• THE GERMAN TELECOMMAND GROUND STATION FOR HELIOS-A NEW CONCEPT

      Öttl, H.; Holl, H.; Institut für Flugfunk und Mikrowellen (International Foundation for Telemetering, 1972-10)
      The new German Telecommand Station for the HELIOS project differs from previous DSN stations in several respects (new concept). Automation has been developed to such an extent that all normal manual operations (subsystem adjustments, station operating etc.) will be performed by computer. Manual back-up mode is also provided. For interference reasons (with existing microwave links) the antenna has to be designed for optimum side-lobe suppression rather than optimum gain. Another new aspect is the continuous use of the spacecraft receiver (engineering model) for simulated command reception and checking.
    • ON-BOARD FERRITE CORE MEMORIES WITH MEGABIT CAPACITY

      Reiner, H.; Florjancic, M.; Zentrallabor of SEL (International Foundation for Telemetering, 1972-10)
      For intermediate data storage in scientific satellites a ferrite core buffer memory with a capacity of 0.5 . . 2 Mbit was developed as a replacement of the hitherto used magnetic tape memories. For this memory a 3 D-organization with a pulse program especially adapted for buffer use was applied. For the realization of the access-circuitry multichip semiconductors in hermetically sealed flatpacks were combined with tantalum thin film resistor networks. A new small volume rugged memory stack was used. The cores used had an outer diameter of 0.5 mm. For this system a new flexible equipment practice is used which leads to a high component density. Furthermore, a 0.5 Mbit random access ferrite core memory was developed for the Helios satellite. This satellite will go into orbit in June 1974. The prototype model has a mass of 4.5 kg, overall dimensions of 194 x 210 x 207 mm, a volume of 7.08 W. (432 cu. inch) and has a power consumption of 2 Watts in stand-by and of 4.8 Watts at a bit rate of 16 kbit/s. It works satisfactorily within a temperature range of -45 to +75° C.
    • SOLID STATE POWER AMPLIFIERS AT L- AND S-BAND

      Schmidt, B.; Deutsche Forschungs-und Versuchsanstalt fur Luft-und Raumfahrt (International Foundation for Telemetering, 1972-10)
      Efficient solid state amplifiers in the L- and Sband have been accomplished with transistors and varactors. Power outputs of 10 W and more have been realized in microstrip technique with efficiencies of 40 % in the L-band and 30 % in the S-band.
    • DYNAMIC REQUIREMENTS FOR DIVERSITY COMBINERS

      Streich, R. G.; Little, D. E.; Pickett, R. B.; ITT-Federal Electric Corporation (International Foundation for Telemetering, 1972-10)
      In order to provide nearly continuous data on missile and Space launches, polarization diversity is utilized at acquisition sites. Diversity signals are also combined to further reduce data dropouts. It is shown in this report that the right hand circular (RHC) and left hand circular (LHC) signals undergo rapid transients during certain portions of the flight, and that the channel dropouts are sometimes independent. The nature of the transients is described and a test set which simulates the transients discussed. Finally bench test data is compared with flight test data to verify that combiners with rapid transient response are required to cope with the RF transients.
    • IMPROVEMENTS IN DEEP-SPACE TRACKING BY USE OF THIRD-ORDER LOOPS

      Tausworthe, R. C.; Crow, R. S.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1972-10)
      Third-order phase-locked receivers have not yet found wide application in deep-space communications systems because the second-order systems now used have performed adequately on past spacecraft missions. However, a survey of the doppler profiles for future missions shows that an unaided second-order loop may be unable to perform within reasonable error bounds. This article discusses the characteristics of a simple third-order extension to present second-order systems that not only extends doppler -tracking capability, but widens the pull-in range and decreases pull-in time as well.
    • BIT SYNCHRONIZATION

      McRae, D. D.; Smith, E. F.; Radiation Incorporated (International Foundation for Telemetering, 1972-10)
      In this paper the trade off between acquisition and noise performance for several bit synchronizer techniques are examined. Results are presented for random NRZ input data with an initial frequency offset between the incoming bit rate and the a priori estimate of this rate.
    • RECONSTRUCTION OF ANALOG SIGNALS AND CHOICE OF SAMPLING RATES IN TELEMETRY

