Now showing items 21-40 of 67268

    • Test Range Spectrum Management with LTE-A

      Picha, Bob; Nokia Corporation of America (International Foundation for Telemetering, 2018-11)
    • BLIND ADAPTIVE EQUALIZER FOR MULTIPATH ENVIRONMENT IN LOW ELEVATION AERONAUTICAL TELEMETRY

      Ke, Zhou; Dalong, Yang; Shunqin, Xie; Xianglu, Li; Tao, Dai; Institute of Electronic Engineering, China Academy of Engineering Physics (International Foundation for Telemetering, 2018-11)
      It has been proved that multipath and timing-varying channels usually cause significant performance degradation, especially for low elevation scenario (0o~5o) in aeronautical telemetry. Channel models for various scenarios of the whole take-off process will be described in this paper. And we will present the experimental testing results to characterize the performance of a blind adaptive constant modulus algorithm (CMA) equalizer applied for PCM-FM receiver in low elevation aeronautical telemetry scenarios, including parking scenario, taxiing scenario, take-off scenario and far-flight scenario. The test results showed that the equalizer improved the signal quality and achieved a remarkable bit error rate (BER) performance gain in the multipath fading scenarios.
    • IMPACT OF PARAMETER SELECTION IN SOFT-DECISION FEEDBACK TURBO EQUALIZATION

      Nassr, Husam; Kosbar, Kurt; Missouri University of Science & Technology, Dept. of Electrical & Computer Engineering (International Foundation for Telemetering, 2018-11)
      In wireless communication systems, turbo equalization has been used to mitigate the intersymbol interference caused by dispersive channels. Despite its computational complexity, turbo equalization achieves high performance compared to systems that implement the equalization and coding processes separately. The large performance gain achieved through turbo equalization comes from exchanging soft information between the equalizer and decoder in an iterative manner. However, the computational complexity of turbo equalization can be a significant challenge for systems with limited hardware capabilities. This paper examines the performance gain versus computational complexity trade-off for a soft-decision feedback turbo equalizer (SDFTE).We show how to select parameters that achieve a desired performance specification, while minimizing implementation overhead. Sample results are presented from a simulation of a system using a Proakis channel exhibiting severe ISI using QPSK, 8PSK and 16QAM modulation schemes.
    • COGNITIVE EQUALIZATION FOR HF CHANNELS

      Teku, Noel; Bose, Tamal; Univ Arizona, Dept Elect & Comp Engn (International Foundation for Telemetering, 2018-11)
      In the High Frequency (HF) band, ranging from 3-30 MHz, long-range communications can be obtained by bouncing signals off the ionosphere without any significant infrastructure. However, the ionosphere changes rapidly, which can cause potentially harmful effects to the transmitted signal. This has motivated research into using adaptive equalization in this band to reverse these effects. However, a disadvantage of this technique is that based on the equalizer model and learning algorithm used, the error propagation may become significantly large, resulting in insufficient equalization to respond to these variations. To counter this, we investigate the usage of cognitive equalization, where an adaptive equalizer is equipped with the ability to change its structure (i.e. number of taps, step size, etc.) based on the current channel conditions and use probability of error to characterize its performance.
    • COMPARISON OF FPGA EQUALIZER IMPLEMENTATIONS FOR HIGH-SPEED DATA TELEMETRY

      Schmalz, Daniel; Lennon, Joseph; Wang, Enkuang; Brothers, Timothy; Georgia Tech Research Institute (International Foundation for Telemetering, 2018-11)
      This paper examines the real-time implementation of equalization techniques. Telemetry RF channels are formidable due to the nature of desert test ranges – specifically due to multipath, changing path loss from environmental effects, and thermal distortions. This challenge is further complicated by the high velocity nature of test assets. Optimization of channel equalization in a real-time scenario is essential for high speed data telemetry over extended distances. This paper examines the mathematical background of equalization techniques and presents results based on FPGA implementations. The results were obtained from Vivado High Level Synthesis (HLS), which generates HDL from C/C++, as well as traditional VHDL coding. The contribution to the state of the art in this paper is the determination of the technological maturity of HLS versus traditional hand coding and the comparison of FPGA implementations of equalization algorithms against current platforms.
    • ON THE PERFORMANCE OF FILTER BASED EQUALIZERS FOR 16APSK IN AERONAUTICAL TELEMETRY ENVIRONMENT

