• How to Build a High Accuracy, 100 Channel, PCM Encoder for $29.95

      Powell, David G.; Naval Air Warfare Center Weapons Division (International Foundation for Telemetering, 1992-10)
      Pulse Code Modulation (PCM) Encoders are extensively used in instrumentation and telemetry systems. Commercially available encoders are available from several sources and vary in complexity depending on the application. Encoders often include analog signal conditioning, a system clock, and one or more digital input ports. Many of these systems also cost several thousand dollars and the cost goes up when high data accuracy of one or two percent is required. This paper describes a low cost approach which has been used in production telemetry applications with great success and which yields a PCM encoder with data accuracies of better than 2%.
    • Simulation of Binary Continuous Phase Modulation Combined with (1,2)-Convolutional Encoder

      Carden, Frank; Osborne, William; Alhussiny, Karim; New Mexico State University (International Foundation for Telemetering, 1992-10)
      In this paper the performance of a (1,2)-convolutional encoder combined with continuous phase modulation is simulated. A binary sequence is used inconjunction with the above encoder and a modulation index of (h=1/4). A full response 1REC frequency shaping function is used to maintain phase continuity. A binary (uncoded)CPM with the above modulation index is also simulated. The performance in terms of the probability of bit error event is plotted against signal to noise ratio for both coded and the uncoded CPM schemes. The asymptotic performance of both schemes is plotted along with MSK for comparison purposes. The simulation algorithm used in this paper utilizes the Block Oriented System Simulator known as BOSS. The major components of this simulation are the encoder and the decoder. The encoder consists of binary random data generator and a (1,2)-convolutional encoder combined with a channel vector encoder and a random white gaussian noise generator. The decoder consists of the following modules: sequential vector bank, inner product unit, metric calculator unit, multi stage trellis, symbol decoder and error counter module.
    • ASW-II: Advanced Satellite Workstation for the UHF Follow-On Satellite Program

      Hamilton, M. J.; Abbott, R.; Eggan, P.; Golber, D.; Hsieh, S.; Jordan, L.; Le, T.; Newcomb, R.; Sutton, S.; Ton, T.; Yu, C.; Zechiel, S.; The Aerospace Corporation (International Foundation for Telemetering, 1992-10)
      ASW-II (Advanced Satellite Workstation, Version II) has been developed and delivered as an operational prototype in support of the Ultra High Frequency (UHF) Follow-On satellite. It provides unified and coordinated real time reception and storage of satellite telemetry, display of both real time and stored telemetry, expert-system analysis of spacecraft status, and an information navigator system that stores and presents information about the spacecraft. The architecture is modular and reconfigurable, and it provides support for multiple analyst workstations. There are several unusual aspects of the design. The entire telemetry history of the satellite is regarded as a continuum by the user, with ASW-II automatically tracking and displaying contact periods. A "streams" mechanism organizes the telemetry in such a way that the user can interactively define new derived parameters and have them presented graphically. Both real time and archived data can be displayed simultaneously. The user has very flexible controls for all display interfaces using mouse and window technologies.
    • A Flexible Voice Communication System for a Real-Time Mission Control Facility

      Pappas, Johnny J.; Eglin Air Force Base (International Foundation for Telemetering, 1992-10)
      Due to the complexity of real-time missions, an increasing number of participants, and the critical nature of test missions, providing a reliable, versatile voice communication network for mission support entities has become essential. A voice communication system has a direct impact on the effectiveness of every mission and the safety of mission personnel. Each participant must satisfy unique functional and operational communication requirements. This paper addresses the functional, operational, and ergonomic aspects associated with a voice communication system for the Central Control Facility (CCF) at the Air Force Development Test Center (AFDTC), Eglin AFB, Florida. The communication system was purchased from an Edwards AFB Digital Switch requirements contract.
    • A Brief Look at Delta Modulation

