Quadrant is COMSOFT’s response to growing demands from the aviation industry, pressured by lowering investment budgets and increasing safety demands. Quadrant starts with COMSOFT’s compact and self-contained ADS-B and Multilateration Ground Station, including a 1090 MHz and a GPS antenna system. Quadrant can be set up easily, anywhere.

Quadrant embodies a perfect trade-off between a high level of performance and reliability and low investment.

The Ground Station directly connects to IP networks and supports remote and interactive system configuration. Once set up, the Quadrant ADS-B Ground Station transmits surveillance data to up to 20 different client systems compliant to the ASTERIX standard.

The sensor features auto adjustment of sensitivity and signal noise level. This supports an easy installation without the need for specialised RF tools or time consuming, laborious installation procedures. All system parameters can be set remotely using the Quadrant Control and Monitoring System (QCMS), which ensures permanent performance supervision during operation.

Thanks to its high precision clock the ground station can also form the cornerstone of a network for multilateration surveillance.

• Passive
  • ADS-B Sensor
  • Networked ADS-B Sensors
  • Multilateration Network
• Active
  • Site Monitor
  • Reference Transponder
  • Remote Interrogator
• Comprehensive
  • Mode S
  • Mode A
  • Mode C
  • ASTERIX CAT020
  • ASTERIX CAT021
  • Integrated and Expandable Systems
• Robust
  • Rugged Sensors and Interrogators
  • Remote Upgrades
  • Remote Control and Monitoring

ADS-B provides a surveillance capability in regions of airspace where aircraft are suitably equipped. The increasing quality of aircraft equipage will mean that ADS-B becomes an important and cost-effective surveillance solution. Quadrant ADS-B Ground Stations can provide such a solution as a single ground station or a distributed network. In either case, the air picture integrates with existing systems using industry standard messaging formats.

Quadrant provides an independent position measurement using multilateration. The arrangement of sensors, and the timing information they collect, enables accurate positions to be determined for wide and local area systems.

ADS-B provides a “read-only” solution to the information available in aircraft. Mode S enables selective addressing of aircraft to request specific items of information. Quadrant becomes “active” with the introduction of its Interrogator Ground Stations.

The combination of Interrogators and ADS-B sensors enables Quadrant to become a replacement for Mode S radar. It provides a cost-effective replacement for Mode S and, with its distributed nature, includes inherent redundancy.

The ability to interrogate, receive and multilaterate on Mode A and Mode C completes the Quadrant surveillance offering.

The Quadrant Central Processor is able to combine messages that are identified by remote Quadrant Sensors and provides multiple time-synchronisation options. Wide area and local area synchronisation is provided by GPS and reference transponders respectively. Remote sensors can form local and wide area clusters simultaneously and with a single Central Processor.

The Quadrant Central Processor takes full advantage of the remote intelligence of distributed Quadrant Sensors. Pre-processing and time-stamping in the sensors enables the amount of data transferred to the Central Processor to be kept to a minimum.
Interpreting the data received by a sensor is done centrally. Interpreting is the process for converting digital data into meaningful aircraft parameters: sensors provide bytes and the Central Processor decodes them as DF17, for example.

Interpreting the data also includes taking advantage of the different arrival times. Multilateration is the primary use of arrival times but validation of reported positions is also available.

Multilateration only requires a collection of arrival times and a method of identifying the source of the transmission. The Quadrant Central Processor is designed to multilaterate on any time-stamped message provided by the remote sensors. This enables Mode S, ADS-B and Mode A/C messages to be treated identically as a source for multilateration.

The Quadrant Central Processor provides a common point for collecting messages from remote Quadrant Sensors. It also maintains a common time frame by synchronising the sensor clocks. Multiple time frames can be defined and maintained; the Quadrant Central Processor applies the most appropriate timing correction for the given situation.

There are many regions of airspace where there is insufficient Mode S system coverage or aircraft equipage to provide an acceptable quality of the air situation picture. Key pieces of aircraft information are not provided spontaneously by the aircraft and need to be requested by specific interrogations. Each interrogation produces a response which can be received by sensors and from which the requested information can be decoded.

COMSOFT provides its Interrogator Suite which is a well suited solution to these problems. The suite consists of Mode S and Mode A/C interrogators and an Interrogator Controller application. Each interrogator is deployed to a known location with a tailored transmission power and coverage area. The Interrogator Controller receives a view of the air situation, defines a schedule of interrogations for each interrogator and provides the schedule to each interrogator.
COMSOFT’s Interrogator Suite is designed to integrate with a Quadrant Central Processor. The Interrogator Controller analyses the air situation picture to determine which targets are missing key pieces of information. It uses its knowledge of the available interrogators and the missing information to create and schedule specific interrogations for each interrogator.

ADS-B and multilateration is a new concept for many users and it is important to provide confidence in the availability and performance of the system. The distributed nature of Quadrant requires that the availability of each ground station is monitored and the impact of each ground station on the system performance is analysed.

For an operational system, basic system monitoring is provided to ensure minimum performance levels are assured and to warn users of system degradation.
During installation and validation a more comprehensive set of analysis capabilities is required and these are provided by Quadrant’s analysis suite.
The coverage of each ground station can be measured and reported in real-time and integrated over extended periods.

The aircraft message loading of each sensor can also be measured and reported. The impact on network bandwidth can be adjusted by controlling the message formats provided. This monitoring and control is provided remotely and in real-time: system configuration is greatly simplified.

Operational parameters, such as multilateration accuracy and system coverage, can be analysed in real-time or by using recorded data. Recorded data enables the performance to be validated whilst simulating the loss of one or more redundant ground stations.

The worldwide air transportation community recognises ADS-B as the upcoming surveillance technology. It excels in the provision of precise air traffic surveillance at low investment and operation costs.

Depending on the position data provided by aircraft broadcasting 1090 MHz Extended Squitter signals, the ground station implements an effective measure to realise Air Traffic Control at reasonable costs while offering better performance at equal safety standards.The ADS-B technology is most attractive in areas where the implementation of conventional PSR/MSSR or Mode S radars is difficult or their deployment is inefficient.

ADS-B is suited for En-Route and Approach Air Traffic Control. In addition to easy deployment the Quadrant ADS-B Ground Station offers a highly sophisticated solution to a wide range of users.

In combination with conventional PSR/MSSR or Mode S radars, ADS-B Ground Stations represent an ideal backup alternative or can efficiently eliminate surveillance gaps. This especially applies to regions where radar coverage is limited due to line-of-sight obstruction or in areas where radar coverage has not been established.