SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 6 - March 24, 2006
32 COMMUNICATIONS AND RADAR
Includes radar; radio, wire, and optical communications; land and global communications; communications theory.
For related information see also 04 Aircraft Communications and Navigation; and 17 Space Communications, Spacecraft Communications, Command and Tracking; for search and rescue, see 03 Air Transportation and Safety; and 16 Space Transportation and Safety.
20060007900 National Inst. of Standards and Technology, Boulder, CO, USA
Propagation and Detection of Radio Signals Before, During and After the Implosion of a Large Sports Stadium (Veterans' Stadium in Philadelphia)
Holloway, C. L.; Koepke, G.; Camell, D.; Remley, K. A.; Williams, D. F.; Oct. 2005; 124 pp.; In English Report No.(s): PB2006-101658; NIST/TN-1541; No Copyright; Avail.: CASI: A06, Hardcopy
This is the second in a series of NIST technical notes (TN) on propagation and detection of radio signals in large buildings before, during, and after implosion. The first NIST TN (NIST TN 1540) described a similar experiment carried out on a 13-story apartment building in New Orleans, LA. These data will give first responders a better understanding of what to expect from the radio-propagation environment in disaster situations. The goals of the work are two-fold: (1) to create a large, public-domain data set describing the attenuation in various building types of radio signals in public safety and cellular telephone bands and (2) to investigate various schemes for detecting signals from first responders with radio or from civilians with cell phones who are trapped in voids in a collapsed or partially collapsed building. With the above goals in mind, measurements were carried out on a large sports stadium (the Veteran's Stadium) in Philadelphia, PA. Frequencies near public safety and cell phone bands (approximately 50 MHz, 150 MHz 225 MHz, 450 MHz, 900 MHz, and 1.8 GHz) were chosen for these experiments. Radio transmitters similar to those used by first responders were used. An automated system to measure signal strength was developed. Three different types of signal-strength experiments were performed. NTIS
Implosions; Radio Signals; Signal Detection
20060008002 National Highway Traffic Safety Administration, Washington, DC, USA
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Cell Phone Use on the Roads in 2002
Nov. 2005; 56 pp.; In English Report No.(s): PB2006-106882; DOT HS 809 580; No Copyright; Avail.: National Technical Information Service (NTIS)
With the increasing popularity of cellular phones and public concern about the safety of using phones while driving, there has been increased interest in tracking the incidence of driver cell phone use. This report provides a detailed look at the 2002 data on this topic from the National Highway Traffic Safety Administration, data that comes from NHTSAs National Occupant Protection Use Survey. The survey estimated that during daylight hours, drivers of cars, trucks, vans, and sport utility vehicles used hand-held phones during 4 percent of their driving time in 2002, up from 3percent in 2000. These results were obtained by observing actual traffic. In fact the NOPUS is currently the only source of probability-based observed national data on driver cell phone use. While the NOPUS percentages are small, they indicate a substantial and growing phenomenon, translating into approximately 600,000 drivers on the road at any given time between 8 a.m. and 6 p.m. using hand-held phones in 2002, up from 400,000 in 2000. When combined with data from other surveys on hands-free use, NOPUS finds that nearly 900,000 drivers on the road at any given daylight time are using cellular phones in some manner, whether by holding the phone or using a hands-free device. However, while NOPUS finds an increase in hand-held use behind the wheel, the survey data indicates a shift toward the use of hands-free devices. The growth in hands-free use while driving that occurred between 2000 and 2002 outpaced the growth in hand-held phones (a 33 percent growth for hand-held phones, compared to 100 percent for hands-free). NOPUS first observed cell phone use in 2000, and so the data in this report represents some of the first direct measurements of this form of driver distraction on the road. NTIS
Roads; Wireless Communication; Telephones
20060008004 National Center for Statistics and Analysis, Washington, DC, USA
Traffic Safety Facts. Driver Cell Phone Use in 2005. Overall Results
Glassbrenner, D.; Dec. 2005; 10 pp.; In English Report No.(s): PB2006-106887; DOT HS 809 967; No Copyright; Avail.: National Technical Information Service (NTIS)
