing test levels above 54 dBFS for meaning-

ful results. Check for Firmware Updates at Applica-

tion Start The Bluetooth Duo hardware module can update its firmware in the field, using update files that are included with the APx500 software distribution. See Update Bluetooth Firmware on page 135. APx Identification The upper left side of the dialog displays a number of APx Identification settings readable by other Blue-

tooth devices. Friendly Name The friendly name of the APx Bluetooth module's Source or Sink chip is displayed here. Address The Address of the APx Bluetooth Source or Sink chip is displayed here. APx PIN The APx Bluetooth PIN is displayed here. Device Class Auto Auto uses the Device Class assigned by default:

for the Source chip, 60020C; for the Sink chip, 240408. Custom Custom allows you to select a Device Class for the active APx Bluetooth chip. Use the browse but-

ton to open the Edit Device Class Dialog (page 137). 132 APx500 Users Manual Discovery Auto Discoverable/Pair/Connect When this is selected (the default), the APx Bluetooth Option is discoverable by remote Bluetooth devices. If the remote device initiates pairing, the APx will pair. If the remote device initiates connection, the APx is available to connect for the profiles checked here. Not Discoverable, No Pair/Connect When this is selected, the APx Bluetooth Option is not discoverable by remote devices, and it will not respond to pairing or connection initiated by remote device. SSP Mode APx provides four SSP (Secure Simple Pairing) options. The Just Works choice is used in Bluetooth device relationships that require little security. The Numeric Comparison choices are man-in-the-middle (MITM) interactions for device relationships that require higher security. Choose the SSP Mode that is appropri-

ate for the Bluetooth device you are testing. See More About Secure Simple Pairing on page 142 for detailed information. Just Works Numeric Comparison, Display Only Numeric Comparison, Display+Buttons Numeric Comparison, Keyboard Transmit Power You can choose one of eight RF output transmission power levels between 20 dBm and +8 dBm. The default is +4 dBm. Active Bluetooth Connection If Maintain Active Connection is checked, the APx Bluetooth Option will remain connected to the Blue-

tooth device under test throughout the project, even across Signal Paths. However, if you change to Bench Mode, the Bluetooth device will be disconnected. Profile Configurations The upper right side of the dialog displays a number of APx profile configurations. The controls and settings Chapter 17: Bluetooth I/O here vary with Source or Sink (Target or Controller) set-

tings. Profile Configurations for Source/Target settings Profile Configurations for Sink/Controller settings HFP/HSP Profile If this box is checked, the HFP/HSP profile is enabled. You may elect to use the profile at connec-

tion time, or not. If this box is unchecked, the HFP/

HSP profile will not be available on the connection menu. These further options are available:

Auto Answer Incoming HFP/HSP Calls Wideband Speech (mSBC) Enabled A2DP Profile (when APx Profile is set to Source) If this box is checked, the A2DP profile is enabled for Source. You may elect to use the profile at connec-

tion time, or not. If this box is unchecked, the A2DP profile will not be available on the connection menu. These further options are available:

Codec Settings... This button opens the A2DP Codec Settings dialog. See page 135. A/V Sync Delay Enter A/V Sync Delay into DUT Delay. See page 136. A2DP Profile (when APx Profile is set to Sink) If this box is checked, the A2DP profile is enabled for Sink. You may elect to use the profile at connection time, or not. If this box is unchecked, the A2DP profile APx500 Users Manual 133 Chapter 17: Bluetooth I/O will not be available on the connection menu. These further options are available:

Codec Settings... This button opens the A2DP Codec Settings dialog. See page 135. Clock Recovery Clock Recovery enables or disables the sink clock recovery algorithm. See page 136. Fixed Fixed (the default) sets the A2DP sink sample rate to the negotiated rate.

(Auto) Auto enables the A2DP sink clock recovery algo-

rithm. Report A/V Sync Delay Report A/V Sync Delay to the connected Source device. See page 136.

