Showing papers on "High dynamic range published in 1990"

FBAR filters at GHz frequencies

Abstract: Film bulk acoustic resonator (FBAR) technology, which is used for the design and fabrication of microwave filters, is discussed. Filters are presented which exhibit a combination of low loss, small size, and frequency and bandwidth not attainable by any other type of device. Using a piezoelectric film of zinc oxide as a high Q crystal resonator along with passive components an integrable, high performance bandpass filter is formed. The range of center frequencies achievable is roughly 1 to 5 GHz using current resonator designs. The technique features potentially low cost (since the filters are fabricated by batch processing), and, perhaps most intriguing, the capability of being combined with more complex functions (such as a complete radar receiver) as part of a larger mask set. Other advantages such as moderate power handling capability, good temperature stability, and high dynamic range are discussed. >

Design of fiber optic antenna remoting links for cellular radio applications

Abstract: A procedure is described for the design of fiber-optic RF links which meet cellular radio antenna-remoting requirements, with emphasis on the characteristics of the optoelectronic components which determine system performance. Procedures for selecting combinations of optical and electronic elements to meet specified link performance requirements are presented. A design procedure for analog fiber optic links is summarized, with emphasis on obtaining the low noise and high dynamic range required for receiver links. General formulas to calculate the noise figure, dynamic range, and link power budgets of analog fiber links are derived. Example characteristics are calculated for a link using a state-of-the-art commercially available laser and photodetector. >

X-ray imaging with scintillating glass optical fibres

Abstract: First tests and proposals are presented regarding the use of a scintillating glass optical fibre target as an X-ray converter coupled with a CCD imager. The system appears promising for detecting X-ray images with good quantum efficiency, high spatial resolution and high dynamic range, using the high fluxes of the synchrotron radiation or in medicine, at energies over 10 keV.

CMOS triode transconductor with high dynamic range

Abstract: A CMOS triode transconductor using a novel bias scheme is described. The bias circuit is based on an auxiliary transistor and ensures optimum bias conditions over the entire tuning range. This makes it possible to design low-noise integrated continuous-time filters with a wide tuning range.

Photodetector arrays and architectures for acousto-optical signal processing

Abstract: A review of photodetector arrays and architectures is presented for acousto-optical (AO) signal processing applications, for which the demands on photodetector arrays are substantially greater than for image sensing applications. The primary design considerations for obtaining photodetector arrays with high dynamic range, high sensitivity, high speed, and low crosstalk are discussed. The current status and future needs for detector arrays for AO signal processing are presented. Several novel detector structures and concepts that have potential for future AO optical signal processing use are described.

High-dynamic-range compressive receiver

Abstract: A compressive receiver (10) includes a modulation circuit (14) that modulates the receiver input signal with compensation values equal to the ratio of the transfer function of an ideal linear dispersive delay line to that of the main compressive-receiver linear dispersive delay line (22). An auxiliary linear dispersive delay line (16) dispersively delays the results modulated signal at the reciprocal of the compressive receiver's chirp rate, and the resultant signal is progressively translated in frequency by a frequency translator (18) at the compressive-receiver chirp rate. As a consequence, each point in a signal-frequency component of the input signal is translated to the frequency at which the compensation function was evaluated in modulating the component at that point in time, so the departure of the main dispersive delay line (22) from linearity is compensated for, and increased dynamic range results.

A 6-18 GHz, high dynamic range MMIC amplifier using a feedforward technique

Abstract: Feedforward compensation on a prototype 6-18-GHz amplifier that increases its second and third order intercept points is demonstrated. Measured performance improvement in both distortion and noise figure closely match theoretical predictions, with spurious signal cancellation of approximately=15 dB being observed. These results indicate the potential in utilizing the feedforward concept in future microwave systems applications. >

Performance of 1024-element high-dynamic-range CCD detector array

Abstract: Efforts to improve the state-of-the-art in charge-coupled device (CCD) detector arrays for acousto-optic applications have had considerable success. A program for the improvement of detectors for acousto-optic applications sponsored by Harry Diamond Laboratories in conjunction with Loral Fairchild ImagingSensors, formerly Fairchild Weston Systems, is aimed at increasing high speed CCD detector dynamic rangeto over 65 dB. Other device specifications such as crosstalk and image lag are being addressed in order tomatch the increased dynamic range performance in a 1024 element detector. This paper outlines the keydevice specifications which needed to be addressed, the methods used to achieve improved performance inthese areas, the testing considerations, and the results of recent device testing. 1. Introduction Hybrid optical/digital processors using acousto-optic technology have demonstrated the performanceof a number ofsignal processing functions where high speed and high processing gain are required{1}. Theadvantages that acousto-optics provides are in the reduction of size, weight, and power over a siiuilar all-digital processor.[2} One area of technology development which has been a limitation of these processors

Wide-Area, High Dynamic Range 3-D Imager

Abstract: This paper describes a 3-D laser scanning imager for visual inspection of mounted devices on printed circuit boards (PCB). A 3-D imager for this application must satisfy the following requirements: (1) It must be fast enough to sense a 250 by 330 mm area in 14 seconds; (2) It must have a measurement resolution of at least 125 gm; (3) It must be capable of measuring height and light intensity simultaneously; and (4) It must have an optical dynamic range of at least 10 4. We developed a wide-area telecentric scanning optical system which meets these requirements. It uses retroreflective triangulation optics and digital signal processing hardware. Our system scans a laser beam over a 256 mm length with a resolution of 125 μm, without scanning distortion. The retroreflection triangulation optics collect light reflected from objects on a printed circuit board and focus the image on a position-sensitive detector (PSD). This system measures the profile of objects with a vertical resolution of 30 μm, within a range of 7.6 mm. The digital signal processing hardware has a dynamic range of 10 4 and obtains range data from the output signals of the PSD. Its processing speed is 1M pixels/s. This hardware enables profile measurement of objects having a wide range of light reflectance (about 3000 times), from black devices to glossy metal, with an accuracy of 0.1 mm. This 3-D imager was used in an automated inspection system for PC board-mounted devices. This system detects missing, misplaced, and incorrectly installed devices with an inspection speed of 0.1 s/device.

