The maximum entropy spectral analysis (MESA) technique is examined for use in computing spatial antenna patterns. The problem of split peaks is investigated, and five possible stabilization methods are examined. MESA is applied to data simulated for an 8 element antenna linear array. Split peaks are attributed to interference of noise peaks located in the vicinity of the incident signal. The split peak problem is alleviated with use of the proposed stabilization methods. Results of the investigation indicate that two of the examined averaging techniques provide excellent stabilization for MESA. Antenna patterns, computed with MESA and either of the two averaging methods, contain nearly white noise and substantially enhanced SNR. GRA

The acronym METRRA represents 'Metal R-Radiating Radar'. The METRRA signature tests result from a third harmonic system, since the receive frequency is three times that of the transmit frequency. Of particular significance is METRRA's inherent ability to penetrate foliage. Conventional radar systems provide returns from undesired targets such as trees, water, dense foliage, etc., while the METRRA system does not. The METRRA process is responsive only to man made non linear junctions. Non linear junctions, when radiated by high power RF energy, convert the energy to harmonic frequencies and re-radiating radar. GRA

Television display systems are currently widely used for many image transmission applications other than home entertainment. For many military and commercial uses the quality of the displayed imagery is critical with respect to its effect on observer performance. This dissertation investigates 19 figures of merit (FOM's) that have been proposed as measures of television image quality. Target detection and target recognition study was implemented to determine which of the 19 FOM's correlated highest with performance. The study employed a 525 line, 60 Hz field rate television display system with 2:1 interlace of fields. Nine different display quality conditions were investigated using all combinations of three contrast ratios (50:1, 50:5 and 50:15) and three video bandwidths (6.0 MHz, 1.0 MHz, and 0.4 MHz). Noise was not varied. Three FOM's stood out as promising indicators of display quality and observer performance. The highest correlating FOM was the log band-limited modulation transfer function area (log BLMTFA) closely followed by the just-noticeable difference area-log (JNDA-log), 1/2 cpd and the JNDA-log,

GRA

N79-30441# Sandia Labs., Albuquerque, N. Mex. PROPAGATION OF PLANE WAVES IN GRANULAR

MEDIA

Jace W. Nunziato 1978 10 prefs Presented at Symp. on Continum Mechanical and Statistical Approaches in the Mechanics of Granular Materials, Sendai, Japan, 5 Jun. 1978 (Contract EY-76-C-04-0789)

(CONF-780618-1) Avail: NTIS HC A02/MF A01

Using a one-dimensional formulation of the continuum theory of granular materials, the longitudinal response of two classes of materials was modeled. The two classes are materials with compressible granules, such as pressed powders and sands at

high confining pressures, and flowing materials with incompressible granules, such as sands at low confining pressures. The speed and the amplitude of the various types of acceleration waves possible in each class were considered. In materials with compressible granules, two waves were found to exist, an elastic wave followed by a compaction wave. However, in flowing materials with incompressible granules, the only wave possible was a wave of dilatancy. DOE

N79-30442# Fondazione Ugo Bordoni, Rome (Italy). RESEARCH PROGRAM ON ATMOSPHERIC CONDITIONS INFLUENCE ON RADIOWAVE PROPAGATION AT FREQUENCIES OVER 10 GHz: PROGRESS REPORT AND FIRST CONCLUSIONS [PROGRAMMA DI RICERCA SULLA INFLUENZA DELLE CONDIZIONI ATMOSFERICHE SULLA RADIOPROPAGAZIONE A FREQUENZE SUPERIORI A 10 GHz: STATO DI AVANZAMENTO E PRIME CONCLUSIONI]

Francesco Fedi Mar. 1977 39 p refs In ITALIAN (FUB-23-1977) Avail: NTIS HC A03/MF A01

