Turner, William C.; Electro-Magnetic Processes, Inc. (International Foundation for Telemetering, 1986-10)
      Performance data taken on three candidate telemetry tracking antennas which employ significantly different beam scanning principles are presented. Measurements of antenna feed-induced phase noise were made at S-Band and compared.

      Benet, C.; Wickham, M.; Balzer, J. (International Foundation for Telemetering, 1986-10)
      The success of a communications satellite mission depends not only on the proper operation of the on-board Attitude and Orbit Control System (AOCS), but also on the complex interaction between the spacecraft and the ground control center. In support of a satellite program from its inception to launch and throughout the inorbit life, COMSAT has developed a SATELLITE ATTITUDE AND ORBIT CONTROL SYSTEM FLIGHT SIMULATOR. This paper describes the design and operations of the COMSAT FLIGHT SIMULATOR. The simulator is a real-time, high fidelity, operator interactive, spacecraft hardware in the loop system. The heart of the system is a high precision minicomputer in which the spacecraft dynamics, sensors, actuators and most likely failure modes are modeled. A significant feature of the simulator is a faithful duplication of the command and telemetry functions. The operator can send commands and review telemetered data in the same format as during the mission. The simulator operates in real-time and is flexible enough to either simulate or fully integrate parts of the flight hardware. Such is the case for instance for the on-board computer with its complex programmable control algorithms. However, flight hardware in the loop is in no way limited to any particular unit of the flight subsystem. The simulator can also be remotely linked to the ground station and use actual commands as direct inputs for its operation. A colorgraphics driven by the simulated dynamics displays the spacecraft motions and warns the operator of eventual losses of telemetry and command capabilities during attitude anomalies. Following is a partial list of the FLIGHT SIMULATOR capabilities. S Provide an independent means to evaluate and validate a control system design; S Support the development of Control Center (hardware and software) and serve as a training facility for the control operators; S Develop and verify the spacecraft sequence of events; S Help in developing and evaluating, in real time, the on-orbit Operational and Recovery Procedures; S Maximize satellite life through maneuver optimization, and S Support the satellite mission throughout the spacecraft life, providing a test bed for flight anomaly investigation. This last point is significant since, in general, a satellite operator has no guarantee as to the availability of a spacecraft manufacturer’s facility for the full duration of a satellite mission. The COMSAT FLIGHT SIMULATOR is fully operational and is already supporting the STC/DBS (Satellite Television Corporation/Direct Broadcast Satellite) program. COMSAT concurrently developed a flight simulator for INTELSAT VI. These two simulators represent second-generation designs compared to the first real-time, hardwarein-the-loop simulator which was built for INTELSAT V.

      Sargeant, H.; Interstate Electronics Corporation (International Foundation for Telemetering, 1986-10)
      Predetection recording of spread-spectrum (SS) signals such as GPS transmissions is a desirable objective for both users and developers of equipment designed to receive such signals. (GPS user-equipment development is a lengthy process during which signal simulators are only partially useful.) Upon playback, GPS signals are used by the same or modified receivers so that acquisition, processing, detection and tracking loops can be altered to optimize the receiver parameters. Development of predetect SS signal recording systems is difficult to achieve in practice. Such systems not only must be of suitable phase linearity to preserve the signal content to be extracted but sometimes must also preserve the exact signal-to-noise ratio (SNR) characteristics of the recorded signals. Existing conventional test equipment is unsuitable for deriving value judgments of the quality of a predetect recording system’s output because the SS signal has a negative SNR. This paper reveals that it is possible to use, for this purpose, tape recorders now available on many test ranges in combination with auxiliary equipment similar to that designed for the U.S. Navy’s TRIDENT Program (recording C/A-code data from in-flight missile translators). The basic techniques are described in some detail to enable potential users to understand the necessary equipment concepts and evaluate the author’s approach in terms of their own applications.
    • TABS - an Asynchronous Block Serial Protocol for Multipoint Applications

      Schachter, Paul J.; AT&T Bell Laboratories (International Foundation for Telemetering, 1986-10)
      Since the early 1960’s, AT&T has established a trend toward centralized and remote operations of the transmission network. Thorough and continuous monitoring of global network properties can only be achieved through centralization. As a result, a secondary network has evolved in support of these monitoring functions. The “telemetry network” comprises a system of distributed processors dedicated to analyses of the transmission network, together with all necessary communication links. Monitoring access to the transmission network is provided at special interface points. Often the interface hardware is integrated into the transmission network element itself. AT&T uses a special protocol, TABS, the Telemetry Asynchronous Block Serial protocol, at the interface between the telemetry network and the transmission network.[1] TABS was designed by AT&T Bell Laboratories to optimize the performance and economics of this interface. In this paper, we describe the structure of that protocol, its performance properties and current implementations.

