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At least 955 records · Page 53

Detector For FM Voice Or Digital Signals

Frequency-modulation (FM) detector operates with either analog audio (usually voice) signals or digital signals sent by differential minimum-shift keying (DMSK). Performance expected similar to conventional limiter/discriminator FM detectors. Detector operates at baseband, obviating need for band-pass filtering at intermediate frequency. Baseband version made in very-large-scale integrated circuit. New detector useful in mobile communications, where trend is toward integrated voice and data service.

Davarian, Faramaz↗

The Advanced Communication Technology Satellite and ISDN

This paper depicts the Advanced Communication Technology Satellite (ACTS) system as a global central office switch. The ground portion of the system is the collection of earth stations or T1-VSAT's (T1 very small aperture terminals). The control software for the T1-VSAT's resides in a single CPU. The software consists of two modules, the modem manager and the call manager. The modem manager (MM) controls the RF modem portion of the T1-VSAT. It processes the orderwires from the satellite or from signaling generated by the call manager (CM). The CM controls the Recom Laboratories MSPs by receiving signaling messages from the stacked MSP shelves ro units and sending appropriate setup commands to them. There are two methods used to setup and process calls in the CM; first by dialing up a circuit using a standard telephone handset or, secondly by using an external processor connected to the CPU's second COM port, by sending and receiving signaling orderwires. It is the use of the external processor which permits the ISDN (Integrated Services Digital Network) Signaling Processor to implement ISDN calls. In August 1993, the initial testing of the ISDN Signaling Processor was carried out at ACTS System Test at Lockheed Marietta, Princeton, NJ using the spacecraft in its test configuration on the ground.

Lowry, Peter A.↗

Total Ionizing Dose Effects in 12-Bit Successive-Approximation Analog-To-Digital Converters

Analog-to-digital (A/D) converters are critical components in many space and military systems, and there have been numerous advances in A/D converter technology that have increased the resolution and conversion time. The increased performance is due to two factors: (1) advances in circuit design and complexity, which have increased the number of components and the integration density; and (2) new process technologies, such as BiCMOS, which provide better performance, cost, and smaller size in mixed-signal circuits. High-speed A/D converters, with conversion rates above 1 MHz, present a challenge to circuit designers and test engineers. Their complex architectures and high-performance specifications result in numerous possible failure modes when they are subjected to ionizing radiation. The dominant failure mode may depend on the specific application because the fundamental effects on MOS and bipolar transistors are strongly affected by bias conditions.

Lee, C. I.↗

A parallel VLSI architecture for a digital filter of arbitrary length using Fermat number transforms

A parallel architecture for computation of the linear convolution of two sequences of arbitrary lengths using the Fermat number transform (FNT) is described. In particular a pipeline structure is designed to compute a 128-point FNT. In this FNT, only additions and bit rotations are required. A standard barrel shifter circuit is modified so that it performs the required bit rotation operation. The overlap-save method is generalized for the FNT to compute a linear convolution of arbitrary length. A parallel architecture is developed to realize this type of overlap-save method using one FNT and several inverse FNTs of 128 points. The generalized overlap save method alleviates the usual dynamic range limitation in FNTs of long transform lengths. Its architecture is regular, simple, and expandable, and therefore naturally suitable for VLSI implementation.

Truong, T. K.↗

The NASA computer aided design and test system

A family of computer programs facilitating the design, layout, evaluation, and testing of digital electronic circuitry is described. CADAT (computer aided design and test system) is intended for use by NASA and its contractors and is aimed predominantly at providing cost effective microelectronic subsystems based on custom designed metal oxide semiconductor (MOS) large scale integrated circuits (LSIC's). CADAT software can be easily adopted by installations with a wide variety of computer hardware configurations. Its structure permits ease of update to more powerful component programs and to newly emerging LSIC technologies. The components of the CADAT system are described stressing the interaction of programs rather than detail of coding or algorithms. The CADAT system provides computer aids to derive and document the design intent, includes powerful automatic layout software, permits detailed geometry checks and performance simulation based on mask data, and furnishes test pattern sequences for hardware testing.

