Studio Technologies Model 5401A Dante Leader Clock

The Model 5401A Dante Leader Clock provides precise timing signals for applications that utilize the Dante® audio-over-IP media networking technology. The unit implements a high-performance IEEE® 1588 precision time protocol (PTP) server, compatible with the requirements of Dante and capable of simultaneously supporting the timing needs of up to hundreds of Dante-compatible devices. As expected, the Model 5401A provides the PTP v1 (IEEE 1588-2002) compatibility that's required by Dante. In addition, the unit supports PTP v2 (IEEE 1588-2008) for AES67 applications. A word clock output provides a general-purpose timing reference for use by external devices. The Model 5401A also generates eight sine-wave audio tones on Dante transmitter (output) channels which can be useful during audio network installation, maintenance, and operation. A sync input connection allows the Model 5401A's internal oscillator to be synchronized with a variety of timing and reference signals.

Features:

• Dedicated Leader clock for Dante audio-over-IP and AES67 applications
• High-performance IEEE 1588 PTP v1 and v2 servers
• Internal temperature-stabilized frequency reference
• Compatible with external word clock, video sync, and 10 MHz sources
• Word clock output with selectable rates
• Eight configurable audio tone signals
• Three Gigabit Ethernet interfaces support independent Dante and management networks
• Webpage management and USB flash drive software updating
• AC mains and 12 volts DC powering
• Lightweight enclosure, single rack-space (1U) mounting

The Model 5401A is suitable for use in fixed and mobile broadcast facilities, post-production studios, commercial and educational theater environments, and entertainment applications. Only power and one, two, or three Ethernet network connections are required for full operation. Using Dante's inherent capabilities two Model 5401A units can serve in primary and secondary Leader clock roles for redundant operation.

The unit's three Gigabit Ethernet ("GigE") network interfaces can be configured for use in a range of network implementations. For high-performance applications two of the interfaces can support Dante redundancy operation while the third is used for accessing the management webpages. To meet the latest interoperability standard the Model 5401A's Dante implementation supports AES67-2018. The unit also supports the Dante Domain Manager™ (DDM) software application.

An integrated web server allows fast and flexible monitoring and configuration of the unit's networking, clocking, and Dante performance. Front-panel indicators, an LCD display, and pushbutton switches provide users with direct access to key operating parameters.

The Model 5401A can be powered by 100-240 V, 50/60 Hz mains or a source of 12 volts DC. Both can be simultaneously connected to provide redundant operation. The lightweight enclosure mounts in one space (1U) of a standard 19-inch rack. Industry-standard connectors are used for Ethernet, DC power, and AC mains interconnections. Updating the Model 5401A's operating software can be easily performed using a standard USB flash drive.

Applications
Applications for the Model 5401A include broadcast and post-production facilities, college and university audio networks, arenas, stadiums, and corporate installations — virtually any application where substantial numbers of Dante-compatible devices are utilized. The Model 5401A will serve as a stable and consistent Leader clock for the entire Dante "network." And, as expected, the Model 5401A is compatible with all Dante devices, no matter what their primary function or manufacturer. Applications that utilize devices compatible with AES67 will also benefit from the Model 5401A's resources.

Why a Dedicated Dante Leader Clock?
With Dante ubiquitous in fixed and mobile facilities of all sizes and types, the need arose for a cost-effective, purpose-designed, dedicated Leader clock. While an inherent strength of Dante networking is its carefully implemented use of IEEE 1588 to ensure that all connected devices maintain a common timing reference, the actual performance can vary widely depending on the specific Dante devices in use and the overall number of devices on a network. There are many Dante-compatible devices that can provide adequate basic performance as a Leader clock, but with the Model 5401A networked audio systems get the benefits of a high-performance "Primary Leader" PTP server, along with additional unique capabilities. The unit's feature set, along with the associated internal hardware and software, was designed to provide optimum performance, flexibility, and system integrity.

Timing Sources
The Model 5401A can provide excellent Leader clock performance using its accurate and stable internal oscillator, which is temperature-stabillized and exceeds the capability of standard Dante devices by at least an order of magnitude. While its standalone performance is excellent, the Model 5401A can also be "locked" to a variety of external signals for integration into facilities that include a central or main timing reference. Compatible signals include word clock, video reference, and 10 MHz.

Word clock is a square wave signal that is often used as a timing reference in audio-only facilities. Several word clock rates, including 48 and 96 kHz, are compatible with the Model 5401A's sync input. Video reference ("sync") signals are found in most broadcast and post-production facilities. The Model 5401A supports the most-common video format/rate combinations including "black burst," bi- and tri-level HD, and several that are specifically intended for 4K applications. Industrial and commercial facilities often utilize a GPS-disciplined source of 10 MHz as a timing reference. This sine-wave signal is typically compatible with the Model 5401A's sync input.

Word Clock Output
The Model 5401A generates a precise word clock output signal that can be used as a timing reference for related equipment. It's specifically intended for "locking" digital audio devices in applications that use the Model 5401A to provide timing reference signals for the associated Dante equipment. In this way, all devices in an installation will share a common timing reference.