      Arabian, Farah; Rice, Michael; BYU, Department of Electrical and Computer Engineering (International Foundation for Telemetering, 2018-11)
      16APSK is a candidate modulation for aeronautical telemetry because it has better spectral efficiency than SOQPSK-TG, but requires a linear RF power amplifier. This paper investigates the BER performance of filter-based equalizers for 16APSK operating over multipath channels measured at Edwards AFB. The results show that decision feedback equalizers outperform the other equalizers and are capable of providing excellent multipath mitigation.
    • AUTONOMOUS NAVIGATION IN DYNAMIC ENVIRONMENTS

      Buxton, Jonas; Thomure, Logan; Downs, Roger; Bosanko, Garrett; Kosbar, Kurt; Missouri University of Science and Technology (International Foundation for Telemetering, 2018-11)
      Robotic systems that operate indoors are often unable to rely on GPS, and dynamic environments prove difficult to navigate for robotic systems that rely on SLAM (Simultaneous Location and Mapping). Autonomous navigation without the use of GPS or SLAM techniques require a system to rely on more fundamental hardware and software concepts. The challenge is made even greater when the system is intended to fly, interact with moving targets, and avoid moving obstacles. This is the design criteria that our autonomous multirotor is adhering to for the International Aerial Robotics Competition. This paper will describe the purpose behind each of our multirotor's sensors, such as LIDAR (Light Detection and Ranging) systems and Optical Flow sensors, that enable it to accurately interact with its environment without SLAM techniques, as well as the multirotor's onboard software that powers its autonomous capabilities.
    • DYNAMIC OBSTACLE CHARACTERIZATION AND AVOIDANCE FOR UNMANNED AERIAL SYSTEMS

      Norland, Kyle; Marcellin, Michael W.; Univ Arizona, Dept Syst & Ind Engn (International Foundation for Telemetering, 2018-11)
      To address the challenge of avoiding dynamic obstacles during the course of the 2018 SUAS competition, a multistage obstacle characterization and avoidance algorithm was designed and implemented. The obstacle characterization section begins with simple base assumptions about behavior and goes through several more advanced stages of obstacle characterization and prediction as more data arises and advanced behavior is detected. The path finding section of the algorithm uses a recursive Monte Carlo path sampling function with a flexible structure that allows for usage with varying computational budgets. It also restricts its computational usage depending on the level of variability in the obstacles.
    • BYU MARS ROVER AT THE 2018 UNIVERSITY ROVER CHALLENGE

      Rozsa, Jace; Averett, Tyler; Killpack, Marc; Rice, Michael; Brigham Young University (International Foundation for Telemetering, 2018-11)
      This paper describes the design and performance of the BYU mars rover with an emphasis on the wireless communications system and the transmission and reception of data vital to the performance of the rover.
    • A New Network Telemetry technique In Aviatic Flight Tests

      Xingguo, Zhang; Hong, Li; Guojin, Peng; Zanchao, Wang; Chinese Flight Test Establishment (International Foundation for Telemetering, 2018-11)
      In order to address the issue of insufficient telemetry frequencies in flight tests, a telemetry transmission solution is proposed to transmit the principal parameters and HUD video for multiple aircrafts based on bi-directional wireless network. All the key points including the wireless transmission architecture for airborne and ground integration, network resources management, and dynamic configuration of airborne test system are illustrated. The research result has been verified in flight tests, and the experimental methods and results are presented as well.
    • Network Scheduling Algorithm with Efficient Backfill Process in the iNET

