Flight experiments conducted by the Electronic Navigation Research Institute

In order to prepare for future deployment of SSR (secondary surveillance radar) mode S with DAPs (downlink aircraft parameters) function in Japan, ENRI (Electronic Navigation Research Institute) has started research and development of new SSR mode S. DAPs function enables ground station to obtain aircraft information such as selected altitude, rollangle, magnetic heading and so on. When DAPs function is employed as a means of ATC (air traffic control), reliability of DAPs data is critically important. The purpose of this paper is to compare DAPs data with original FMS (flight management system) source data to validate radar system function and to test the reliability of DAPs data. This time, we picked up B737-800 and B747-400 and selected aircraft parameters in GICB (Ground Initiated Comm-B) 40, 50 and 60 as an analysis target of DAPs data. These are known as Mode S EHS (enhanced surveillance) which becomes mandatory in the part of Europe. In this paper, we first describe our experimental mode S system with DAPs function. Then, DAPs data have been compared with the data stored in aircraft flight recorder. As a result, we presented that the values of DAPs agreed with those of airborne stored data except in a few parameters.

The L-Band Digital Aeronautical Communications System (LDACS) is a possible successor of the VHF Datalink mode 2 (VDLm2) for continental aeronautical communications. It is a cellular broadband digital data link system, foreseen for regularity-of-flight and safety-communications. As of 2023, LDACS has successfully been flight trialled numerous times, the final Standards and Recommended Practices (SARPS) have been endorsed by ICAO and LDACS has been introduced to the Internet community in the form of an informational Request For Comments (RFC). LDACS will support IPv6 based digital voice, Aeronautical Telecommunications Network (ATN)/Internet Protocol Suite (IPS) traffic and enable multiple new applications such as 4D trajectories, secure Ground Based Augmentation System (GBAS), Alternative Positioning Navigation and Timing (APNT) and secondary surveillance capabilities.Any newly developed critical infrastructures system must provide strong cybersecurity. This is especially true for system handling safety-critical data from a range of applications. As such, a dedicated cybersecurity architecture for LDACS has been developed and is part of the LDACS standard. In cooperation with the Electronic Navigation Research Institute (ENRI), the German Aerospace Center (DLR) demonstrated and evaluated the main features of the cybersecurity architecture: the Mutual Authentication and Key Establishment (MAKE) protocol and user-data protection. The objective of this paper is to provide a detailed insight into the security measures and present the LDACS security validation results based on real radio hardware.

Secondary Surveillance Radar (SSR) has capability of datalink including Downlink Aircraft Parameters (DAPs). DAPs is expected to improve air traffic surveillance function and performance. DAPs is classified into 2 groups; Elementary surveillance (ELS) and Enhanced surveillance (EHS). ELS and EHS are being deployed within some part of European airspace. Preparing for future use of DAPs in Japan, Electronic Navigation Research Institute (ENRI) developed SSR mode S sites and has been collecting DAPs data. In order to employ DAPs for Air Traffic Control (ATC) service, the reliability of data is significant. ENRI started development of DAPs monitoring system, applying algorithms developed by Lincoln Laboratory which use acceptability thresholds based on the measurement accuracy of Mode S sensor to validate DAPs values. This paper reports the examination results of tests for static information of avionics configuration and status, and preliminary analysis of test results for DAPs dynamic values.

Electronic Navigation Research Institute (ENRI) had started to construct a total air traffic control (ATC) simulation facility in 1993. An airport tower ATC simulator and a flight simulator have been developed and ENRI is now carrying out several experiments and simulation. In this paper, a coupling method of three or more virtual reality spaces for creating a larger ATC simulator is mentioned and some basic ideas of the coupling method are also explained.

