• ANALYSIS OF INERTIAL MEASUREMENT DATA FROM A MODEL ROCKET PAYLOAD

      Long, David G.; Francis, Benjamin; Brigham Young University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      As part of a student-educational experience in telemetry, beginning undergraduates build, program, and test small payloads flown in model rockets. These payloads, nicknamed “femtosats,” collect and transmit real time telemetry on the rocket’s performance. The femtosats measure the inertial motions of the model rocket, providing info to extract the flight path. The individually student-designed femtosat circuit board includes a simple inertial measurement sensor that collects acceleration data in the form of x, y, z acceleration vectors which are transmitted in real-time to a radio ground station. The focus of this paper is the collection and analysis of the data from the telemetered inertial measurement sensor and how it can be interpreted and applied in simple model rocket motion analysis.
    • DFT-BASED FREQUENCY OFFSET ESTIMATORS FOR 16-APSK

      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.
    • DOPPLER POWER SPECTRA FROM VEHICLE-TO-EVERYTHING PROPAGATION EXPERIMENTS

      Rice, Michael; Harrison, Willie K.; Norman, Kalin; Jensen, Benjamin; Brigham Young University, Dept Electrical and Computer Engineering (International Foundation for Telemetering, 2019-10)
      This paper presents the results of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) propagation experiments. The experimental results are summarized by Doppler power spectra. Our measurements indicate the need for a dynamic system that can handle the variable channels experienced in vehicle-to-everything communications.
    • ON CARRIER FREQUENCY AND PHASE SYNCHRONIZATION FOR CODED 16-APSK IN AERONAUTICAL MOBILE TELEMETRY

      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.
    • POLARIZATION DIVERSITY AND EQUALIZATION OF FREQUENCY SELECTIVE CHANNELS IN TELEMETRY ENVIRONMENT FOR 16APSK

      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.