      Evdokimov, V. P.; Kolesnikov, L. I. (International Foundation for Telemetering, 1972-10)
      The reconstruction of the form of analog signals by samples by means of linear filtration is considered. Precision criterion - mean square reconstruction error and the maximum reconstruction error probability. Linear filters (reconstructing functions) of increasing difficulty are considered together with an optimal filter. A signal model is introduced by means of large set of correlation functions. The calculations of reconstruction errors are carried out for different reconstructing functions. The tables and the figures allow to determine reconstruction errors, to estimate the necessity of decreasing complexity of the filter and to choose the type of filter. The results of calculations and the recommendations of choosing the sampling rates of the sensors are made in the paper can be used by the experimenters and specialists in telemetry.
    • DIGITAL FM DEMODULATION TECHNIQUES

      Garodnick, Joseph; Goldmark Communications Corp. (International Foundation for Telemetering, 1972-10)
      Digital systems have been heavily emphasized over the past decade because of their intrinsic trouble free operation, multiplexed signal handling capabilities, and the complex processing techniques possible through the use of small special and general purpose digital computers. The digital evolution has also allowed system cability to increase, while size, cost and power consumption decrease. Functions previously deemed impossible to implement are now being constructed in production facilities. When digital techniques are used for source encoding in a wide band communications network (such as two-way CATV), information is transmitted and received digitally with Small error probalility compared to analog signals, especially when carriers and media take the form of cable, laser beams and fiber optics where line repeaters are used in lieu of amplifiers.
    • DIGITALLY IMPLEMENTED CLOCK ACQUISITION LOOPS FOR LOW SNR DATA SIGNALS

      Schoolcraft, R. W.; Magnavox Research Laboratories (International Foundation for Telemetering, 1972-10)
      The development of powerful error correction codes for binary data channels has generated a requirement for high performance clock acquisition loops. These loops must provide clean estimates of the data clock at very low data SNR in order to prevent dissipation of the coding gain through noise in the data recovery timing. The key element in high performance clock loops is the method of extracting clock information from the received data stream. Three loops are described which illustrate several extraction concepts and which can be used as design guides. The first loop extracts clock information by use of the function D(t)•D(t+ T/2). The extractor is implemented almost entirely with digital logic elements and is very compact. The third loop is extremely efficient due to the use of a time window which is open for only a short time around the transitions of the data. Its implementation is heavily analog. The second loop is a hybrid of the first and the third falls between them in both performance and complexity. Performance curves are presented for the three loops in terms of data SNR degradation as a function of data SNR and loop bandwidth. Experimental data is presented for the first loop.
    • THE COMPLEX DIGITAL FILTER AND ITS APPLICATIONS IN DIGITAL SIGNAL PROCESSING

      Lebowitz, S. H.; Computer Sciences Corporation (International Foundation for Telemetering, 1972-10)
      Digital computer simulation of communication systems have been gaining wide acceptance and usage as a tool for analysis. In some cases, when the number of independent parameters is large or the processes are highly nonlinear, it is the only viable technique. In most digital computer simulations, the digital representation of bandpass filters can impose serious synthesis problems when conventional digital filter synthesis techniques are utilized. It is shown that the use of a complex (real and imaginary) technique of digital filter synthesis can eliminate several of the synthesis problems associated with conventional techniques. Three applications of the com lex technique are described in this paper. The three applications discussed in this paper are listed below with a short description of each. 1. A lowpass-to-bandpass transformation is described that preserves all lowpass characteristics of the filter. For instance the gain and group delay functions remain symmetrical for any center frequency and bandwidth. 2. The synthesis of analytic representations of real signals can be easily achieved by the use of a complex digital filter. An important advantage of analytic signals is that their envelope and phase are instantaneously available. 3. Equalization of bandpass characteristics can be effected at lowpass and then shifted to the proper frequency without any undesirable warping effects. Complex digital filter synthesis has been described previously, but very little emphasis has been placed on the application of this technique. Advances in the art of miniature high speed digital circuitry will allow the advantages of complex filtering to be realized in actual systems as well as digital simulations.
    • LONG LIFE 100 W TRIODE FOR ATC AND TELEMETRY TRANSPONDERS