Driver cell phone use increased in 2005, with 6 percent of drivers on hand-held phones in 2005 nationwide compared to 5 percent in 2004. This result is from the National Occupant Protection Use Survey (NOPUS), which provides the only probability-based observed data on driver cell phone use in the USA. The NOPUS is conducted annually by the National Center for Statistics and Analysis of the National Highway Traffic Safety Administration (NHTSA). The 2005 rate translates into 974,000 vehicles on the road at any given daylight moment being driven by someone on a hand-held phone. It also translates into an estimated 10 percent of vehicles in the typical daylight moment whose driver is using some type of phone, whether hand-held or hands-free. The 2005 survey also found the following: Hand-held use increased in a number of driver categories, including female drivers (from 6 percent in 2004 to 8 percent in 2005), drivers age 16-24 (8 percent in 2004 to 10 percent in 2005), and drivers in suburban areas (4 percent in 2004 to 7 percent in 2005). The incidence of drivers speaking with headsets on while driving also increased in 2005, from 0.4 percent of drivers in 2004 to 0.7 percent in 2005. In the first nationwide probability-based estimate of the incidence of hand-held device manipulation, the survey found that 0.2 percent of drivers were dialing phones, checking PDAs, or otherwise manipulating some hand-held device while driving in 2005. NTIS
Safety; Traffic; Wireless Communication; Telephones
20060008664 Bureau of the Census, Washington, DC, USA
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Economic Census 2002: Information, Industry Series. Broadcasting Services (Except Internet)
Dec. 2004; 36 pp.; In English Report No.(s): PB2006-103848; EC02-51I-09; No Copyright; Avail.: CASI: A03, Hardcopy
The economic census is the major source of facts about the structure and functioning of the nation's economy. It provides essential information for government, business, industry, and the general public. Title 13 of the USA Code (Sections 131, 191, and 224) directs the Census Bureau to take the economic census every 5 years, covering years ending in '2' and '7.' The economic census furnishes an important part of the framework for such composite measures as the gross domestic product estimates, input/output measures, production and price indexes, and other statistical series that measure short-term changes in economic conditions. Specific uses of economic census data include the following: Policymaking agencies of the federal government use the data to monitor economic activity and to assess the effectiveness of policies; State and local governments use the data to assess business activities and tax bases within their jurisdictions and to develop programs to attract business; Trade associations study trends in their own and competing industries, which allows them to keep their members informed of market changes; and Individual businesses use the data to locate potential markets and to analyze their own production and sales performance relative to industry or area averages. The Information sector (sector 51) comprises establishments engaged in the following processes: (a) producing and distributing information and cultural products, (b) providing the means to transmit or distribute these products as well as data or communications, and (c) processing data. The main components of this sector are the publishing industries, including software publishing, and both traditional publishing and publishing exclusively over the Internet; the telecommunications industries; the industries known as Internet service providers and Web search portals, data processing industries, and the information services industries. NTIS
Broadcasting; Census; Economics; Industries; Information Systems; Internets
20060008665 Bureau of the Census, Washington, DC, USA
Economic Census 2002: Information, Industry Series. Internet Publishing and Broadcasting
Dec. 2004; 34 pp.; In English Report No.(s): PB2006-103849; EC02-51I-10; No Copyright; Avail.: CASI: A03, Hardcopy
The economic census is the major source of facts about the structure and functioning of the nation's economy. It provides essential information for government, business, industry, and the general public. Title 13 of the USA Code (Sections 131, 191, and 224) directs the Census Bureau to take the economic census every 5 years, covering years ending in '2' and '7.' The economic census furnishes an important part of the framework for such composite measures as the gross domestic product estimates, input/output measures, production and price indexes, and other statistical series that measure short-term changes in economic conditions. Specific uses of economic census data include the following: Policymaking agencies of the federal government use the data to monitor economic activity and to assess the effectiveness of policies; State and local governments use the data to assess business activities and tax bases within their jurisdictions and to develop programs to attract business; Trade associations study trends in their own and competing industries, which