Mohanty, Nirode C.; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      An adaptive equalizer, based on a minimum mean square error criterion, has been derived for the purpose of extracting PSK signals transmitted through an unknown and asymmetric channel. The weights of the equalizer are obtained by using a simple formula containing the transform of the parallel channels. The performance of the equalizer is expressed in terms of the variance of the estimation error. The error is shown to be much less than that of the direct demodulated data.

      Zimmerli, Dana W.; Elston, Steve; Magnavox Advanced Products and Systems Company; BDM Corporation (International Foundation for Telemetering, 1985-10)
      This paper describes the design and performance of a flexible data link system for test and training range communications. To support a wide variety of range applications, this data link provides variable length messages, participant store-and-forward relays, remote data stations, three modes of operation - TDMA, polled, and carrier sense, and a transmitreceive range of more than 80 miles. The data link is adaptable to different message rates and sizes to support different types of missions. For example, a high dynamics aircraft mission can be supported by two-way 400 bit messages from 25 aircraft 10 times per second; a tactical armor mission can be supported by two-way 200 bit messages from 500 participants once per second. The data link is designed with packet radio and pseudonoise spread spectrum techniques to combat common range communication problems such as multipath fading, host vehicle obscuration, coexistence, interference, and vehicle dynamics. Data link performance is presented to show the flexibility and adaptability to various range communication requirements.

      Hoefener, Carl E.; Stone, James; Interstate Electronics Corporation (International Foundation for Telemetering, 1985-10)
      When applying the Global Positioning System (GPS) to Time, Space, and Position Information (TSPI), the use of GPS frequency translators should be considered. The primary space positioning problem in the test and evaluation applications is trajectory reconstruction. Although this can be accomplished by flying a GPS receiver on the test vehicle and telemetering its position to the ground, there are significant advantages to translating the “L” band GPS signals to “S” band, and transmitting the broad band signal to the ground for processing. A translator-based system offers several advantages. Physical advantages include smaller size, lower weight, and lower cost. Technical advantages include: 1) ground station data aiding that provides a 6 dB advantage, 2) elimination of system bias errors, 3) computation complexity at the ground station vs. the vehicle under test, and 4) the ability to reconstruct a test scenario enabling flexibility in data analysis techniques.

      Hales, John C.; Boeing Aerospace Company (International Foundation for Telemetering, 1985-10)
      A key milestone for every telemetry design is that date when everyone agrees on a definition of the design requirements. Unfortunately, specifications often become obscured as test constraints change, additional requirements are uncovered, test objectives are more clearly defined, and budgets are cut in half. Historically, telemetry designs using technology, hardware, and philosophy that pre-date Christopher Columbus have caused obvious rigidity to the system design and its operation. Once completed, program managers become ruefully aware that these systems are difficult (if not impossible) to modify and are always very costly to change. Telemetry systems available today offer the flexibility necessary to accommodate a frequently changing measurement list. Not only can the measurement list be changed, it can be changed during the course of a test in progress. If requirements expand, hardware may be added. If the test is a non-destructive test, the system can be configured for use on future programs.

      Shaw, Harold; Lawrence, Francis A.; New Mexico State University; Syndetix, Inc (International Foundation for Telemetering, 1985-10)
      In early 1981, the Physical Science Laboratory (PSL) was tasked by the Air Force Geophysics Laboratory (AFGL) to develop a portable Pulse-Code Modulation (PCM) telemetry station that would acquire and support the higher PCM data rates from Ariestype rocket payloads. The station would have to provide real-time and near real-time calibration, prelaunch and launch test support to AFGL researchers involved in space vehicle probe analysis. The station would also have to utilize a flexible software system, transportable hardware, and be easily expanded to meet the continually growing and varied needs of the researchers.

      Gauthier, Kathryn L.; Wright-Patterson Air Force Base, Ohio (International Foundation for Telemetering, 1985-10)
      The Advanced Range Instrumentation Aircraft (ARIA) is an airborne platform designed to receive, record, process, and retransmit telemetry data. This paper will provide a brief overview of ARIA capabilities and focus on a specially modified ARIA – the Cruise Missile Mission Control Aircraft (CMMCA). Currently utilized in cruise missile testing, CMMCA features on-board real-time display of telemetry data as well as remote command and control of the test missile.

