Bluetooth Capture Diversity

With Vanguard, Ellisys engineers have introduced yet another disruptive industry first – Bluetooth capture diversity.  This technique involves a co-operational replication of a whole-band capture engine, an Ellisys innovation introduced on its prior Bluetooth analyzers.  Additionally, Both antennas can be angularly displaced on the analyzer unit, externally cabled and placed at optimal locations by the user to improve the spatial volume of the reception, or placed nearer specific devices under test to reduce packet error rate. 

Bluetooth packets can be degraded and missed by both Bluetooth test equipment and Bluetooth devices due to antenna positioning, signal strength issues, or RF interferences such as Wi-Fi and a variety of consumer electronics operating in the same band as Bluetooth.  Certain packet exchanges are critical to Bluetooth connections, encryption processes, and applications, and if missed can cause serious issues with communications between devices or characterizations provided by test and analysis equipment.  Smart software algorithms developed by Ellisys engineers are applied to the dual capture channels, and when combined with spatial and angular flexibilities provided by this technique, can significantly improve the capture process and result in reductions in received packet error rates.

Bluetooth t-ZERO Tracking Technology

Bluetooth LE Audio includes two types of audio transports – broadcast and connection-oriented, called Broadcast Isochronous Streams and Connected Isochronous Streams. Each transport presents new challenges to Bluetooth test and analysis equipment due to new protocol requirements involving the establishment and security of isochronous connections.

To address these challenges, Ellisys engineers have developed t-ZERO, proprietary technology that delivers high-fidelity capture of isochronous traffic from the initial instance of isochronous traffic, without gaps or any other limitations. This technology, available on the Bluetooth Vanguard Advanced Wireless Analysis System, also eliminates the cumbersome requirement for engineers to provide the security keys to the analyzer in advance of an isochronous capture process.

LC3 Auto-Detect

The Low Complexity Communications Codec, or LC3, is particularly ideal for Bluetooth LE as it provides a high degree of quality, even at its lowest data rates. This architectural flexibility, which includes a wide selection of bit rates, allows developers to easily manage trade-offs between audio quality and power consumption, enabling extensions to battery life or even smaller battery sizes. Ellisys Bluetooth Analyzers include detailed decoding for LC3 traffic.

An innovative feature, based on an Ellisys-designed, test equipment-grade LC3 codec, allows for automatic determination of LC3 configuration parameters. Historically, test equipment implementations have required a complete and error-free capture of audio codec configuration parameters to properly capture, characterize, and replay audio.

With this auto-detect innovation, even with otherwise critical configuration packets corrupted by interferences or low signal strength, LC3 audio is still recognized, understood, captured, and available for further analysis. Even incorrect configuration implementations will not prevent LC3 capture.

Synchronized Analog Audio Capture

The Audio Grabber is a small accessory for use with all Ellisys Bluetooth analyzer models. It allows for precise, time-synchronized capture and measurement of audio latencies involving analog audio signals and I2S (Inter-IC Sound) digital audio inputs, all synchronized to any other traffic streams captured by the analyzer, such as Bluetooth wireless audio, Host Controller Interface (HCI) traffic, Wi-Fi, I2C, UART, and others.

Wi-Fi Capture using a Hardware-Accelerated Protocol Engine

With Vanguard, Wi-Fi is captured using an innovative, Ellisys-designed hardware-accelerated protocol engine. With lower-performance Wi-Fi capture tools that use a software-based capture approach, such as that which can be done with just about any computer, the capture process is done with a processor involved. This approach can limit the speed and timing accuracy of the capture – packets can be missed when the processor is outmatched by the incoming streams. With Vanguard’s specially designed protocol engine, the capture is driven directly and without processor dependence to guarantee throughput and minimize latency.

All-Channels Capture of 802.15.4 WPAN

IEEE 802.15.4 is a technical standard that provides the lower-layer support of higher protocols network specifications like Thread, Zigbee, 6LoWPAN and RF4CE.  Increasingly, this Low-Rate Wireless Personal Area Network (LR-WPAN) technology is being used on devices, modules, and SoC’s that also employ Bluetooth and/or Wi-Fi. 

The Bluetooth Vanguard captures all 16 WPAN channels used in the 2.4GHz band, including associated RF characteristics, all in precise synchronization with all other traffic streams captured by the analyzer.

