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In this paper the design details of a wide band Sanky phase shifter have been given. This phase shifter can be used with phase-sensitive detectors which are required to work with variable reference frequencies. The phase shifter uses its own built-in oscillator that provides the reference frequency.
A phase-shifting network is essential in phase-sensitive detectors to compensate for the phase shifts occurring in an amplifier system. This network, which is normally used in the reference channel, often comprises R-C networks. The input and output of such networks are both sinusoidal. With such networks the 'control' cannot be calibrated, as the phase shift introduced for a certain amount of the 'control' movement is frequency dependent. Since, in switching-mode-operated phase-sensitive detectors, the reference is a train of square waves, a modified version of the Sanky phase shifter (Sankaranarayanan 1973) can be used to introduce necessary phase shifts and the 'control' can be straight away calibrated independent of frequency as described in this paper. Although, De Sa and Molynenx (1964) and Adby (1968) have suggested two different techniques for this purpose, the modified Sanky phase shifter becomes very handy and elegant to get the phase shifted. However, in this case, instead of using the normally available L-C or R-C type of oscillator to provide the sinusoidal wave train for excitation, an oscillator that gives a sinusoidal wave generated from a triangular wave has to be used. This is due to the fact that it is essential to have a constant amplitude triangular wave independent of frequency for phase shifting in the Sanky phase shifter. In this paper the design details of a wide band Sanky phase shifter have been given. This phase shifter can be used with phase-sensitive detectors which are required to work with variable reference frequencies. The phase shifter uses its own built-in oscillator that provides the reference frequency.
A... [ABSTRACT FROM AUTHOR]

In many aircraft-tracking systems the following problem is of importance in correlating radar returns with tracks: Given the aircraft position and velocity at time t--changet and the limits on the ability of the aircraft to maneuver and/or change speed, what is the set of all possible aircraft positions at time t? We call this set the reachable set (or set of attainability) at time t. This paper uses the Pontryagin maximum principle to derive a set of equations for describing the reachable set. [ABSTRACT FROM AUTHOR]

Several upper bounds have recently been derived by the present authors, and others, for the improvement in performance achievable by an optimum adaptive receiver with respect to a receiver which, although optimum for its state of a priori information, is not adaptive to other states of prior information. This earlier work has been characterized by the general Bayesian approach to the detection problem, i.e. the criterion of optimality chosen has been to minimize the total average cost of incorrect decisions. The present paper considers the important special case of Neyman-Pearson detectors where the probability of false alarm is constrained to a pre-assigned value. Several interesting properties of these detectors are derived. In particular, it is shown that, in the presence of gaussian noise, amplitude adaptivity yields no advantage, whereas adaptivity with respect to other signal parameters generally results in a lower error probability, or conversely, in a higher probability of correct detection. As an illustrative application of the theory, the improvement in performance obtained by measuring the phase of a signal transmitted through a Rayleigh-fading channel is evaluated in detail. [ABSTRACT FROM AUTHOR]

The article presents abstracts of various papers related to police science that were previously published in several periodicals. The article "Radar Bullet Tracer," by George E. Toles presents information on an experimental radar technique that has been devised which may offer a means of sniper detection to police agencies. Using Doppler radar techniques, the system detects incoming projectiles of high velocity and provides range and trajectory information. Another article discussed is "Police Academies Can Teach the Recognition and Preservation of Trace Evidence," James W. Osterburg. In this article a course outline is offered which the author feels will result in an awareness of trace evidence by the criminal investigator resulting in a greater degree of professionalism. One of the articles discussed is "A Serious Error Possibility in Spectrographic Firing Distance Determinations," by A. Schontag. The article explains that the inverse firearm residue-distance relationship does not hold below 1 cm. At very close firing ranges the amount of deposit decreases with decreasing distance, and the penetration of the wound by the firearm residue increases. When close range firing is suspected, a sample should be taken from within the wound. In cases where multilayer fabric had covered the skin, examination of all layers is suggested. 17 photographs illustrate the text.

A new instrument is described for the measurement of folding twist on two-ply yam for yams in the range 6 to 35 turns per inch. In the system used, yarn is passed continuously through a mechanical detector consisting of a stylus that rests on the yarn and approximately measures its projected diameter. A photoelectric system converts the measured diameter into an electrical signal, which is electronically processed to give a digital count for each half twist in the yarn. This information is also presented as a curve that continuously monitors the twist and as a print-out of the number of half turns per 10-in. length of yarn. An outline is given of the methods currently in use to measure folding twist. [ABSTRACT FROM AUTHOR]

Describes a digital event recorder for use with a variety of sensing mechanisms. Features of the device; Applications of the digital event recorder; Possible uses of the device in zoological and recreation studies.