(Auto) (the default) Auto reports the APx Bluetooth Sink chip A/V Sync Delay. Custom Custom allows you to enter an arbitrary A/V Sync Delay value to be reported. AVRCP Profile (when APx Profile is set to Tar-

get) If this box is checked, the AVRCP profile is enabled for Target. You may elect to use the profile at connection time, or not. If this box is unchecked, the AVRCP pro-

file will not be available on the connection menu. The latest AVRCP supported by APx is version 1.4. As an alternative, you may choose AVRCP version 1.0 here. These further options are available:

Playback Status See page 137. Absolute Volume (Remote) See page 137. Commands Change Generator Settings. See page 138. AVRCP Profile (when APx Profile is set to Controller) If this box is checked, the AVRCP profile is enabled for Controller. You may elect to use the profile at connec-

tion time, or not. If this box is unchecked, the AVRCP profile will not be available on the connection menu. The latest AVRCP supported by APx is version 1.4. As an alternative, you may choose AVRCP version 1.0 here. These further options are available:

Playback Status See page 137. 134 Absolute Volume (Local) See page 137. Scan The lower left area of the dialog has controls and set-

tings to scan for nearby Bluetooth devices. Scan for Devices This button initiates a scan to identify all the discover-

able Bluetooth devices within range. Discovered devices are listed in the Current Devices List. Scan Duration This setting limits the scan time to the value set. The maximum time is 48 seconds. The default is 10 sec-

onds. Get Friendly Names By default, APx asks for a devices friendly name. In automated processes, this process adds extra time. Uncheck this checkbox to disable this feature. Filter Devices From Scan You can filter the scan so only a certain Bluetooth Device Class will be shown. Click the browse button to open the Edit Device Class dialog. Device Class You can select a Device Class as a filter for the scan. Use the Class Dialog (page 137). browse button to open the Edit Device Max Devices You can limit the number of devices found in the fil-

tered scan here. The default is 10 devices. Current Devices List The Current Devices List occupies most of the lower part of the dialog. This grid shows the devices discovered in the scan, along with information fields. There are controls to pair, unpair, connect, disconnect, initiate actions and to copy the device Bluetooth address and link key. Select a device to configure the relationship. Clear Devices You can choose to remove all devices from the list, or all paired devices, or all unpaired devices. When a device is removed from the list, any pairing informa-

tion for that device is also removed. Click Scan to re-

populate the list. Pair Pairing provides a way for devices to exchange link keys. To pair with a device, refer to the documentation received with the device. To enable pairing, you will typically be required to execute a command or series of commands at the device. When pairing is enabled, APx500 Users Manual select the device in the Current Devices List, and click Pair. A Pair Bluetooth Device dialog box will open. Some devices may require the exchange of a PIN code. The APx Bluetooth PIN code is set to 0000; a field in the pairing dialog allows input of a remote devices PIN code. Pairing information is saved in the project, until the Current Devices List is cleared, or the until device is Unpaired. Unpair Unpairs the selected, previously paired device. Connect Connects to the selected, previously paired device. A Connect menu opens. Select the profile you would like to offer to the device. Chapter 17: Bluetooth I/O ware is correct for the APx500 version. If the firmware requires updating, the update will begin immediately and a progress dialog will be displayed. The update may take a few minutes. If Check for Firmware Updates at Application Start is unchecked, the APx500 application will not check for updates at launch. Instead, it will check for updates if and when Bluetooth is selected as an Input or Output. At that time, the update may take a few minutes. If the Bluetooth firmware is the correct version for the APx500 software, you will not be prompted to update. Codec Settings A2DP Codec Settings The Bluetooth A2DP profile always supports the SBC audio codec. Additional codecs are optional. In APx, you can select which optional codecs you would like to support, and edit features of the codecs you choose. Using the arrow icons at the top of the dialog, you can set an order of priority. APx will move from the top-

most codec downward until finding the codec that the DUT supports. Disconnect Disconnects the selected, connected device. Actions Opens various Actions dialogs. This duplicates the function of the Actions button shown on Signal Path Setup, without the necessity of leaving the Bluetooth Settings dialog. See page 139. Copy Copies the device address and key link to the Win-

dows Clipboard. This text can then be pasted into another application or tool. Update Bluetooth Firmware The Bluetooth Duo hardware module can update its firmware in the field, using update files that are included with the APx500 software distribution. If Check for Firmware Updates at Application Start

(located at the top of the Bluetooth Settings panel) is checked, each time the APx500 application is launched it will check to verify that the Bluetooth firm-

Codecs supported, in default order of priority:

aptX HD You can choose to support either or both of the follow-

ing sample rates for the aptX HD codec:

48 kHz 44.1 kHz aptX Low Latency You can choose to support either or both of the follow-

ing sample rates for the aptX Low Latency codec:

48 kHz 44.1 kHz aptX You can choose to support any or all of the following sample rates for the aptX codec:

APx500 Users Manual 135 Chapter 17: Bluetooth I/O APx as A2DP source:

48 kHz 44.1 kHz 32 kHz 16 kHz APx as A2DP sink:

48 kHz 44.1 kHz 32 kHz 16 kHz AAC The AAC codec is fixed at MPEG-2/4, AAC-LC, 44.1 kHz, 2 channels. By default, variable bit rate (VBR) is set. You can dese-

lect variable bit rate to enforce fixed bit rate. SBC You can choose to support any or all of the following sample rates for the SBC codec:

APx as A2DP source:

48 kHz 44.1 kHz 32 kHz 16 kHz APx as A2DP sink:

48 kHz 44.1 kHz 32 kHz 16 kHz Additionally, you can choose to support any or all of the following channel modes:

Joint Stereo Stereo Dual Channel Mono Clock Recovery Bluetooth A2DP Sink Clock Recovery Clock Recovery: Fixed (the default) does not attempt to algorithmically correct transmission errors, but sets the A2DP sink sample rate at the negotiated rate. This provides stable frequency measurements, but may occasionally be subject to glitches due to packet loss or buffer overruns. Generally, we recommend using the Fixed setting, particularly when using the aptX Low Latency codec. Clock Recovery: (Auto) engages an A2DP sink algo-

rithm that compensates for RF packet loss or sample rate drift between source and sink. Ideally, this com-

pensation is unnoticed by the listener, providing a pleasant listening experience; it will, however, create small but measurable sample rate and audio fre-

quency variations. A/V Sync Delay A/V Sync Delay AV Sync Delay features are not supported by the Legacy Bluetooth Option. This feature of A2DP allows the sink device to notify the source device of any rendering delay, enabling the source device to compensate for the delay. For example, a source device may provide video to a television monitor via a hard-wired connection, but route the audio through a Bluetooth A2DP connection to speakers or headphones. Any delay in the audio path will cause the audio to lag the video. If the source device is informed of the rendering delay in the sink device, it can delay the video stream by that amount and maintain proper synchronization between video and audio. A2DP Source When A2DP Source is selected, you can choose Enter A/V Sync Delay into DUT Delay to apply the delay reported by the remote sink device to the APx DUT Delay feature. The delay value entered into DUT Delay is updated each time the remote device reports a new delay value. The Bluetooth Monitor will indicate the delay reported from the remote sink device. If the remote device does not support this feature, the monitor entry will read N/A. A2DP Sink When A2DP Sink is selected, APx provides an A/V Sync Delay value for the remote device to read. For Report A/V Sync Delay you can choose either

(Auto) Auto reports the current delay in the Bluetooth chip internal to the APx, which will vary with config-

uration and connection. or Custom Custom allows you to enter an arbitrary delay value for the remote source device to read. The range is 100 ns to 1.6 s. 136 APx500 Users Manual Edit Device Class This dialog will generate a Bluetooth Device Class hex code from your selections. Choose one or more Major Service Class(es), a Major Device Class, and a Minor Device Class (if available.) This dialog will also identify a Device Class if you type a valid hex code in the Device Class field, and press the Enter key on the PC keyboard. APx Device Class If you have come to this dialog from the APx Custom Device Class setting, click OK to enter the code gener-

ated here as the APx Custom Device Class, which will be asserted in both Source and Sink profiles. Scan Filter Device Class If you have come to this dialog from the Filter Devices From Scan setting, click OK to enter the code gener-

ated here as the scan filter Device Class. Note: this feature is not supported by the Legacy Bluetooth Option. AVRCP Playback Status AVRCP Playback Status features are not supported by the Legacy Bluetooth Option. Playback Status is a feature introduced in AVRCP 1.3. This feature is intended to allow devices such as car kits to ask a phone whether a song is playing or not. This prevents certain out of band audio noises from the user, such as key presses while dialing a phone number. The car kit will suppress audio from the A2DP source device (which is also the AVRCP target) when the play status is not PLAYING. AVRCP Controller profile In the AVRCP Controller profile, APx acts as a A2DP rendering device (a sink such as a speaker or head-

phone), receiving an audio stream from a remote Chapter 17: Bluetooth I/O media player such as a phone. APx uses AVRCP Com-

mands to control the remote media player. When the AVRCP Controller profile is selected, the Playback Status Event checkbox on the Bluetooth Set-

tings panel allows you to enable or disable Playback Status. This setting is enabled by default. Toggling this setting will disconnect any active connection. When the AVRCP Controller profile is selected, and Playback Status Event is enabled, and the connected AVRCP Target device supports this notification, the Play Status is indicated in the Bluetooth Monitor. If the connected AVRCP Target device does not support it, the Bluetooth Monitor should indicate N/A. AVRCP Target profile In the AVRCP Target profile, APx acts as an A2DP source device, sending an audio stream to a remote rendering device (speaker or headphones). APx responds to AVRCP Commands sent from the remote rendering device. When the AVRCP Target profile is selected, the Play-

