• International Telemetering Conference Proceedings, Volume 15 (1979)

      International Foundation for Telemetering, 1979-11
    • A High Performance 8 GHz, 8 PSK Digital Radio

      Russo, Giuseppe G.; Hartmann, Paul R.; Rockwell International (International Foundation for Telemetering, 1979-11)
      Rapid growth and modernization of microwave communications is currently taking place in both the commercial and military environments. Much of this growth is being accomplished through digital transmission, and calls for efficient utilization of frequency spectra allocated for LOS communications. As the bit efficiencies and data rates of digital radio systems have increased, the problems associated with multipath propagation phenomena have become more evident. This is due to the fact that the transmitter signal is randomized before transmission and the system behaves as though it has full loading at all times. To minimize outages and to meet path availability objectives, diversity protection alone, in many instances, is not sufficient. However, diversity protection, coupled with an acaptive equalizer, will meet the objective in all but a few severe cases. This paper describes a digital radio system operating in the 8 GHz band with 8 PSK modulation and nominal data rates of 45 Mb/s or 90 Mb/s. Multipath propagation and its effects on digital transmission are discussed. Improvements in bit error rate threshold obtained through the use of an adaptive equalizer designed into the receiver are also presented.
    • Future Performance Limitations for Ground and Spaceborne Millimeter Wave Receiver Systems

      Cardiasmenos, Apostle G.; Alpha Industries (International Foundation for Telemetering, 1979-11)
      Recent developments in the technology for millimeter wave receiving equipment make a much more promising case for increased utilization of millimeter waves in telecommunication links. Low system noise figure coupled with large achievable antenna gain in small earth terminals make a good case for millimeter direct satellite broadcast links. Future technology trends indicate that use of the 80-100 GHz region of the spectrum will be beneficial and useful in the 1985-1990 timeframe.
    • Millimeter-Wave Receiver Components

      Bernues, F.; Pusateri, P.; Hughes Aircraft Co. (International Foundation for Telemetering, 1979-11)
      This paper presents an overview of the state-of-the-art performance of mm-wave receiver front-end components. Topics covered include filters, diplexers, mixers (broadband and narrowband) and local oscillators (free-running and phase-locked). Examples of mm-wave receiver front-end configurations are given and performance tradeoffs are discussed.
    • Tunable Millimeter-Wave Communications

      Becker, Stanley; AIL Division of Eaton Corporation (International Foundation for Telemetering, 1979-11)
      A communication link operating at 5 millimeters can be designed to take advantage of the properties of the oxygen absorption band to provide relatively interference free and secure communications. A tunable transmitter and receiver were developed to demonstate the adaptability of such a link to varying propagation and potentially hostile EMI conditions.
    • Millimeter-Wave Technology Overview

      Wiltse, James C.; Georgia Tech (International Foundation for Telemetering, 1979-11)
      Millimeter-wave technology has progressed rapidly during the past several years. A summary is given of the state-of-the-art in components, devices, and techniques and their uses in several system applications. Although present systems activity includes work on radar, guidance, remote sensing, radio astronomy and spectroscopy, the applications to communications are emphasized.
    • Navy Shipboard Weapon Information Telemetry System

      Dahl, Ernie A.; Bates, L.; Naval Ship Weapon Systems Engineering Station (International Foundation for Telemetering, 1979-11)
      The paper presented by NSWSES at the 1975 ITC Conference in Washington, DC, described the Portable High Frequency Telemetry System (PUTTS) being assembled for NATO. This system used the best of the then standard state of the arts commercial components and was used for shipboard missile data receiving/recording and for quick look missile performance evaluation. In 1977 the Naval Sea Systems Command made funds available to update the AN/SKQ-3 system by utilizing the RF assembly similar to that used in PUTTS. This new RF assembly provided dual antennas for (1) a wide angle for verticle launch and initial acquisition; (2) narrow beam high gain for long range tracking. The RF unit also included frequency scan with automatic lock when a signal was received, and sector search. In 1978 funding was received from Australia and Iran to procure additional PUTTS. These units (PUTTS III) were updated to handle faster intercept rates as well as improved range tracking and adapt the new RF features from the SKQ-3 Mod. Added to this were the capability to handle both PAM and PCM data with light weight hardware. These systems were completed and the Australian unit system was delivered after acceptance tests with U.S. fleet operation in the Gulf of Mexico. As a result of these successful improvements a new portable system has been built to (1) adapt microprocessors to the set-up of data format; (2) Provide automatic selection remote control of the RF head within the antenna frame; (3) provide the basic data to make automatic processing possible when and if desired; (4) Add the new low noise GASFET preamp to the system to increase the range; (5) Add capability for four receivers in the space presently occupied by the dual receivers to permit the handling of the new missiles with dual RF outputs and (6) provide the capability of system checking of all modules from the antenna through the system to the paper read-out device. This paper now presents the new updated system combining the state of the art development in programming, remote control, low noise preamps, miniature RF assembly, matrix control programming as well as automatic data set up and selection for data processing.
    • A Proposed Time Code Standard for Telemetry and Space Applications

