To test audio devices across both Bluetooth Classic and Bluetooth 5 standards, measurement equipment must ideally have reliable connectivity to these interfaces and the ability to provide stimulus across the range of profiles and codecs that Bluetooth audio devices use. Audio Precision's Bluetooth 5 module provides an interface to audio devices using the latest version of the Bluetooth specification, including LE Audio devices utilizing Unicast and Auracast, useful for designers and manufacturers of earbuds, headphones, headsets, hearing aids, speakers, automotive infotainment systems, etc. Our Bluetooth Duo delivers a wider selection of A2DP codecs, faster pair and connection times, an increased feature set within APx500 measurement software, and improved RF shielding for use in production test environments.
Technote 123: Measuring Bluetooth A2DP Profile Audio Quality
The A2DP Bluetooth® profile is used for high quality music transmission, employing a variety of supported codecs that include MPEG-1, MPEG-2, MPEG-4, AAC, ATRAC, aptX and aptX Low Latency. This technote illustrates how the APx Bluetooth option is used to control and monitor codec selection, measure latency, and test all essential audio parameters such as frequency response and THD+N for Bluetooth-enabled music playback devices.
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A Step by Step Guide tosetting up the APxBluetooth Duo Module
For users getting familiar withthe APx Bluetooth Duo module,get a step-by-step guide toconfigure APx500 software(v4.5 software or later) and pairit with your device-under-test(DUT).
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APx Bluetooth 5 OptionDatasheet
Audio Precision's third-generation Bluetooth@ module,the APx Bluetooth 5, deliversBluetooth LE Audio capabilities.APx Bluetooth 5 supportsBluetooth specification v5.4,with Unicast Voice (transmitand receive), Unicast Music(transmit), and Auracast(broadcast transmit).
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APx Bluetooth Duo Option Datasheet
The APx Bluetooth Duo deliversa wider selection of A2DPcodecs. faster pair andconnection times, increasedfeatures within the APx500software, and improved RFshielding for use in productiontest environments. It supportsBluetooth core specificationv4.2, HFPv1.7, HSP v1.2, AVRCPv1.4 and A2DPv1.3.
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Quick Tip 141-BluetoothDuo Module
This brief video provides a briefoverview of the Bluetooth DuoI/O module, including itsintegration with APx500measurement software. Themodule is an available option forboth B Series and LegacyAPx555, APx52x and APx58xaudio analyzers.
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More about BluetoothSSP Mode
APx provides four SSP (SecureSimple Pairing) options, and thisarticle explores how to choosethe option that is appropriatefor the Bluetooth device you aretesting.
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An Introduction to the Bluetooth 5 LE Audio Interface for APx
In this video, Audio Precision General Manager Daniel Knighten introduces the Bluetooth 5 LE interface module for APx analyzers, demonstrating how to measure audio performance for Bluetooth 5 LE–compatible devices.
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As a technology, Bluetooth is effectively a part of everyday life, a fact that reflects its great utility. That flexibility is reflected in the various Bluetooth profiles used in a wide range of consumer devices from headphones and headsets to loudspeakers (smart or otherwise) and even vehicle infotainment systems. There are four main profiles in Bluetooth Classic which pertain to audio measurement:
Hands Free Profile (HFP) – device as source (Audio Gateway) or sink (Hands Free). Bi-directional audio using CVSD and mSBC (wideband speech) audio codecs.
Headset Profile (HSP) – device as source (Audio Gateway) or sink (Headset). Bi-directional audio using CVSD and mSBC (wideband speech) audio codecs.
Advanced Audio Distribution Profile (A2DP) – device as source or sink. High-quality stereo audio using one of a selection of audio codecs.
Audio Video Remote Control Profile (AVRCP) – device as source (Target) or sink (Controller). AVRCP supports A2DP with transport controls, delay compensation and absolute volume settings.
Bluetooth 5 measurement presents new complexities by bringing to market the following technologies:
Unicast Music & Voice – these provide point to point audio streaming replacing the functionality previously provided by A2DP (Advanced Audio Distribution Profile) and HFP (Hands-Free Profile) in Classic, v4 and earlier, Bluetooth implementations.
LC3 – a new audio codec promoted as providing higher quality audio while requiring less power.
Auracast – a completely new feature which allows an audio stream to be broadcast to many receivers. This feature is being promoted by h
An audio device being evaluated may need to be tested for multiple profiles and, potentially, as both source and sink for each profile. This means any measurement system must support the same profiles as both source and sink, along with the various codecs in use by the device.
The function of a codec is to encode audio at the source and decode it at the sink. This means reducing the data rate in the process but doing it as transparently as possible, since the performance of different codecs can affect perceived audio quality. No codec is linear and therefore will always degrade measured performance as compared to a linear device. As such, unexpected harmonics, noise, or other unusual artifacts may be seen when analyzing measurement signals through codecs.
Regardless of profile selected, a Bluetooth device is constantly transmitting and receiving radio signals. When sending audio, the device functions as an audio source; when receiving audio, the device functions as an audio sink. When testing a Bluetooth speaker, for example, an audio test system’s output would be configured as a Bluetooth source, and its input would be configured as analog, connected to a microphone that picks up the speaker’s acoustic output. When testing a microphone (as found in a Bluetooth headset), the audio test system’s output would be configured as analog to drive a loudspeaker to acoustically stimulate the microphone, and the instrument’s input would be configured as a Bluetooth sink.