allows them to keep their members informed of market changes; and Individual businesses use the data to locate potential markets and to analyze their own production and sales performance relative to industry or area averages. The Information sector (sector 51) comprises establishments engaged in the following processes: (a) producing and distributing information and cultural products, (b) providing the means to transmit or distribute these products as well as data or communications, and (c) processing data. The main components of this sector are the publishing industries, including software publishing, and both traditional publishing and publishing exclusively over the Internet; the telecommunications industries; the industries known as Internet service providers and Web search portals, data processing industries, and the information services industries. NTIS
Broadcasting; Census; Economics; Industries; Information Systems; Internets
20060008667 Bureau of the Census, Washington, DC, USA
Economic Census 2002: Information, Industry Series. Telecommunications
Nov. 2004; 44 pp.; In English Report No.(s): PB2006-103850; EC02-51I-11; No Copyright; Avail.: CASI: A03, Hardcopy
The economic census is the major source of facts about the structure and functioning of the nation's economy. It provides essential information for government, business, industry, and the general public. Title 13 of the USA Code (Sections 131, 191, and 224) directs the Census Bureau to take the economic census every 5 years, covering years ending in '2' and '7.' The economic census furnishes an important part of the framework for such composite measures as the gross domestic product estimates, input/output measures, production and price indexes, and other statistical series that measure short-term changes in economic conditions. Specific uses of economic census data include the following: Policymaking agencies of the federal government use the data to monitor economic activity and to assess the effectiveness of policies; State and local governments use the data to assess business activities and tax bases within their jurisdictions and to develop programs to attract business; Trade associations study trends in their own and competing industries, which allows them to keep their members informed of market changes; and Individual businesses use the data to locate potential markets and to analyze their own production and sales performance relative to industry or area averages. The Information sector (sector 51) comprises establishments engaged in the following processes: (a) producing and distributing information and cultural products, (b) providing the means to transmit or distribute these products as well as data or communications, and (c) processing data. The main components of this sector are the publishing industries, including software publishing, and both traditional publishing and publishing exclusively over the Internet; the telecommunications industries; the industries known as Internet service providers and Web search portals, data processing industries, and the information services industries. NTIS
Census; Economics; Industries; Information Systems; Telecommunication
20060008669 Bureau of the Census, Washington, DC, USA
Economic Census 2002: Information, Industry Series. Internet Service Providers, Web Search Portals, and Data Processing Services
Nov. 2004; 38 pp.; In English Report No.(s): PB2006-103851; EC02-51I-12; No Copyright; Avail.: CASI: A03, Hardcopy
The economic census is the major source of facts about the structure and functioning of the nation's economy. It provides essential information for government, business, industry, and the general public. Title 13 of the USA Code (Sections 131, 191, and 224) directs the Census Bureau to take the economic census every 5 years, covering years ending in '2' and '7.' The economic census furnishes an important part of the framework for such composite measures as the gross domestic product estimates, input/output measures, production and price indexes, and other statistical series that measure short-term changes in economic conditions. Specific uses of economic census data include the following: Policymaking agencies of the federal government use the data to monitor economic activity and to assess the effectiveness of policies; State and local governments use the data to assess business activities and tax bases within their jurisdictions and to develop programs to attract business; Trade associations study trends in their own and competing industries, which allows them to keep their members informed of market changes; and Individual businesses use the data to locate potential markets and to analyze their own production and sales performance relative to industry or area averages. The Information sector (sector 51) comprises establishments engaged in the following processes: (a) producing and distributing information and cultural products, (b) providing the means to transmit or distribute these products as well as data or communications, and (c) processing data. The main components of this sector are the publishing industries, including software publishing, and both traditional publishing and publishing exclusively over the Internet; the telecommunications industries; the industries known as Internet service providers and Web search portals, data processing industries, and the information services industries. NTIS