back Status Event checkbox on the Bluetooth Set-

tings panel allows you to enable or disable Playback Status. This setting is enabled by default. Toggling this setting will disconnect any active connection. When the AVRCP Target profile is selected, and Play-

back Status Event is enabled, you can navigate to Actions >A2DP Sink/AVRCP > Playback Status to open a dialog to set a response to the remote AVRCP Controller (sink) device. The Playback Status control provides a menu that has the following options: Auto, Stopped, Playing, Paused, Fwd Seek, Rev Seek, Error. The default selection is Auto. For any choice except Auto, the selected Playback Sta-

tus will be passed to the AVRCP Controller device. If Auto is selected, APx will set the status to Playing when the generator is turned on. When A2DP stream-

ing is started, the playback status will be Paused when the generator is off. When A2DP streaming is stopped, the playback status will be Stopped when the generator is off. The Playback status value is only updated when the active audio stream is A2DP. Playback status changes should not be made when the audio path is SCO. Absolute Volume AVRCP Absolute Volume control features are not supported by the Legacy Bluetooth Option. AVRCP Absolute Volume Control is a feature intro-

duced in AVRCP 1.3. This feature is intended to allow the source device to specify a percentage value of full APx500 Users Manual 137 Chapter 17: Bluetooth I/O volume to the rendering device (speaker or head-

phones). The rendering device responds with a notifi-

cation of the current absolute volume level. APx supports features of Absolute Volume Control in both the AVCRP Controller (A2DP sink) and Target

(A2DP source) profiles. AVCRP Controller profile In the AVRCP Controller profile, APx acts as a A2DP rendering device (a sink such as a speaker or head-

phone), receiving an audio stream from a remote media player. APx uses AVRCP Commands to control the remote media player. When the AVRCP Controller profile is selected, the Absolute Volume checkbox on the Bluetooth Settings panel allows you to enable or disable Absolute Vol-

ume. This setting is enabled by default. Toggling this setting will disconnect any active connection. When Absolute Volume is enabled in the AVRCP Con-

troller profile and the remote Target (source) device supports Absolute Volume, you can navigate to Actions

> A2DP Sink/AVRCP > Absolute Volume to open a dia-

log to set an Absolute Volume level value, which can be read by the remote AVRCP Target device. Values are integers from 0-127. If the Target device does not support Absolute Volume, this control is unavailable. ..in a sequence When the AVRCP Controller profile is selected, a sequence step is available to set the Absolute Volume level on the A2DP sink device. When the step is included in a sequence and loaded on an APx ana-

lyzer that does not support Absolute Volume, an error occurs when the step is executed. When the step is included in a sequence and loaded on an analyzer that supports Absolute Volume, but connected to a remote device that does not support it, an error occurs when the step is executed. In a sequence when the AVRCP Controller profile is selected, and the remote AVRCP Target device sup-

ports Absolute Volume, the Absolute Volume level set in the local A2DP sink device (the APx analyzer) is dis-

played on the report for each measurement in the sequence. AVRCP Target profile In the AVRCP Target profile, APx acts as an A2DP source device, sending an audio stream to a remote rendering device (speaker or headphones). APx responds to AVRCP Commands sent from the remote rendering device. When the AVRCP Target profile is selected, the Abso-

lute Volume checkbox on the Bluetooth Settings panel allows you to enable or disable Absolute Volume. This setting is enabled by default. Toggling this setting will disconnect any active connection. When Absolute Volume is enabled in the AVRCP Tar-

get profile and the remote AVRCP Controller (sink) device supports Absolute Volume, you can navigate to Actions >A2DP Sink/AVRCP > Absolute Volume to open a dialog to send an Absolute Volume command to the remote AVRCP Controller device. Values are integers from 0-127. If the remote AVRCP Controller device does not support Absolute Volume, this control is unavailable. When the AVRCP Target profile is selected, and the remote AVRCP Controller device reports its Absolute Volume level, the level is read and displayed in the APx Bluetooth Monitor. If the remote device does not sup-

port Absolute Volume control, the Bluetooth Monitor indicates N/A for this value. When the AVRCP Target profile is selected, a nested sweep parameter called Absolute Volume is avail-

