Weir, Malcolm; Ampex Data Systems Corporation (International Foundation for Telemetering, 2019-10)
      Specialist test establishments have historically placed significant reliance on “security through obscurity”. With increasing “always on” connectivity and the drive to leverage commercial products, the threat space has widened significantly while the sophistication of attack vectors has evolved. Access through vulnerabilities embedded within a platform’s communications, flight controls, or other on-board access points leave organizations vulnerable to attack, exploitation, and loss of revenue or property. Cyber and operational security associated with all aspects of aircraft technologies is becoming increasingly critical. This paper investigates techniques and procedures by which aircraft and space vehicles can be compromised by and protected against cyber-attacks.

      Geoghegan, Mark; Nusair, Marwan; Quasonix (International Foundation for Telemetering, 2019-10)
      The majority of aircraft telemetry antennas transmit a linearly polarized wave. These linearly polarized signals are often received by two orthogonal (left and right hand) circularly polarized receive antennas, each of which has 3 dB polarization loss. Under nominal conditions, a diversity combiner can be used to coherently add the two received signals, thereby restoring the 3 dB loss. Recent flight tests have revealed that the signals radiating from the aircraft are actually elliptically polarized or even circularly polarized, leading to degraded combiner performance. This paper describes how the transmit polarization can be transformed from linear to circular, why this degrades combiner performance, and how to mitigate this effect.

      Rice, Michael; Redd, Bryan; Briceno, Ximena; Brigham Young University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      This paper examines the problem of carrier phase and frequency estimation for coded 16-APSK in aeronautical mobile telemetry. Given the fact that coded systems tend to operate at lower signalto-noise ratios than uncoded systems, the synchronizer must operate at these lower signal-to-noise ratios. For a 30 kHz frequency offset and a 10 Mbit/s 16-APSK signal, the conventional phase lock loop (PLL) system does not achieve consistent lock to be a useful approach. Consequently, a blind feed-forward approach, based on the FFT, and an initialized feedback approach based on the PLL were examined. The feed-forward estimator is capable of achieving BER ideal performance for Eb/N0 ≥ 6 dB using 1024 symbols. The feedback estimator, initialized using a feed-forward estimate based on 1024 symbols is also capable of achieving BER ideal performance for Eb/N0 ≥ 6 dB. Both synchronizers require a sufficiently good blind estimate: the estimate based on 2014 symbols appears to be the minimum value to achieve good performance.

      Borah, Deva K.; Curry, Elam; New Mexico State University, Klipsch School of Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      Spatial modulation techniques have the ability to convey information by both the positions of active antennas as well as the symbols they transmit. Such techniques include the generalized spatial modulation (GSM) that can provide high spectral efficiency. In general, however, the total number of available symbols in GSM is not a power of two. Therefore, selection of a symbol alphabet from the available symbols is needed. This is a numerically complex problem. In this paper, we propose to significantly reduce the complexity of the GSM symbol set selection problem by grouping antennas together to form blocks, thus producing block GSM (BGSM) symbols. A previously developed iterative combinatorial method is extended to BGSM symbol selection. The effects of the Rician K-factor, BGSM symbol block size, and antenna configuration on the performance and design complexity are studied. The algorithm is found to significantly reduce the complexity of the BGSM symbol set selection problem.

      Rice, Michael; Arabian, Farah; Brigham Young University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      Providing RHCP and LHCP outputs from the antennas vertical (V) and horizontal (H) dipoles in there sonant cavity within the antenna feeds is the current practice of ground-based station receivers in aeronautical telemetry. The equalizers on the market, operate on either LHCP or RHCP alone, or a combined signal created by co-phasing and adding the RHCP and LHCP outputs. In this paper, we show how to optimally combine the V and H dipole outputs and demonstrate that an equalizer operating on this optimally-combined signal outperforms an equalizer operating on the RHCP, LHCP, or the combined signals. Finally, we show how to optimally combine the RHCP and LHCP outputs for equalization, where this optimal combination performs as good as the optimally combined V and H signals.