      Kumar, Rajendra; California State University (International Foundation for Telemetering, 1986-10)
      A new least squares algorithm is proposed and investigated for fast frequency and phase acquisition of sinusoids in the presence of noise. This algorithm is a special case of more general adaptive parameter estimation techniques. The advantages of the algorithms are their conceptual simplicity, flexibility and applicability to general situations. For example, the frequency to be acquired can be time varying, and the noise can be non-gaussian, nonstationary and colored. As the proposed algorithm can be made recursive in the number of observations, it is not necessary to have a-priori knowledge of the received signal-to-noise ratio or to specify the measurement time. This would be required for batch processing techniques, such as the Fast Fourier Transform (FFT). The proposed algorithm improves the frequency estimate on a recursive basis as more and more observations are obtained. When the algorithm is applied in real time, it has the extra advantage that the observations need not be stored. The algorithm also yields a real time confidence measure as to the accuracy of the estimator.

      PIETERS, BERNARD; DIRECTION DES ESSAIS (International Foundation for Telemetering, 1986-10)
      The development of ballistic missiles and launch vehicles in the last twenty five years has required the engineering, perfecting and introduction of suitable testing and measuring facilities, more particularly telemetry equipment. We purpose to recall the major milestones of the evolution in this field of techniques throughout that period and to try to define some prospects for the future. We do not pretend to give a historical account, but only our thought on an industrial experience that we have lived through. Therefore, we entreat the reader’s indulgence for the non-exhaustive character of this paper and perhaps for some unintentional errors or distortions.
    • International Telemetering Conference Proceedings, Volume 22 (1986)

      International Foundation for Telemetering, 1986-10

      SHVARTSMAN, VLADIMIR A.; Electronic Design & Research Co., Inc. (International Foundation for Telemetering, 1986-10)
      The introduction of a phase/frequency-locked loop (PFLL) technique made the task of transmitting information with a high degree of accuracy less cumbersome. The PFLL became possible after a high precision, continuous type phase/frequency-to-voltage converter/demodulator (PFVCD) was developed. It performance at a wide frequency band (DC-80 KHz), dynamic range up to 120 dB, and precision pulse width discrimination has made possible to build fast hopping PFLL based coherent timemultiplex PM-PM system with only few tenths of a degree of radians spacing between channels. A parallel type decoder was built to demodulate and separate individual channels. It employed the PFVCD which n-shape (ideal) bandpass characteristic and high level linearity eliminates crosstalk and minimizes distortion of an original signal.

      Knight, Paul; Pacific Missile Test Center (International Foundation for Telemetering, 1986-10)
      Since the late 1970’s the telemetry processing and display requirements of the Pacific Missile Test Center have been handled by the Telemetry Data Handling System. With the increasing use of embedded computers on test vehicles and the requirements to process and display larger volumes of data at higher data rates, many programs will soon exceed the capabilities of the Telemetry Data Handling System. The Telemetry Processing System is a replacement of the Telemetry Data Handling System that will be brought online in the Pacific Missile Test Center’s Telemetry Data Center in 1990. The Telemetry Processing System is required to meet the processing and display requirements of the Pacific Missile Test Center’s range users for the next decade. A discussion of the functional implementation and performance requirements of Telemetry Processing System is presented.

      Davis, Edward L.; Grahame, William E.; Loral Instrumentation (International Foundation for Telemetering, 1986-10)
      When flight testing helicopters, it is essential to process and analyze many parameters spontaneously and accurately for instantaneous feedback in order to make spot decisions on the safety and integrity of the aircraft. As various maneuvers stress the airframe or load oscillatory components, the absolute limits as well as interrelated limits including average and cumulative cycle loading must be continuously monitored. This paper presents a complete acquisition and analysis system (LDF/ADS) that contains modularly expandable array processors which provide real time acquisition, processing and analysis of multiple concurrent data streams and parameters. Simple limits checking and engineering units conversions are performed as well as more complex spectrum analyses, correlations and other high level interprocessing interactively with the operator. An example configuration is presented herein which illustrates how the system interacts with the operator during an actual flight test. The processed and derived parameters are discussed and the part they play in decision making is demonstrated. The LDF/ADS system may perform vibration analyses on many structural components during flight. Potential problems may also be isolated and reported during flight. Signatures or frequency domain representations of past problems or failures may be stored in nonvolatile memory and the LDF/ADS system will perform real time convolutions to determine the degrees of correlation of a present problem with all known past problems and reply instantly. This real time fault isolation is an indispensable tool for potential savings in lives and aircraft as well as eliminating unnecessary down time.

