GNSS technology has been used in Defence & Security applications for many years; areas such as the traditional military uses within avionics and other guidance systems, personal warfighter and convoy navigation to asset tracking and rescue. These applications and the increased integration of Position Navigation & Time (PNT) into command and personal information systems mean that the robustness and availability of PNT is under closer scrutiny than ever before. One component of this scrutiny is operational availability.

Operational Availability

This is the availability of a PNT solution at all times for whatever type of system is deployed. Consider for Airborne Soldiers, GNSS technology is used to provide guidance to the drop zone in night or inclement weather operations via commercial receivers or military grade devices. In the case of the US Joint Precision Airdrop Systems (JPADS), GPS guidance receivers provide navigation and steering commands

GNSS Repeating (or Retransmission)

These locations can be inside an aircraft hangar/maintenance facility, inside the aircraft itself or even inside a vehicle when mobile warfighters are being deployed. GNSS or GPS Repeating is the technique by which live GNSS signals are made available to the (primarily) mobile devices within the location.

Chronos Technology Limited provides a full repeating service from designing the layout and implementation of the solution to comprehensive after-sales support.

• Hangar Systems for the Royal Air Force
• Portable & Fixed systems for within Military transport aircraft (C-130 Hercules, C117 Globemaster, CH47 Chinook)
• Intra-vehicle systems for troop ground transportation systems
• Portable systems for Special Forces

These type of systems are also applicable to applications such as Military Free Fall, High Altitude Low Opening (HALO) and High Altitude High Opening (HAHO) as the equipment each unit carries must have continuous availability and not lose satellite signal visibility from being in the aircraft.

Benefits of GNSS Re-radiation for Military applications are:

• Eliminates delay in TTFF when exiting the hangar, aircraft or vehicle
• Maintains Situational Awareness (SA) with valid location reporting, even from inside vehicles
• Reduces mobile device battery consumption as no reacquisition processing required
• Full verification of position (inc altitude) prior to a jump
• Eliminates need to maintain equipment out of protective hangar/maintenance unit, covert installation with the ability for fully test.
• Maintains equipment in "hot" condition for units on immeditate alert status

Timing

GNSS systems are often also used to provide timing for communications systems in a Military environment as this enables efficient and cost effective network synchronisation to be able to provide secure voice and data communications.

Defence & Security GNSS Infrastructure

GNSS RF Signal distribution in Military environments often has to meet specific, exacting and exhaustive standards such as MIL-STD-461 (Control of electromagnetic interference) which means equipment must undergo rigorous testing to ensure it meets these standards. Other infrastructure concerns are that in some locations the use of copper as the RF transport mechanism is not possible, perhaps due to classification of an enclave. In these cases RF-on-Fibre solutions can be used to ensure that the GNSS receiver is able to use live GPS without compromising any security aspects, important in Military or other agency installations.

Security Related Products

Chronos Technology works with a number of Defence & Security organisations globally to provide Homeland Security related products, in addition to the Defence/Military focussed products described above. One such product, the Chronos CTL3500 is a handheld GPS Interference Monitor is designed to detect the presence of too much GPS satellite power or interference broadcasting on the satellite navigation L1 channel, which could indicate inadvertent interference or intentional electronic warfare attacks intended to jam GPS signals.

• Can be used for monitoring and detecting of GPS interference
• Ideal for operations and support engineers to check GPS antenna installations
• Check your roof-top installations for interference from other sources and adjacent GPS antenna
• Check you are not accidentally rebroadcasting the GPS signal from a poorly made or corroded cable/connector/antenna assembly

Chronos has recently been awarded UK Govt funding for a research program called SENTINEL which has security related application, please see the specialist SENTINEL page for more information.