      Skiffington, Barbara; Carrig, Jim; Kornell, Jim; General Research Corporation (International Foundation for Telemetering, 1985-10)
      This paper describes an expert system prototype which approaches some issues of satellite command and control. The task of the prototype system is to assist a spacecraft controller in maneuvering a geosynchronous satellite for the purpose of maintaining an accurate spacecraft pointing angle, i.e. station keeping. From an expert system’s point of view, two features of the system are notable. First, a tool for automated knowledge acquisition was employed. Because the domain experts were in Maryland while the AI experts were in California, a means to automate knowledge acquisition was required. Second, the system involves a blend of simulation and expert systems technology distributed between a DEC VAX computer and a LISP machine (a special purpose AI computer). This kind of distribution is a plausible model for potential real-world installations.

      Qishan, Zhang; Wenguan, Zhang; Zhiying, Mu; Beijing Institute of Aeronautics and Astronautics (International Foundation for Telemetering, 1985-10)
      A unified approach to the multiplex is proposed in terms of the orthogonal functions. It is called quadrature division multiplex, or Q D M in short. The orthogonal function is essential to the multiplex. Except these functions mentioned above, there are other orthogonal functions which are suitable for engineering practice. The orthogonality of the functions is used for the division of signals. A block diagram of Q D M is briefly described. The perfomances of the Q D M system are analysed. The speciality of the Q D M is simple and good. A model of the Q D M is built in our laboratory. A New type of bridge function is presented. It is called copy-shift bridge functions, which may be very useful for multiplex.

      Mavretic, A.; Zrilic, D.; Zhou, R.; Boston University College of Engineering (International Foundation for Telemetering, 1985-10)
      A new realization of non-recursive digital filters using operation on ternary delta modulated signal is proposed. Direct operation on ternary delta modulated signal will be derived mathematically and a hardware implementation of ternary arithmetic operation will be shown. The primary advantage of the ternary scheme is the simplicity of the hardware and reduction in connections and interconnections between chips and interchips. The results show the possibility of applying ternary arithmetic operation in variety of areas including VLSI environment.

      Ren, Li Ke; Beijing Research Institute of Telemetry (International Foundation for Telemetering, 1985-10)
      Generally, the data acquisition equipment used in space vehicles mainly consists of logic program control, multiplexer-encoder, output driver, power supply for dc conversion and so on. Today telemetry technology has been deeply concerned with computer science. So how to make the telemetry system more flexible and versatile and how to design a multiplexer-encoder (data collector or remote unit as is called in a programmable telemetry system) with good compatibility and powerful function has become one of the most important things of developing a new generation of telemetry system. In 1960s, most of the telemetry systems were of typical coded time-division multiplexing. The sampling program of this system is fixed and its bit rate and frame format are unvaried, so it is difficult for a system to accommodate the requirements of various kinds of measurements, especially when there are comparatively more parameters to be measured, and most of which are of slow-changing. As the sampling rate is designed in accordance with the upper-limited signal frequency that we need to measure, so the validity of the slow-changing data is very low. And onced the telemetry equipment has been developed, it is very difficult to change the sampling rate, the bit rate and the frame format. With the development of electronic devices, more devices can be integrated in a small chip, so the programmable telemetry had been pulled off in early 1970s. This article deals with mainly a few programmable multiplexer-encoders and microprocessor-controlled multiplexer-encoders used in our actual research work and applications.
    • Autonomous Control and Data Acquisition for Advanced Satellite Systems

      Turner, Tim; Gulton Industries, Inc. (International Foundation for Telemetering, 1985-10)
      Autonomous operation is rapidly becoming a requirement for most new spacecraft systems. An autonomous spacecraft greatly simplifies the ground station processing and monitoring requirements, freeing ground station capabilities for other important tasks. The T2C2 (Telemetry, Timing, Command and Control) System has been conceived and architected to facilitate spacecraft autonomy. The T2C2 architecture is ideally suited for onboard closed-loop control, redundancy management, housekeeping and other autonomous functions. This paper provides an overview of the T2C2 architecture and its applications in the design and implementation of an autonomous spacecraft.

