GyroCal Offshore

Professional Offshore Heading Calibration, Verification & Integrity Software

Precision Navigation. Trusted Results.

GyroCal Offshore is a Windows desktop application developed by Worldwide Survey Dynamics for the calibration, verification, quality control and lifecycle management of heading systems used on hydrographic and offshore survey vessels. It brings sensor acquisition, survey-reference reduction, gyro-error determination, uncertainty analysis, multi-method fusion, MBES alignment, integrity monitoring and reporting into one traceable workflow.

Rather than relying on disconnected spreadsheets and separate field calculations, GyroCal Offshore provides a consistent environment in which the surveyor can acquire the heading data, define the independent reference, solve the calibration, review residuals and quality indicators, quantify uncertainty, compare or combine methods and preserve the evidence required to support the final result.

Product status: GyroCal Offshore is currently completing Windows release qualification and Microsoft Store onboarding. Public availability and licensing information will be announced by Worldwide Survey Dynamics.

GyroCal Offshore Quayside calibration workspace showing surveyed vessel marks, heading observation controls, calibration results and QC.

Why GyroCal Offshore

Heading calibration offshore is rarely a single calculation. A defensible result depends on the relationship between the gyro or heading sensor, the vessel body frame, the independent survey reference, geodetic reference system, observation quality, time synchronization, environmental effects, sensor noise and the uncertainty of every contributing quantity.

GyroCal Offshore is designed around that complete measurement chain. The operator can work with several recognized field approaches while maintaining one heading convention, one correction convention and one audit trail throughout the project. The software clearly distinguishes grid heading, meridian convergence, true reference heading, indicated heading, the resulting gyro error and the correction to apply.

For calibration results, the convention is presented explicitly:

Gyro error a₀ = indicated heading − true reference heading

Correction to apply = true reference heading − indicated heading

This removes a common source of sign errors when transferring calibration results between survey calculations, vessel systems and reports.

Complete Operational Workflow

A typical GyroCal Offshore workflow starts by connecting the relevant heading source and creating a traceable recording session. The survey reference is then defined using the appropriate calibration or verification method. GyroCal reduces the observations, applies the geodetic relationship between grid and true directions where required, calculates the heading error and correction, evaluates residuals and quality controls, and passes the solution into uncertainty, fusion, integrity and reporting workflows as appropriate.

The result is not only a correction value. The operator receives the reference heading, indicated mean, method status, residual statistics, uncertainty information, quality warnings and supporting evidence needed to understand whether the result is suitable for use.

Sensor acquisition and recording workspace for live heading inputs and traceable raw-data capture.

Live Sensor Acquisition & Recording

The Acquisition workspace connects GyroCal Offshore directly to heading data sources. It supports Serial, TCP, UDP and multicast transport modes, configurable source and sensor identifiers, expected update rate, serial baud rate, host/group and port settings, and optional NMEA checksum enforcement.

Incoming messages can be monitored live while the operator records the source into a session capture. When a capture is closed, GyroCal produces a SHA-256 hash so the recorded evidence can subsequently be checked for change. This links the calibration result to the data actually observed in the field instead of relying only on manually copied numbers.

Quayside Calibration

The Quayside workflow is intended for a vessel alongside or otherwise positioned so that surveyed vessel marks can be observed in a projected coordinate system. The operator enters the body-frame coordinates of vessel reference marks and their surveyed Easting/Northing positions, along with the relevant survey-control information and measurement uncertainty.

GyroCal determines the vessel reference direction from the surveyed geometry, calculates the grid heading, evaluates meridian convergence at the reference location, converts the reference to true heading where required, and compares the result with the synchronized gyro heading window or a manually supplied indicated heading.

The calibration output includes method status, number of targets, grid heading, meridian convergence, true reference heading, indicated mean, gyro error, correction to apply, reference-geometry uncertainty, residual RMS and maximum residual.

Example calibration result table. The presentation separates the measured reference, indicated heading, gyro error, correction and QC statistics.

Total Station Calibration

The Total Station workflow allows the surveyor to work from an occupied station and backsight together with observations to vessel targets. It reduces the observations into target coordinates and derives the independent vessel heading from the resulting geometry.

Quality-control information includes reduced target coordinates, observed/reduced angles, face-closure information, grid azimuth, slope or horizontal distance as applicable to the reduction path, and coordinate uncertainty. The resulting vessel heading is then compared with the as-found gyro observation using the same heading and correction conventions used throughout GyroCal Offshore.

This provides a more direct workflow for field teams who hold raw or reduced total-station observations rather than already-computed bow/stern coordinates.