      Fischer, John; Perdue, Lisa; Orolia (International Foundation for Telemetering, 2019-10)
      GNSS is key to effective situational awareness, providing critical Positioning, Navigation and Timing (PNT) telemetry data for mobile military operations. Yet GPS/GNSS jamming and spoofing attacks are on the rise. The combination of low-cost hardware, open source software, and tutorials on YouTube have fostered the proliferation of these malicious acts. Beyond intentional disruption, other factors such as environmental conditions and conflicts with other electronic systems can result in unreliable or even unavailable GNSS data. The disruption of GNSS for increasing periods of time through jamming/spoofing must now be an essential test component in most test scenarios today. How can one still provide reliable Time-Space Position Information (TSPI) during periods of GNSS denial? Key mobile military operations that rely on continuous and trusted PNT telemetry data from GNSS include: SatCom on the Move (SOTM), Command, Control, Communications, Computer, Intelligence, Surveillance and Reconnaissance (C4ISR), Airborne Communications Relay, Synthetic Aperture Radar, and Combat Search and Rescue (CSAR). Techniques and technologies used in battlefield systems to provide alternative sources of PNT data during a GNSS outage, can also be used on the test range. This paper will identify technologies, best practices and strategies for GNSS jamming/spoofing detection and protection systems and testing protocols to maintain a state of PNT readiness.
    • Adaptive OFDM for Aeronautical Channels

      Moazzami, Farzad; Dean, Richard; Zegeye, Wondimu K.; Alam, Tasmeer; Morgan State University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      Previous work modeled the cruise phase of an aeronautical channel and showed how the channel varied as a function of height, distance, and speed. What was apparent from that analysis was that the ``cruise" channel was remarkable stable and varied slowly and predictably over time. The steady state channel reflected a 2-ray multipath model which exhibits deep nulls in the spectrum which affects serial tone modems significantly. Further the application of parallel tone modulation improves performance except for that portion of the band which was degraded by the null. This points to the use of Adaptive OFDM (AOFDM) structure wherein tones are only sent in portions of the band which are strong and not areas where the signal is weak. This work develops a method for capturing a profile of the Signal to Distortion Ratio (SDR) for each tone for each frame and over time. It also develops a method for converting the SDR per tone to estimate the optimum QAM modulation scheme for each tone for application in Link Dependent Adaptive Radio (LDAR).

      Tamakuwala, Jimmy B.; Sonar, Souvik; Jena, Avijit; Integrated Test Range, DRDO Chandipur; Defense Research and Development Organization (International Foundation for Telemetering, 2019-10)
      BER is regarded as the link-performance metric in a digital communication system. It is a function of Eb/N0 and is dependent on the modulation scheme used. This relation is often used in prediction of ground telemetry systems performance for a mission configuration. However, there is no objective way of comparing the post flight results, as BER measurement in a flight test is not practically feasible for want of transmitting sufficient reference bit patterns. In this paper, an indirect way of computing BER and, in turn, link Eb/N0 is proposed for a PCM/FM link based on the frame synchronised data logged by the ground telemetry equipment. Using known quantities like bit rate and frame rate, a quantity defined as frame loss rate is computed. Applying the relations between frame loss probability, frame sync pattern and SFID information in the PCM format, an approach for bit error probability is demonstrated based on field data. By using a sliding window over a fixed length of data, BER for the entire flight duration can be determined as a function of flight time with the step size of the length of data window.

      Uetrecht, Jim; Quasonix, Inc. (International Foundation for Telemetering, 2019-10)
      Best-Channel Selection (BCS) uses real-time data quality metrics (DQM) to select the best demodulated bits from Channel 1, Channel 2, and the Combiner of dual-channel receivers. Laboratory testing has demonstrated a substantial reduction in bit error rate (BER) relative to individual channels (including the Combiner) under some synthesized link conditions, with no degradation in BER under the remainder of tested link conditions. This paper extends those results to real-world flight tests.