      Calvez, Cliff A.; Deputy Commander for Network Development and Integration (International Foundation for Telemetering, 1986-10)
      This paper presents an architectural overview of the Air Force Satellite Control Facility (AFSCF) with emphasis on the on-going development effort of the AF Satellite Control Network (AFSCN). The AFSCF originated twenty-seven years ago, and has evolved into a global satellite service network. This worldwide network is composed of twelve RTSs, located at seven geographically dispersed locations, and a Satellite Test Center (STC) at Sunnyvale, California. The AFSCF provides real-time telemetry, tracking, and commanding (TT&C) service to Department of Defense (DoD) spacecraft and launch vehicles. To cope with the projected operational workload and to reduce life cycle costs, the AFSCF began a major effort several years ago to modernize the Network. The two programs, (Data Systems Modernization and Automated Remote Tracking Station) in this effort will bring about major changes in the Network’s current configuration and operations concept. Another program, the development of the Consolidated Space Operations Center (CSOC), also introduces major changes to the network architecture. Additionally the formation of the USAF Space Command has profound impacts on the AFSCN and its development effort. With these changes, brought about in response to changing DoD space support requirements, the AFSCF network has grown through expansion and modernization of its tracking, data processing, and communication capabilities. This paper discusses the past, the present, and the impending changes to the AFSCN as it continues to evolve in support of the DoD space programs.

      Plecity, Mark S.; ARIA Programs Division, Wright-Patterson Air Force Base, Ohio (International Foundation for Telemetering, 1986-10)
      The Advanced Range Instrumentation Aircraft (ARIA) is an airborne platform to receive, record, process and retransmit telemetry data. This paper presents a summary of ARIA’s capabilities with emphasis on airborne testing of the Advanced Medium Range Air to Air Missile (AMRAAM) program. The unique test scenarios, as well as current and future telemetry requirements of the AMRAAM test program are discussed.

      Engel, Jim; Pacific Missile Test Center (International Foundation for Telemetering, 1986-10)
      Providing realtime telemetry collection to the Pacific Missile Test Center’s (PMTC) range users presents some unique problems. Operations are staged in an open sea environment with participants often at very low altitude and/or far from land based collection instrumentation. This paper will present an overview of the airborne telemetry collection instrumentation that has been developed at PMTC to overcome these problems and will discuss some of the operational problems encountered in its use.

      Lee, Lester H.; Recortec, Inc. (International Foundation for Telemetering, 1986-10)
      Description of various off-line magnetic tape cleaning techniques and testing process to measure defects of tape before using it for tape recording applications. Discussions are made on the type of cleaning methods and also the ways and means to achieve better evaluation results.

      Law, Eugene L.; Pacific Missile Test Center (International Foundation for Telemetering, 1986-10)
      This paper discusses measured performance of double density recording. Tests were conducted using different recorders, playback machines, and magnetic tapes. The main topics discussed are slot signal-to-noise ratio (SNR) and high density digital bit error rate (BER).

      Schoeck, Kenneth O.; Western Space and Missile Center (International Foundation for Telemetering, 1986-10)
      The Western Space and Missile Center has requirements to record high bit rate PCM telemetry data in both predetection and post-detection formats. Recording time is inadequate using standard wideband instrumentation magnetic tape recorder/reproducers. Using double density recording technology, recording time can be doubled, but results in some degradation in recorder performance. This paper discusses the effects of double density recording on recorder performance and on the quality of high bit rate telemetry data.

      Jeske, Harold O.; Sandia National Laboratories (International Foundation for Telemetering, 1986-10)
      An increase in the maximum power flux-density (pfd) permitted from satellites in the 2025 to 2300 MHz band is currently under consideration by IRAC. This analysis assumes the worst case conditions for interference to telemetry operations at the missile test ranges as a result of current and proposed satellite pfd levels. Assumptions in the analysis include the maximum permitted power flux-density with uniform energy distribution over the band of interest, polarization compatibility, and alignment of the telemetry station, the missile and the satellite. It was found that the performance of essentially all missile telemetry receiving systems may be appreciably degraded by even the lowest pfd limits currently permitted. For the higher pfd limits under consideration, degradations in the order of 40 dB are to be expected at stations with dish antennas of only five foot diameter. An increase in the size or gain of an antenna will reduce the probability of interference, because of its decreased beamwidth, but will also increase the performance degradation because of the station’s increased figure of merit, G/T. For satisfactory missile telemetry operation under these conditions, the normal missile’s telemetry received signal-to-noise ratio would have to be well over 40 dB to overcome satellite interference. The results of the analysis are actually independent of all receiving station parameters except the station’s figure of merit, G/T. Probability of interference is not addressed because of the variation of conditions and missions of the various test ranges as well as the unknown number of satellites and their characteristics - present and future. If missile and satellite telemetry is to coexist in the 2200 to 2290 MHz band, the implementation of several recommendations is considered necessary. The recommendations are; 1) Satellite pfd levels should remain at the current limits; 2) Coordination between the satellite controllers and the range operations must be established; and 3) Multiple telemetry receiving stations with significantly different aspect angles with respect to the test vehicle during the test should be used.