Census; Data Processing; Economics; Industries; Information Systems; Internets
20060008670 Bureau of the Census, Washington, DC, USA
Economic Census 2002: Information, Subject Series. Establishment and Firm Size (Including Legal Form of Organization)
Nov. 2005; 136 pp.; In English Report No.(s): PB2006-103853; EC02-51SS-SZ; No Copyright; Avail.: CASI: A07, Hardcopy
The economic census is the major source of facts about the structure and functioning of the nation's economy. It provides essential information for government, business, industry, and the general public. Title 13 of the USA Code (Sections 131, 191, and 224) directs the Census Bureau to take the economic census every 5 years, covering years ending in '2' and '7.' The economic census furnishes an important part of the framework for such composite measures as the gross domestic product estimates, input/output measures, production and price indexes, and other statistical series that measure short-term changes in economic conditions. Specific uses of economic census data include the following: Policymaking agencies of the federal government use the data to monitor economic activity and to assess the effectiveness of policies; State and local governments use the data to assess business activities and tax bases within their jurisdictions and to develop programs to attract business; Trade associations study trends in their own and competing industries, which allows them to keep their members informed of market changes; and Individual businesses use the data to locate potential markets and to analyze their own production and sales performance relative to industry or area averages. The Information sector (sector 51) comprises establishments engaged in the following processes: (a) producing and distributing information and cultural products, (b) providing the means to transmit or distribute these products as well as data or communications, and (c) processing data. The main components of this sector are the publishing industries, including software publishing, and both traditional publishing and publishing exclusively over the Internet; the telecommunications industries; the industries known as Internet service providers and Web search portals, data processing industries, and the information services industries. NTIS
Census; Economics; Industries; Information Systems
20060008754 Stanford Univ., Stanford, CA, USA
A New Approach to Decentralized Array Processing
Wax, Mati; Kailath, Thomas; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 40.7.1 - 4.7.4; In English; See also 20060008748 Contract(s)/Grant(s): AF49-620-79-C-0058; DAAG29-79-C-0215; DAAG29-81-K-0057; Copyright; Avail.: Other Sources
The problem of of decentralizing the processing in a passive array composed of subarrays at geographically dispersed sites is addressed. A new scheme, based on obtaining estimates of the covariance matrices from each subarray is presented, and its performance is compared to the conventional triangulation method. It is shown that the new scheme offers improved accuracy with only a modest increase in the communication load. Moreover, unlike the conventional triangulation scheme, it does not require any data association step; the data association is done automatically in the proposed algorithm. Author
Algorithms; Triangulation; Covariance; Estimates; Matrices (Mathematics)
20060008763 Hindustan Aeronautics Ltd., Hyderabad, India
Modified Distribution Free CFAR Processor for Clutter Edges and Multi-target Situations
Srinath; Nagarajan, V.; Chaturvedi, G. K.; Dhage, S. D.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.2.1 - 47.2.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
Performance of CFAR processors gets degraded at clutter edges and in multi target situations. Solutions suggested to tackle one problem degrades the performance in the other. In this paper, we show how both the problems can be handled reasonably well by using a modified version of distribution free CFAR processor[B]. Analytical results for the normal homogeneous interference situation and simulation results for the non-homogenous situations (clutter edges and multitarget situations) are presented Author
Clutter; Targets; Adaptive Filters; Edges
20060008805 Hindustan Aeronautics Ltd., Hyderabad, India
Tracking a Maneuvering Target in Clutter-a New Approach
Nagarajan, V.; Chidambara, M. R.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.1.1 - 47.1.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