able. This parameter allows the AVRCP Controller

(A2DP sink) device manufacturer to test audio output at various levels, plotted on one graph. ..in a sequence When the AVRCP Target profile is selected, a sequence step is available to set the Absolute Volume level on the remote device. When the step is included in a sequence, and loaded on an APx analyzer which does not support Absolute Volume, an error occurs when the step is executed. When the step is included in a sequence, and loaded on an analyzer that does sup-

port Absolute Volume, but the remote device does not support it, an error occurs when the step is executed. In a sequence when the AVRCP Target profile is selected and the remote AVRCP Controller device sup-

ports Absolute Volume, the Absolute Volume level reported by the remote device is read by APx and dis-

played on the report for each measurement in the sequence. Commands Change Generator Settings When APx is configured for A2DP Source AVRCP Tar-

get, the APx generator can now respond to certain AVRCP commands. AVCRP Target profile In the AVRCP Target profile, APx acts as an A2DP source device, sending an audio stream to a remote rendering device (speaker or headphones). APx responds to AVRCP Commands sent from the remote rendering device. When the AVRCP Target profile is selected, the Com-

mands Change Generator Settings checkbox on the Bluetooth Settings panel allows you to enable or disable this feature. This setting is enabled by default. 138 APx500 Users Manual AVRCP generator commands are only acted upon when the active measurement has a generator with an ON/OFF button, and the generator is not disabled. Commands The AVRCP command Play turns the generator On The AVRCP command Pause turns the Generator Off The AVRCP command Stop turns the Generator Off, and stops A2DP streaming. The AVRCP command Next Track increases the generator Frequency equivalent to pressing the up arrow on the frequency control in the panel The AVRCP command Prev Track decreases the generator Frequency equivalent to pressing the down arrow on the frequency control in the panel. The AVRCP command Volume Up increases the generator Level on Ch1 equivalent to pressing the up arrow on the level control in the panel. Volume Up messages are not received in legacy Bluetooth modules. The AVRCP command Volume Down decreases the generator Level on Ch1 equivalent to pressing the down arrow on the level control in the panel. Vol-

ume Down messages are not received in legacy Bluetooth modules. Steps in connecting APx to a Bluetooth device There are 3 steps involved in setting up a connection between any Bluetooth devices. APx500 software pro-

vides more visibility and control of options for these communication steps than most DUTs. Discovery Discovery scans the area and lists any Bluetooth devices that are not undiscoverable (hidden). Many devices are undiscoverable by default, and must be set to a discoverable mode through a switching sequence. Pairing Pairing establishes a mutual, secure relationship between devices that have at least one compati-

ble profile. Pairing is stored in non-volatile memory in each device. Devices can pair with more than one other device. Connection Paired devices can connect using compatible pro-

files and roles. Connection enables exchange of audio or control data. Each device can connect with only one device at a time. Chapter 17: Bluetooth I/O Process for discovery, pairing and con-

nection Actions Dialogs Bluetooth Actions are commands that can be sent from the APx analyzer to the Bluetooth device. The cur-

rent Bluetooth profile(s) and connection determine which commands are available in the Bluetooth Actions dialog box. Typical Actions Dialog Bluetooth Actions for A2DP Source, HFP AG, AVRCP Target For this profile set, these actions are available:

A2DP Source For A2DP Source, the actions are Start Streaming / Stop Streaming HFP Audio Gateway For HFP Audio Gateway, the actions are Open SCO Dial Ring Close SCO APx500 Users Manual 139 Chapter 17: Bluetooth I/O Hangup A SCO is a Synchronous connection-ori-

ented link, which is the type of radio link Bluetooth uses for voice data. The SCO link is used in the APx supported protocols HFP and HSP. Bluetooth Actions for A2DP Source, HSP AG, AVRCP Target For this profile set, these actions are available:

A2DP Source For A2DP Source, the actions are Start Streaming / Stop Streaming HSP Audio Gateway For HSP Audio Gateway, the actions are Open SCO Close SCO Ring Bluetooth Actions for A2DP Sink, HFP Hands Free, AVRCP Controller For this profile set, these actions are available:

A2DP Sink/AVRCP For A2DP Sink/AVRCP, click the AVRCP... button to open the Send AVRCP Command transport controls panel:

PREVIOUS TRACK REWIND FAST FORWARD NEXT TRACK PLAY PAUSE STOP VOLUME UP VOLUME DOWN MUTE HFP Hands-Free For HFP Hands Free, the actions are Answer Reject Call Hangup Open SCO Close SCO AT Commands For AT Commands, click the AT Commands... button to open the Send AT Commands panel. See page 140. Bluetooth Actions for A2DP Sink, HSP Headset, AVRCP Con-

troller For this profile set, these actions are available:

A2DP Sink For A2DP Sink/AVRCP, click the AVRCP... button to open the Send AVRCP Command transport controls panel:

PREVIOUS TRACK REWIND FAST FORWARD NEXT TRACK PLAY PAUSE STOP VOLUME UP VOLUME DOWN MUTE HSP Headset For HSP Headset, the actions are Button Open SCO Close SCO Bluetooth: Send AT Commands Dialog You can open the Send AT Commands dialog by click-

ing Actions > AT Commands from Signal Path Setup, or from the context menu opened by right-clicking in the Bluetooth Monitor. You must have an APx input or output configured for Bluetooth, and be paired and connected to an appro-

priate Bluetooth HFP profile device. Phone Call To make a phone call, enter a new phone number in the Number field and click Call, or click Redial Last Number. Disconnect a phone call by clicking Hangup. AT Command Enter any valid AT command as a text string, and click Send to transmit the command to the connected device. More About Bluetooth... General Bluetooth is a short-distance (a few meters) control, data, and audio communications wireless technology. Bluetooth replaces wires in the users personal area. Bluetooth uses low power, frequency-hopping radio in the 2.4 GHz band. Communication is two-way (for handshaking, metadata, etc); some profiles (HFP, for 140 APx500 Users Manual example) support duplex audio (both directions simul-

taneously); some profiles (A2DP) support only simplex audio (one direction per connection). Typical uses are mouse, keyboard, cell phone, head-

phones, hands-free talk and listen. APx Bluetooth Option An APx Bluetooth Option module must be fitted in the analyzer instrument to enable Bluetooth transmission and reception. See Bluetooth Option on page 9. Bluetooth Profiles Bluetooth has about 30 profiles that describe the capabilities and/or current operating modes for Blue-

tooth devices. For devices to communicate, they must support and share a common profile. For example, a wireless mouse uses the HID profile, which has no audio capabilities. Wireless head-

phones use the A2DP profile, which has no cursor control capabilities. The Bluetooth profiles these devices use are not compatible with each other. APx supported profiles The APx Bluetooth Option supports four Bluetooth pro-

files. The supported profiles are A2DP (Advanced Audio Distribution Profile) This is a one-way (source or sink), relatively high-

quality stereo audio profile. HFP (Hands Free Profile) This is a bi-directional voice communications audio profile that includes AT-type commands for phone use. Legacy Bluetooth DUTs support only the CSVD codec at sample rate of 8 kHz; HFP 1.6 compatible DUTs support the wideband voice mSBC codec at a sample rate of 16 kHz. HSP (Head Set Profile) This is a simpler version of HFP, using the CSVD codec at 8 kHz and a reduced set of AT com-

mands. AVRCP (Audio Video Remote Control Profile) This provides Play-Pause-Forward-Reverse remote control transport-type commands to con-

trol an audio source. This profile is typically used in conjunction with A2DP for personal audio player applications. More about Supported Bluetooth Profiles HSP HSP is the Head Set Profile. This profile supports voice-quality audio, using the CVSD codec at 8 kHz sample rate. This profile is used for phone-to-headset communication. Chapter 17: Bluetooth I/O Roles Supported roles are AG Audio Gateway (the phone) and HS Headset. Audio Audio flows in a duplex (bi-directional) mode, connect-

ing the Audio Gateway device to the Headset device. Actions A subset of AT commands are also supported for phone operations. HFP HFP is the Hands Free Profile. This profile supports voice-quality audio, using the CVSD codec at 8 kHz sample rate or the HFP 1.6 wideband speech mSBC codec at 16 kHz*. This profile is used for phone-to-

headset communication and for phone-to-car kit hands free communication.

*Note: HFP 1.6 wideband speech is only available if the mSBC codec is supported by your Bluetooth module hardware. See Blue-

tooth Option on page 9 for more informa-

tion. Roles Supported roles are AG Audio Gateway (the phone) and HF Hands Free (the headset or car kit mic/

speaker). Audio Audio flows in a duplex (bi-directional) mode, connect-

ing the Audio Gateway device to the Hands Free device. Actions A subset of AT commands are also supported for phone operations. Compared to HSP, HFP provides a few more AT commands for hands-free convenience, such as last number redial. A2DP A2DP is the Advanced Audio Distribution Profile. This profile supports higher bit rate, higher performance stereo audio. Roles APx supported profile roles are source (transmitting audio) and sink (receiving audio). Audio is distrib-