      Krishen, Kumar; Erwin, Harry O.; Johnson Space Center (International Foundation for Telemetering, 1986-10)
      This paper presents a review of the ranging and tracking systems/techniques used in the past NASA programs. A review of the anticipated requirements for future rendezvous and docking operations is also presented as rationale for further development of the technology in this area. The first American rendezvous in space was between Gemini VI-A and Gemini VII and took place on December 15, 1965. The Gemini vehicles were equipped with a noncoherent pulse radar. The target vehicle carried a transponder to assist the radar in target acquisition. Angle tracking was accomplished by the phase-comparison monopulse technique. In the Gemini, Apollo, and Skylab programs, the rendezvous and/or docking were manual operations supported by radar measurements and visual observations. The Shuttle rendezvous radar is a Ku-band, pulse-Doppler radar which doubles as a communications transceiver. This radar is not accurate enough to support close-in stationkeeping or docking. An automatic soft-docking capability has been established as a requirement for future space operations. Millimeter wave and laser radar systems have shown promise in satisfying the needed accuracy requirements and size constraints (for space applications) compared to the microwave systems for proximity attitude, position and velocity measurements. A review of these systems and their capabilities is presented in this paper. Rather than developing a separate sensor to satisfy the requirements of each new spacecraft, a hybrid design is proposed for a versatile system which can satisfy the needs for different spacecrafts and missions.

      Eccles, Lee; O’Brien, Michael; Anderson, William; Boeing Commercial Airplane Company; Fairchild Weston Systems, Inc. (International Foundation for Telemetering, 1986-10)
      The Boeing Commercial Airplane Company presently uses an Airborne Data Analysis and Monitor System (ADAMS) to support extensive qualification testing on new and modified commercial aircraft. The ADAMS system consists of subsystems controlled by independent processors which preprocess serial PCM data, perform application-specific processing, provide graphic display of data, and manage mass storage resources. Setup and control information is passed between processors using the Ethernet protocol on a fiber optic network. Tagged data is passed between processors using a data bus with networking characteristics. During qualification tests, data are dynamically selected, analyses performed, and results recorded. Decisions to proceed or repeat tests are made in real time on the aircraft. Instrumentation in present aircraft includes up to 3700 sensors, with projections for 5750 sensors in the next generation. Concurrently, data throughput rates are increasing, and data preprocessing requirements are becoming more complex. Fairchild Weston Systems, Inc., under contract to Boeing, has developed an Acquisition Interface Assembly (AIA) which accepts multiple streams of PCM data, controls recording and playback on analog tape, performs high speed data preprocessing, and distributes the data to the other ADAMS subsystems. The AIA processes one to three streams in any of the standard IRIG PCM formats using programmable bit, frame and subframe synchronizers. Data from ARINC buses with embedded measurement labels, bus ID’s, and time tags may also be processed by the AIA. Preprocessing is accomplished by two high-performance Distributed Processing Units (DPU) operating in either pipeline or parallel environments. The DPU’s perform concatenation functions, number system conversions, engineering unit conversions, and data tagging for distribution to the ADAMS system. Time information, from either a time code generator or tape playback, may be merged with data with a 0.1 msec resolution. Control and status functions are coordinated by an embedded processor, and are accessible to other ADAMS processors via both the Ethernet interface and a local operator’s terminal. Because the AIA assembly is used in aircraft, the entire functional capability has been packaged in a 14-inch high, rack-mountable chassis with EMI shielding. The unit has been designed for high temperature, high altitude, vibrating environments. The AIA will be a key element in aircraft qualification testing at Boeing well into the next generation of airframes, and specification, design, development, and implementation of the AIA has been carried out with the significance of that fact in mind.

      Evans, Alan G.; Naval Surface Weapons Center (International Foundation for Telemetering, 1986-10)
      The TI 4100 Geodetic Global Positioning System (GPS) Receiver has been field tested in several environments. These include collocation rooftop tests near reflective equipment, isolated desert positioning tests, and shipboard survey tests. The receiver data consisted of pseudorange (code) and biased Doppler range (phase) measurements on both L1 and L2 frequency channels. This paper compares differences between ionospherically corrected pseudorange and biased Doppler range measurements to demonstrate the significant effects of signal multipath on the pseudorange measurements. That is, pseudorange signal multipath effects can be isolated, detected, and statistically modeled using only the above measurements. Examples are given for various receiver antenna locations. Day-to-day comparisons are made to demonstrate the repeated multipath effects due to repeated satellite-to-antenna geometries. The results can be used to analyze and statistically model pseudorange multipath effects for possible improved positioning and GPS satellite orbit determination accuracy.