Wideband signal processing for emitter location

Abstract: The location of a fixed transmitter may be determined by processing the signals collected by two moving receivers. This process involves the simultaneous determination of the difference in propagation delay from the transmitter to the receivers and the rate of change of delay difference induced by the motion of the receivers. This paper describes a system approach to the real time computation of a cross ambiguity function (CAF) for wideband signals, such as frequency hopping radios, that is designed around a wideband optical processor. The optical processor subsystem generates a wideband CAF (delay, delay rate of change coordinates), as opposed to a narrowband CAF (delay, frequency shift coordinates), includes a narrowband interference suppression capability and high dynamic range. A system functional description is presented along with location performance estimates. The optical processor subsystem concept, a compact implementation approach and estimated performance are also discussed.

Fast scanning acoustooptic spectrum analyzer with high dynamic range.

Abstract: An acoustooptic spectrum analyzer is described that is based on a new method of measuring spatial light intensity distribution in the Fourier plane. Instead of a detector array, an acoustooptic Bragg cell combined with a fast high dynamic range detector is used. With special driving signals, a time-bandwidth product of >1000, a speed of 40 dB can be achieved.

High Dynamic Range Radio Receiver Preamplifier in BiCMOS Technology

Abstract: A low noise, high dynamic range wide-band amplifier matching either a telescope or a wire antenna for SW receivers is presented. The amplifier features low noise, low distortion and rail to rail swing capability. With 5 V single supply, a signal of 4 V pp can be driven into 500 ?//10 pF load. For the wire antenna, the measured equivalent input noise is 0.25 ?V rms within 2.5 kHz IF band and a high dynamic range of 135 dB is achieved. For the telescope antenna, the measured noise is 0.21 ?V rms and the dynamic range is 136 dB without the use of any AGC.

Ultra Broadband Extended Dynamic Range MMIC DLVA

Abstract: Design, fabrication and experimental results of a 2 to 18 GHz high dynamic range MMIC DLVA featuring short recovery time are presented. This fast DLVA is a Successive Detection Logarithmic Amplifier. The microwave part consists of five 2-18 GHz GaAs MMIC stages ; each stage is composed of MMIC amplifiers, active power divider, attenuator and Schottky detector. Detected outputs levels are video limited before summation to obtain a logarithmic video response over a 65 dB extended dynamic range. No use of logarithmic video amplifier ensure short recovery time less than 200 ns over the whole dynamic range.

Probability Distribution of Received Interference Levels in the HF Band

Abstract: : HF interference typically spans a wide dynamic range and often has a high density of detectable interferers. In the design and evaluation of communications systems it is often useful to be able to characterize the HF environment by means of an analytic model. Based upon a series of recent measurements of the HF environment, we have concluded that a lognormal distribution is a reasonable model of the observed HF interference. These data were collected using a wideband (2 MHz), high dynamic range spectrum analysis system, and consisted of short-term time averages of the magnitudes of FFT bin outputs spaced at 610 Hz. Spectral plots and associated probability distributions are presented spanning a frequency range from 1.5 to 19 MHz for various averaging parameters. In almost all cases, the distributions of the bin averages were found to be well modeled by the lognormal distribution for levels well above the background noise. In some cases, the fit was excellent over a 50 dB range of levels.

High-dynamic-range modulator for microwave phased arrays

Abstract: Microwave phased-array antennas using fiber optic technology demand high dynamic range (DR) electro-optic modulators (EOM) to enhance system performance. A wide DR EOM must have high sensitivity, low nonlinearity and an optimized extinction ratio. This paper describes some techniques to improve of EOM sensitivity and extinction ratio.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Definition of the concept of an interferometric spectrum analyser for the detection of frequency hopping radios (u)

Abstract: : The concept of a high resolution, large bandwidth and high dynamic range acousto-optic spectrum analyser for the detection of frequency hopping radios is described. The high resolution is achieved by selecting large time- aperture Bragg cells while the high dynamic range is obtained by using heterodyne detection in an interferometric structure. The large bandwidth is produced by a scanning process. An example of the probability of detection for a specific selection of parameters is given.

High dynamic range discriminator for measurements with fragmented heavy ions

Abstract: The design of an event discriminator with a practical dynamic range of at least 2000:1 and its application to measurements in fragmented heavy ion beams are described. Such beams are formed by particles with a wide range of values of dE/dx, and the determination of fragment composition by a simple, portable instrument that can be used under a variety of experimental conditions requires the measurement of the dE of all particles in a single experiment. Histograms of dE/dx vs. residual energy for a /sup 20/ne fragmented beam, showing events with Z ranging from 1 to 10, are presented. >

High dynamic range operation of the Fairchild CCD181 line scan camera

Abstract: A commercially available self-scanning linear sensor array has been operated in an unconventional manner to produce an optical dynamic range in excess of 85 dB.

Device for shaping frequency analog signals, with high dynamic range

Abstract: The present invention relates to a device for shaping a frequency analog signal, characterised in that it comprises means S defining a variable reference threshold V.ANA, the changes in which, governed by the level of the input signal, follow a non-linear sequence, and a comparator 10 which receives from a first input 12 an input signal to be shaped and which receives on a second input 14 the reference threshold V.ANA.