We consider the problem of tracking a maneuvering target in clutter. In such an environment, missed detections and false alarms make it impossible to decide,with certainty,the origin of the received echoes. Two inadequacies in the existing approaches It]to handle this problem are: 1. Optimisation of detection characteristics has not been considered and 2. Features that can be used in the plot-to-track association are restricted to a specific class. This paper presents a new approach free of these limitations. Tracking a maneuvering target i n clutter becomes feasible and tracking performance of weak targets is improved. A novel false track detection criterion is also introduced. Author
Targets; Clutter; Maneuvers; Tracking (Position)
20060008806 Indian Inst. of Tech., Bombay, India
Distribution Free Doppler Processor
Nawathe, S. P.; Rao, B. V.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.5.1 - 47.5.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
The purpose of this paper is to investigate the performance of a typical Doppler processor when the received clutter data is correlated. As the classical theories of statistical inference do not provide a tractable procedure for consideration of correlated non-gaussian random variables, it is necessary to resort to Monte Carlo simulation. A technique based on the theory of Best Linear Prediction followed by an appropriate nonlinear transformation enables consideration of correlated clutter with any arbitrary distribution. It is observed that the processor discussed in the paper exhibits distribution free characteristics in the case of correlated clutter. Author
Doppler Radar; Clutter; Central Processing Units
20060008807 Mitsubishi Electric Corp., Kamakura, Japan
Side-lobe Canceller Response for Pulse Interference
Ohmuro, Takashi; Tachibana, Yasuo; Kondo, Michimasa; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.7.1 - 47.7.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
The side-lobe canceller response for the pulse train interference is discussed. This type of the interference is caused by jammings or the radiation from other radar. The differential equation which governs the control weight of the canceller is solved and the solution is related to several operational parameters of the canceller such as the loop filter time constant, the loop gain, the interference power, the repetition period, the duty factor of the pulse and so on. Based on the results obtained here, the optimum loop gain and time constant can be selected to satisfy the given conditions for cancellation. Author
Sidelobes; Pulse Radar; Electromagnetic Interference
20060008808 Tianjin Inst. of Marine Technology, Tianjin, China
A Method for Computation of Wideband Ambiguity Function and the Numericalanalysis of the Bat's Sonar Signal
Lin, Zhen-Biao; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.11.1 - 47.11.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
A method for implementing the wideband ambiguity function(WAF) is proposed. By this method the Doppler compression version of a signal is computed by frequency domain interpolation. A good agreement between calculated 3D-diagram and the theoretical expression is shown. The WAF program implemented on minicomputer allows to calculate various parameters of signal. Its application to studying 50 sonar signals emitted by a bat(Myotis mystacinus) discloses why bat uses differently structured echolocation signals during detection, identification, pursuit and capture of an insect. Author
Bats; Ambiguity; Broadband; Numerical Analysis; Sonar
20060008812 Tokyo Univ., Japan
Synthesis by Rule of Voice Fundamental Frequency Contours of Spoken Japanese From Linguistic Information
Hirose, Keikichi; Fujisaki, Hiroya; Yamaguichi, Mikio; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 2.13.1 - 2.13.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
A number of utterance samples of complex sentences of Japanese were analyzed using the model for the process of fundamental frequency contour generation, with special emphasis on the relationship between a fundamental frequency contour and its underlying lexical, syntax and semantic information. Phrase commands of the model were found to be roughly classified into three groups according to the level of corresponding node of the syntactic tree of a sentence, while accent commands were found to be roughly classified into two groups according to the type of accentuation. A set of rules was constructed for generating fundamental frequency contours of complex sentences of Japanese from linguistic information. Perceptual tests of naturalness of intonation using synthetic speech with rule-generated fundamental frequency contours indicated tile validity of the rules. Author
Japan; Linguistics; Voice; Contours; Frequencies; Mathematical Models