The article provides information on a study concerning the weather radar measurement of bird migration. It is known that radar becomes an important tool for the studies of bird migration. However, it is difficult to estimate bird densities from echo densities on the radar screen. The use of the Weather Bureau's new WSR-57 radar for bird migration research is also discussed. The shorter pulse of this radar has greater resolution but only detects birds when they are highly concentrated in the air. The fading of pulse radar signals reduces the number of perceptible returns because of the distribution of the numbers of targets among the radar.

The article offers information on the instrumentation requirements such as engineering, biological application and oceanographic application requirements for oceanographic research in marine biology to help oceanographers, biologists, and instrument manufacturers. The engineering requirements include the needs for automated instrumentation systems for the detection and recording of environmental and ecological parameter and analysis, and the requirement for automatic data collection. The biological application requirements include physiological and biological monitoring instrumentation and sensing devices, and the oceanographic application requirements include the need for detection and measurement of location and pattern of luminescent organisms as well as biological data sensors.

A device named "dream detector" was constructed to automatize the technique of studying dreams during the REM period of sleep (REMP). The principle of the dream detector is to identify the REMP automatically by counting the number of electrooculographically recorded REMs during the period of relative silence in EMG records. When the count number of EMs reaches a preset value, an alarm buzzer is turned on automatically to awaken the S. In preliminary experiments on 5 Ss, 62 out of 70 REMPs (88.6%) in a total of 16 experimental nights were correctly detected by using this device. In only 5 instances (3.5%) was the buzzer turned on during periods other than REMPs. The rate of correct detection was 56% for the first REMP of the night, 93% for the second REMP, and 100% for the following REMPs. [ABSTRACT FROM AUTHOR]

An instrument has been designed which will print maximum, minimum, and mean heart rate (HR) data for 10-sec sample periods. The basic components are three detector circuits which sample and hold voltage levels proportional to the values measured, a digital voltmeter for "reading" these values, and a solenoidoperated adding machine to print out HR data in beats per minute. This apparatus greatly reduces the time required for transcribing cardiotachometer tracings into digital form for statistical analysis. [ABSTRACT FROM AUTHOR]

Thermography is an exciting new modality in many areas of medicine. As more sophisticated infrared detectors become available and as our experience grows, we undoubtedly will find this instrument to be indispensable in our modern electronic, clinical armamentarium. [ABSTRACT FROM AUTHOR]

The article demonstrates the extraterrestrial life detection techniques used in the study of exobiology in the high school biology laboratory. Introducing the study of exobiology to students at the high school level can serve to enhance and reinforce the biological learnings of a terrestrial nature. The study of exobiology will introduce the rarely seen science of astronomy into the interdisciplinary structure of biology. The Gulliver is a life detecting instrument which detects bacterial growth by determining the formation of radioactive carbon dioxide from carbon labeled substrates. Another instrument, the Multivator, attempts to detect microbe life by the presence of specific catalysts, particularly phosphatase. Measurement of microbiological growth is the basis of an instrument known as the Wolf Trap.

A study is made of the capabilities of a surveillance system to detect and track submarines that are in a region that is under surveillance. The operation consists of barrier searches for submarines entering the region, area searches for submarines that have entered the region undetected, tracking procedures to hold contact on detected submarines, and special searches to regain contact when contact has been lost. The capabilities of the surveillance system are found for a general distribution of submarine on-station times, under the assumption that the recontact rate decreases with increasing time after loss of contact. [ABSTRACT FROM AUTHOR]

The article discusses a dental instrument designed to test thermal pulp. The authors describe temperature-controlling and monitoring equipment that they developed to test dental thermal sensitivity in a more practical and accurate way than previous instruments. A schematic of the instrument is included.

The article reports on the development of novel ways and techniques to trace nuclear explosions by researchers from the U.S. Works by Norman J. Holter and W. R. Glasscock aimed to detect atomic bomb testing, have generated great interests from the scientific community. The work illustrates a simple, cheap, but highly effective technique. The apparatus was set up by Holter and Glasscock at Helena, Montana, for a different purpose, namely to study the natural radioactivity of the air, and of rain and snow samples, as a possible aid in discovering large bodies of radioactive ore.