Dual-GNSS Heading Transfer

The Dual GNSS workflow uses the independently surveyed antenna baseline in the vessel body frame together with the GNSS-derived baseline observed during the calibration epoch. The software considers the relationship between the vessel-frame baseline and the geodetic baseline, synchronized attitude information and GNSS quality before calculating the transferred heading reference.

The workflow is particularly useful where a validated dual-antenna GNSS reference is available and a heading sensor is being checked or transferred against that reference.

Known-Range Calibration

The Known Range workflow supports calibration against a surveyed range or alignment defined by reference marks. GyroCal evaluates the range reference, the relationship between the range and vessel alignment, the observation stability and the indicated gyro heading before determining the resulting calibration correction.

This method is useful for repeatable vessel checks at facilities where a surveyed heading range or alignment has been established and maintained.

Reciprocal Heading Calibration

The Reciprocal workflow evaluates forward and reverse heading observations as paired measurements. The software calculates pair closure and correction diagnostics, allowing the operator to assess the internal consistency of reciprocal observations rather than treating each heading independently.

Reciprocal observations provide a useful independent check where vessel manoeuvring and field conditions allow controlled observations in opposing directions.

Celestial Calibration

The Celestial workflow provides a structured route for heading calibration using a celestial or astronomical reference. It records the reference information, observation quality, synchronized heading window and quality limits before calculating the heading correction.

This retains celestial methods as an independent reference option while bringing their results into the same digital QC, uncertainty and reporting framework used by the other calibration methods.

Fixed-Reference Verification

The Fixed Reference workflow supports heading transfer or verification against a known fixed object or structure. The operator records the provenance of the fixed reference, the reference transfer information and simultaneous vessel-position/fixed-object bearing observations. A synchronized gyro window and configurable quality limits are then used to evaluate the heading system.

This is suitable for controlled verification activities where a defensible fixed-object reference is available but a conventional quayside mark geometry is not being used.

Course-Over-Ground Check

The COG Check workflow provides an operational verification based on a fitted GNSS track during straight, stable vessel motion. GyroCal evaluates the fitted track together with the as-found gyro window and monitoring limits. An optional validated water-current model can be introduced where appropriate to the selected verification strategy.

COG is treated as a verification/checking workflow rather than being automatically assumed to be equivalent to a surveyed static reference. The operator can therefore use it as supporting evidence without losing the distinction between direct calibration and dynamic operational verification.

Calibration Planning & Estimability

The Planner is designed to answer an important question before or during a calibration campaign: can the intended observations actually resolve the parameters being requested?

The operator can define the sensor class, project design target, requested calibration parameters, external constraints, planned heading-domain observations and closed-turn rate-domain observations. GyroCal evaluates the design matrix and provides estimability information so poorly observable parameters can be identified before a field campaign is accepted as complete.

This reduces the risk of collecting a large amount of data that cannot uniquely support the required calibration model.

Noise Characterisation

The Noise workspace analyses heading residual series rather than assuming every sample is statistically independent. It evaluates residual behaviour, autocorrelation and effective sample size and feeds the resulting information into a structured Type-A/Type-B uncertainty budget.

For long observation windows and correlated heading sensors, this is important because thousands of samples do not necessarily provide thousands of independent observations. GyroCal therefore separates sample count from the effective information content of the dataset.

Robust Estimation

The Estimator provides a robust state-space/harmonic estimation path for multi-parameter heading-system analysis. The solution includes robust observation handling, parameter recovery, uncertainty information and parameter-correlation diagnostics.

This allows the software to move beyond a single mean offset when a calibration campaign is intended to estimate a richer heading-error model. Down-weighting and diagnostic outputs help prevent isolated poor observations from silently dominating the solution.

Final Uncertainty

The Uncertainty workspace combines the relevant uncertainty contributions into the final calibration uncertainty. Outputs include combined standard uncertainty, expanded uncertainty, parameter uncertainties, covariance/correlation information and a Type-A/Type-B traceability budget.

Where the selected solution path supports it, Monte Carlo agreement can be used as an independent numerical cross-check of the analytical uncertainty result. The objective is to make the reported correction inseparable from the uncertainty statement that defines how well that correction is known.

Multi-Method Fusion

The Fusion workspace allows compatible calibration evidence from more than one method to be combined using covariance-aware generalized least-squares logic. Instead of simply averaging corrections, GyroCal considers the uncertainty and dependency structure of the contributing results and reports the associated weights and covariance information.

This is useful when a project has, for example, independent quayside, GNSS and other verification evidence and the surveyor needs a controlled method for deciding how those results should contribute to the final accepted calibration.