      Roh, Dongseok; Oh, Jonghun; Agency for Defense Development (International Foundation for Telemetering, 2018-11)
      One of the major advantage of integrated Network Enhanced Telemetry (iNET) system is data backfill. In the iNET, network data server requests signal retransmission from the on-board recorder when the signal dropout is detected, and data is retransmitted which leads successful reception. If there are numerous test articles (TA), however, multiple backfill process for signal request and data retransmission can cause undesirable capacity waste. This paper describes the improved backfill process in iNET with multiple TAs. This process includes grouping and scheduling algorithm within TAs, and the orthogonal and non-orthogonal transmission. The system model and results are analyzed by simulation.
    • Telemetry System Based on MESH Network and Its Application

      Guo, Pingfan; Liu, Ming; Li, Hong; Zhu, Hongxiang; Chinese Flight Test Establishment (International Foundation for Telemetering, 2018-11)
      In the flight test, the advantages of network telemetry have gradually emerged, and their application fields will also be expanded. This paper introduces a network telemetry system based on MESH net and its application in flight test, a ground station can receive telemetry signals of several planes at the same time; the components and functions of the system are described, the advantages of this network telemetry system, existing problems and suggestions on future improvements are presented.
    • NETWORK BASED TIMING MECHANISMS TO SUPPORT PRECISE ALIGNMENT OF REAL-TIME STREAMS

      Kovach, Bob; IPtec, Inc. (International Foundation for Telemetering, 2018-11)
      The efforts to implement the distribution of real-time information streams via IP packet-based networks in the range environment have largely utilized the recovery of timing information via implicit techniques, such as adaptive clock recovery. These techniques allowed the alignment of streams with disparate delay characteristics to accuracies on the order of 1 millisecond. With the availability of techniques to distribute high accuracy timing information to network nodes, the capability to recover and align real time streams on the order of microseconds is possible. This paper will focus on a methodology to perform precision stream alignment that utilizes timestamping and the IEEE 1588 Precision Time Protocol (PTP) as a clock source. IEEE 1588 is currently utilized in cellular networks to deliver synchronization to remote network elements, providing superior accuracy and stability. The paper will review expectations for performance and discuss considerations in system level design to optimize timing distribution performance and ultimately stream alignment accuracy. System elements and their effect on performance will be identified and characterized. Finally, a TM Gateway implementation example which utilizes PTP coupled with hardwareassisted timestamping techniques to align recovered TM streams to a high degree of accuracy will be described. Real world results for clock accuracy and expectations for stream alignment accuracy will be shared.
    • ACCELERATING STANDARDS COMPLIANT TMNS RADIO IMPLEMENTATIONS

      Newton, Todd A.; Timme, M. Wayne; Southwest Research Institute® (International Foundation for Telemetering, 2018-11)
      IRIG 106-17 defines interoperable two-way network telemetry interfaces for the wired as well as the dynamic TDMA air interface. While the air interface is based on the familiar SOQPSK-TG waveform, a TmNS-based radio contains a dynamic TDMA MAC regulated by Link Management through the use of RFNMs. This paper illustrates the TmNS-based radio aspects of the IRIG standard by describing our experience utilizing a two-track approach for accelerated TmNS compliant radio development. We have divided the architecture by engineering discipline lines (Communications vs. Computer Engineering). Doing so allowed us to accelerate the design, simulation, and test tasks while using a common code base across various transceiver implementations. Discussion includes a description of the software modules that provide TmNS interfaces for standards compliant radio functionality such as the TDMA MAC, RFNM processing, system management, and MDL configuration as well as system-level integration testing.
    • TELEMETRY DATA ON DEMAND: THE KEY TO UNDERSTANDING THE TELEMETRY NETWORK REVOLUTION

      Reinwald, Carl; Laulima Systems (International Foundation for Telemetering, 2018-11)
      The telemetry network revolution takes aeronautical flight testing from a broadcast-only paradigm to a TM-data-on-demand paradigm. This paper explores this paradigm shift, focusing on fundamental architectural changes enabled by incorporating telemetry networking technologies into a flight test system. Two concepts are presented to help understand the TM-data-on-demand paradigm: retrieving and processing recorded data from a test article during a mission and onboard dynamic data analysis and compression. An example flight test system with both SST and TmNS components provides a foundation to further explore the paradigm-shifting capabilities a telemetry network brings to flight test. In addition to TM-data-on-demand, the current static spectrum allocation methodology must also be replaced with a more agile, bandwidth-on-demand paradigm. When both TM-data-on-demand and bandwidth-on-demand capabilities have been realized, a new era of efficient flight testing will emerge.
    • CODE-AIDED TIMING SYNCHRONIZATION FOR MULTI-H CPM AT LOW SIGNAL-TO-NOISE RATIO