Gould, J. M.↗

DSP-based non-coherent dual detector demodulator for land mobile radio channels

This paper outlines the development of a digital demodulator suitable for the non-coherent detection of various modulation formats including: Phase Shift Keying (PSK), Continuous Phase Frequency Shift Keying (CPFSK) and Frequency Modulation (FM). The demodulator design concept has been derived with a view towards a single integrated circuit (IC) implementation. Two detectors, one non-coherent and one differentially coherent, operate concurrently, providing data detection and automatic frequency control (AFC). Bit error rate results are provided which illustrate the receiver performance in white Gaussian noise.

Saulnier, Gary J.↗

Automatic Range Changer For SWR Meter

Commercial unit modified for antenna-pattern measurements. Addition of automatic range-changing circuit converts Hewlett-Packard 415E standing-wave-ratio (SWR) meter into radio-frequency detector suitable for computer-controlled measurements of radiation patterns of antennas. Modification gives SWR meter effective dynamic range of at least 40 dB. Includes two digital lines communicating one of four range settings to controlling computer and one digital line to inhibit transfer of data when range being changed. Ideal instrument for use in applications involving computer-controlled monitoring of power when large changes in signal level expected.

Dengler, Robert J.↗

Digital control of magnetic bearings in a cryogenic cooler

This paper describes the design of a digital control system for control of magnetic bearings used in a spaceborne cryogenic cooler. The cooler was developed by Philips Laboratories for the NASA Goddard Space Flight Center. Six magnetic bearing assemblies are used to levitate the piston, displacer, and counter-balance of the cooler. The piston and displacer are driven by linear motors in accordance with Stirling cycle thermodynamic principles to produce the desired cooling effect. The counter-balance is driven by a third linear motor to cancel motion induced forces that would otherwise be transmitted to the spacecraft. An analog control system is currently used for bearing control. The purpose of this project is to investigate the possibilities for improved performance using digital control. Areas for potential improvement include transient and steady state control characteristics, robustness, reliability, adaptability, alternate control modes, size, weight, and cost. The present control system is targeted for the Intel 80196 microcontroller family. The eventual introduction of application specific integrated circuit (ASIC) technology to this problem may produce a unique and elegant solution both here and in related industrial problems.

Feeley, J.↗

Reconfiguration of Analog Electronics for Extreme Environments: Problem or Solution?

This paper argues in favor of adaptive reconfiguration as a technique to expand the operational envelope of analog electronics for extreme environments (EE). In addition to hardening-by-process and hardening-by-design, "hardening-by-reconfiguration", when applicable, could be used to mitigate drifts, degradation, or damage on electronic devices (chips) in EE, by using re-configurable devices and an adaptive self-reconfiguration of their circuit topology. Conventional circuit design exploits device characteristics within a certain temperature/radiation range; when that is exceeded, the circuit function degrades. On a reconfigurable device, although component parameters change in EE, as long as devices still operate, albeit degraded, a new circuit design, suitable for new parameter values, may be mapped into the reconfigurable structure to recover the initial circuit function. Partly degraded resources are still used, while completely damaged resources are bypassed. Designs suitable for various environmental conditions can be determined prior to operation or can be determined in-situ, by adaptive reconfiguration algorithms running on built-in digital controllers. Laboratory demonstrations of this technique were performed by JPL in several independent experiments in which bulk CMOS reconfigurable devices were exposed to, and degraded by, low temperatures (approx. 196 C), high temperatures (approx.300 C) or radiation (300kRad TID), and then recovered by adaptive reconfiguration using evolutionary search algorithms. Taking this technology from Technology Readiness Level (TRL) 3 to TRL 5 is the target of a current NASA project.