      Geoghegan, Mark; Nusair, Marwan; Quasonix (International Foundation for Telemetering, 2019-10)
      The migration of aeronautical telemetry systems to C band has prompted a fresh look at many historically uninteresting facets of telemetry links. The effects of higher cable losses and smaller antenna beamwidths, for example, have been recognized and accounted for. Recent flight tests at Edwards AFB with a propeller-driven aircraft have revealed another such effect, which we have termed “prop chop”. Realtime data quality metric (DQM) values showed a periodic fluctuation in DQM, related to the aircraft engine speed. An investigation of this phenomenon using detailed electromagnetic simulation of a transmit antenna in the presence of a propeller shows a mechanism for this interference, both when the propeller is in front of the transmit antenna and when it is behind the transmit antenna. This paper compares the electromagnetic propagation simulation results to measured values from the field.
    • Implementation and Benefits of Best Source Selection

      Gerstner, Grant; Normyle, Dennis; NAVAIR Atlantic Division (International Foundation for Telemetering, 2019-10)
      A comprehensive guide to implementing best source selection at a test range. This paper uses the history of the Atlantic Test Range's implementation as a guide to show the steps needed to implement Best Source Selection. It also discusses the advantages to best source selection at all levels of implementation.

      Shoudha, Shamman Noor; Saquib, Mohammad; Univ Texas, Dept Electrical Engineering (International Foundation for Telemetering, 2019-10)
      This paper analyzes the effect of Long-Term Evolution (LTE) uplink interference on the performance of Aeronautical Telemetry S-band users. A MATLAB simulation environment is used to analyze the interference effect using SOQPSK-TG and 64-QAM modulation schemes for telemetry and LTE transmitters, respectively. An ideal Surface Acoustic Wave (SAW) filter followed by a 2-by-2 symbol detector is used in the telemetry receiver. To ensure a target bit error rate (BER) of 10-5, depending on the LTE spectrum mask, the Carrier-to-Interference (C/I) ratio requirement is -15.4, -32.4 and -30 dB for data rates 1; 5 and 10 Mbits/s, respectively.

      Hill, Terry; Quasonix (International Foundation for Telemetering, 2019-10)
      Multipath distortion has been a major source of data corruption in aeronautical telemetry signals for decades. In recent years, however, adaptive equalizers have begun to appear in telemetry receivers. These equalizers offer the promise of mitigating or even eliminating the damage done by the multipath channel, and many ranges are adopting their use. Unfortunately, there have not been any standardized tests by which to quantify the efficacy and limitations of adaptive equalizers. This paper presents a generalized test methodology for making a quantitative performance assessment of any adaptive equalizer, along with representative test results for one particular adaptive equalizer.
    • Augmenting Cybersecurity in Telemetry Post Processing Environments with Insider Threat Analysis

      Kalibjian, Jeff; Perspecta (International Foundation for Telemetering, 2019-10)
      Mature companies implement robust cybersecurity practice in their organizations by deploying a layered defense comprising many differing security tools whose functionality complements one another. Tools such as firewalls, Anti-Virus (AV), Intrusion Detection/Prevention (IDS/IPS), Data Leak Protection (DLP), and Security Information and Event Management (SIEM) can be rolled out in many combinations to create very effective cyber defenses. A general premise is that organizations are trying to keep “bad guys” out. In recent years, focus has been shifting to address the potential for malicious (insider) employees who may wish to take actions to compromise the firms they work for as an increasing number of incidents are attributed to insiders. After reviewing the insider threat landscape as well as accepted methodologies for detection; application to telemetry post processing environments will be discussed with example deployment scenarios explored.
    • Multi-Stage Attack Detection Using Layered Hidden Markov Model Intrusion Detection System

      Moazzami, Farzad; Dean, Richard; Zegeye, Wondimu K.; Morgan State University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      Intrusion Detection Systems (IDS) based on Artificial Intelligence can be deployed to protect telemetry networks against intruders. As security solutions which encrypt radio links do not accommodate the ever evolving network attacks and vulnerabilities, new defense mechanisms using machine learning and artificial intelligence can play a significant role for telemetry networks. This paper proposes a multi-layered Hidden Markov Model (HMM) IDS that addresses multi-stage attacks. This is due to the fact that intrusions are increasingly being launched through multiple phases instead of single stage intrusion. This layered model divides the problem space into smaller manageable pieces reducing the curse of dimensionality associated with HMMs. To verify the application of this model for real network, the NSL-KDD dataset is used to train and test the model.