Information on the role of rainfall in atmospheric attenuation of radiowaves at frequencies higher than 10 GHz was collected in order to precisely define the phenomenon. Statistics were compiled on attenuation as a function of instantaneous rainfall intensity values on given sets of other parameters. Data collected over a seven year period was systematically elaborated and initial results indicate that one more year of measurements are sufficient for the formulation of a practical rainfall attenuation definition as well as for identifying those areas where work needs to be done. Author (ESA)

N79-30443#

Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt, Oberpfaffenhofen (West Germany). Inst. fuer Flugfunk und Mikrowellen. CALCULATION OF HETERODYNE-DETECTION WITH FOCUSED RADIATION

Friedrich Malota Sep. 1978 27 p refs In GERMAN; ENGLISH summary Report will also be announced as translation (ESA-TT-552)

(DLR-FB-78-20) Avail: NTIS HC A03/MF A01; DFVLR, Cologne DM 11,30

The advantages in the application of heterodyne-detection with focused radiation are described. Several possibilities for detection are explained and the signal to noise ratios are computed using a basis the three-dimensional formulation of the focus region (Lommelfunction). The dependence of the signal to noise ratio on the distance between the detector and the focal plane is investigated in detail. The results and the limitations of the computational methods are discussed. Author (ESA)

Two breadboard models of cardioid coverage TT and C antennas were analyzed and tested in order to improve their electrical performances. These antennas were tested both when isolated and when mounted on a spacecraft mock-up. Results obtained based on specification requirements are compared with a reference antenna. Of the two configurations examined (antenna A, with skirt, giving 120 deg half-angle coverage and antenna B, without skirt, giving approximately 140 deg coverage), both showed improvement. A modified coupler intended to improve the feeding network was also added to the system. Mathematical modeling is described and good agreement between theoretical and experimental results is shown. Author (ESA)

N79-30445# Siemens A.G., Munich (West Germany). Fachgeb

iet Weitverkehrstechnik.

RF-SENSOR-SYSTEM USING A SATELLITE BROADCAST ANTENNA Final Report

Heinrich Bruentrup, Ulrich Scherner, Gerhard Schindler, Bernhard Spicker, and Werner Vallentin Bonn Bundesmin. fuer Forsch.

The feasibility of a Beam Pointing Error Indicating System which does not derive its beam pointing error information from the position of the antenna beam center with reference to the coverage area center, but from the optimal illumination of the coverage edge was investigated. Characteristic components of the system are several beacon stations (grounds segment), a sensor receiving device, and a reference antenna (space segment). Beacon frequency is within the frequency range 12.5 to 12.75 GHz. The sensor receiving device includes an RF-switch (signal comparator), a receiver, a demodulator, and an evaluation circuit for processing beacon signal information. Results shown that with the selected operating mode (regional time division multiplex) an accuracy of better than 0.01 deg is achieved. Author (ESA)

Analysis aids and data bases for predicting the performance of 100 MHz 100 GHz communication systems are presented and briefly described. They are loosely grouped into the following functional categories: (1) computations of transmission loss and radar returned power; (2) computations of desired to undesired signal ratios; (3) computations of atmospheric and precipitation parameters: (4) data bases and associated programs; (5) performance of digital communication systems; and (6) miscellaneous programs. Sources are given for the analysis aids, data bases, and additional information. GRA

A software package was developed which automatically measures and analyzes received signal level of four microwave communication receivers. An initial manual calibration directed by the program is stored on a data tape cartridge. The software uses the IEEE 488-1975 bus to run the test unattended for one month. Data are sampled on each receiver four times per second with a typical resolution of 3 dB over a 60-dB dynamic range. In addition to an analysis each hour during the test, programs may be run after the test to list and plot cumulative distributions and hourly medians on a peripheral graphic plotter. The graphs are drawn and annotated completely under software control. GRA

Design standards and recommendations for the implementation of compatible, effective communications systems for emergency medical services (EMS) using the UHF frequencies allocated by the FCC are provided. Five major task areas were studied which involved visiting seven major operational EMS communications systems, formulating design standards, investigating disaster situations, studying the interoperation of EMS with other public safety services, and studying the possible use of innovative communications concepts in EMS systems. The potentially severe problems that are likely to develop as UHF EMS systems become more widespread are indicated and design