      Chi, Andrew R.; Goddard Space Flight Center (International Foundation for Telemetering, 1979-11)
      A computer oriented time code designed for users with various timing requirements is proposed. Its format meets with the packet data format requirement of the new data handling and management concept, known as the NASA End-to-End Data System (NEEDS). It is equally applicable to spacecraft and ground users. The time code is arranged in parallel groups of binary numbers containing day, second, millisecond, microsecond, and nanosecond resolutions. The day count system is a four digit number truncated from Julian day numbers known as Truncated Julian Day (TJD). It has a repetition period of 27.379 years. Four options of resolutions in seconds, milliseconds, microseconds, and nanoseconds are offered. They are formatted in 4, 6, 7, and 8, eight-bit Byte words, respectively. To identify each resolution option of the time code, a variable prefix code consisting of 1 to 3 bits is used. This paper will present in detail the time code and its applications.
    • Serial PCM Recording Standard

      Law, E. L.; Hedeman, W. R., Jr.; Pacific Missile Test Center (International Foundation for Telemetering, 1979-11)
      This standard includes recommendations for pre-detection PCM recording, post-detection PCM recording, and serial high density digital recording using IRIG analog wideband recorder/ reproducers. The serial high density digital standard, based on studies conducted at the Pacific Missile Test Center, recommends the BI∅/-L code for packing densities up to 15 kilobits per inch and the randomized NRZ-L code (with 15-stage register length for packing densities up to 25 kilobits per inch. The signals are recorded using bias and the standard IRIG record levels. The minimum recommended reproduce rate (without special electronics) for randomized NRZ-L is 200 kilobits per second.
    • Optimum Digital Data Storage on Magnetic Tape

      Hedeman, W. R., Jr.; Law, E. L.; Pacific Missile Test Center (International Foundation for Telemetering, 1979-11)
      An instrumentation magnetic tape recorder, free of tape drop-outs, wow and flutter, is simulated by filters and a chromatic noise source. At a fixed bit error probability the capacity of the link is measured as a function of rms signal-to-noise ratio for NRZ-L, Manchester and Miller codes. Two operating regions are observed: (1) noise limited at low values of SNR and (2) band limited at high values of SNR. In the noise limited region doubling the data rate requires a 6 dB increase in SNR; in the band limited region an increase of approximately 12 dB is required to produce the same result. The conclusion is that, for baseband recording of digital data, operation should be in the noise limited region slightly below the transition to the band limited region. If SNR margin is available at this operating point more data per square of tape can be stored by increasing the number of tracks rather than increasing the storage per track. The theoretical penalty of 3.5 dB for the Miller code bit detector should, and does, result in a data rate decrease to .67 of the data rate with the NRZ-L code at the same SNR in the noise limited region. For the Manchester code the transition to the band limited region occurs at a lower SNR than for either NRZ-L or Miller codes. It is concluded that the Manchester code would result in approximately the same data storage per square of tape as NRZ-L, and more than Miller, if the number of tracks is doubled.
    • Inertial Upper Stage/Shuttle Orbiter Communications