      Madon, Phiroz; Ziegler, Robert; Samtani, Sunil; Koval, Aleksey; Harasty, Daniel; Triolo, Anthony; Shen, Qiong; Agarwai, Anjali; Galletti, Michele; Gadgil, Shrirang; et al. (International Foundation for Telemetering, 2019-10)
      A Spectrum Usage Measurement System (SUMS) characterizes the actual use of telemetry spectrum at DoD flight test ranges. The system tracks daily usage in a measurements repository, which becomes an invaluable resource, allowing querying, reporting and analytics, for defending against future spectrum sell-offs, and for providing insights into improving spectrum efficiency. The question is how do we quantify spectrum usage in space, time and frequency? And how do we certify “actual usage”, as opposed to simple assignment and claims that the spectrum was planned to be used? We discuss techniques for addressing these challenges. The system draws upon spectrum mission planning data, a network of sensors of various types, and a correlation algorithm. A scaling problem wrt characterizing the spatial extent of the spectrum usage is solved. Correlation, using heterogeneous data sources at a test range with numerous RF emissions prompts a heuristics and flexible rules-based approach.

      Rice, Michael; Redd, Bryan; Ebert, Jamison; Twitchell, Autumn; Brigham Young University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      In this paper, we analyze several DFT-based frequency offset estimators for use with the 16-APSK digital modulation scheme. Even a small frequency offset between radio transmitters and receivers can cause phase information to be lost, so a system to align the phases is required to reliably demodulate PSK signals. These estimators have been adapted for 16-APSK from methods originally intended for use with QPSK and CPM. These methods consist of a coarse search and a fine search with an optional dichotomous search to improve accuracy. We analyze the estimator error variance and bit error rate associated with several methods of frequency estimation. These estimators exhibit small estimate error and variance and can provide bit error rates close to the ideal AWGN BER.

      Kosbar, Kurt; Lipina, Jacob; Christmas, Austin; Marcolina, Rebecca; Missouri University of Science and Technology (International Foundation for Telemetering, 2019-10)
      This paper discusses the development of wireless inertial measurement units (IMUs) designed to transmit data from a prototype Mars rover to a remote base station. These nine degree of freedom, multi-chip modules provide measurements for linear acceleration, angular rotation velocity, and magnetic field vectors for the rover’s chassis and robotic arm end-effector. To facilitate integration into these dynamic systems, each unit is independently powered and has a form factor of 108 cc. IMU data is sent from 32-bit microcontrollers with embedded IEEE 802.11 b/g/n Wi-Fi to the rover via UDP transport through a custom publish/subscribe distributed IP protocol. Data is relayed over two circular polarized omnidirectional antennas to the base station’s dual linear MIMO Yagi-Uda antenna. The information gathered provides operators a heading and orientation to improve situational awareness, as camera visuals are often inadequate.

      Marcellin, Michael; Collett, Anthony; Ma, Tiffany; Craddock, Zane; Garcia, Gerardo; George, Charles; Univ Arizona, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      On amusement park rides, vibrations against the rails of the track and the cars’ wheels can strain and damage the track. This is especially true for older coasters, whose tracks have worn significantly over time. While manual inspection of the track is necessary, an automated system that monitors the stress on the track will help detect anomalies, ensuring a safe experience for the passengers. We have designed a system of sensors that can monitor these vibrations. Sensors placed on a segment of track will measure the lateral and vertical vibrations, wirelessly transmitting the level of strain on the track to a base station. If vibrations reach a threshold level, the base station will be alerted of excessive strain. The system will create a graph of points where vibration is worse than other points, to pinpoint what areas need to be fixed the most. This will decrease maintenance costs and ensure increased safety for patrons of these rides.

      Rotundo, Alfred; US Army - Army Futures Command; CCDC - Armament Center - Precision Munition Instrumentation Division (International Foundation for Telemetering, 2019-10)
      Developed an on-board-recorder (OBR) to capture both in-bore acceleration and in-flight canister expulsion forces for an artillery projectile. The instrumentation recorded on the OBR was fed into a model to simulate these forces. The OBR’s space claim was limited to the expulsion cavity of the artillery projectile. The OBR was equipped with an analog sensor suite that recorded battery, expulsion pressure, high-g in-bore axial accelerometer data, and radial spin data. Utilizing 8 channels of the ADC on the DSP, the sensors are recorded into both volatile SRAM and NOR Flash memory. The OBR matched both weight and center of gravity of the tactical artillery round. To accomplish this, multiple housing materials and potting materials were utilized. The OBR survived multiple shots. The OBR was instrumented successfully on 4 rounds, allowing an accurate model and simulation to be created to increase design reliability and minimize failures on future designs