In Japan, DFMC(Dual-Frequency Multi-Constellation) SBAS(Satellite Based Augmentation System) messages can be received via satellites, and the environment for conducting demonstrations is already in place. However, there are only a few reports showing its usefulness so far, because no receiver supporting DFMC SBAS has been available in Japan. For this reason, we have developed a receiver that supports DFMC (Dual-Frequency Multi-Constellation) SBAS (Satellite Based Augmentation System) messages transmitted from QZSS (Quasi-Zenith Satellite System). ICAO (International Civil Aviation Organization) is working on the standardization of the next generation SBAS. The next-generation SBAS called DFMC SBAS solves the ionospheric delay on the receiver side by using two frequencies. The conventional method provides grid-by-grid ionospheric delays so that positioning errors occur depending on the position within each grid. Also, it cannot support sudden ionospheric changes because the ground station estimates corrections and uplink the data to satellites before broadcasting. On the other hand, the next-generation DFMC SBAS solves the ionospheric delay on the receiver side, so that stability of positioning accuracy is achieved. Since it supports multiple constellations, the positioning rate is improved with the larger number of satellites it uses. As a result of these, the overall benefit of improved availability is achieved with the next generation SBAS in terms of time and locational “continuity,” “availability of SBAS service even in areas with high ionospheric activity,” and “resilience to frequency interferences and ionospheric storms.” CORE Corporation, with ENRI (Electronic Navigation Research Institute), has been developing receivers that support the augmentation information broadcasted from QZSS. During the trial phase, we used a programmable software receiver for establishing specifications of DFMC receivers and confirmed the capability of DFMC SBAS. QZSS is currently in the verification phase, and we have been working on hardware that support various configurations to carry out more tests. Currently, in Japan, ENRI broadcasts the next-generation DFMC SBAS messages generated from L5S-I signals of QZSS Units 2-4 on trial. With the current QZSS, it is difficult to broadcast messages in the full DFMC SBAS format due to functional restrictions, so the existing SBAS format is temporarily adjusted for use. Broadcasting of messages in the complete format of the next generation DFMC SBAS will start with the QZSS satellites to be launched in and after 2020. The prototype we have developed receives the next-generation DFMC SBAS messages generated by ENRI via QZSS L5S-I signals and realizes the next-generation DFMC SBAS positioning in real-time. This receiver supports not only the specifications of the above-mentioned messages broadcasted on trial but also the specifications of the next-generation DFMC SBAS messages which are 4-bit preamble and Manchester encoding. Also, in order to flexibly respond to the spreading codes used by the satellites, PRN can be changed to any number between 1 to 210. In order to enable the ex-post verification, three types of data are output: “SBAS messages broadcasted,” “observation data used for positioning,” and “ephemeris data.” The prototype provides three positioning modes, NPA (Non-Precision Approach), APV (Approach Procedure with Vertical Guidance), and PA (Precision approach). The positioning results include locations, horizontal and vertical protection levels, and the DOP information. The information on the satellites used to calculate protection level and DOP information are also output. Continuity and availability of DFMC SBAS are confirmed with this information. In this presentation, we will describe the development of the DFMC SBAS receiver for the above QZSS L5S signals, discuss the results of our evaluation of the DFMC SBAS using the developed receiver, and show the improvement of availability and continuity based on the test results in areas with high ionospheric activity and in the environment affected largely by multiple constellations.

The National Aerospace Laboratory of Japan (NAL) and the Electronic Navigation Research Institute (ENRI) are researching a new aircraft operations concept, named NOCTARN, based on three-dimensional flight trajectories shared between aircraft and air traffic control (ATC) via digital data link and negotiated using Control Pilot Data Link Communications (CPDLC). It is proposed to incorporate a route modification function that would be invoked each time a route were assigned to modify the predefined trajectory based on wind conditions and aircraft performance in order to improve path tracking in strong wind while avoiding requiring maneuvers that could lead to loss of control. Route modification could also be used to assure separation between aircraft. This paper reports on the investigation by flight simulation into pilot acceptance of the NOCTARN system, the effects of route modification based on wind conditions and CPDLC operation upon manual flight control performance and pilot workload. The results indicate that modified routes successfully reduced path deviation and lowered pilot workload, and that the introduction of CPDLC procedures had no significant impact on manual flight control. Flight experiments further demonstrated that the proposed system and procedure is acceptable to the pilots.

