Murat Imay, Serkan Sapaz and Hakan Özyürek – Tualcom / Deutsche Aircraft GmbH

This paper introduces a cutting-edge bidirectional telemetry system designed to revolutionize communication capabilities in flight test applications. The system supports downlink speeds of up to 8 Mbps and uplink speeds of up to 1 Mbps, with a range of up to 250 km. At its core, the system integrates TUALCOM data links with original waveforms, enabling a robust, multi-node mesh network. This innovative air-to-air network extends communication range by allowing airborne systems to act as nodes, forming a dynamic, masterless network that enhances distance to ground systems. The network features self-healing and self-forming ad hoc capabilities, along with precise RF distance calculation and time synchronization, providing critical time and location data during missions.

Unlike conventional telemetry systems, this solution delivers unparalleled flexibility and scalability, as the number of nodes in the network can be expanded as needed. The system’s physical layer capabilities enable long-range, high-data-rate communication, while the unique network layer algorithm ensures reliable relaying capabilities.

 This paper details the practical implementation of the telemetry system within the D328 Deutsche Aircraft flight test campaign, highlighting its advantages over traditional solutions. Key use cases include data acquisition and relay between multiple airborne systems and ground stations, demonstrating the system’s potential to significantly enhance range and reliability in demanding environments. By reducing dependency on direct line-of-sight, this approach paves the way for more robust and efficient telemetry operations in future aerospace applications.

Benjamin Kupferschmidt and Kathy Rodittis – Curtiss Wright

The Inter-Range Instrumentation Group’s (IRIG) 106 Chapter 7 standard provides a method for embedding variable length, well-defined data formats within a Chapter 4 Pulse Code Modulation (PCM) stream. Chapter 7’s approach to embedding data streams within a PCM format offers several strengths and weaknesses. This paper will explore the pluses and minuses of the Chapter 7 standard and propose some alternative approaches that have been used successfully.

Francisco Fernández Casuso – AIrbus Defence & Space

The purpose of this article is to show the evolution of the Airbus bidirectional telemetry project to achieve robust, efficient and high quality bidirectional telemetry. It will address the steps of the last stage, discuss the successes and the problems that have arisen from it.

The ultimate goal of this project is to develop two-way telemetry with equivalent capabilities in range, bandwidth and latency, while incorporating new features such as native networking or beyond line-of-sight communication (BLOS). To achieve this, a new system integrating high gain antennas with dipoles and advanced transmitter/receiver technologies such as beamforming and MIMO will be implemented.

The objective of this stage is to reduce and minimize the risks of bringing a new system to an aircraft that generates high costs, thus debugging the problems in a test environment easier to solve and with fewer risks. The aim is to achieve such confidence in the technology as to ensure that we can then go flying with the minimum probability of failure. Therefore, the aim is to confirm range, power and radiation data, but not only that, also to see how the communication works, what happens if there are link problems, etc.

This new technology implies a major change in aircraft and ground architecture, as well as a new way of working. Thus, this article will discuss the problems encountered and their mitigations. Finally, the next steps and future uses of the project will be discussed.

Mahmut Kürşad Arpacıoğlu, Mustafa Melik Geçgel, İpek Çerşil Polat, Ayşe Bilsel, Hatice Çelik, Furkan Kamil Tut, Enes Alperen Şahin, Yeter Ateş, Muhammet Kürşat Serçeli, Arda Ulusan and Ökkeş Furkan Turna – Turkish Aerospace Industries, Inc.

Due to critical roles of the telemetry data in a flight test campaign it is aimed to transmit the data without loss however data losses occur for many reasons.

To determine the causes for the telemetry losses a study has been performed. The configuration of ground system components (antennas, receiver, BSS, etc.) in the telemetry system and the parameters obtained from those components recorded with the position and attitude information gathered from the aircraft under test has been monitored in real-time and analyzed in post process. The mentioned parameters which are analyzed made that possible to detect the reasons for the data loss and gave hints to improve the telemetry system components or the process of how the mission is performed.