uted in one direction only, from the source device to the sink device. Audio The SBC codec is mandatory; Audio Precision Blue-

tooth Options also support the aptX codec. The Blue-

tooth Duo option also supports aptX HD, aptX Low Latency and AAC codecs. In A2DP Source, the APx Bluetooth transmitter mutes the audio when the aver-

age signal level falls below 54 dBFS for more than 1 APx500 Users Manual 141 Chapter 17: Bluetooth I/O second. We recommend maintaining test levels above 54 dBFS for meaningful results. AVRCP AVRCP is the Audio/Video Remote Control Profile. This profile is used in conjunction with A2DP, and pro-

vides transport controls such as Play, Pause, Reverse, Forward, etc. Roles Supported profile roles are controller and target. Note: when APx is the target, AVRCP com-

mands are ignored. More about Bluetooth SSP

(Secure Simple Pairing) Mode SSP is required for devices using Bluetooth v 2.1 and later. Bluetooth v 2.0 and earlier devices use Legacy Pairing. APx provides four SSP (Secure Simple Pairing) options. You must choose the option that is appropriate for the Bluetooth device you are testing. Man-in-the-middle (MITM) Man-in-the-middle or MITM is the term used in Blue-

tooth technology to refer to Secure Simple Pairing mechanisms that require human interaction. One device may display a PIN, for example, and the user may be required to enter the same PIN using a key-

board on a second device. MITM methods add secu-

rity to the pairing process. APx SSP Modes Just Works This mode is used in Bluetooth device relationships that require little security, such as headsets. User interaction is not required. Numeric Comparison, Display Only Some Bluetooth devices have only a display screen to interact with a user; an example is a car kit (car ste-

reo head unit). Use this mode when APx is playing the role of such a device. A use case would be testing a smart phone. APx would be an A2DP Sink, HFP with a display only (the car kit), and the DUT would be the smart phone. The phone would initiate pairing, and APx would display the PIN transmitted from the phone. The user would confirm

(using a button on the phone) that the PIN displayed in APx matched the PIN on the phone. Numeric Comparison, Display+Buttons Some Bluetooth devices have a display screen and one or more buttons to interact with a user; the but-

ton may be used for a binary (Yes/No) response to a query. An example is a smart phone. Use this mode when APx is playing the role of such a device. A use case would be testing a car kit. APx would be an A2DP Source, HFP Hands-Free with a display and but-

tons (the smart phone), and the DUT would be the car kit. APx would initiate pairing and transmit a PIN to the DUT. The DUT would display the PIN, and the user would confirm (using a button in the APx prompt dia-

log) that the PIN in the DUT display and the APx PIN matched. Numeric Comparison, Keyboard Some Bluetooth devices have a numeric or alphanu-

meric keyboard to interact with the user. An example is a computer used as an audio source, distributing iTunes audio to a home entertainment system. Use this mode when APx is playing the role of such a device. There are not obvious use cases in audio test for this mode, which is include in APx for completeness. A non-audio test use case would be pairing a Bluetooth keyboard to a tablet computer. The computer would display a PIN, and the user would enter a PIN (using the keyboard) that matches the PIN on the tablet screen. Legacy Pairing Bluetooth v2.1 and later devices (such as APx) are per-

mitted to use Legacy Pairing modes when pairing with a Bluetooth v2.0 or earlier device. Glossary of Bluetooth terms These terms are used in the Audio Precision Blue-

tooth audio testing implementation. A2DP is the Advanced Audio Distribution Profile, with two roles: source and sink. This profile supports higher bit rate, higher performance stereo audio, with sam-

ple rates up to 48 kHz. The SBC codec is manda-

tory; codecs such as mp3, AAC, apt-X and others are optionally supported. AG is the duplex Audio Gateway role, used in HFP and HSP. AG is the node (such as a car kit) that medi-

ates between the user and the mobile phone. apt-X is an optional high-performance codec used in A2DP. AT command is an audible signal used to control a device. AT commands are a PSTN (Public Switched Telephone Network) legacy. AVRCP is the Audio/Video Remote Control Profile. This profile is used in conjunction with A2DP, and pro-