20060008824 Virginia Polytechnic Inst. and State Univ., Blacksburg, VA, USA
An Improved Signal Restoration Method Using Frequency Domain Information
Yu, Kai-Bor; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 37.12.1- 37.12.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
This paper addresses the problem of using frequency domain information for improved signal restoration. Specifically we want to estimate the underlying signal from degraded measurements when we are given (i) the distribution of the frequency components (ii) the bounds on the signal spectrum. We also assume that the energy of the noise is bounded by a known constant. The first problem is formulated as a constrained minimization of the windowed power in the frequency domain where the prior information is injected by the choice of window. The second problem is formulated as finding the feasible region which is the intersection of ellipsoids which are determined from the bounds on the signal spectrum and noise energy. This formulation is computationally very involved and we avoid this difficulty by finding an ellipsoid which will tightly bound the intersection. The geometric center if the resulting ellipsoid provides a good estimate of the underlying signal. Author
Frequency Domain Analysis; Signal Processing; Optimization
20060008875 Purdue Univ., West Lafayette, IN, USA
One Approach to Microprocessor Implementation of 4800 B/S Data Modem for Telephone Channels
Milutinovic, Veljko; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 44.11.1 - 44.11.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
The microprocessor-based implementation of data modems has been attracting a great deal of scientific interest in the past decade. It is a kind of an interdisciplinary field where both information theory and microprocessor engineering strongly interact. A number of different microprocessor-based modems are available on the market. For most of the modems with speeds above 2400 b/s it is common that implementation is based on the bit-slice processor. In case of speeds above 2400 b/s, it is considered that slow and cheap MOS microprocessors (e.g., Intel 8085) can be used only at the cost of simplifications in the algorithms for signal demodulation and detection, i.e., at the cost of decreased performance. This paper, however, describes the MOS microprocessor-based implementation of the 4800 b/s modem which was achieved without deterioration of modem performance. Author
Telephones; Microprocessors; Channels (Data Transmission); Signal Detection
20060008877 MacDonald, Dettwiler and Associates Ltd., Richmond, British Columbia, Canada
A Programmable Signal Processing Element Designed for an Efficient Data-Driven Signal Processing Architecture
Lim, J.; Kalanj, G. N.; Cumming, I. G.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 44.16.1 - 44.16.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
This paper describes the architecture of a Programmable Signal Processing Element (PSPE) which has been designed to serve as a building block in a High Thoughput Signal Processor (HTSP). The HTSP has been designed for Synthetic Aperture Radar (SAR) processing applications and itself contains a number of modern design features which allow it to meet the demanding performance requirements of SAR processing. The principle of the HTSP architecture will also be presented in the paper. Author
Signal Analyzers; Signal Processing; Architecture (Computers); Synthetic Aperture Radar
20060008888 Rome Univ., Rome, Italy
Clutters Cancellation Using Autoregressive Techniques
Bucciarelli, T.; Picardi, G.; Prestifilippo, E.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.3.1 - 47.3.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
The spectral estimation of received signal is the most modern approach used in the radar to distinguish useful targets in clutter environment. In this paper we are analysed the clutter cancellation properties with three clutter models, so we think to have filled a great dynamics of practical conditions; the clutter estimation error is also evaluated in terms of improvement factor losses. Author
Clutter; Targets; Cancellation; Errors
20060008889 Strathclyde Univ., Glasgow, UK
Target-Clutter Identification by Lattice Processors
Arslanian, A. S.; Durrani, T. S.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.4.1 - 47.4.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
Conventional processors for analysing pulsed Doppler returns employ either fixed digital filter schemes for target location, or FFT processors for identifying target velocities. In this paper a new configuration is proposed for processing radar returns which employ a lattice structure. Based upon the underlying probability distribution of the complex reflection coefficients; closed form analytical expressions, maximizing detection probabilities for given false alarms, are presented which allow the use of a lattice as a detector by setting thresholds on the associated reflection coefficients in order to identify a signal from background noise. Using clutter models for ground clutter and weather clutter it is shown that in some circumstances the lattice can be used to identify a target in clutter environment. Author
