Why CRPA GNSS Antennas Matter for Ports and Shipping—and How to Choose the Right Solution?

A vessel approaching a busy harbour depends on more than a position displayed on an electronic chart. The bridge team must interpret traffic, maintain clearance from hazards, follow pilotage instructions and coordinate with shore-based services. Reliable positioning supports these decisions, but an unreliable satellite-navigation input can introduce uncertainty across several connected systems at once.

This is why GNSS resilience matters to both shipping companies and port operators. On 25 March 2025, the International Maritime Organization, International Civil Aviation Organization and International Telecommunication Union jointly called for stronger protection of satellite-navigation services, greater system resilience, interference reporting and the retention of conventional navigation infrastructure for contingency support.

CHREDSUN offers GNSS protection options for lawful civilian and commercial applications, including suppression-focused anti-jamming antennas and models combining anti-jamming with anti-spoofing functionality. With array configurations ranging from four elements to dual 16-element systems, customers can evaluate protection levels against their platform constraints and operational requirements.

The goal is not to replace seamanship or independent navigation. It is to strengthen the satellite-reception stage of a wider maritime safety strategy.

1. Why GNSS Disruption Matters Beyond the Receiver

Ships and ports use satellite-derived position, velocity and time for multiple operational functions. Depending on the installation, GNSS data can support electronic charts, AIS position reporting, radar functions using GNSS inputs, route monitoring, traffic management and timing-dependent equipment.imo+1

This creates an important dependency: several screens may appear to agree because they are receiving the same underlying information.

If that common input becomes unreliable, agreement between displays is not necessarily independent confirmation. A bridge team may need to investigate:

• An unexpected position on the electronic chart.

• Disagreement between radar observations and charted position.

• Implausible changes in course or speed over ground.

• AIS information that does not match observed traffic.

• Alarms associated with lost or degraded navigation inputs.

UK maritime guidance specifically warns against relying entirely on one position-fixing source and recommends regular checks using independent means. It also explains that an electronic chart system cannot establish the vessel’s true position merely because its supplied position appears plausible.

For a shipping operator, GNSS protection is therefore not just about keeping a receiver online. It is about reducing the risk that unavailable or misleading information propagates into operational decisions.

2. Jamming and Spoofing Require Different Questions

A useful procurement process separates two threats rather than treating all GNSS interference as one problem.

The international joint statement identifies both jamming and spoofing as harmful interference affecting satellite-navigation services. ITU describes spoofing as GNSS-like transmissions that can cause a vessel or aircraft receiver to calculate erroneous positions and provide false guidance.

This distinction changes antenna selection.

A suppression-focused anti-jamming antenna should not automatically be advertised as an anti-spoofing system. Where false navigation information is a credible operational concern, buyers should request a configuration explicitly specified and tested for anti-spoofing.

Equally, anti-spoofing protection should not be presented as a guarantee against every possible false-signal scenario. Performance remains dependent on the selected hardware, processing, receiver configuration and test conditions.

3. What a CRPA System Adds to GNSS Reception

CRPA stands for Controlled Reception Pattern Antenna. A complete CRPA protection system combines a multi-element antenna array with appropriate signal-processing electronics.

Rather than simply amplifying everything arriving at one antenna, array processing adjusts how signals from the different elements are combined. This enables directional interference mitigation: the system can reduce sensitivity toward unwanted signals while attempting to preserve usable satellite reception.

CHREDSUN’s combined-protection product documentation describes array-based processing at the receiver front end to mitigate suppression interference and spoofing. Selected systems also provide processed RF output for an external receiver and navigation-data output through an integrated receiver configuration.

For integrators, this creates two possible paths:

• Retain a compatible external GNSS receiver and evaluate a processed RF connection.

• Evaluate an integrated receiver configuration that supplies navigation data through a digital interface.

Neither path is automatically compatible with every bridge, vehicle controller or survey system. Frequency coverage, RF levels, electrical interfaces, protocols and downstream data requirements must be checked.

4. Why Ports Need a Broader View Than Shipboard Navigation Alone

The port environment includes more than commercial vessels. It may also include survey craft, unmanned surface vessels, autonomous yard vehicles, mobile mapping equipment and shore-based monitoring systems.

These platforms have different constraints. A compact robotic vehicle may have limited space and power. A survey vessel may prioritize receiver compatibility and measurement quality. A larger installation may accommodate a higher-capacity array but require additional environmental and interface validation.

The maritime sector’s reliance on PNT extends to shore-based operations as well as vessels. The UK Maritime and Coastguard Agency’s October 2026 guidance explicitly addresses shipowners, harbour authorities, port operators, VTS providers and other maritime stakeholders reliant on PNT services.

For this reason, a port should begin by mapping its dependencies:

1. Which equipment receives GNSS position or time?

2. Which systems share a common receiver?

3. What happens if the information disappears?

4. What happens if incorrect information continues to be accepted?

5. Which independent sources remain available?

This review helps determine where GNSS reception protection would provide the greatest practical benefit.

5. Two CHREDSUN Product Routes: Anti-Jamming or Combined Protection

CHREDSUN’s product range supports two distinct selection routes.

Suppression-focused GNSS anti-jamming antennas

These products are intended for applications where the primary requirement is to reduce specified RF interference affecting satellite reception.