      Huth, G. K.; Udalov, S.; Axiomatix (International Foundation for Telemetering, 1979-11)
      The Inertial Upper Stage (IUS) system is intended for DOD and NASA space vehicle (S/V) launches from the Shuttle Orbiter. Prior to and during the IUS launch, commands must be transmitted to the S/V and IUS and the telemetry data must be communicated to the Orbiter. This paper describes the communication links between the IUS and the Orbiter, with particular emphasis on the RF link equipment and performance. The transponder equipment carried on board the IUS system is also described.
    • Space Shuttle Payloads Support Capability

      Torres, Frank; Rockwell International (International Foundation for Telemetering, 1979-11)
      The NASA/Rockwell Space Shuttle with its highly versatile avionics and electrical provisions for use by the Shuttle payloads will provide an efficient system for future national space program activities and space program activities from foreign countries. This paper summarizes the avionics and electrical payload capabilities and interface characteristics. It includes a description of the command and data systems interface, the caution and warning system interface, and the aft flight deck accommodations; the electrical power distribution system; and the standard mixed cargo harness.
    • Random Coding Bounds for Noncoherent mFSK Multiple-Access Channels

      Omura, Jim K.; University of California, Los Angeles (International Foundation for Telemetering, 1979-11)
      We investigate a time-varying trellis coded multiple-access scheme using noncoherent mFSK signals. Techniques similar to this were originally proposed by Cohen, Heller, and Viterbi and more recently in a mFSK form by Viterbi. In these multiple-access systems van der Muelen Ahlswede Liao, Gaarder and Wolf , Kasami and Lin, Weldon and Wolf have shown that the decoded symbols of one user can be used to reduce the "multiple-access noise" to other users and thus allow for a larger achievable rate region than one would expect with conventional time division multiple-access techniques. In some cases, specific codes were investigated. Peterson and Costello and Chevillat have extended these earlier works to convolutional and trellis codes. In this case the decoder is designed as a "super" Viterbi decoder that regards all transmitter trellis codes combined to form a single "super" trellis encoder. In this paper we investigate the noncoherent mFSK scheme discussed by Viterbi and generalize to single level and multi-level energy detectors with a single "super" Viterbi decoder at the receiver. The main results are random coding bounds for the general case where L users each have remotely located time-varying trellis encoders of constraint length K. We assume throughout that the channel is noiseless, and symbol timing synchronization is maintained among the L users. These assumptions are being relaxed in the thesis research of Sorace.
    • Convolutional Error Detection on an Additive White Gaussian Noise Channel

      King, Maurice A., Jr.; The Aerospace Corporation (International Foundation for Telemetering, 1979-11)
      Concatenated coding schemes involving a convolutional inner code and a block outer code have occasionally been used in communication systems that are very intolerant of errors. In these schemes the vast majority of channel errors are corrected by the convolutional decoder while the block outer code is used to detect convolutional decoder errors. Block code words containing detected errors are erased. Soft decision Viterbi convolutional decoders operate by comparing path metrics and selecting the path with the largest metric (the maximum likelihood path). There is a substantial amount of information in the path metrics that is not used in this pick-thelargest decision. It is proposed that some of this information be used in a probabilistic decoding error detection scheme. Such a detection scheme would obviate the use of the block outer code. The result is a bandwidth savings at the cost of some additional processing of the convolutional code metrics.
    • U. S. Domestic Communication Satellite Systems

      Martin, D. H.; The Aerospace Corporation (International Foundation for Telemetering, 1979-11)
      Domestic communication satellite (domsat) systems in the United States have a history of 14 years. Currently, several systems are in operation and another will be in early 1981. In recent years, many papers have been published, each describing certain details of a specific system. In contrast, this paper presents an overview and comparison of all the systems. As a background to this survey, the U. S. domsat history is briefly reviewed. The system overview then begins with a look at the satellites. Their basic designs are compared pictorially and through tabular data. Communication subsystems are also compared. The survey then goes on to the terminals, the terrestrial parts of the systems. Representative terminal characteristics are discussed. Finally, the various communication services offered by these systems are described.
    • Appendix: Eighteenth Annual Report of the Telemetering Standards Coordination Committee

      Pizzuti, Michael (International Foundation for Telemetering, 1979-11)
    • A Review of the Public Broadcast Service TV Distribution System and Plans for the National Public Radio System