MBES Patch & Boresight Alignment

The MBES Patch workspace extends the heading-calibration environment into multibeam alignment. It supports patch-site assessment and the estimation/review of boresight parameters with covariance and robust observation diagnostics.

This allows heading-system calibration evidence and multibeam alignment evidence to be managed within the same overall vessel-calibration environment rather than as unrelated calculations.

Integrity & Configuration Control

The Integrity workspace protects the accepted calibration state. It can freeze the accepted configuration and associate it with SHA-256 evidence, monitor configuration bindings, identify integrity blockers and support fault-detection/isolation diagnostics.

The intent is to answer not only “what was the calibration?” but also “is the vessel still in the configuration for which that calibration was accepted?” Changes to relevant installation/configuration evidence can therefore be surfaced rather than allowing an old correction to remain implicitly trusted after the vessel configuration has changed.

Reporting, Impact Analysis & Release Evidence

The Reports workspace connects calibration results to traceable evidence and lifecycle decisions. GyroCal supports deterministic report payloads in JSON, CSV, XML and PDF formats and maintains the relationship between evidence hashes, accepted configuration and release status.

Where an integrity event or configuration change occurs, the reporting architecture supports impact analysis, including identification of last-known-good and potentially affected periods and controlled quarantine/disposition of affected evidence rather than silently treating an entire historical dataset as invalid.

Clean, Tabular Calibration Results & QC

Customer-facing result screens use structured tables so the operator can review values without interpreting console-style output. Calibration metrics, residuals, reduced coordinates, uncertainty budgets, parameter recovery, covariance information and affected-run information are presented in consistent tabular layouts.

Residual/QC table showing target-level Easting, Northing, planar and standardized residual information.

Geodetic Awareness: Grid Heading Is Not Automatically True Heading

A central design principle in GyroCal Offshore is the explicit treatment of geodetic direction. Survey control is frequently held in a projected grid, while many marine heading sensors report true heading. GyroCal therefore retains grid heading and true heading as distinct quantities and calculates meridian convergence where the selected workflow requires conversion between them.

This is particularly important for offshore and hydrographic work because a calibration based on grid azimuth alone can produce a materially different correction from one referenced correctly to true north. The software makes this relationship visible in the final result instead of burying it inside a spreadsheet formula.

Traceability from Raw Observation to Final Correction

GyroCal Offshore is designed so that a calibration can be followed from the original sensor observation through the reference geometry and geodetic reductions to the final correction and uncertainty. The workflow can preserve source identifiers, sensor identifiers, session information, survey-reference metadata, observation quality, residuals, uncertainty contributions, hashes and report evidence.

This supports internal QA/QC, repeat surveys, vessel re-verification, technical review and investigation of changes between calibration campaigns.

Who GyroCal Offshore Is For

GyroCal Offshore is designed for hydrographic surveyors, offshore surveyors, marine geomatics professionals, survey engineers, vessel calibration teams, multibeam specialists, system integrators, shipyards, survey contractors, QA/QC personnel and organizations responsible for the performance and traceability of marine heading systems.

It is applicable to conventional hydrographic vessels as well as offshore survey and construction vessels. The architecture is also intended to support heading-system workflows associated with increasingly automated and unmanned marine platforms where defensible calibration evidence remains essential.

Windows Deployment

GyroCal Offshore is being qualified as a 64-bit Windows desktop application with a self-contained commercial runtime. The deployed application packages the required Qt runtime, QML modules, plugins and geodetic resources so an operational workstation does not need a development environment such as Visual Studio, Qt SDK, CMake or vcpkg.

Installer, repair, uninstall, reinstall, user-data persistence, runtime dependency and portable-package workflows are being subjected to automated release qualification before public distribution.

Product Development & Authorship

GyroCal Offshore is developed by Worldwide Survey Dynamics.

Author / Lead Developer: Olalekan Odunaike Email: olalekan@wsd-survey.com Website: https://wsd-survey.com/

The product is built around practical offshore and hydrographic calibration workflows with an emphasis on defensible geodesy, measurement uncertainty, QA/QC, traceability and operator usability.

Product Status & Availability

GyroCal Offshore is currently in final Windows release qualification and Microsoft Store onboarding. The software is not yet being represented as a fully released public production product. Worldwide Survey Dynamics will publish availability, licensing, system requirements and release information when qualification and distribution onboarding are complete.

Request a Demonstration or Product Information

Organizations interested in GyroCal Offshore, field evaluation, future licensing, vessel-calibration workflow integration or technical collaboration can contact Worldwide Survey Dynamics.

Email: olalekan@wsd-survey.com Website: https://wsd-survey.com/ Contact: Use the Worldwide Survey Dynamics website contact page.