The Federal Communications Commission is actively participating in joint United States-Canadian Communications Technology Satellite (CTS-Canadian Hermes') experimentation to evaluate the potential use of small, relatively simple, inexpensive earth receiving terminals for satellite broadcasting, and provide technical guidance to FCC Commissioners and U.S. participants in international conferences. The FCC to date has: (1) tested five different smail receive-only terminals under a great variety of environment conditions, thereby acquiring a wealth of operational experience as well as certain concrete experimental results; (2) accomplished the first (insofar as can be determined) actual satellite-to-home television reception; and (3) conducted many demonstrations of high power satellite television reception with small earth terminals, notably for FCC Chairman Charles D. Ferris and for members of Congressional and FCC Commissioners' staffs, as also for NHK and other Japanese visitors in advance of the March 1978 launch of the Japanese Broadcast Satellite Experiment (BSE). GRA

The design of an automatic tracking system applicable to shipborne non-moving target indicator radars is considered. The system is based on the stationary plot filter (SPF), which cancels stationary and slow moving detections and also provides data for both control of the first threshold and adaption of the track confirmation rules. The design of the system is discussed, with the emphasis on the SPF. Some experimental results are presented, which show how the performance of the filter is affected by the values of its parameters and also compares the performance of the SPF based approach with that of the more conventional moving target indication. J.M.S.

Avail: NTIS HC A11/MF A01

The relations between the main system functions search, acquisition, and tracking and their radar counterparts detection, interference reduction, and position finding of an experimental radar system (ELRA) are explained. For automatic track initiation a lot of radar tasks with different parameters are handled partly simultaneously and partly sequentially which demands various kinds of data transfer between the radar antennas and the tracking computer. It is pointed out that the radar physics and the tracking process require a variable integration time for optimum signal processing dependent on the target range, direction, and estimated cross section and on the information from a clutter map and that adaptive clutter suppression and jammer cancellation can be included with modest reduction of the efficiency. The demand for a high detection probability and location accuracy and limitations in power and time with long-range surveillance systems are overcome by a multiple-beam J.M.S. concept using interlaced transmit-receive processing.

N79-30468# Shape Technical Center, The Hague (Netherlands). Command Control and Systems Div.

DESIGN CONSIDERATIONS FOR RADAR TRACKING IN CLUTTER

H. B. Driessen In AGARD Strategies for Autom. Track Initiation Jun. 1979 14 p refs (For primary document see N79-30454 21-32)

Avail: NTIS HC A11/MF A01

The performance of an automatic tracking logic in a mixed environment of false and real plots is studied. The problem is investigated with Monte Carlo simulation. The investigation is a sensitivity analysis for five important parameters: (1) radar detection probability; (2) clutter density: (3) smoothing parameters; (4) gate size; and (5) maximum number of consecutive misses. The results are applicable to the design of a tracking J.M.S. logic of an automatic air traffic control system.

N79-30459# Plessey Radar Ltd., Addlestone (England).
SOME ASPECTS OF MULTI-RADAR TRACKING

A. R. Morley and A. S. Wilsdon In AGARD Strategies for
Autom. Track Initiations Jun. 1979 14 p ref (For primary
document see N79-30454 21-32)
Avail: NTIS HC A11/MF A01

Three different aspects of a multi-radar simulation study aimed at determining the best tracking organization and algorithms are presented. The first aspect is that of tracking groups of aircraft which are not all individually resolvable. Simulation showed that a manually defined quadrilateral enclosing the aircraft could be used for filtering the formation while tracking was performed by evaluating the centroid of the group and tracking it as a single entity. In any tracking system height is required primarily for tactical reasons, but in a multi-radar tracking system it is also required for the co-ordinate conversion of the measured plot position to the common tracking plane. There is therefore an additional requirement to produce accurate height information in order to improve the tracking performance. The height accuracy can, in general, be improved by height filtering. A possible algorithm is described. The implications of uncoupling the multi-radar Kalman filter are considered in terms of tracking performance. It is shown that under certain circumstances the tracking performance is considerably degraded when an uncoupled Kalman filter is implemented. A.R.H.