The word clock output rate can be selected to be 44.1, 48, 88.2, or 96 kHz. The underlying timing source for the word clock output is derived from the Model 5401A's main timing source. As previously reviewed, the internal oscillator, if desired, can be "locked" to an external source. The main timing source is divided and processed by the Model 5401A's logic circuitry to create the highly stable word clock output. This ensures that the word clock output is synchronized with the unit's PTP server functionality.

Audio Reference Signals
The Model 5401A generates eight sine-wave audio reference signals intended for general-purpose use. They are individually configurable in level and frequency. These audio "tones" are available from the Model 5401A by way of Dante transmitter (output) channels and can be connected, using the Dante Controller application, to Dante receivers (inputs) on related equipment. The flexibility of being able to interconnect signals (create Dante "subscriptions") between all Dante devices on a network allows the audio reference tones to be used for a variety of purposes. Configuration choices allow the frequency and level of each sine-wave signal to be optimized for use in specific applications.

Leader Clock Support for Dante Networks
A core part of the technology underlying Dante audio-over-IP networking ensures that all connected devices follow a common timing reference. This is accomplished using the IEEE 1588-2002 precision time protocol (PTP v1). Any connected Dante device can be used as a Leader clock; there is no requirement that a dedicated Leader clock device be utilized to realize adequate functionality. However, the actual performance can vary widely depending on the specific Dante devices available and the overall number of Dante devices on a network.

Many Dante devices utilize the 2- or 4-channel Ultimo™ ULT or UXT integrated circuits to implement Dante connectivity. While Ultimo devices will fully support Dante audio transport, they are not well suited to serve as a Leader clock. Ultimo's PTP performance is limited and does not have the ability to synchronize with an external timing reference. Other Dante devices may use the Brooklyn II module or Broadway integrated circuit to support Dante connectivity. In some cases, these devices can provide good basic performance as a Leader clock.

However, problems and limitations may arise when these devices are called upon to perform "double duty," serving in both a primary function (such as analog-to-Dante interfacing or audio signal processing) as well as acting as a Leader clock. This is understandable as the main purpose of these devices is to serve functions other than acting as a primary synchronization reference. Timing related features, such as allowing connection of a video bi- or tri-level sync signal is rarely, if ever, supported. And PTP performance can degrade when the computing power of a device is intended primarily for handling and manipulating digital audio signals. This can lead to the required PTP resources being in short supply when the number of Dante devices that need timing messages moves into the hundreds. Also, firmware updates, cabling changes, and other maintenance tasks typically associated with a general-purpose Dante device would impact the Leader clock functionality for an entire installation.

The Model 5401A was specifically designed to support a Dante-based audio system's Leader clock requirement. And the unit's generation of audio tones and implementation of the word clock output utilize hardware that is separate from that associated with its PTP functionality. As such, this secondary functionality will not interfere with PTP operation. Unlike a general-purpose Dante device, once mounted in an equipment rack and the required interconnections are made, the Model 5401A will perform its tasks without risk of interruption due to conflicting resource demands.

Flexible Networking Capability
Using the Dante Controller application program, the Model 5401A's three Gigabit Ethernet ports can be selected to operate in one of four modes: Switched, Redundant, Switched+Mgmt, and Redundant+Mgmt. This should allow virtually any desired networking implementation to be easily achieved.

In the Switched mode a single Ethernet connection to either of the Model 5401A's two Dante Ethernet ports will provide Dante Leader clock functionality. The remaining Dante Ethernet port will provide Dante network "loop-through" capability and can be used to interface with another piece of Ethernet-connected equipment. The management Ethernet port will be used to access the Model 5401A's monitoring and configuration webpages.

In the Redundant mode two independent Ethernet connections are made to the Model 5401A's two Dante Ethernet ports, enabling Dante's redundant networking capability. Again, the management Ethernet port will be used to access the Model 5401A's monitoring and configuration webpages. Using either of these network modes allows separate network connections to be maintained for Dante audio and management purposes.

In the Switched+Mgmt mode a single Ethernet connection is used for both Dante Leader clock functionality as well as providing access to the Model 5401A's management webpages. The remaining Dante Ethernet port will provide network "loop-through" capability and can be used to interface with another piece of Ethernet-connected equipment.

In the Redundant+Mgmt mode two independent Ethernet connections can be made to the Model 5401A's two Dante Ethernet ports. This will enable Leader clock capability for applications that utilize Dante redundancy. Access to the Model 5401A's management webpages will be made by way of the Ethernet connection made to the primary Dante Ethernet port.

Operating Power
The Model 5401A allows an AC mains source of 100-240 V, 50/60 Hz to be directly connected. It can also be DC powered using a 10-18 volt source that is connected via a broadcast-standard 4-pin XLR connector. If both AC and DC power sources are connected the unit will be powered by the AC mains supply. Only if the AC mains source fails will appreciable power be drawn from the DC source. This allows a source of DC, typically an external power supply or broadcast-style battery, to serve in a backup capacity. With this arrangement normal operation can continue even if AC mains power is lost.

Future Capabilities
The Model 5401A was designed so that its capabilities can be enhanced in the future. A USB connector, located on the unit's back panel, allows the main and FPGA firmware (embedded software) to be updated using a USB flash drive. The Model 5401A's Dante firmware can be updated using one of the unit's Ethernet connections, helping to ensure that the Dante capabilities remain up to date. All software files and configuration parameters are stored in non-volatile memory.