      Ugarte, Alberto (International Foundation for Telemetering, 1992-10)
      The principle behind delta modulation systems is introduced. Having developed the principles of delta modulation systems, a system that performs delta modulation is developed and tested to see how well the system performs by using sinusoids and speech as the input to the system. This is then followed by a comparison of delta modulation and pulse code modulation to show that, overall, delta modulation is better than pulse code modulation.
    • An Object-Oriented System for Telemetry Data Management

      Tolat, Viral V.; Stanford University (International Foundation for Telemetering, 1992-10)
      In this paper we describe an object-oriented software system for realtime telemetry data management and display. The system has also been designed to be used as the primary means of data management during post-mission activities. The software system consists of three parts: the data interface library, the data format specification and the display applications. The data interface library contains a set of object definitions and procedures to provide uniform access to heterogeneous data streams. The data format specification is used by the data interface library to extract data from the raw data stream. The display applications use the data interface library to access the data and present it to the user. Currently, the interface between the data format specification and the data interface library is implemented procedurally and is modeled after a device driver. Each format is assigned a unique id and then accessed via that id. A data stream may be accessed by any number of different format specifications. A future implementation will separate the data format specification into a separate process with a message or RPC based interface. Therefore the data may be kept on remote systems and accessed in a transparent fashion. In addition, this model will support operation in distributed heterogeneous computing environments. This system handles multiple simultaneous data streams and applications can access data from different streams relatively transparently. This is possible since data variables (objects) to be displayed are specified by a syntax that contains the specification of both the data streams and the format to use. In addition, the concept of a primary stream is introduced to allow the user to scroll through one data stream and have the other streams follow. Synchronization between streams is based on time information in the data streams. Several applications have been written including various stripchart displays a tabular display and some other custom displays. A data analysis application similar to the UNIX program "awk" is currently under development. It will provide the user with the ability to extract data, i.e., report generation, for display or further analysis in an object-oriented manner.
    • F/A-18 Data Reduction at the Naval Air Warfare Center, China Lake, California

      Smith, Darren C.; Naval Air Warfare Center - Weapons Division (International Foundation for Telemetering, 1992-10)
      The current F/A-18 data reduction/analysis system is incapable of meeting increased customer demands. A new system has been developed and is based on new technologies. In the process of developing the new system, the design team had to divorce themselves from the current system and consider what the ideal system would consist of. This was accomplished with great success in the areas of timeliness of data turn around, customer satisfaction, and increased efficiency.
    • A Transputer Based 3D-Graphics System

      Alvermann, Klaus; Institute for Flight Research (International Foundation for Telemetering, 1992-10)
      The Institute for Flight Mechanics operates the flying simulators ATTAS (a wing aircraft) and ATTHeS (a helicopter), their respective ground based simulators and uses realtime and offline simulations for system identification and other purposes. Based on a parallel transputer architecture, a 3D-graphics tool for visualization and view simulation to be used with the simulations has been developed. The tool uses data received by telemetry, realtime data from a simulation, or recorded data to show the movement and orientation of an aircraft in realtime 3D-graphics. The aircraft or scene may be observed from any point of view. Placing the camera in the cockpit of the aircraft and showing the environment results in a view simulation. The use of a parallel transputer architecture allows a modular and scalable structure, i.e. the system may be adapted to the needs of the application. By adding software modules and transputers we may include 24 bit colour, shadowing, a higher resolution, a better shading algorithm or other things which are required by an application. On the other hand we may remove transputers to get a small and cheap system if the requirements are low. A small system may consist of only 8 transputers, whereas a big system may include 50 or 60 transputers.
    • A Fast Realtime Simulation of a Complex Mechanical System on a Parallel Hardware Architecture