      Kellow, Robert S.; Rockwell International (International Foundation for Telemetering, 1979-11)
      Nationwide Television Programming for the Public Broadcasting Service is now being carried by the largest integrated network of Earth Stations ever constructed by a single turn-key contractor. The 165 station network, including 5 remote origination transmit terminals, was completed significantly ahead of a schedule established two years before. Such an accomplishment required carefully orchestrated efforts between customer and contractor in the areas of system and equipment design and qualification, site selection and design, frequency coordination, equipment scheduling, on site construction, site installation and test effort mobilization. Unusual and unexpected constraints were often encountered, requiring resourceful and innovative solutions. Performance records since early 1978 when initial operations began indicate the reliability, availability and cost improvement goals of the system have been exceeded by a significant margin. A similar system for the National Public Radio, involving 205 stations (15 with transmit capability) is currently in the early stages of implementation.
    • Microprocessor-Based Analog Voice Scrambling Techniques

      Udalov, Sergei; Axiomatix (International Foundation for Telemetering, 1979-11)
      Analog voice privacy techniques provide the advantage of being compatible with the 3 kHz audio bandwidth of the existing radio and telephone channels. The degree of privacy provided by an analog voice scrambling technique, however, is proportional to the number of time and frequency elements into which the voice signal can be divided as well as to the number of permutation patterns according to which the elements are scrambled. This implies the requirement for a high degree of signal-processing capability. Microprocessorbased implementations of an analog voice scrambling device provide a large potential for signal processing and scrambling. Furthermore, they provide this potential at a reasonable cost, small volume and moderate power consumption. In addition, a single microprocessorbased analog voice privacy device can be configured in software to yield various degrees of privacy, depending on a particular use and circumstances. Also, a variety of auxiliary functions such as timing, code generation, synchronization and analog-to-digital conversion can be time-shared within the same microprocessor chip, thus minimizing the requirement for support hardware. The purpose of this paper is twofold: (1) to provide an overview of the existing analog voice privacy techniques, and (2) to specifically outline the capabilities of the microprocessor-based analog voice privacy system design, with a particular emphasis on achieving an analog scrambled signal compatible with the 3 kHz nominal audio bandwidth of the existing radio and telephone channels. Also, workable algorithms used for microprocessor-based analog voice scrambling in frequency as well as in time domain are described. Tape recordings of the voice scrambled and recovered with these algorithms are presented for comparison.
    • The Application of Frequency Offset Advantage (FOA) in Frequency Coordination

      Raghavan, Srini; Armes, Jerry; Spectrum Analysis & Frequency Engineering (International Foundation for Telemetering, 1979-11)
      A major telecommunications growth area at this time is narrowband digital transmissions via satellites. With the availability of low cost 5 and 10 meter earth stations, and readily available digital ground equipment, this trend can be expected to continue for some time. With the degree of frequency congestion which exists currently in the 6 GHz band, the frequency coordination of these earth stations will become more and more difficult. Since the data rate is generally 56 KBPS or 1.544 MBPS, the satellite uplink carrier frequency is often selected to give a degree of isolation from standard frequency plans used by the terrestrial common carriers. The amount of offset advantage in db to be conceded from a given frequency separation between satellite and terrestrial carriers is a matter of controversy however. This paper describes a computer program written to provide the necessary calculations, the underlying models, and results in the form of parametric curves which can be used directly to obtain the offset advantage for a given carrier separation.
    • What The System Link Budget Tells the System Engineer or How I Learned to Count in Decibels

      Sklar, Bernard; The Aerospace Corporation (International Foundation for Telemetering, 1979-11)
      Because it is analytically straightforward, link budget analysis often takes a back seat in engineering curricula, yet this technique represents one of the most important tools available to communications engineers and managers. This paper presents a tutorial examination of link budget development, with an emphasis on satellite communications systems, and catalogues the typical sources of loss and noise. In addition, it treats the concepts of the range equation, free space, antenna gain and effective area, system temperature, and digital versus analog parameters. This paper also illustrates a typical budget and tradeoffs using a communication satellite example.