Field Programmable Transistor Array (FPTA)↗

Advanced High-Definition Video Cameras

A product line of high-definition color video cameras, now under development, offers a superior combination of desirable characteristics, including high frame rates, high resolutions, low power consumption, and compactness. Several of the cameras feature a 3,840 2,160-pixel format with progressive scanning at 30 frames per second. The power consumption of one of these cameras is about 25 W. The size of the camera, excluding the lens assembly, is 2 by 5 by 7 in. (about 5.1 by 12.7 by 17.8 cm). The aforementioned desirable characteristics are attained at relatively low cost, largely by utilizing digital processing in advanced field-programmable gate arrays (FPGAs) to perform all of the many functions (for example, color balance and contrast adjustments) of a professional color video camera. The processing is programmed in VHDL so that application-specific integrated circuits (ASICs) can be fabricated directly from the program. ["VHDL" signifies VHSIC Hardware Description Language C, a computing language used by the United States Department of Defense for describing, designing, and simulating very-high-speed integrated circuits (VHSICs).] The image-sensor and FPGA clock frequencies in these cameras have generally been much higher than those used in video cameras designed and manufactured elsewhere. Frequently, the outputs of these cameras are converted to other video-camera formats by use of pre- and post-filters.

Glenn, William↗

A custom high-stability pulse generator for the test of a novel in-situ magnetic sensor developed to detect radiation damage in undulators

High-performance analog-to-digital converters (ADC) have been widely applied in many areas of science. For instance, magnetic field measurements based on the Faraday’s induction law require high-precision voltmeters to measure induced voltages. In this study in the context of free-electron lasers technology, the Magnetic Measurements Team at SLAC National Accelerator Laboratory proposed a novel in-situ radiation damage detection system (RDDS) for detecting small field variations in undulators. The system measures the flux change in a flexible printed-circuit coil attached to the magnet array during the undulator gap movement. The gap movement changes the magnetic field, which induces a voltage signal in the coil that is measured and integrated with an ADC. Although the system is capable of detecting relative flux changes better than 100 ppm, drift in the ADC’s gain or offset can cause apparent changes in the relative flux. This paper describes the first attempt to developed a high-precision verification circuit to perform ADC testing in the framework of the novel RDDS. The circuit generates a reference voltage pulse with a voltage–time integral relative precision better than 50 ppm for a few hundreds of mVs — the typical order of magnitude measured with the RDDS. The circuit’s design combines a fast and precise switch with a low-noise voltage reference. Long-term measurements allowed statistical analysis and showed that averaging the voltage–time integral of ten pulses gives the required 50 ppm stability. Moreover, reproducibility tests confirmed that the circuit’s output is invariable under small power supply instabilities and equipment shutdown. Instruments and applications designed to quantify the magnetic field by integrating voltage signals may use the pulse generator proposed in this paper for verification purposes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Primitive quantum gates for dihedral gauge theories

We describe the simulation of dihedral gauge theories on digital quantum computers. The nonabelian discrete gauge group $D_N$-- the dihedral group -- serves as an approximation to $U(1)\times\mathbb{Z}_2$ lattice gauge theory. In order to carry out such a lattice simulation, we detail the construction of efficient quantum circuits to realize basic primitives including the nonabelian Fourier transform over $D_N$, the trace operation, and the group multiplication and inversion operations. For each case the required quantum resources scale linearly or as low-degree polynomials in $n=\log N$. We experimentally benchmark our gates on the Rigetti Aspen-9 quantum processor for the case of $D_4$. The fidelity of all $D_4$ gates was found to exceed $80\%$.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Design, development, and fabrication of a electronic analog microminiaturized electronic analog signal to discrete time interval converter

The microminiaturization of an electronic analog signal to discrete time interval converter is presented. Discrete components and integrated circuits comprising the converter were assembled on a thin-film ceramic substrate containing nichrome resistors with gold interconnections. The finished assembly is enclosed in a flat package measuring 3.30 by 4.57 centimeters. The module can be used whenever conversion of analog to digital signals is required, in particular for the purpose of regulation by means of pulse modulation. In conjunction with a precision voltage reference, the module was applied to control the duty cycle of a switching regulator within a temperature range of -55 C to +125 C, and an input voltage range of 10V to 35V. The output-voltage variation was less than + or - 300 parts per million, i.e., less than + or - 3mV for a 10V output.