142 APx500 Users Manual vides transport controls such as Play, Pause, Reverse, Forward, etc. Roles are Controller and Tar-

get. to legacy HFP. These data rates and newly sup-

ported codecs such as mSBC enable WBS (Wide-

band Speech) performance. Chapter 17: Bluetooth I/O Connect Paired devices can connect using compatible pro-

files and roles. Connection enables exchange of audio or control data. Each device can connect with only one device at a time. CVSD is Continuously Variable Slope Delta modulation, the codec used in HSP and legacy HFP profiles. With HFP 1.6, higher data rates enable the use of a higher quality codec called mSBC. Device address Every Bluetooth device has a unique 48-bit device address, in APx500 displayed in hex format, such as 00:f4:b9:c3:a0:cc. Device class A Bluetooth device class is a code that identifies the type of device. Some Bluetooth devices will only recognize devices of a certain class. Discovery Bluetooth devices that are not paired can discover each other when they are in range. Some devices allow users to make the device undiscoverable. duplex refers to a bi-directional audio channel, across which speaking and listening can occur simultane-

ously. eSCO Extended SCO, available in the Bluetooth 1.2 speci-

fication. Adds new packet types (EV1, etc.) and more flexibility in channel parameters, allows retransmission of bad packets. Also see SCO. EV1 First of a series of packet types available with eSCO, as opposed to the HV1, etc. packet types in SCO. Friendly name is an optional name for a Bluetooth device, more easily understood and remembered than the device address. An example is iPhone. HF is Hands Free, the duplex phone role in the HFP profile. HFP is the Hands Free profile, intended to allow hands-

free device operation in an automobile. It is similar to HSP, with more phone controls. Roles are AG and HF. HFP 1.6 is a revision of the HFP specification, which allows new packet types and higher data rates compared HS is Head Set, the duplex phone role in the HSP pro-

file. HSP is the Head Set profile, intended to enable Blue-

tooth mobile phone use. Roles are AG and HS. HV1 First of a series of packet types available with SCO, as opposed to the EV1, etc. packet types in eSCO. Link key is a shared secret exchanged in pairing. mSBC is a monaural version of the SBC codec, optimized for use in the HFP 1.6 profile. This codec and the higher available sample rates enable Wideband Speech operation. Pair Bluetooth devices that have discovered each other can be paired by exchanging a link key to form a bond. For some devices, pairing is automatic upon discovery; for others, user interaction is required. Pairing establishes a mutual, secure relationship between devices that have at least one compatible profile. Pairing is stored in non-volatile memory in each device. Devices can pair with more than one other device. PIN code A Personal Identification Number embedded in a device or provided by a user that is exchanged in a pairing negotiation. Profile One of a number of defined Bluetooth relationships covering a range of devices and use cases. A device can support more than one profile, and devices can be paired acknowledging more than one profile. role A role is a defined use of a device within a profile. In A2DP, for example, the roles are source and sink. For HFP, the roles are AG and HF. SBC

(Sub-band Codec), the mandatory codec for the A2DP Profile. Other codecs are allowed. SCO is a synchronous connection oriented channel, a full duplex data channel with 64 kbit/s data rate in each direction. The CVSD codec is used, and the three HV types of data packets are available. Also see eSCO. APx500 Users Manual 143 Chapter 17: Bluetooth I/O sink is the term used for the device that receives audio in a uni-directional system. source is the term used for the device that transmits audio in a uni-directional system. SSP is Secure Simple Pairing, the pairing methods required in Bluetooth v2.1. Audio Precision sup-

ports the SSP Just Works, Numeric Comparison and Passkey Entry methods. Per FCC 15.19(a)(3) and (a)(4) This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. Per FCC 15.21, CAUTION to the USER- changes or modifications not expressly approved by AUDIO PRECISION (the party responsible for compliance) could void the user's authority to operate the equipment. 8.4 User Manual Notice for Licence-Exempt Radio Apparatus This device complies with Industry Canadas licence-exempt RSSs. Operation is subject to the following two conditions:

(1) This device may not cause interference; and

(2) This device must accept any interference, including interference that may cause undesired operation of the device. 8.4 Manuel de l'utilisateur Avis pour un appareil radio exempt de licence Cet appareil est conforme aux normes RSS exempts de licence d'Industrie Canada. L'opration est soumise aux deux conditions suivantes:

(1) Cet appareil ne doit pas provoquer d'interfrence; et

(2) Cet appareil doit accepter toute interfrence, y compris les interfrences susceptibles de provoquer un fonctionnement indsirable de l'appareil NOTICE TO THE USER - This equipment is intended to be used only with the Antenna originally supplied. Do NOT susitute or replace the Antenna with a different type or design. Contact Audio Precision to order a replament Antenna - AP part Number for a replacement Antenna is 4543.5024 144 APx500 Users Manual NCC 5.25-5.35