This paper highlights the study which has increased the ability of tracking the a/c under test, gave indicators to detect if the malfunction has been occurred on a/c transmitting system or on ground receiving system, eased to detect the reason for the data loss such human / software error, physical obstacles between the transmitting and receiving systems or the shadowing effect of the a/c geometry due to the maneuver which has been performed.

Blaise Barbe, Davy Ralliard Rousseau, Isabelle Carpentier and Louis-Marie Lecoeur -Safran Data Systems

SAFRAN DATA SYSTEMS is a leading telemetry and safety solutions provider with legacy customers such as Ariane and Vega and a growing customer base from New Space companies worldwide (America, Asia, Europe). To better prepare for the New Space era, a product line of satellite based telemetry solutions is developed to address all types of vehicles, trajectories, and spaceport requirements.

*PROPOSAL*

Traditional telemetry communication systems rely on ground stations located along the trajectory, which are costly to install and maintain, and constrain the possible trajectories.

For satellite based telemetry systems, the onboard unit takes its inputs from the vehicle, and transmits the telemetry information on a set of antennas. The transmission addresses communication satellites, but also ground stations if available.

These solutions are compatible with commercial communication satellites, in the L-band, but evolution to S-band and other frequency bands is already considered.

Special care has been taken to give full coverage for any space port on Earth (on the mainland and/or sea-based) and any trajectories, even polar based, with a comfortable link budget at all times, by selecting sufficient satellites.

At the same time, configuration has been kept as simple as possible to enable last-minute frequency changes or trajectory adjustments.

In fact, the communications systems does not require to know the actual trajectory ahead of time, and uses the position and attitude of the vehicle as inputs.

In preparation of the flight, the reservation of communication beams has also been optimized.
A specific mode for spaceport safety assessment will be included, so that the very same system can also be used for ground-based Flight Termination Systems which require continuous and low-latency telemetry reporting for the first minutes of flight, regardless of vehicle position and attitude.

A first demonstration flight is coming up in 2025, thanks to the partnership with VIASAT.

The ultimate solution will weigh less than 5kg, including antennas, excluding cabling.

*SYNTHESIS*

Safran Data Systems’ satellite based telemetry transmission system could prove to be the ideal solution for fast and easy recovery of flight data for the coming launch vehicles, for sizes ranging from nano to heavy.

*FURTHER EXTENSION*

Safran is also developing a prototype of uplink data transmission to the vehicle, this could be used for numerous applications, from inflight telemetry selection, return trajectory synchronisation, etc..

Xue Zhao, Xiaoqian Yi and Zitan Sun – Commercial Aircraft Corporation of China Ltd, COMAC

In recent years, the traditional PCM/FM telemetry system has increasingly struggled to meet the demands of flight test telemetry applications due to their low transmission rates and limited resilience against multipath interference and Doppler frequency shifts. To address these challenges, this paper proposes a novel telemetry system architecture based on Orthogonal Frequency Division Multiplexing (OFDM) technology. Firstly, the expected performance metrics of the proposed multi-carrier telemetry system are outlined, and link margin calculations are performed to verify its feasibility. Subsequently, the network architecture of the system is presented, followed by a detailed and efficient layered protocol stack design inspired by LTE and NR standards, to enhance system stability, efficiency, and manageability. Finally, the paper highlights the advantages of the proposed OFDM-based telemetry system, demonstrating its potential to overcome the limitations of traditional approaches.

Jean Marc Gaubert, Adrien Pompée and Soundarya Srinidhi – Atmosphere

LEO / 5G could be a game-changer for flight test telemetry, offering high-speed, low-latency, and global connectivity at an affordable cost. Thanks to CNES and ESA support, ATMOSPHERE has pioneered this new field through the development of a first light LEO 5G connectivity solution. Compatible with Low Earth Orbit constellations and ground networks supporting 5G, as well as Iridium Certus satellite constellation, the solution developed by ATMOSPHERE was certified in 2024. The airborne terminal developed by ATMOSPHERE is a low-swap unit, primarily targeting unmanned aircraft vehicles (UAV) and stratospheric balloons. ATMOSPHERE currently collaborates with several OEMs, integrators and agencies on pilot operations. Initial tests have successfully demonstrated the capability to transmit platform telemetry and video stream in real-time over satellite and terrestrial networks. The proposed paper will present the challenges faced by ATMOSPHERE in the development process, provide preliminary return of experience from pilot operations, and introduce future opportunities for flight test telemetry use cases.