ALGORITHMS FOR SIMULTANEOUS AUTOMATIC TRACK INITIATION IN MULTIPLE RADAR NETWORKS

Karl Brammer, Franz Herzmann, Albert Kainzinger, and Norbert Knoppik In AGARD Strategies for Autom. Track Initiation Jun. 1979 17 p refs (For primary document see N79-30454 21-32) Avail: NTIS HC A11/MF A01

In a system which uses tracking facilities of equal authority collocated at every radar station, redundant communication links between the stations provide a failure tolerant data exchange capability. Algorithms are described which lead to a unique system track for a target entered into the system by several radar sensors, while each of the collocated tracking facilities starts an individual track by pooling radar information from its own sensor and from neighboring sensors seeing the same target. The functions

One of several promising concepts for netting radars in a tactical air surveillance system employs track-while-scan radars having scan periods of from 4 to 12 seconds. Such scan periods are too long to yield an acceptably high probability of automatic association of measurements with tracks when the surveillance region contains many highly maneuverable targets. As presented, the radars overcome this limitation by being connected into a non-hierarchical net over which measurement data is pooled. In the system concept described, most targets will be seen by twenty or more radars. If all radars able to see a target shared the resulting data with the entire system, the communications bandwidth required would be excessive. To avoid this problem, an algorithm was devised that dynamically selects a 'best' subset of the system's radars to track each target, thus, simultaneously achieving a high probability of correct association (and hence of maintaining track) while requiring reasonable communications bandwidths. This performance is achieved without centralized control. The concept was verified using a detailed computer simulation called TACRAN (Tactical Air Control Radar Net); some simulation results are presented. A.R.H.

N79-30462# Societe Industrielle des Nouvelles Techniques Radioelectriques et de l'Electrique Francaise, Asnieres.

PRIMARY AUTOMATIC TRACKING RADAR IN A MILITARY APPROACH AND ASSEMBLY CENTER [POURSUITE AUTOMATIQUE RADAR PRIMAIRE DANS UN CENTRE D'APPROCHE ET DE RECUEIL MILITAIRE]

A. Poch In AGARD Strategies for Autom. Track Initiation Jun. 1979 5 p In FRENCH (For primary document see N79-30454 21-32)

Avail: NTIS HC A11/MF A01

Automatic tracking radar in a military center is confronted with problems related to both the environment and to operational exploitations. Special algorithms, adapted in an extremely short time, are used to process targets developing in dense zones at low altitudes, by performing the following functions: (1) constituting a moving map, supported in real time, by recognized plots of the coverage; (2) rapid automatic initiation on plots at contact, beginning from a self adaptive criteria, as a function of the creation zone in the radar coverage: assembly zone, landing/takeoff zone, surveillance zones; (3) associating contact-targets, considering the correct conditions for approach: fixed echoes, atmospheric clutter, speed, and the performance and location of very disparate targets; and (4) the automatic, real-time adaptation, of related parameters as a function of the development of targets: accelerations, decelerations, turning, and lack of radar detection. These algorithms are incorporated into a compact program and used on a minicomputer.

Transl. by A.R.H.

N79-30463# Communications Research Centre, Ottawa (Ontario). Communications Dept.

