Syrinx is a 600 kHz Doppler Velocity Log (DVL) for surface and subsea vehicles. It combines the high altitude, high resolution features of 300 kHz and 1200 kHz DVLs in a single, easy to install navigation instrument. The adaptive bottom lock technology inside Syrinx provides consistency and reliability over challenging and changing topography and works at an altitude higher than 85% of the world’s subsea infrastructure. This reduces the amount of time a vehicle has to dive on free inertial.

An optional firmware upgrade can be deployed to enable ADCP functionality if water profiling is a mission requirement. A combined DVL+ADCP mode means that Syrinx can perform navigation and profiling without the need for separate instruments.

A highly capable and versatile Doppler Velocity Log

Syrinx can be used as a standalone DVL or ADCP, as part of an integrated navigation system, or perform all these functions at once. This is possible due to alternating DVL and ADCP measurements, and simultaneous Ethernet and serial outputs capable of ping rates of up to 25 Hz. Syrinx’s multi faceted capability means that only one DVL/ altitude/ADCP sensor is required for ROV control, Survey crews, and profile monitoring, saving on cost and vehicle payload space.

The unit runs an embedded System Manager using a web browser, eliminating the need to install dedicated PC software. This allows configuration and testing of Syrinx prior to deployment, control of Syrinx during subsea operations, and visualisation of the navigation data. The hardware and vehicle interfacing has been designed to be easy to install, set up and use and is compatible with DVL/ADCP mounting arrangements from third parties. With similar dimensions to existing DVLs and ADCPs, there should be no need for modifications to subsea vehicles in order to upgrade to Syrinx. PD0, PD3, PD4, PD6, PD13 telegrams are supported for integration to third party navigation systems.

When tightly integrated with Sonardyne’s INS, SPRINT, unmatched DVL aided navigation can be achieved. This allows for enhanced performance through optimisation of beamlevel data passed between Syrinx and SPRINT to aid velocity prediction and outlier rejection, with positioning able to continue even if one or two DVL beams are unavailable.

Syrinx’s onboard processor is able to report high resolution water velocity layer data by streaming PD0 format messages. This makes it suitable for ADCP applications or AUVs measuring water flow to update their positioning algorithms.


In open water, Syrinx is able to give a robust velocity output in a stationary environment, even at low altitude, giving long term accuracy with low bias errors in the range of a few tens of micro-metres per second. In this mode, Syrinx measures the phase change between backscatter return from each pulse using a wideband correlation technique. Sound is reflected back from many scatterers located on the seabed within a small footprint. Navigation can continue uninterrupted through partial sector obstruction and large differences in path length on an irregular seabed. A robust, low-altitude mode makes navigating near structures more precise for surveys such as metrology.


Syrinx excels at all altitudes thanks to its improved reliability adaptive bottom lock combined with low noise electronics and fully linear signal processing techniques. These techniques help prevent loss in output measurements, including when navigating over challenging terrain of any type. Unlike many DVLs, Syrinx can continue to output data at very high update rates when operating at very low altitudes (<1metre).

ADCP Performance

Syrinx ADCP can capture current profiles to a depth of more than 80 m in a single ping – this allows a large portion of the water column to be monitored without resorting to an additional lower frequency profiling device or averaging (thereby reducing temporal resolution). Water velocities can be compensated for vessel speed by leveraging Syrinx’s excellent DVL performance in DVL+ADCP mode.

Syrinx ADCP can also be tightly integrated with SPRINT. While Syrinx DVL navigation data is being exported to SPRINT, Syrinx can ingest inertial velocities from SPRINT to compensate water profiles for vessel motion when bottom tracking is compromised. This allows absolute water velocities to be measured even under challenging conditions, such as high altitude or a moving seabed


A 4,000 metre rated titanium housing is supplied as standard to meet the requirements of modern Work-Class ROVs. Syrinx 6,000 metre models and OEM (no housing) versions are also available. Syrinx’s transducers have been designed, built and tested in-house to provide maximum performance, and can be individually replaced, reducing ownership costs and repair time. The entire array is water blocked meaning that should damage occur to the transducer array, the unit’s electronics are isolated from water ingress.

The Syrinx DVL OEM is a class leading Doppler Velocity Log that builds on Sonardyne’s existing product range of acoustic instrumentation by bringing to market a high integrity, high performance instrument. The OEM version contains the Core electronics for custom integration.

ADCP functionality is available as an optional firmware upgrade for Syrinx, SPRINT-Nav, or Syrinx OEM. This allows water profiling capability within the same instrument, reducing ownership costs. A lightweight Windows application, Echo Observer, is also available. This allows ADCP data to be visualised before, during, and after a mission, to ensure the profile quality meets requirements.


For the ultimate integration, SPRINT and Syrinx are also now available as a single combined unit with integral pressure sensor. The result is one of the smallest inertial DVL instruments available on the market suitable for almost any ROV and survey task.

Syrinx ADCP and SPRINT can also be tightly coupled for outstanding profiling performance. This capability is enabled by a few simple configuration steps, and the result is impressive: Profile velocities compensated for vessel motion, even when bottom tracking is compromised.


Syrinx is designed and manufactured entirely in the UK. This means it can be exported to countries within the European Union and selected others (including the USA) without the need for a specific export licence.