Joseph Molnar, Lam Pham, Matthew Dillon, Er-Hsien Fu, Lan Tran, Matthew Feid and Eric Makara – US Naval Research Laboratory

The radio frequency (RF) spectrum is a vital resource that has become increasingly limited due to rising demand and inefficient spectrum allocation and assignments. With spectrum availability shrinking, modern spectrum-dependent systems (SDS) must coexist within co-assigned bands. Additionally, efficient spectrum management requires real-time monitoring to identify potential assignment errors and unauthorized access in the band. At the Naval Research Laboratory, we managed, provided technical oversight, and tested the development of a spectrum management system consisting of three core components: RISA (Risk Informed Spectrum Access), OSCAR (Operational Spectrum Comprehension, Analytics, and Response), and MICCA (Multi-band Control Channel Architecture). We worked with our industry partners to develop the three components. These partners included: Peraton Labs (OSCAR), Leidos (RISA), and Shared Spectrum Company (MICCA). The objective of RISA is to provide risk assessment of planned and ongoing field events through multi-swarm particle swarm optimization (MS-PSO) and deep learning of the signals environment to identify authorized occupants. OSCAR serves as an intuitive visualization tool that reduces the cognitive load for spectrum managers through identifying, localizing, and summarizing assignment violations. MICCA provides an approach for reliable delivery of spectrum plans/policies that was issued by the spectrum manager via OSCAR to the SDS systems. MICCA also monitors the position and performance at each SDS in order to provide the diagnostics to OSCAR and RISA. A Capstone field demonstration event in August 2024 was conducted to evaluate the implementation of the integrated system. The effectiveness of the system’s capabilities was evaluated through a set of scenarios. The scenarios were designed to demonstrate multiple functions: the evaluation of spectrum risk throughout an evolving exercise, the identification and localization of entities violating spectrum assignments, the spectrum policy dissemination, monitoring and control of spectrum dependent systems, and the identification and characterization of spectrum occupants. This paper presents the system-of-systems, describes the evaluation scenarios, presents the results, and provides analysis and observations for enhancement.

Yi Zhou, Xiaoqian Yi and Zitan Sun – COMAC Flight Test Center

In the flight testing of civil aircraft, telemetry signals are influenced by various factors such as noise, reflection, occlusion, and atmospheric absorption. These factors can increase the Bit Error Rate (BER) of the telemetry signal received through the telemetry link, ultimately leading to a degradation in signal quality. This paper discusses Low Density Parity Check (LDPC) forward error correction, which can be integrated into the telemetry link to enhance link margin and rectify random errors arising from transmission anomalies. An LDPC encoder and decoder module were incorporated to establish a new telemetry link utilizing SOQPSK modulation. Experimental results demonstrate that LDPC is an effective error correction method; furthermore, the IRIG 106 recommends its use for telemetry link.

Tim Chalfant and Sergio Penna – ICTS

A review of international and domestic spectrum issues that can challenge the future use of radio frequency telemetry after the recent 2023 World Radiocommunications Conference. Several agenda items addressed there have a potential for telemetry spectrum encroachment and are presented in this paper. Topics of interested in future World Radiocommunications Conferences are also presented. International telemetry vendors, suppliers, and users need to be aware of, and potentially engage with their national administrations on these items.

The authors represent the International Consortium for Telemetry Spectrum (ICTS, www.telemetryspectrum.org) which was formed in 1999 and is chartered under the sponsorship of the International Foundation for Telemetering (IFT). The IFT (www.telemetry.org) is a non-profit organization dedicated to serving the professional and technical interests of the telemetering community.