ANALYSIS OF SECOND AND THIRD ORDER STEADYSTATE TRACKING FILTERS

A. W. Bridgewater In AGARD Strategies for Autom. Track Initiation Jun. 1979 11 p refs Sponsored by the Dept. of Natl. Defence, Ottawa, Ontario (For primary document see N79-30454 21-32)

Avail: NTIS HC A11/MF A01

In a multi-target environment, the heavy processing load on even the most powerful radar tracking systems makes it necessary to sacrifice theoretical optimality for practical feasibility in the tracking process. One approach is to adopt sub-optimal methods for track estimation using steady-state adaptive alpha-beta and alpha-beta-gamma filters, which are derived from the Kalman

A statistical method for track validation was introduced which uses a sequential likelihood ratio test procedure. The test discriminates between tracks of the wanted objects and false tracks on the basis of the target detection probability and the local false alarm probability. The latter is estimated for each search plot in a clutter map which is a list of stored clutter echos. The map is updated in real time and the list organization technique provides a set of converging volumina containing the estimation point so that nonparametric estimates can be obtained by testing on uniformity. Core memory and computing time requirements allow real time operation in a multipurpose computer programmed in higher level language. M.M.M.

N79-30465# Forschungsinstitut fuer Funk und Mathematik, Werthoven (West Germany).

SOFTWARE STRUCTURE AND SAMPLING STRATEGY FOR AUTOMATIC TARGET TRACKING WITH A PHASED ARRAY RADAR

G. vankeuk In AGARD Strategies for Autom. Track Initiation Jun. 1979 13 p refs (For primary document see N79-30454 21-32)

Avail: NTIS HC A11/MF A01

The software system used for multi-target tracking in the experimental phased array system under construction at the FFM is described as well as the introduction on the application to Kalman filters for tracking maneuvering targets. In contrast of the situation with conventional radars, the additional degree of freedom to adapt the scan period on the estimated lack of information with regard to each individual track is analyzed for the electronically steerable radar case. A sampling strategy is developed and analyzed that minimizes the tracking frequency considering the shape of the detection probability within a tracking beam pointing towards the predicted target position. Adapting the scan interval a constant track accuracy in space can be achieved taking the various dynamical and geometrical restrictions into consideration. An optimal spatial extension of this uncertainty volume can then be derived. As the sampling frequency of course also depends on the assumed maneuvering capabilities of the target under track, the extension of the optimal uncertainty volume depends only on the beam splitting ratio of the used monopulse angle finding technique. M.M.M.

N79-30466# Forschungsinstitut fuer Funk und Mathematik, Werthoven (West Germany).

THE FORMATION TRACKING PROCEDURE FOR TRACKING IN DENSE TARGET ENVIRONMENT

G. Binias In AGARD Strategies for Autom. Track Initiation Jun. 1979 11 p refs (For primary document see N79-30454 21-32)

Avail: NTIS HC A11/MF A01

The strategy of formation tracking presented is characterized by the substitution of raid tracks for single target tracks. The raid tracks are correlated and updated by plot-clusters. The formation track consists of one central track and several marginal tracks containing the whole information about the mean cinematical behavior and the spatial extension of the tracked formation. Special investigations were directed to the following problems: formation track initiation, formation track evolution, decision and control procedures with regard to formation track

splitting, and formation track junction. The efficiency of formation tracking can be demonstrated by a few one dimensional examples of appropriate airspace situations.

M.M.M.

system DAISY (digital automated information processing system) was studied. R.E.S.

N79-30467# Mitre Corp., Bedford, Mass.

PERFORMANCE OF AUTOMATIC TRACK INITIATION LOGIC IN SPECIFIC TARGET ENVIRONMENTS

G. E. Lindeberg, A. S. Margulies, and P. A. Smyton In AGARD Strategies for Autom. Track Initiation Jun. 1979 10 prefs (For primary document see N79-30454 21-32) (Contract F19628-78-C-0001) Avail: NTIS HC A11/MF A01

Two generalized analytical computer models were developed to provide data for a parametric assessment of various ATI algorithms which attempt to replicate the surveillance operator's judgmental processes. One model was used to investigate the initiation of tracks on actual targets and the other was used to determine the track initiation performance based only upon false reports. This performance dichotomy is valid for the anticipated NAEW target environment. It was concluded that there are several ATI algorithms which would yield satisfactory performance. Even within this set of acceptable algorithms, however, some criteria provide enhanced performance in initiation of true targets at the expense of a relatively larger number of false track initiations and there are others for which the converse is true. The level of false target reports per scan, the expected target speeds, and the speed with which real targets are initiated are all significant factors in the construction of the ATI feature and their ramifications are discussed in detail. M.M.M.