      Oertel, C.-H.; Gelhaar, B.; Institute for Flight Research (International Foundation for Telemetering, 1992-10)
      Real-time computation speed is an additional requirement for simulations. It is necessary for 'man-in-the-loop' systems like flight simulators and for 'hardware-in-the-loop' systems where real components like new closed loop controllers are tested under realistic conditions. In the past a lot of companies have designed and built special purpose simulation computers which are very powerful but expensive and not handy enough for 'in-the-field-tests'. The progress in computer science shows a trend to distributed systems where multiple processors are running in parallel to improve the performance dramatically. At the DLR Institute for Flight Mechanics a computer system, based on the transputer, was designed to achieve the real-time simulation capabilities for the ROTEST model rotor. This four-bladed rotor is a 2.5 scale of the BO105 main rotor, equipped with elastic blades, operating at 1050 rpm. After an introduction to the ROTEST rotor, including the demands upon the simulation, a short introduction to transputers and the associated philosophy is given. The next part of the paper presents the characteristics of the simulation model, its mathematical description and the transputer architecture on which it is running. In the last part of the paper the input and output processes to the simulation are described. This includes a real-time representation of the rotor and an oscilloscope like output device, as well as analogue input and output devices to a controller.
    • An Integrated Approach to Real Time Flight Test as Seen from Down Under

      Slezak, Ken; Crouch, Viv; Loral Data Systems; Aircraft Research and Development Unit (International Foundation for Telemetering, 1992-10)
      The Aircraft Research and Development Unit (ARDU) is the flight test authority for the Royal Australian Air Force (RAAF). ARDU was born out of a requirement to handle the testing of developmental aircraft and weapons during Word War II. Its nucleus was established in 1941 and one of its first tasks was to evaluate the flying qualities and performance of captured Japanese aircraft. Today, ARDU provides "one-stop shopping" for flight testing all aircraft, weapons and systems in the RAAF and Australian Army Inventory. As directed by the RAAF, ARDU also performed flight testing on Royal Australian Navy aircraft, as well as novel and unique aircraft such as lighter-than-air and museum restored aircraft that are of historical importance.
    • Software Considerations in the Control of Digital Communications Switching Systems

      Ward, Ronald P.; Communications Systems Technology, Incorporated (CSTI) (International Foundation for Telemetering, 1992-10)
      Today's complex implementations of integrated packet and circuit switched digital communications networks demand that the software used for controlling these systems be robust, fault tolerant, and capable of runtime recovery from all but the most severe of operational errors. The typical modern switched communications system includes the use of multiple circuit switches, each with potentially thousands of end-user interfaces. Further, these switches are often inter-connected to each other via high-capacity trunks. A single connection between two end-user interfaces often traverses a number of intermediate circuit switches in order to effect the end-to-end communications desired. In this complex, distributed environment, the establishment and dissolution of end-to-end user connections involve far more than simple binary connection states indicating the existence, or non-existence, of a link. More commonly, a single end-to-end connection requires multiple node links across multiple, heterogeneous interfaces. The command and control software used to establish, monitor, and dissolve these connections must be capable of dealing with errors which arise at any node along the way in a consistent and reliable manner. Most critically, the system software must be capable of maintaining an accurate, multi-level mapping of distributed resources' availability, allocation, and status. Further, the software must have the capability of "healing itself" during operational run-time when it can, and of accurately reporting the nature of inconsistencies caused by anomalous events that cannot be fixed on the fly. The Edwards Digital Switch (EDS), developed by CSTI, provides a case study of possible solutions, and potential pitfalls, that can arise in the design, development, and implementation of the controlling software in today's dynamic, distributed communications' system architectures.
    • The Architecture and Design of Parallel Processing for Real-Time Multiplexing Telemetry Data

      Jun, Zhang; Qishan, Zhang; Beijing University of Aeronautics and Astronautics (International Foundation for Telemetering, 1992-10)
      The parallel processing technology has been widely applied to many science and engineering technical fields, also to telemetry. In particular, telemetry develops towards the trend of large capacity, high rate, several data streams and programmable formats. This sets a still higher demand on processing for real-time multilexing telemetry data. On the basis of analyzing of the characteristics of telemetry data processing (TDP), the parallel processing conception and methods are adopted, countering multiiple-channel data streams of different objects, several architectures of parallel processing for real-time multiplexing telemetry data are presented. It makes better use of the concurrency during the process of TDP and handles the telemetry information effectively in every processing level of the whole telemetering information processing system. The paper shows the property comparison of these parallel processing architectures and main features too. Experiments have indicated that it is an economical and effective method to improve the performance of telemetry information processing system by using paralle processing architecture which is based on concurrency of telemetry data processing.
    • Multichannel Digital Signal Processor Based Red/Black Keyset

