• AERONAUTICAL TELEMETRY FADING SOURCES AT TEST RANGES

      Rice, Michael; Law, Eugene; Brigham Young University; NAWCWPNS (International Foundation for Telemetering, 1997-10)
      This paper describes the two main causes of fading encountered at test ranges. The first cause of fading results from nulls in the transmit antenna gain pattern. Variations in the received signal level are a result of changes in the gain pattern as the spatial relationship between transmitter and receiver change. The second cause of fading is due to multipath interference. This occurs when multiple copies of the transmitted signal with different delays arrive at the receiver and are phased relative to each other so that destructive interference occurs.
    • Analysis of JDAM Tests at China Lake

      Rice, Michael; Welling, Kenneth; Brigham Young University (International Foundation for Telemetering, 1997-10)
      This paper examines telemetry signal levels of the Joint Direct Air Munition (JDAM) tests at China Lake NAWC. Significant received signal level variations were observed as the munition approached impact. This paper presents and examines two simple multipath models to explain the received signal variations. The first model assumes a flat earth and a single specular multipath reflection. The second model uses the actual contour of the earth and considers a number of specular multipath reflections. The first model (which assumes the single multipath reflection) more accurately reproduces the variations in the received signal level than the second.
    • Antenna Gain Pattern Effects on Multipath Interference in Aeronautical Telemetering

      Rice, Michael; Friend, Daniel H.; Brigham Young University (International Foundation for Telemetering, 1997-10)
      This paper examines the effect of antenna gain pattern on multipath fades for a typical aeronautical telemetry system. Assuming a parabolic reflector antenna at the tracking station and a single specular reflection as the source of multipath, an expression for the fade depth which incorporates the attenuating effects of the antenna gain pattern is derived. A representative example is presented which demonstrates the utility of the expressions derived.
    • BER ANALYSIS OF AN F-16 TEST RUN AT EDWARDS AFB

      Rice, Michael; Friend, Daniel; Brigham Young University (International Foundation for Telemetering, 1997-10)
      This paper analyzes the bit error rates (BER) using data recorded during an F-16 test at Edwards Air Force Base in September, 1996. The effects of multipath fading on BER are presented. It is shown that significant increases in BER can occur when the received signal power remains at an acceptable level. Recordings of the received power spectrum during the test show that these BER increases are caused by frequency selective fades due to multipath interference. This paper illustrates that in these cases, significant data degradation can occur without drops in the received signal power.
    • Burst Analysis of Bit Errors on an F-16 Test Flight at Edwards AFB

      Rice, Michael; Welling, Kenneth; Landon, David; Brigham Young University (International Foundation for Telemetering, 1997-10)
      Bit errors induced by multipath interference occur in short bursts with relatively long intervals of error-free propagation. This paper analyzes the bursty nature of bit errors by examining synthetic error sequences generated from received voltage levels measured during low-altitude F-16 flights at Edwards AFB. The error gap distribution (which is a cumulative distribution function of the length of the error free intervals) and the block error probability are computed from the data. These parameters are useful in assessing the performance of error control coding strategies.
    • IRIG-106: A Design Exercise for Digital Communications

      Rice, Michael; Brigham Young University (International Foundation for Telemetering, 1997-10)
      This paper describes a design project which combines the simulation capabilities of the Communications Tool Box in SIMULINK® with the IRIG-106 standard. The design project is part of a senior level digital communications course offered in the Department of Electrical & Computer Engineering at Brigham Young University and functions as an introduction to the Telemetering Program at BYU which is funded by the International Foundation for Telemetering.
    • SYSTEM PERFORMANCE OF THE ACTS MARITIME TERMINAL

      Rice, Michael; Perrins, Erik; Brigham Young University (International Foundation for Telemetering, 1997-10)
      The Advanced Communication Technology Satellite (ACTS) Mobile Terminal (AMT) has been deployed aboard the USS Princeton (CG 59) in an experiment to test the viability of K and Ka band technology in military communication applications. Pilot tone data recorded on-board the USS Princeton (CG 59) show that most variations in the received power level result from antenna tracking errors and did not appear to be caused by obstructions from the ship superstructure. The data also showed that multipath interference was negligible. The data studied in this paper were gathered during ship maneuvers in the Caribbean (13E 33’ N, 76E 16’ W) in late May 1997 and in the Eastern Pacific (6E 34’ N, 79E 40’ W) in early June 1997. The relationship between pitch/yaw/roll and received power levels is studied. Plots showing received power (time series) are presented to aid in link budget calculations.