Clutter; Targets; Mathematical Models; Lattices (Mathematics); Central Processing Units
20060008890 Concordia Univ., Montreal, Quebec, Canada
Resolution of Range and Doppler Ambiguities in Medium PRF Radars in Multiple-Target Environment
Reddy, N. Sridhar; Swamy, M. N. S.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.6.1 - 47.6.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
In medium pulse-repetition frequency (PRF) radars, ambiguities may arise in both range and Doppler measurements. Efficient techniques have been established to resolve the range ambiguity of a single isolated target using multiple PRF's. In this paper, we describe a simple algorithm to resolve the Doppler ambiguity using the discrete Fourier transform (DFT) output of two PRF's. A condition on the relative values of the two PRF's is derived to account for the errors due to the finite bandwidth of DFT filters. A third PRF is used to identify the declarations of a particular target in different PRF's. Range ambiguities are then resolved in a straightforward manner. A fourth PRF is made use of to extract blindspeed targets. The proposed method is computationally efficient and can be used even when ambiguous returns from several targets are received. Author
Pulse Repetition Rate; Targets; Doppler Radar; Algorithms
20060008891 Case Western Reserve Univ., Cleveland, OH, USA
On Applications of Linear Prediction Filtering to Small Wavelength Doppler Weather Radar Signal Processing
Sitterle, Jeffrey J.; Baxa, Ernest G., Jr.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.8.1 - 47.8.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
This paper examines the problem of reduced signal-to-noise ratios in small wavelength (2 cm) Doppler weather radars. Using adaptive linear prediction filters, two solutions to the noise problem are presented. Through simulation techniques, an adaptive mean frequency estimator, based on Griffiths' method of instantaneous frequency measurement, is tested and compared to the pulse pair estimator. It is shown that when both the adaptive and pulse pair estimators are used on narrowband signals (sampled at the pulse repetition frequency) the pulse pair method is superior. However, when the adaptive estimator is tested on signals sampled at the radar's intermediate frequency, the adaptive method has a smaller variance. Finally, the use of an adaptive noise canceller is shown to significantly increase signal-to-noise ratios and improve the pulse pair estimator's quality when the adaptive noise canceller is used as a preprocessor before sampling at PRF rates. In both of the adaptive filtering cases, it is noted that the non-stationarities associated with airborne weather radar implementations do not affect filter performance since adaptive filtering techniques have the ability to track changes in the input signal's statistics. Author
Doppler Radar; Linear Prediction; Meteorological Radar; Signal Processing; Algorithms
20060008892 Bolt, Beranek, and Newman, Inc., Cambridge, MA, USA
An Efficient Procedure for Broadband Doppler Compensation
Mucci, Ronald A.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '84); Volume 3; 1984, pp. 47.9.1 - 47.9.4; In English; See also 20060008748; Copyright; Avail.: Other Sources
Frequently, it is necessary to compress or expand a function by scaling independent variables relating to time and/or distance. For example, the Doppler phenomena, caused by a change in the position of the source of a waveform measured radially from the position where the waveform is received, affects the time scale of the received waveform. For applications that do not satisfy the narrowband criterion, a procedure other than frequency translation is needed to produce a scaling of the independent variable of time to compensate for the Doppler effect. An approach, intended for discrete time applications, involves the two-step process of interpolation and decimation. The proper scaling factor is obtained by interpolation by an integer factor L and decimating, i.e., decreasing the sampling rate, by an integer factor K. The computationally efficient procedure which uses FIR filters is described: the corresponding expressions are derived for the interpolation errors associated with this procedure. Also, modifications to this procedure are described. One such modification is used to accommodate time varying scale factors; another incorporates frequency translations to accommodate uncertainties in the scale factor. Author
Broadband; Doppler Effect; Interpolation
Source: NASA
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