      Smith, Quentin D.; Communications Systems Technology, Incorporated (CSTI) (International Foundation for Telemetering, 1992-10)
      This paper addresses a method to provide both secure and non-secure voice communications to a DS-1 network from a common keyset. In order to comply with both the electrical isolation requirements and the operational security issues regarding voice communications, an all-digital approach to the keyset was developed based upon the AD2101 DSP. Protocols that are handled by the keyset include: Multiple PTT modes, hot mike, telephone access, priority override, direct access, indirect access, paging, and monitor only. Special features that are addressed include: independent channel by channel assignment of access protocols, headset assignment, speaker assignment, and PTT assignment. Multiple microprocessors are used to implement the foregoing as well as down-loadable configurations, remote keyset control and monitoring, and composite audio outputs. Partitioning of the digital design provides RED to BLACK channel isolation and RED channel to AC power isolation of greater than 107 dB.
    • Edwards Digital Switch System Overview

      Switzer, Earl R.; Straehley, Erwin H.; Edwards Air Force Base; Straehley Associates (International Foundation for Telemetering, 1992-10)
      The Edwards Digital Switch (EDS) is a digital communication system that provides advanced voice networking capabilities to the Edwards Test Range. The EDS is a member of a new family of all-digital switching systems that internally handle data in digital form. To accommodate analog voice and data circuits, conversions between analog and digital formats occur at the system interfaces. The EDS consists of six groups of configuration items: System-level control and monitoring is centralized in the Control and Display Subsystem. Workstations provide subsystem-level control and monitoring. The Central Switching Subsystem, as the primary interface with the range environment, provides system connectivity to radios, telephone circuits, and communications links to other facilities. It integrates the EDS with links to the Control Room Switching Subsystems. Each Control Room Switching Subsystem connects individual user stations within a Mission Control Room or other localized area. The user equipment element consists of a Subscriber Terminal Unit, Channel Expander, and interface panels for headsets, foot switches, and speakers. The Remote Radio Control Unit optimizes usage of available frequencies, allowing control of tunable radios from the Control and Display Subsystem. *The original name, Edwards Communication Switching System (ECSS) was changed to Edwards Digital Switch (EDS) in 1990. The Site Selection Unit facilitates the handover of voice communications between receiver sites when a long-range test is monitored. The system architecture is based on a central system-level control element, a central switch, multiple subsystem-level control elements, multiple subsystem switches, and end-equipment items that are interconnected through the switch network. The EDS combines multiple voice communications applications in a single system. The system is being expanded to integrate voice and data switching. Its major function is support of multiparty networked voice communications within Mission Control Rooms and between other test participants. Other voice functions are an intercom capability including both Direct Access (hot line) and Indirect Access (dial-up), subscriber loop connections to the base-level telephone exchange, and the Public Switched Network System. Digital interfaces allow integration of ciphertext data and Time Space Position Information data switching functions. A system based on the EDS design has also been installed by the Air Force at Eglin AFB. Engineering studies for systems that make use of the EDS design are currently underway by the Navy at China Lake and the Army at White Sands Missile Range. The EDS project office has actively pursued promising program management concepts such as: specifying nondevelopmental items, requiring industry standard interconnectivity and interoperability, and using a multiyear fixed-price requirements-type contract to encourage multiservice participation.
    • Fully Remote Controlled Telemetry Tracking Antenna System