Secondary Surveillance Radar (SSR) Mode S is an air traffic control radar system with improved surveillance and datalink capability. In SSR Mode S system, each Mode S ground station (GS) has Interrogator Identifier (II) code. II code is set in interrogation and signals. It makes possible transponders identify the source site of interrogation and GS distinguish the destination of reply. International Civil Aviation Organization (ICAO) standard prepares 4bits space in interrogation and reply for II code. Fifteen II codes are available for GS. As the number of SSR mode S GS increases, SSR operator is not able to assign II codes without conflicts between neighboring GS. This problem is called II code shortage problem. If the same II code is assigned to neighboring GS that have overlapping coverage, GS is not able to achieve continuous aircraft surveillance in overlapping area. To overcome the problem, GS is required to have II code coordination function. To prepare for the II code shortage problem in Japan, Electronic Navigation Research Institute (ENRI) developed SSR mode S with II code coordination function and conducted validation of fundamental functions in 2008. In this paper, we mention II coordination technique, experimental system and experiments. Then we show the results of validation.

The standard algorithm for alignment of DNA sequences using dynamic programming has been implemented on the Cray MTA-2 (Multithreaded Architecture-2) at ENRI (Electronic Navigation Research Institute), Japan. Descriptions of several variants of this algorithm and their measured performance are provided. It is shown that the use of full/empty bits (a feature unique to the MTA) leads to implementations that provide almost perfect speedup for large problems on 1-8 processors. These results demonstrate the potential power of the MTA and emphasize its suitability for bioinformatic and dynamic programming applications.

: Ionospheric scintillation is the rapid amplitude and phase fluctuation of transionosphere radio waves due to local irregularity of the ionosphere. At low magnetic latitudes, amplitude scintillation often occurs after sunset around equinox periods, especially in the maximum of solar activity. GPS signal fading due to scintillation can cause receiver loss of lock. To assess the effect of ionospheric scintillation on the MTSAT Satellite-based Augmentation System (MSAS), the Electronic Navigation Research Institute (ENRI) has conducted observations of ionospheric scintillation since March 1999. Strong scintillation has been observed, some of which continued over 10 min with an elevation mask of 15 deg. The number of satellites tracked by the receiver decreased distinctly by 1–4 for about 3 h when strong scintillation occurred. This result indicates that ionospheric scintillation has the potential to affect GPS and must be taken into account for satellite-based augmentation system (SBAS) operation in the area near the magnetic equator.

With the aim of achieving an efficient and economical aeronautical network, the Aeronautical Telecommunication Network/Internet Protocol Suite is being standardized at the International Civil Aviation Organization (ICAO). The L-band Digital Aeronautical Communications System (LDACS) is also currently under discussion at ICAO for the next-generation air-to-ground aeronautical communication system that is compatible with Internet Protocol (IP) network. Previously, the Electronic Navigation Research Institute in Japan developed the LDACS physical layer experimental system (LPES) and evaluated the basic physical layer characteristics of the LDACS. In this study, we evolved the LPES and developed upper layer protocols to realize real-time end-to-end IP communication. To develop the system faster and at lower-cost, a software defined radio platform is selected so that we can re-use the platform for other future aeronautical communications system by changing only the software. This paper provides an overall system description and some basic evaluation results of our developed prototype. The preliminary tests conducted using a signal generator show that our prototypes were well implemented according to the LDACS specification. The overall system tests conducted using the prototype airborne and ground stations indicate the successful cell entry process and real-time IP end-to-end communication.

With the rapid increase in air traffic demands, the more accurate and reliable tracking systems for aircraft surveillance are required to improve the capacity, safety and efficiency of air traffic control (ATC) services. As a considered part of the surveillance infrastructure, Secondary Surveillance Radar (SSR) Mode S has been widely utilized in the ATC applications. In the Mode S Enhanced Surveillance (EHS), the Downlink Aircraft Parameters (DAPs) are available for obtaining updated and detailed information from aircrafts. For the performance evaluation of Mode S EHS, Electronic Navigation Research Institute (ENRI) has constructed an aircraft surveillance system which is composed of two SSR Mode S radars. And compared with the Kalman filter and IMM (Interacting Multiple Model) estimator, the α-β filter has low computation cost and configuration complexity. If the maneuvers of aircrafts can be detected in real time, it is possible to select appropriate gains to make a trade-off between good noise reduction and good tracking through maneuvers. In this paper, a DAPs based adaptive tracking system which consists of a simple α-β filter with several different models and a maneuver detector is proposed. The system enables dynamically selecting the optimal filter model according to the different motions of aircrafts. Moreover, as the availability and certification of DAPs cannot be guaranteed, the integration of the elementary surveillance and the enhanced surveillance is also implemented. The results of computer simulations and practical experiments show the effectiveness of proposed system by comparing with the standard IMM estimator.