Understanding Coexistence Issues

Wi-Fi and WPAN are common sources of interference with Bluetooth communications, as much of the spectrum used by these standards is the same as that used by Bluetooth.  To properly characterize these contentions, Vanguard provides capture of Wi-Fi 802.11a/b/g/n/AC 3×3 and WPAN in precise synchronization with all other supported wired and wireless transmissions. 

Understanding interference sources and related hardware and stack behaviors, how Bluetooth devices attempt to avoid these interferences, and the negative effects these interferences have on Bluetooth performance and interoperability is an important task for many Bluetooth engineers. 

Additionally, Wi-Fi, WPAN and Bluetooth are often co-resident on a single chip, and this design approach presents substantial test and operational challenges. Vanguard has a variety of innovative features designed to enable engineers to manage these challenges.  Understanding the timings of Wi-Fi transmissions, the timing of these transmissions relative to Bluetooth packets or wired interfaces such as HCI or discrete logic inputs, the power levels of these transmissions, and packet details, is quite important to the general task of ensuring proper radio coexistence.

Bluetooth Mesh Networking

The Bluetooth Mesh Networking specifications define a broad spectrum of device and systemic requirements for a large-scale many-to-many network using Bluetooth LE wireless technology.  Bluetooth mesh networks can greatly increase the range of Bluetooth communications by using a message relay approach and are inherently uncomplicated and inexpensive to deploy, as there are no requirements for a central router or computer.

The Bluetooth Vanguard provides support for capture, decode, and decryption of Mesh features, including a variety of mesh-specific security mechanisms and protocols.

Emerging Features Support

The reconfigurable Bluetooth analyzer is an Ellisys innovation.  All Ellisys Bluetooth analyzer systems are reconfigurable with software updates.  Ellisys maintains close relationships with radio developers worldwide and with the various technical groups involved in outlining new Bluetooth features and specifications.  This approach allows new features to be added even in the conceptual stages, long before such features become standardized in a public release of the Bluetooth specification.  This is a huge advantage to Bluetooth radio developers, and to the Bluetooth developer ecosystem in general, as radio developers can test new features well before they are committed to silicon, greatly reducing chances of re-spins or discoveries of issues in the marketplace, post-spin.  This also raises the quality aspects of general Bluetooth radio development, effectively bringing a better product to integrator companies, and in the end, better products to consumers.

Choices in Power and Control

Vanguard conveniently provides multiple choices to the user for system control and power.  Conveniently, the user can control and power Vanguard using networkable Gigabit Ethernet (1GbE) which utilizes Power over Ethernet (PoE), or USB Type-C™, which utilizes Superspeed USB 3.1 Gen 1 (5Gbps) and USB Power Delivery.  As needed, the user may also operate and power the system using an external DC supply (provided).  

Software Overview

Timing view

Timing is everything as they say, and with Bluetooth, it’s always an important focus.  Multitudes of timing parameters defined by the Bluetooth specification are system-critical.  It is understandably important to characterize these timings efficiently and accurately.  Hardware and software timing issues are often the source of many interoperability and performance issues that challenge Bluetooth engineers. 

The Timing view displays a multitude of information along a common timestamp, including Bluetooth and Wi-Fi packets, HCI traffic (UART, SPI, and USB), generic communications (SWD, I2C, UART, and SPI), and logic signals.  A variety of data throughput and packet transmission statistics are included to complete the approach.  Several timing features, both manual and automated, are provided.

Throughput

Understanding device data throughout performance is a common task for wireless engineers. These metrics are the domain of the Throughput view, which provides throughput by device and by L2CAP or SCO/eSCO channel and Wi-Fi communications. A convenient statistical overlay provides information on how various transmission inefficiencies may be affecting throughput, such as packet retransmissions.

Channels

The Channels view feature provides easy-to-understand visual and statistical analyses on various per-channel transmission characteristics, including packet retransmissions, header errors, and payload errors.  This information can be useful in understanding where in the Bluetooth spectrum devices are communicating and the spectral areas (channels) they are avoiding, generally due to external interferences.  This information is provided for the duration of an entire capture and can be configured to characterize all devices in the vicinity or specific devices. 