      Payne, E.; Haider, Franz; Scientific-Atlanta, Inc.; MBB Deutsche Aerospace (International Foundation for Telemetering, 1992-10)
      This paper describes a high performance telemetry receiving antenna tracking system which utilizes unique software to allow full remote control of the tracking antenna, two telemetry receivers, and a diversity combiner. Features include a modular pedestal design, electronically scanned tracking feed (ESCAN), mouse-driven software which uses full screen representation of selected components, and a joystick linked through serial interface to the control computer to allow slewing of the antenna axes. This state-of-the-art system allows operation from the front panel of the controlled devices and over extended distance via fiber-optic buss extenders.
    • Closed-Loop Tracking System Provides Reference for Data Collection Exercises

      Wallace, Keith; Weinberg, Patrick; Veda Incorporated; Wright Laboratory (AART) (International Foundation for Telemetering, 1992-10)
      A computational system was developed to support data collection for advanced airborne technology research. Basic research is conducted using a variety of sensing devices for collection of flight characteristics data from aircraft. To maximize control over as many variables as possible during research activities, a controlled aircraft tracking environment is needed to provide reference data for real-time operation and post-mission analysis. The solution to this requirement is realized with the ACMI Interface System (ACINTS). The ACINTS extracts real-time tracking data from a closed-loop telemetered tracking array, reprocesses needed parameters, provides reference data (positioning and control commands) to the sensor device, and records aircraft kinematics for later correlation with other collected data.
    • Universal Interface Between Telemetry Processors and Chart Recorders

      Brimbal, Michel; Kelly, Fred; GOULD Inc., Test & Measurement (International Foundation for Telemetering, 1992-10)
      Chart recorders currently in use on telemetry ranges are connected to telemetry processors via a series of Digital to Analog Converters (DAC) systems. A new modular interface system receives data directly from the processor broadcast bus and distributes them to up to ten digital chart recorders. This interface is programmed from a computer to assign individual tags to each one of the display channels. This system eliminates DAC's and patch panels. It simplifies display system operation, speeds up transition from test to test and reduces maintenance costs.
    • Neural Network Application to Telemetry Frame Synchronization

      Massey, David E.; Goddard Space Flight Center (International Foundation for Telemetering, 1992-10)
      This paper looks into the use of neural network software as applied to the classical signal to noise concern when dealing with space to ground data communications. Use of a digital neural network to extend the correlation range of Pulse Code Modulation (PCM) down into noise is investigated. Conventional synchronization pattern correlation is done with digital logic comparisons on a sliding window with a set number of bit mismatch errors allowed. Correlation with a neural network does pattern recognition with a weighted network of artificial neurons that have been trained to recognize the sync pattern within noise. The output of such a neural network will produce a best guess of the correct pattern.
    • How The User Relates to a Large Range Telemetry System

      Chavez, Tomas; Strock, O. Jud; White Sands Missile Range; Loral Data Systems (International Foundation for Telemetering, 1992-10)
      The Telemetry Data Handling System (TDHS) at the Telemetry Data Center in White Sands Missile Range (WSMR), New Mexico, has been in operation since January 1990. It is one of the world's largest integrated range telemetry systems, and certainly the most versatile in weapons support capability. The system supports one of the world's busiest test ranges, serving all U.S. Military Services as well as NASA and others. This paper looks at the White Sands system from the user's view, examining the ways in which it is configured for several weapons tests in a typical day, and the way in which it can run foreground launch support and background pre-launch activities simultaneously. This system has grown in functional capability since its installation, both in hardware and in software. This paper analyzes that growth to see the reasons and methods. Also, near-term additional growth is addressed.
    • Real Time Telemetry Data Synthesis with the TMS320C25

      Jun, Yao; Shi-yan, Liu; Xinan Electronic Engineering Institute (International Foundation for Telemetering, 1992-10)
      This paper presents the method of real time telemetry data synthesis for multi-beams and multi-receivers system in theory. For the practical implementation, we introduce a TMS320C25-based data synthesis board. Through a large number of simulating experiments, the satisfactory results are obtained, which obviously improve the performance of telemetry system. Therefore, all those technigues and results have the value of practical applications.