      Shunqin, Xie; Ke, Zhou; Dahai, Chen; Xianglu, Li; Institute of Electronic Engineering, China Academy of Engineering Physics (International Foundation for Telemetering, 2018-11)
      In order to solve the problem of timing synchronization at low signal-to-noise ratio(SNR) for Multi-h CPM, a code-aided early-late loop(ELL) algorithm is proposed. The algorithm is based on the iterative detection of serially concatenated Multi-h CPM with convolutional codes. The ELL timing estimator based on sequence detection is extended to the maximum-logarithmic maximum a posteriori (max-log MAP) detection. By using the information updated by iterative detection, the timing accuracy of multi-h CPM can be improved at low SNR. The simulation results show that, even when the bit signal-to-noise ratio (Eb/No) is as low as 3dB~5dB, the estimating variance of the proposed synchronization can be close to the Cramer Rao bound(MCRB) of ARTM CPM. After this timing synchronizing, the detection performance of the 10th iteration is only 0.03dB loss compared with the performance with ideal synchronization.
    • CRTM C-band Lab Test Results

      Picha, Bob; Nokia Corporation of America (International Foundation for Telemetering, 2018-11)
    • FLIGHT SIMULATION WITH DYNAMIC AERONAUTICAL CHANNEL MODEL

      Alam, Tasmeer; Moazzami, Farzad; Dean, Richard; Morgan State University, Department of Electrical and Computer Engineering (International Foundation for Telemetering, 2018-11)
      This paper includes the design, modeling and analysis of the aeronautical channel which includes the dynamics of flight simulation. For any given flight path scenario in the cruise state it is well understood that the channel is fitted by a 2 ray model. The dynamics of this model can be generated using the two-ray ground reflection model which is based on the position, velocity, and direction of the aircraft. The dynamic aeronautical channel model includes Doppler shift and delay spread for each path of a channel model. This paper shows how each parameter is created for modelling the dynamic channel. The design of such channel model will help the telemetry community to incorporate channel dynamics in computer simulation to improve the accuracy of flight simulation in the design and pre-test stages. Further, it can provide insight to the selection of modulation, equalization and coding for such channels.
    • CFO Estimation by Exploiting Channel Sparsity in Aeronautical Telemetry

      Afran, Shah; Saquib, Mohammad; Rice, Michael; The University of Texas at Dallas; Brigham Young University (International Foundation for Telemetering, 2018-11)
      In this paper, we explore a carrier frequency offset (CFO) estimation scheme with sparsity-constraint (SC) on the aeronautical telemetry channels. This SC CFO estimator is implemented in two steps. In the first step, channel support is recovered by combining compressed sensing techniques with the CFO estimate based on the non-sparsity constraint (NSC) on the channel. Next we use the estimated channel support to derive the SC CFO estimator. Simulations are performed to compare the performance of the SC CFO estimator against the existing NSC CFO estimators using shaped offset QPSK version TG (SOQPSK-TG) modulated iNET-formatted data over an aeronautical test channel.
    • USING GPS RECEIVER 1PPS OUTPUT TO VERIFY TIME STAMP ACCURACY AND MEASURE PROPAGATION DELAY

      Knudtson, Kevin; Moreno, Antonio; NASA Armstrong Flight Research Center; NASA Armstrong Flight Research Center, Arcata Associates Inc. (International Foundation for Telemetering, 2018-11)
      A simple pulse overlay circuit using a logic OR gate was developed to overlay a precise leading edge 1 pulse per second time reference marker from a global positioning system receiver onto a non-return -to- zero-level pulse code modulation telemetry data stream to validate time stamp accuracy and measure propagation delay in telemetry equipment.