      Kellerer, J.; Schneider, W.; Siemens AG (International Foundation for Telemetering, 1972-10)
      Further development of the Siemens planar triode type RH7C-c used in the Mariner IV S-Band transponder resulted in the conduction-cooled type YD 1380 and air-cooled version YD 1381. These metal ceramic tubes produce a CW output power of 100 W in L/S-Band with a high efficiency around 40%. Small signal gain is 17 dB, and a large signal gain of 14 dB with a 20 MHz bandwidth is achieved. Life of selected sample tubes exceeds 25,000 hours, three times higher than the figure specified for the Mariner IV tube. These tubes incorporate an osmiated metal. dispenser cathode to achieve long life with stable performance. This type of cathode is exceptionally resistant to bombardment by electrons turned back to the cathode as a result of transit-time effects in the cathode-grid space. In transponder applications this allows long intervals between maintenance to be specified for the output stages. Because of the rugged tube design and low weight of the complete amplifier, the YD 1380/81 is also suited for spacecraft applications. An air-cooled, 100 W CW amplifier for 1.6 GHz has a diameter of only 74 mm and length of 175 mm. The laboratory prototype including triode YD 1381 weighs 900 gms, but this weight can be halved if necessary. Fig. 1 shows the tubes YD 1380 and YD 1381. The main applications for these new tubes are in ATC systems, telemetry, L-band communication UHF and L-band TV (ETV) and SSB microwave link equipment.
    • ON-BOARD REGISTRATION AND REDUNDANCY REDUCTION METHOD FOR QUASISTATIONARY POISSON PROCESSES

      Khodarev, J.; Nikolayev, V.; Skobkin, I.; Shtarkov, J.; Vassiliev, E. (International Foundation for Telemetering, 1972-10)
      Many processes in space are related to Poisson flows of particles. Usually, the aim of experiment is to study the intensity of such a flow. Each of the samples obtained in the course of measurement represents the number of particles detected during a sampling period and sample values are related with the flow intensity only statistically. So the less the sample value is, the greater the r.m.s. error in estimating the flow intensity. With any fixed "accumulation time" values of some samples are too small to provide required accuracy. Hence, these are redundant from the view-point of telemetering them to the Earth. A simple method is suggested for reducting this redundancy which assures a preset r.m.s. accuracy of measurement. The main feature of the method is that the accumulation lasts until the number of registrated particles reaches a preset level. In this case the "accumulation time" is variable and thus data compression is completely accomplished by appropriately organized aquisition.
    • A SINGLE CHANNEL COMMAND DETECTOR FOR DEEP SPACE MISSIONS

      Knapp, Siegbert; AEG-TELEFUNKEN Laboratories (International Foundation for Telemetering, 1972-10)
      AEG-TELEFUNKEN has developed a Single Channel Command Detector which will be used in the solar probe HELIOS. This command detector demodulates command data, PSK-modulated on a subcarrier with a symbol error-probability of less than 1x10^-5 at an input signal to noise ratio of 13,2 db per symbol-length. The command detector consists of two succeessive second-order phase locked loops and a matched filter. The subcarrier synchronizer loop tracks the 512 Hz subcarrier, the bitsynchronizer loop performs data-synchronisation and in contrast to former space concepts, requires no additional power. The matched filter correlates the input signal and its estimate, generated by the subcarrier synchronizer-loop. The integration over exact dataperiods is dumped by the bitsyncpulse. This command detector enables the HELIOS Receiver chain to demodulate command data with less than 1 error in 100 000 symbols over a distance of ~ 300 mill. km. Due to sophisticated digital decoding of the HELIOS Decoder, this error-probability results in 1 false command being executed in 64 years.
    • TIMING ACCURACIES OF RANGE INSTRUMENTATION SYSTEMS

      Matthews, Frank L.; ITT-Federal Electric Corporation (International Foundation for Telemetering, 1972-10)
      Comparison of telemetry inertial guidance data with radar and optical data requires that all data be accurately time tagged. Timing errors which accumulate, particularly in telemetry data processing, exceed range user requirements. The paper classifies the sources of timing errors, discusses how the errors are measured, provides typical values, and shows how the uncertainties are reduced to tolerable levels.
    • USE OF IMPLANTED TELEMETRY IN VASCULAR RESEARCH

      Rader, R. D.; Stevens, C. M.; Henry, J. P.; Meehan, J. P.; University of Southern California (International Foundation for Telemetering, 1972-10)
      This paper outlines a program to study the development and progression of essential hypertension in dogs through the use of totally implanted telemetry. In light of the role that social interaction may play in the development of hypertension in man, emphasis is placed on inducing and monitoring the effects of social strain in the dog: and because of the role the kidney may play in the development of hypertension, a model for renal flow has been developed. The effect that pharmacological concentrations of vasodilator and vasoconstrictor agents have on renal hemodynamics are evaluated. Preliminary data from investigations on the renal hemodynamics of unrestrained dogs in various stages of psychophysiological stress are presented.
    • A VERY HIGH SPEED HARD DECISION SEQUENTIAL DECODER