      Mohanty, Nirode C.; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      The performance of a code tracking loop for a spread spectrum signal can be severely deteriorated in the presence of an interference signal. The interference signal is modeled as a signal with the same code but with a different delay and carrier frequency. The variance of the tracking delay error is derived in terms of loop bandwidth, chip duration, the interference and signal power and bandpass filter bandwidth and the power spectral density of the additive Gaussian noise.

      QUIDET, A.; ELECTRONIQUE SERGE DASSAULT (International Foundation for Telemetering, 1985-10)
      For nearly 20 years, ELECTRONIQUE SERGE DASSAULT has been developing several data acquisition systems, in particular in-flight test systems, excluding sensors, means for recording on magnetic tape and transmission by telemetry processes (Figure 1). It may be noted in passing that these systems have been named EMMANUEL, SAMUEL, RACHEL and DANIEL (Figure 2). These systems have allowed the control of in-flight testing for numerous aeronautical programmes both civilian and military, such as for the recent FALCON 900 and MIRAGE 2000 programmes. The tests undertaken related to the performance characteristics of the aircraft itself and, especially during the last few years, the performance characteristics of the airborne avionics. Present and future in-flight test requirements have spurred ELECTRONIQUE SERGE DASSAULT to undertake the design and development of a revised DANIEL System, referred to as the system of the nineties : DANIEL 90.

      Ng, Wai-Hung; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      For space monitoring systems, it is necessary to compress the transmitted data to minimize the power and bandwidth requirements. Although there are many data compression techniques, here we will only discuss the sample reduction technique because it is the best candidate for cases when the signal contains many redundant samples and the resolution requirement for the reconstructed signal is very high. In this paper, we introduce a new code to further reduce the compressed signal data derived from the sample reduction technique. The main advantage of this approach is that we can minimize the transmission data rate without requiring a priori knowledge of the signal distribution property. In addition, it can also reduce the buffer size requirement. Examples are given for clarification and discussion.

      Mohanty, Nirode C.; The Aerospace Corporation (International Foundation for Telemetering, 1985-10)
      A demand access Satellite Communication System for multiple users has been analyzed. A number of channels, m 1, of each satellites are necessary to coordinate the self-served users to allow access to a satellite having s channels. m depends upon traffic intensity and number of top priority users. A waiting time period for a Poisson arrival and exponential holding time M/M/s system for “preemptive resume” discipline has been derived. There is a significant reduction in waiting time in accessing the channel and in transmission time over other access schemes. There is no waiting time for a top priority user, either in accessing the channel or in transmitting its messages, when the appropriate number of order wires is used.

      Wickham, M. E.; COMSAT Laboratories (International Foundation for Telemetering, 1985-10)
      An advanced microwave power leveling loop (MPLL) was conceived, designed, fabricated, tested, and used during spacecraft in-orbit testing. The primary function of the MPLL is to maintain constant RF power transmitted from an earth station antenna during spacecraft in-orbit transponder testing. The MPLL utilizes nonlinear analog electronics with flexible signal path routing under microprocessor control. It achieves a power control dynamic range of greater than 50 dB with better than 0.1 dB of control resolution. Power level step changes of 20 dB can be accomplished in under 10 ms. The MPLL is IEEE-488 bus controllable and is designed for use in automated in-orbit test systems to facilitate the measurement process and produce more repeatable results than have previously been possible. Measurements performed with the aid of the MPLL include transponder frequency response, group delay, gain, and saturation level. The system can also be operated in a manual mode, and utilizes state-ofthe-art human interfacing techniques such as a display/entry panel and a rotary encoder control knob. This paper describes the MPLL design process, including computer simulation work and breadboard testing. Performance and temperature chamber test results are presented for breadboard and manufactured units.