Schoenfeld, A. D.↗

Patient ECG recording control for an automatic implantable defibrillator

An implantable automatic defibrillator includes sensors which are placed on or near the patient's heart to detect electrical signals indicative of the physiology of the heart. The signals are digitally converted and stored into a FIFO region of a RAM by operation of a direct memory access (DMA) controller. The DMA controller operates transparently with respect to the microprocessor which is part of the defibrillator. The implantable defibrillator includes a telemetry communications circuit for sending data outbound from the defibrillator to an external device (either a patient controller or a physician's console or other) and a receiver for sensing at least an externally generated patient ECG recording command signal. The patient recording command signal is generated by the hand held patient controller. Upon detection of the patient ECG recording command, DMA copies the contents of the FIFO into a specific region of the RAM.

Fountain, Glen H.↗

Optoelectronic signal processing for phased-array antennas; Proceedings of the Meeting, Los Angeles, CA, Jan. 12, 13, 1988

Papers are presented on fiber optic links for airborne satellite applications, optoelectronic techniques for broadband switching, and GaAs circuits for a monolithic optical controller. Other topics include the optical processing of covariance matrices for adaptive processors, an optical linear heterodyne matrix-vector processor, and an EHF fiber optic-based array. An adaptive optical signal processing architecture using a signed-digit number system is considered along with microwave fiber optic links for phased arrays.

Bhasin, Kul B.↗

Ultra Small Aperture Terminal for Ka-Band SATCOM

An ultra small aperture terminal (USAT) at Ka-band frequency has been developed by Lewis Research Center (LeRC) for data rates up to 1.5 Mbps in the transmit mode and 40 Mbps in receive mode. The terminal consists of a 35 cm diameter offset-fed parabolic antenna which is attached to a solid state power amplifier and low noise amplifier. A single down converter is used to convert the Ka-band frequency to 70 MHz intermediate frequency (IF). A variable rate (9.6 Kbps to 10 Mbps) commercial modem with a standard RS-449/RS-232 interface is used to provide point-to-point digital services. The terminal has been demonstrated numerous times using the Advanced Communications Technology Satellite (ACTS) and the 4.5 in Link Evaluation Terminal (LET) in Cleveland. A conceptual design for an advanced terminal has also been developed. This advanced USAT utilizes Microwave Monolithic Integrated Circuit (MMIC) and flat plate array technologies. This terminal will be self contained in a single package which will include a 1 watt solid state amplifier (SSPA), low noise amplifier (LNA) and a modem card located behind the aperture of the array. The advanced USAT will be light weight, transportable, low cost and easy to point to the satellite. This paper will introduce designs for the reflector based and array based USAT's.

Acosta, Roberto↗

Adaptive piezoelectric sensoriactuator

An adaptive algorithm implemented in digital or analog form is used in conjunction with a voltage controlled amplifier to compensate for the feedthrough capacitance of piezoelectric sensoriactuator. The mechanical response of the piezoelectric sensoriactuator is resolved from the electrical response by adaptively altering the gain imposed on the electrical circuit used for compensation. For wideband, stochastic input disturbances, the feedthrough capacitance of the sensoriactuator can be identified on-line, providing a means of implementing direct-rate-feedback control in analog hardware. The device is capable of on-line system health monitoring since a quasi-stable dynamic capacitance is indicative of sustained health of the piezoelectric element.

Clark, Jr., Robert L.↗

Wire-Wrap Chatter Detector

Monitoring circuit responds to changes in resistance as little as 0.1 ohm. Has been used to detect defective wire-wrap connections during thermal and vibration tests. Defect is indicated to operator by light-emitting diode and by increase in count on a two-digit display.

Fisch, G. Z.↗