      Gilhousen, K. S.; Lumb, D. R.; LINKABIT Corporation; NASA (International Foundation for Telemetering, 1972-10)
      There are numerous applications for high data rate coding systems for earth orbiting space-missions with power limited links. Studies indicated that a 40 Mbps hard decision sequential decoder would best meet the requirements. A prototype decoder has been designed and fabricated using the fastest commercially available digital integrated circuits, MECL III. Thus far, an internal computational rate of 70 Million computations per second has been achieved. Computational efficiency of the decoding algorithm was greatly improved by incorporating two modifications to the Fano algorithm; “double quick threshold loosening” and “diagonal steps.” Preliminary results indicate that an output error rate of 10^-5 can be achieved with E(b)/N(o) less than 5.4 dB at data rates up to 40 Mbps. At lower data rates, even less signal energy is required. This decoder is believed to be at least 5 times faster than any previous sequential decoder.
    • IMPLANTABLE ULTRASONIC BLOOD FLOWMETERS

      Meindl, J. D.; Stanford University (International Foundation for Telemetering, 1972-10)
      Accurate measurement of pulsatile blood flow can be achieved on a chronic basis in research animals through the use of totally implantable ultrasonic flowmeters. The continuous wave Doppler flowmeter provides an attractive technique for measurement of flow velocity at a particular location such as the center of the lumen; the pulsed Doppler flowmeter is attractive for measurement of flow velocity distribution or profile across the vessel and lumen diameter, and hence volume flow. Both instruments can be electronically precalibrated and exhibit no baseline or scale factor changes during chronic experiments. Custom designed silicon monolithic integrated circuits offer significant advantages in reduced size and power drain as well as improved reliability in these instruments.
    • IMPLANTABLE TELEMETRY IN THE CHIMPANZEE

      Stone, H. L.; Sandler, Harold; Fryer, Tom; Marine Biomedical Institute; NASA Ames Research Center (International Foundation for Telemetering, 1972-10)
      The chimpanzee has been proposed as a possible human analogue for a myriad of human disease states. The lack of knowledge about the cardiovascular system in this animal or the cardiovascular response to stress is understandable because of the cost and handling problems with the chimpanzee. Part of this difficulty, namely handling, can be overcome with the proper selection of cardiovascular instrumentation. Implantable telemetry systems have the advantage that the animal does not have to be handled for any reason. Several animals have been successfully used with implantable telemetry units in the chest. A vigorous antibiotic therapy program must be used for the first few days after surgery, but there have not been any complications after this period of time. The life of the implanted unit has been prolonged by the use of a power switch which also allows remote collection of data. At the present time there is one such unit still functioning 14 months after implantation. The ease with which these units can be used makes them ideally suited for use in the chimpanzee. Examples of the various types of data collected are given and described briefly.
    • MANAGEMENT OF A MAGNETIC TAPE DUBBING AND EVALUATION STATION

      McKelvey, George R.; Schoeck, Kenneth O.; ITT-Federal Electric Corporation; Vandenberg Air Force Base (International Foundation for Telemetering, 1972-10)
      An instrumentation magnetic tape dubbing and evaluation station is being established at SAMTEC in an effort to improve the quality of data provided to the range users. An analysis of the problems associated with the dubbing process along with the development, configuration and operation of the station are presented.
    • CONTRIBUTIONS TO THE DESIGN OF FUTURE ON-BOARD DATA PROCESSING SYSTEMS FOR SCIENTIFIC SPACE-CRAFT EXPERIMENTS

      Frohlich, H.; Schweizer, G.; Domier AG (International Foundation for Telemetering, 1972-10)
      Requirements for programmable dataprocessors are discussed in this paper. This is done based on the experience of the development of electronic hard-wired modules for a series of scientific space-craft experiments. The operation and the realisation of three characteristic experiments with the present technology is described. Flow diagrams are shown for cornputer control and data-processing for these experiments. From the flow diagrams some preliminary requirements for general usable programmable data processors are derived and means are shown how the requirements can be implemented.