Piconet

Bluetooth technology has become very popular among consumers and continues to evolve into new applications and markets, leading to more complex use cases. The only way to support these new use cases is to create more complex topologies, for example, Mesh Networking.

Debugging complex topologies has always been a difficult task, but Bluetooth Vanguard is up to the task with its powerful wideband radio capable of capturing any traffic from any device, including the most complex topologies. The Piconet view helps developers visualize their topol ogies live while capturing, and also provides a play-back feature showing step-by-step evolution of topology changes.

HCI Analysis (PRO)

Wireless traffic is the primary element of debug information for Bluetooth engineers, but Host Controller Interface (HCI) traffic can be an equally important complement of information for getting a clear and complete picture of a given situation. Bluetooth Vanguard supports capture of HCI transports over USB, UART, and SPI. HCI traffic is captured concurrently with the wireless traffic and other wired streams using the same precision clock for perfect synchronization and timing analysis and is decoded and displayed in various formats.

HCI capture is also a very convenient feature when working with devices that implement newer-generation security features, such as Secure Simple Pairing (SSP) or Secure Connections (SC).  The Ellisys analysis software automatically extracts any Link Key exchanged over HCI and uses it to decrypt the wireless traffic, all without any user interaction.

Another common debug application involves comparison of audio streams, both over-the-air, and over HCI.  These streams can be played live, exported to WAV, looped, and otherwise closely examined for differences in quality and performance, helping the Bluetooth engineer to root cause issues to stack or coexistence issues.

Spectrum Analysis (PRO)

The Spectrum view feature provided by Vanguard displays raw RF spectrum information in the busy and unlicensed 2.4GHz ISM band in which Bluetooth operates.  This feature is yet another Ellisys innovation.  Other users of this band include Wi-Fi, LTE, ZigBee, ANT, microwave ovens, and a broad range of other proprietary and commercial technologies.  These users can and do interfere with each other, and it is often necessary to have a better understanding of the wireless environment.

The capture of raw RF spectrum is the perfect tool for characterizing and debugging coexistence issues, RF attributes, and low-level RF operations.  Signal strength of all emitters (RSSI) is displayed using absolute values on flyovers and using color-gradients.  A configurable resolution of up to 1 microsecond is available.  This raw RF information is displayed in synchronization with captured Bluetooth and Wi-Fi packets.  Channel avoidance schemas (Adaptive Frequency Hopping behaviors) are overlaid, enabling a keen understanding of the complexities of the instantaneous RF challenges encountered by any given Bluetooth link.

Packet errors, retransmissions, and header errors are each characterized visually and statistically, along with adaptive frequency hopping (AFH) employed by any given link.  Various approaches are provided to allow timing measurements.

Logic Analysis (PRO)

The logic analysis feature allows for capture of external logic signals, in synchronization with the wireless, HCI, and all other traffic steams.  Any digital signal is supported, including general-purpose I/Os (GPIOs) or dedicated pins such as TX/RX Active.  One of the many applications for this feature is keeping track of a device’s power consumption in various states, by using dedicated hardware such as comparators for determining whether key thresholds are exceeded.

These signals are visualized with 5-nanosecond precision and compared with the other captured streams in the powerful Timing view of the Ellisys software.

Integrated Audio Analysis

Captured audio streams can be easily played back, even during capture. LC3 traffic is automatically detected using a test equipment-grade LC3 codec, even without capture of LC3 configuration traffic. LE Audio is detected immediately, at the initial anchor points, using tZERO proprietary technology. Finding packets carrying specific audio portions or at specific events is easily done.

Audio captured over HCI or from an Audio I2S input [PRO] can be played back. This enables characterization of the complete audio chain, including the uncompressed audio provided to the source, the audio transmitted wirelessly, and the decoded audio at the receiver device. Audio streams are exportable to WAV format.

Errors Detection

The analyzer software alerts the user to a variety of errors detected for both wired and wireless captures.  Physical, protocol, and profile layer errors, including packet and transactional errors, are automatically highlighted without any need to search through the capture.  Errors are highlighted on a color-coded system to indicate the relative severity of the errors, summarized in a dedicated status column in each protocol overview, and described in the Details view or with pop-up messages on fly-over in the Overviews.  Incomplete payloads, missing or incorrect field values, center frequency violations, timing violations, missing responses, and CRC errors are among the errors indicated.