A radar tracking system was developed for use in the terminal area. The extractor is referred to as a Sensor Receiver and Processor (SRAP). It detects both primary radar and secondary radar targets and correlates the two for transmission to the central computer. The primary radar extractor portion of the SRAP employs a rank order quantizer as the first detector so that quantizing of signals is done on a non-parametric basis. The device also employs a dynamic correlation measurement technique to produce a tight clutter false alarm control. The automatic radar terminal system 3 computer program was modified to accept data already azimuthally correlated between primary and secondary signals. Author

N79-30470# Royal Netherlands Navy. Den Helder (Netherlands). EXPERIENCE WITH AUTOMATIC TRACKING SYSTEMS OF THE ROYAL NETHERLANDS NAVY

Leo Stigter In AGARD Strategies for Autom. Track Initiation Jun. 1979 7 p (For primary document see N79-30454 21-32) Avail: NTIS HC A11/MF A01

The problems encountered and the experience gained with automatic tracking systems for the modern frigates of the Royal Netherlands Navy are described. The on board data handling

Radar data processing in STRIDA is carried out by three types of processing: (1) extraction (which digitalizes, extracts and filters radar information); (2) tracking (which elaborates and updates the group of tracks for each radar); and (3) merging (which enables the establishment of a general air traffic chart). These functions are entirely automatic and are implemented in the different network centers. The process of initiation and update of tracks is performed in two steps: firstly, at a mono-radar level, and then, at a multi-radar level. This technique gives the advantage of limiting the number of false tracks while being sure of creating every new track. It also enables the establishment of a general air traffic chart by dynamically choosing the best radar detection for each track. R.E.S.

N79-30473# Hughes Aircraft Co., Fullerton, Calif. System
Analysis Section.

ESTABLISHMENT OF AIR DEFENSE SENSOR REQUIRE-
MENTS FOR AUTOMATIC AIRCRAFT TRACKING
Martin Dana In AGARD Strategies for Autom. Track Initiation
Jun. 1979 10 p (For primary document see N79-30454 21-32)
Avail: NTIS HC A11/MF A01

The functional relationship between air defense requirements and the capabilities of the target acquisition, tracking, identification, threat evaluation and weapon assignment, and weapon subsystems was investigated. Some alternative methods for assessing quantitatively the relationship between total air defense system performance and the performance of the individual subsystems are discussed. A detailed analytic model of system versus subsystem performance was derived. The sensor and sensor processing related functions--that is, acquisition, tracking. identification and acquisition of designed targets by fire control radars--were emphasized in the derivation. Although the communication subsystem is a vital element of an integrated air defense system, communications was not considered except to note that a system which can transmit the required information to and from the command and control subsystem without excessive delays due to traffic and queueing problems is required. R.E.S.

N79-30254*# Jet Propulsion Lab., Calif. Inst. of Tech., Pasadena. Communications Systems Research Section.

A GENERALIZATION OF BINARY MINIMUM SHIFT KEYING AND STAGGERED QUADRIPHASE SHIFT KEYING MODULATION

J. L. Massey In its The Deep Space Network 15 Aug. 1979 p 26-40 refs (For primary document see N79-30248 21-12) Avail: NTIS HC A06/MF A01 CSCL 17B

N79-30256*# Jet Propulsion Lab., Calif. Inst. of Tech., Pasadena. Radio Frequency and Microwave Subsystems Section.

A PROTOTYPE DSN X-S BAND FEED: DSS 13 APPLICATION Status Report

W. Williams, D. Nixon, H. Reilly, J. Withington, and D. Bathker In its The Deep Space Network 15 Aug. 1979 p 51-60 refs (For primary document see N79-30248 21-12) (SR-3) Avail: NTIS HC A06/MF A01 CSCL 20N