運輸省電子航法研究所電子航法開発部航法システム研究室(国内,ラボラトリーズ)

A ground-based augmentation system (GBAS) is a navigation system using global navigation satellite system (GNSS) that enables precision approaches and landing for aircraft. In May 2010, the International Civil Aviation Organization (ICAO) Navigation Systems Panel (NSP) working group completed development baseline standards and recommended practices (SARPs) for GBAS ground subsystems to support GBAS approach service type D (GAST-D), which refers to Category III precision approach services using the single-frequency L1-C/A signal. The Electronic Navigation Research Institute (ENRI) developed a prototype of the GAST-D ground subsystem to operationally validate the development baseline SARPs. Owing to the fact that ionospheric delays with large spatial gradients represent one of the most significant risks to the integrity of the GAST-D operation, the system was installed in a low magnetic latitude region where plasma bubble causes steep spatial gradients in the ionospheric delay. Preliminary results were reported to the NSP working group before the development baseline SARPs were approved in December 2016 with an expectation that they would go into effect in 2018. Here, we report the development of a prototype for a GAST-D ground subsystem to validate the development baseline SARPs and preliminarily evaluate the system’s performance.

The current ground-based collaboration environment is not sufficient to enable the full range of benefits defined in the ICAO Global Air Navigation Plan (GANP). In order to achieve a safe, secure, high-performing, and sustainable global air traffic management, the collaborative information exchange should be achieved for not only ground operational systems but also connected aircrafts. However, it is difficult for the current command-and-control Air-to-Ground (A/G) communication approaches to satisfy different and extensive information exchanges between the aircraft and the air navigation service providers. To promote the implementation of information collaborative environment in pre-departure phase and improve operational awareness and Collaborative Decision Making (CDM) through information exchange, the Electronic Navigation Research Institute (ENRI) has developed a test system. Several practical experiments have been deployed based on the integration of these systems to show the benefit of A/G SWIM (System-Wide Information Management) integration. In this paper, the concept and the technical framework of A/G SWIM integration are introduced. To provide timely, relevant, accurate, authorized, and quality-assured information for high-assurance operation, the multi-layered system architecture and the collaborative information exchange technology are proposed. Moreover, the development of practical validation system for ground taxiing experiment is presented. Finally, the definition and comparison of communication quality, information quality, and service quality for constructing the collaborative operating environment to include interactions of A/G stakeholders, systems, and services through the A/G SWIM integration are discussed.KeywordsSystem-Wide Information Management (SWIM)Air Traffic Management (ATM)Collaborative information exchangeCommunication network

Downlink Aircraft Parameters (DAPs) is one of Secondary Surveillance Radar (SSR) Mode S datalink functions. It enables a ground station to obtain real-time aircraft information such as selected altitude and ground speed. DAPs improves efficiency, capacity, and safety of Air Traffic Control (ATC) service. To employ DAPs for ATC service, the reliability of DAPs is important. However, some aircraft are transmitting wrong or erroneous DAPs data. Those data hinders the use of ATC service. In order to ensure the reliability of DAPs data, Electronic Navigation Research Institute (ENRI) developed a DAPs validation system. In the first phase of the development, two DAPs validation techniques are implemented. One technique is based on the methodologies developed by Massachusetts Institute of Technology (MIT) Lincoln Laboratory. The other technique uses tests to detect errors due to transmission problems. By using these techniques, we evaluated DAPs data collected at our experimental SSR mode S ground station. The results show that the proposed techniques can detect erroneous data, and enhance the reliability of DAPs.