      Shituan, Shen; Li, Zhou; Qishan, Zhang; Beijing Institute of Astronautics and Astronautics (International Foundation for Telemetering, 1985-10)
      In this paper a Haar telemetry system is introduced. There are two key points for construction of the Haar telemetry system: to generate Haar function waveforms and to design a multivalue logic multiplier. First, we discuss the way of building the Haar function generator. There are several ways to solve this problem. One of them will be introduced in some detail. Secondly, the multivalue logic multiplier is described. The multiplier consists of three parts: operational amplifier, switching element and its control circuit. Thirdly, according to the relationship between Haar waveforms and switching control wignal, we combine the multiplier with the generator as a whole which is called Harr function modulator. The function of the modulator is the same as Haar function generator plus a number of multipliers, but the circuit of which is greatly simplified. The experimental results show that the new system is effective and as compared with Walsh system the Haar one seems to be a little better.

      Dapore, Mark; Cincinnati Electronics Corporation (International Foundation for Telemetering, 1985-10)
      Command Destruct Receivers are used on all launch vehicles for the purpose of initiating flight termination. The up-link command signal is a UHF carrier frequency modulated with Inter-Range Instrumentation Group (IRIG) audio tones. Typically three commands are used to control and terminate the flight: ARM, DESTRUCT, and OPTIONAL command. The combination and sequence of specified IRIG tones determines the command to be issued. The decoder portion of the command destruct receiver determines the presence and sequence of IRIG tones. Through the use of a microprocessor and digital signalprocessing-technology, Cincinnati Electronics has designed and developed a digital decoder which detects four IRIG tones simultaneously. The digital decoder provides stabilities and repeatabilities unattainable with analog decoders. Reliability and reproducibility are also superior when using the digital approach through the elimination of select and variable components. This improved performance of the decoder is a result of crystal controlled digital filtering and a constant false-alarm rate provided by the microprocessor. The digital filtering is achieved through Finite Impulse Response digital filters. There are a number of additional features provided by the digital decoder. Self-testing of portions of the receiver and correcting for temperature drift can be performed by the decoder. The digital decoder can have its command sequences reprogrammed in the field allowing separate control and termination of each vehicle in a multiple vehicle launch. Also, acceptance test data, date of manufacture, total time unit has been powered up, and other data can be stored inside the Command Destruct Receiver and recalled when needed.

      Natali, Francis D.; Socci, Gerard G.; Stanford Telecommunications, Inc. (International Foundation for Telemetering, 1985-10)
      Digital processing techniques and related algorithms for receiving and processing space vehicle downlink signals are discussed. The combination of low minimum signal to noise density (C/No), large signal dynamic range, unknown time of arrival, and high space vehicle dynamics that is characteristic of some of these downlink signals results in a difficult acquisition problem. A method for rapid acquisition is described which employs a Fast Fourier Transform (FFT). Also discussed are digital techniques for precise measurement of space vehicle range and range rate using a digitally synthesized number controlled oscillator (NCO).

      Bubb, Keith W.; Wright-Patterson Air Force Base, Ohio (International Foundation for Telemetering, 1985-10)
      The 4950th Test Wing, at Wright-Patterson Air Force Base, Ohio, is converting four Boeing 707-320C aircraft into EC-18B Advanced Range Instrumentation Aircraft (ARIA). In addition to the antenna and electronic equipment required to collect telemetry data in support of NASA and DOD space and missile programs, the EC-18B will be equipped with a Sonobuoy Missile Impact Location System (SMILS), an optics system, and a meteorological sampling system. Once these systems are added, the EC-18B ARIA will be the most versatile and capable airborne mobile instrumentation platform in the world. They will be able to collect telemetry data from various space and missile systems; acoustically determine the geodetic impact point of reentry vehicles at any location; obtain photographic and video data from reentry vehicles as they pass through the earth’s atmosphere; and provide local atmospheric data in support of worldwide US ballistic missile tests through the year 2000 and beyond.