They can be considered for civilian platforms where interference-related loss of GNSS availability is the main issue. Selection should be based on the relevant frequency bands, tested interference types, source geometry and platform integration requirements—not only the product name.

GNSS anti-jamming and anti-spoofing antennas

Combined-protection models add explicitly specified spoofing-mitigation capabilities.

For example, the AJ-SX370D specification describes protection against suppression interference, replay spoofing, generative spoofing and mixed interference conditions. It also includes reporting of interference power, interference-source count and spoofing detection information.

These functions can provide useful inputs for monitoring and application-level responses. However, the antenna’s status output does not automatically become a bridge alarm, an autonomous safe-stop command or a navigation-integrity decision. Those responses must be designed and validated in the host system.

6. Choosing Between Four Elements and Dual 16-Element Arrays

Array size is an important selection factor, but it is not a complete performance specification. Customers should not assume that more elements automatically provide anti-spoofing, centimeter-level positioning or compatibility with a particular vessel system.

The following table provides a starting point for discussing CHREDSUN’s product range, rather than a universal deployment prescription.

There are two separate decisions: the array architecture and the protection function. A customer may need a compact combined anti-jamming/anti-spoofing antenna, or a larger suppression-focused product. The correct choice follows the risk assessment.

“Dual 16-element” also must not be interpreted as permission to double the published number of interference sources. Use the interference capacity stated for the exact product.

7. A Product Example: What AJ-SX370D Offers—and What Still Needs Verification

AJ-SX370D illustrates a higher-capacity CHREDSUN option. It is not a universal recommendation for all vessels or port installations.

These values are taken from the product specification.

The spoofing-source figure requires an important qualification: spoofing signals with J/S ≥30 dB are treated as suppression-type interference and require additional anti-suppression channels. The published jammer and spoofing counts should therefore not be presented as an unconditional “15 plus eight” simultaneous guarantee.

For maritime projects, buyers should separately confirm applicable approvals and installation requirements. An IP rating, operating-temperature range or industrial product specification should not be described as proof of marine type approval, salt-mist qualification or suitability for every vessel installation.

8. Accuracy, Interference Tolerance and Navigation Integrity Are Different

A successful evaluation distinguishes three questions:

• How accurate is the position under the stated conditions?

• How much specified interference can the system tolerate?

• How does the complete installation identify an unreliable solution?

For example, AJ-SX370D’s built-in receiver specification gives horizontal accuracy of ≤7 m and vertical accuracy of ≤9 m at 95%, with PDOP ≤4. Those figures are not a claim of centimeter-level RTK performance.

Similarly, the published interference-to-signal ratios are not interchangeable with measured antenna null depth or a guaranteed protection radius.

Customers requiring survey-grade positioning, precise autonomous movement or specialized timing should evaluate the antenna, receiver, correction service, processing delays and monitoring architecture together. Protection of the GNSS RF input and achievement of the application’s accuracy requirement are related, but separate, engineering tasks.

9. Installation and Acceptance Testing Should Reflect the Real Platform

For a vessel or port project, acceptance should focus on the installed system rather than a specification sheet alone.

A practical evaluation plan should include:

AJ-SX370D’s installation instructions recommend airflow below the metal base and an unobstructed receiving surface. When installed beneath a cover, the material above it should provide at least 92% L-band transmission.

These requirements need to be reconciled with the actual vessel structure and equipment arrangement. A qualified integrator should also assess the surrounding RF environment, cable routing, power protection and any applicable vessel or port requirements.

10. CRPA Supports Maritime Resilience; It Does Not Replace Independent Navigation

Reception protection is valuable, but it must not become a new reason to trust GNSS without question.

A maritime resilience strategy should combine:

1. Reception protection to reduce the effect of specified interference.

2. Monitoring to identify degraded or suspicious information.

3. Independent navigation references and practiced contingency procedures.

UK maritime guidance recommends regular independent position checks and explains how radar techniques, including parallel indexing, can support navigation when GNSS is unavailable. It also warns that AIS should not be relied upon alone for collision avoidance.www

CHREDSUN antennas belong in the reception-protection layer. Depending on the model, they can also supply monitoring information. They do not replace radar, visual lookout, passage planning, crew judgment or approved navigation equipment.

11. Selecting a CHREDSUN Solution for Your Maritime Project

The most useful starting point is a clear application description—not simply a request for the largest array.

When contacting CHREDSUN, provide:

• Platform type: vessel, survey craft, USV, port vehicle or fixed installation.

• Required GNSS signals and receiver model.

• Whether the concern is suppression interference, spoofing or both.

• Accuracy, update-rate and timing requirements.

• Available power, payload and installation space.

• Intended environmental conditions and approval requirements.

• Preferred RF or digital navigation-data interface.

• Monitoring, fallback and acceptance-test expectations.

CHREDSUN’s range from four-element to dual 16-element configurations allows customers to consider different levels of GNSS protection. The selection should match the actual task, not rely on an assumption that one model serves every maritime application.

For product selection, technical discussions or integration inquiries, contact the CHREDSUN team by email or WhatsApp. The objective is to identify an appropriate civilian GNSS protection solution—and verify how it will operate within your wider navigation system.